Insects

Article

31 pages, 764 KiB

Open AccessEditor’s ChoiceArticle

Genotype-by-Diet Interactions for Larval Performance and Body Composition Traits in the Black Soldier Fly, Hermetia illucens

by Christoph Sandrock, Simon Leupi, Jens Wohlfahrt, Cengiz Kaya, Maike Heuel, Melissa Terranova, Wolf U. Blanckenhorn, Wilhelm Windisch, Michael Kreuzer and Florian Leiber

Insects 2022, 13(5), 424; https://doi.org/10.3390/insects13050424 - 30 Apr 2022

Cited by 8 | Viewed by 3350

Abstract

Further advancing black soldier fly (BSF) farming for waste valorisation and more sustainable global protein supplies critically depends on targeted exploitation of genotype-phenotype associations in this insect, comparable to conventional livestock. This study used a fully crossed factorial design of rearing larvae of [...] Read more.

Further advancing black soldier fly (BSF) farming for waste valorisation and more sustainable global protein supplies critically depends on targeted exploitation of genotype-phenotype associations in this insect, comparable to conventional livestock. This study used a fully crossed factorial design of rearing larvae of four genetically distinct BSF strains (F_ST: 0.11–0.35) on three nutritionally different diets (poultry feed, food waste, poultry manure) to investigate genotype-by-environment interactions. Phenotypic responses included larval growth dynamics over time, weight at harvest, mortality, biomass production with respective contents of ash, fat, and protein, including amino acid profiles, as well as bioconversion and nitrogen efficiency, reduction of dry matter and relevant fibre fractions, and dry matter loss (emissions). Virtually all larval performance and body composition traits were substantially influenced by diet but also characterised by ample BSF genetic variation and, most importantly, by pronounced interaction effects between the two. Across evaluated phenotypes, variable diet-dependent rankings and the lack of generally superior BSF strains indicate the involvement of trade-offs between traits, as their relationships may even change signs. Conflicting resource allocation in light of overall BSF fitness suggests anticipated breeding programs will require complex and differential selection strategies to account for pinpointed trait maximisation versus multi-purpose resilience. Full article

(This article belongs to the Section Role of Insects in Human Society)

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15 pages, 6265 KiB

Open AccessEditor’s ChoiceArticle

Reactive Oxygen Species Initiate Defence Responses of Potato Photosystem II to Sap-Sucking Insect Feeding

by Ilektra Sperdouli, Stefanos S. Andreadis, Ioannis-Dimosthenis S. Adamakis, Julietta Moustaka, Eleni I. Koutsogeorgiou and Michael Moustakas

Insects 2022, 13(5), 409; https://doi.org/10.3390/insects13050409 - 24 Apr 2022

Cited by 16 | Viewed by 3029

Abstract

Potato, Solanum tuberosum L., one of the most commonly cultivated horticultural crops throughout the world, is susceptible to a variety of herbivory insects. In the present study, we evaluated the consequence of feeding by the sap-sucking insect Halyomorpha halys on potato leaf photosynthetic [...] Read more.

Potato, Solanum tuberosum L., one of the most commonly cultivated horticultural crops throughout the world, is susceptible to a variety of herbivory insects. In the present study, we evaluated the consequence of feeding by the sap-sucking insect Halyomorpha halys on potato leaf photosynthetic efficiency. By using chlorophyll fluorescence imaging methodology, we examined photosystem II (PSII) photochemistry in terms of feeding and at the whole leaf area. The role of reactive oxygen species (ROS) in potato’s defence response mechanism immediately after feeding was also assessed. Even 3 min after feeding, increased ROS generation was observed to diffuse through the leaf central vein, probably to act as a long-distance signalling molecule. The proportion of absorbed energy being used in photochemistry (Φ_PSII) at the whole leaf level, after 20 min of feeding, was reduced by 8% compared to before feeding due to the decreased number of open PSII reaction centres (qp). After 90 min of feeding, Φ_PSII decreased by 46% at the whole leaf level. Meanwhile, at the feeding zones, which were located mainly in the proximity of the leaf midrib, Φ_PSII was lower than 85%, with a concurrent increase in singlet-excited oxygen (¹O₂) generation, which is considered to be harmful. However, the photoprotective mechanism (Φ_NPQ), which was highly induced 90 min after feeding, was efficient to compensate for the decrease in the quantum yield of PSII photochemistry (Φ_PSII). Therefore, the quantum yield of non-regulated energy loss in PSII (Φ_NO), which represents ¹O₂ generation, remained unaffected at the whole leaf level. We suggest that the potato PSII response to sap-sucking insect feeding underlies the ROS-dependent signalling that occurs immediately and initiates a photoprotective PSII defence response to reduce herbivory damage. A controlled ROS burst can be considered the primary plant defence response mechanism to herbivores. Full article

(This article belongs to the Collection Plant Responses to Insect Herbivores)

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18 pages, 2469 KiB

Open AccessEditor’s ChoiceArticle

The Early Season Community of Flower-Visiting Arthropods in a High-Altitude Alpine Environment

by Marco Bonelli, Elena Eustacchio, Daniele Avesani, Verner Michelsen, Mattia Falaschi, Marco Caccianiga, Mauro Gobbi and Morena Casartelli

Insects 2022, 13(4), 393; https://doi.org/10.3390/insects13040393 - 16 Apr 2022

Cited by 5 | Viewed by 3604

Abstract

In mountain ecosystems, climate change can cause spatiotemporal shifts, impacting the composition of communities and altering fundamental biotic interactions, such as those involving flower-visiting arthropods. On of the main problems in assessing the effects of climate change on arthropods in these environments is [...] Read more.

In mountain ecosystems, climate change can cause spatiotemporal shifts, impacting the composition of communities and altering fundamental biotic interactions, such as those involving flower-visiting arthropods. On of the main problems in assessing the effects of climate change on arthropods in these environments is the lack of baseline data. In particular, the arthropod communities on early flowering high-altitude plants are poorly investigated, although the early season is a critical moment for possible mismatches. In this study, we characterised the flower-visiting arthropod community on the early flowering high-altitude Alpine plant, Androsace brevis (Primulaceae). In addition, we tested the effect of abiotic factors (temperature and wind speed) and other variables (time, i.e., hour of the day, and number of flowers per plant) on the occurrence, abundance, and diversity of this community. A. brevis is a vulnerable endemic species growing in the Central Alps above 2000 m asl and flowering for a very short period immediately after snowmelt, thus representing a possible focal plant for arthropods in this particular moment of the season. Diptera and Hymenoptera were the main flower visitors, and three major features of the community emerged: an evident predominance of anthomyiid flies among Diptera, a rare presence of bees, and a relevant share of parasitoid wasps. Temperature and time (hour of the day), but not wind speed and number of flowers per plant, affected the flower visitors’ activity. Our study contributes to (1) defining the composition of high-altitude Alpine flower-visiting arthropod communities in the early season, (2) establishing how these communities are affected by environmental variables, and (3) setting the stage for future evaluation of climate change effects on flower-visiting arthropods in high-altitude environments in the early season. Full article

(This article belongs to the Collection Insects in Mountain Ecosystems)

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18 pages, 2731 KiB

Open AccessEditor’s ChoiceArticle

Field Suppression of Spotted Wing Drosophila (SWD) (Drosophila suzukii Matsumura) Using the Sterile Insect Technique (SIT)

by Rafael A. Homem, Zeus Mateos-Fierro, Rory Jones, Daniel Gilbert, Andrew R. Mckemey, Glen Slade and Michelle T. Fountain

Insects 2022, 13(4), 328; https://doi.org/10.3390/insects13040328 - 26 Mar 2022

Cited by 9 | Viewed by 4180

Abstract

Drosophila suzukii (spotted wing drosophila—SWD) is an economically important pest of soft and stone fruit worldwide. Control relies on broad-spectrum insecticides, which are neither fully effective nor environmentally sustainable. The sterile insect technique (SIT) is a proven, effective and environmentally friendly pest-management tool. [...] Read more.

Drosophila suzukii (spotted wing drosophila—SWD) is an economically important pest of soft and stone fruit worldwide. Control relies on broad-spectrum insecticides, which are neither fully effective nor environmentally sustainable. The sterile insect technique (SIT) is a proven, effective and environmentally friendly pest-management tool. Here, we investigated, for the first time, the potential of using SIT to control D. suzukii in field conditions without physical barriers that limit insect invasion. A proprietary method of rearing and irradiation with X-rays was used to obtain males that were > 99% sterile. Sterile males were released twice per week from April to October 2021 on a site in Kent, UK, where everbearing strawberries were grown in open polytunnels. The infestation of wild female D. suzukii was monitored weekly using red sticky traps with dry lure at the treated site and at two similar control sites that did not receive sterile male releases. Releases of sterile males suppressed the wild female D. suzukii population by up to 91% in comparison with the control sites. We thus demonstrated the feasibility of SIT to achieve season-long control of D. suzukii using early, sustained and dynamically targeted releases of sterile males. This provides a promising environmentally friendly method to control this important pest. Full article

(This article belongs to the Section Insect Pest and Vector Management)

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8 pages, 946 KiB

Open AccessEditor’s ChoiceArticle

Effect of Temperature and Photoperiod on Development, Survival, and Growth Rate of Mealworms, Tenebrio molitor

by Stephan Eberle, Lisa-Marie Schaden, Johannes Tintner, Christian Stauffer and Martin Schebeck

Insects 2022, 13(4), 321; https://doi.org/10.3390/insects13040321 - 24 Mar 2022

Cited by 25 | Viewed by 6248

Abstract

Insects are a potential substitute for conventional meat and can be part of a sustainable human diet due to their valuable nutrients and relatively low environmental production impact. One species that is already produced for human consumption and livestock feed is the mealworm, [...] Read more.

Insects are a potential substitute for conventional meat and can be part of a sustainable human diet due to their valuable nutrients and relatively low environmental production impact. One species that is already produced for human consumption and livestock feed is the mealworm, i.e., larvae of Tenebrio molitor. Knowledge of the effects of temperature, and particularly photoperiod, on mealworm development is scarce, but crucial for the improvement of rearing. Therefore, the effects of three temperatures (20 °C, 25 °C, and 30 °C), in combination with three photoperiods (long-day—16 h:8 h light:dark; short-day—8 h:16 h light:dark, and constant darkness) on mealworm survival, developmental time, and growth rate were tested. We describe a significant effect of temperature on survival rate, developmental time, and growth rate. Furthermore, significant effects of photoperiod on developmental time and growth rate were found. At 25 and 30 °C and constant darkness, the highest survival and growth rate, along with the shortest developmental time, were observed. Our data can be used to improve the mass rearing of mealworms for an efficient production of food and feed. Full article

(This article belongs to the Section Other Arthropods and General Topics)

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14 pages, 3472 KiB

Open AccessEditor’s ChoiceArticle

A Practical Insecticide Resistance Monitoring Bioassay for Orally Ingested Dinotefuran in Anopheles Malaria Vectors

by George John Ian Parsons, Rosemary Susan Lees, Sofia Balaska and John Vontas

Insects 2022, 13(4), 311; https://doi.org/10.3390/insects13040311 - 22 Mar 2022

Cited by 4 | Viewed by 3002

Abstract

Attractive Toxic Sugar Baits (ATSB) deployed outdoors are likely to be particularly effective against outdoor biting mosquitoes and, if they contain insecticides with a different mode of action, mosquitoes resistant to pyrethroids. One such ATSB based on the neonicotinoid dinotefuran is currently under [...] Read more.

Attractive Toxic Sugar Baits (ATSB) deployed outdoors are likely to be particularly effective against outdoor biting mosquitoes and, if they contain insecticides with a different mode of action, mosquitoes resistant to pyrethroids. One such ATSB based on the neonicotinoid dinotefuran is currently under evaluation in Africa. As with any insecticide-based intervention, it will be important to monitor for the possible emergence of vector resistance. While methods for detecting resistance to insecticides via tarsal contact are recommended by the World Health Organization (WHO), these may not be applicable for orally ingested insecticides. Here, a new ingestion assay, appropriate for a controlled laboratory setting, is described using fluorescein sodium salt (uranine) as a feeding marker. Conventional topical application bioassays, more appropriate for routine deployment, have also been used to apply dinotefuran to the thorax of adult Anopheles mosquitoes with an organic carrier to bypass lipid cuticle barriers. The two methods were compared by establishing lethal doses (LD) in several Anopheles strains. The similarity of the ratios of susceptibility to dinotefuran between pairs of pyrethroid susceptible and resistant strains validates topical application as a suitable, more practical and field applicable method for monitoring for the emergence of resistance to orally ingested dinotefuran. A discriminating dose is proposed, which will be further validated against field populations and used to routinely monitor for the emergence of resistance alongside ATSB trials. Full article

(This article belongs to the Special Issue Insecticides for Mosquito Control: Strengthening the Evidence Base)

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14 pages, 1766 KiB

Open AccessEditor’s ChoiceArticle

Larvicidal Activity of Carbon Black against the Yellow Fever Mosquito Aedes aegypti

by Erick J. Martínez Rodríguez, Parker Evans, Megha Kalsi, Noah Rosenblatt, Morgan Stanley and Peter M. Piermarini

Insects 2022, 13(3), 307; https://doi.org/10.3390/insects13030307 - 20 Mar 2022

Cited by 4 | Viewed by 5244

Abstract

The yellow fever mosquito Aedes aegypti is one of the deadliest animals on the planet because it transmits several medically important arboviruses, including Zika, chikungunya, dengue, and yellow fever. Carbon-based nanoparticles (CNPs) derived from natural sources have previously been shown to have toxic [...] Read more.

The yellow fever mosquito Aedes aegypti is one of the deadliest animals on the planet because it transmits several medically important arboviruses, including Zika, chikungunya, dengue, and yellow fever. Carbon-based nanoparticles (CNPs) derived from natural sources have previously been shown to have toxic effects on mosquito larvae and offer a potential alternative to chemical insecticides such as pyrethroids, for which mosquitoes have evolved resistance. However, CNPs derived from industrial sources, such as carbon black, have not previously been evaluated as larvicides. Here, we evaluate the effects of a commercially-available carbon black, EMPEROR^® 1800 (E1800), on mortality and development of pyrethroid-susceptible (PS) and pyrethroid-resistant (PR) strains of Ae. aegypti. We found that E1800 exhibited concentration-dependent mortality against 1st instar larvae of both strains within the first 120 h after exposure, but after this period, surviving larvae did not show delays in their development to adults. Physical characterization of E1800 suspensions suggests that they form primary particles of ~30 nm in diameter that fuse into fundamental aggregates of ~170 nm in diameter. Notably, larvae treated with E1800 showed internal accumulation of E1800 in the gut and external accumulation on the respiratory siphon, anal papillae, and setae, suggesting a physical mode of toxic action. Taken together, our results suggest that E1800 has potential use as a larvicide with a novel mode of action for controlling PS and PR mosquitoes. Full article

(This article belongs to the Special Issue Integrated Management of Public Health Pests)

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19 pages, 1110 KiB

Open AccessEditor’s ChoiceArticle

Interactions between Rice Resistance to Planthoppers and Honeydew-Related Egg Parasitism under Varying Levels of Nitrogenous Fertilizer

by Ainara Peñalver-Cruz and Finbarr G. Horgan

Insects 2022, 13(3), 251; https://doi.org/10.3390/insects13030251 - 1 Mar 2022

Cited by 5 | Viewed by 3683

Abstract

Host plant resistance is the most researched method for the management of planthoppers and leafhoppers in tropical rice. For optimal effects, resistance should be resilient to fertilizer inputs and work in synergy with natural enemies. In field plot experiments, we examined how rice [...] Read more.

Host plant resistance is the most researched method for the management of planthoppers and leafhoppers in tropical rice. For optimal effects, resistance should be resilient to fertilizer inputs and work in synergy with natural enemies. In field plot experiments, we examined how rice resistance and fertilizer inputs affect mortality of planthopper and leafhopper eggs by hymenopteran parasitoids. We used IR62 as a variety with resistance to Nilaparvata lugens (Stål) [BPH], Sogatella furcifera (Horváth) [WBPH] and Nephotettix virescens (Distant) [GLH], and IR64 as a susceptible control. The herbivores were more abundant during wet season sampling in low-nitrogen plots. During this study, parasitoids killed between 31 and 38% of BPH eggs and 24 and 52% of WBPH eggs during four days of field exposure. Parasitism, mainly due to Oligosita spp., was generally higher in high-nitrogen and IR64 plots. Similar densities of eggs in exposed plants suggest that these trends were mediated by semiochemicals and therefore support the Optimal Defense Hypothesis. Honeydew from BPH on IR62 had more xylem-derived wastes than honeydew on IR64. We applied honeydew from both varieties to sentinel plants. Parasitism by Anagrus spp. was higher on plants of either variety treated with honeydew derived from IR62; however, the effect was only apparent in high-nitrogen plots. Results suggest that Anagrus spp., by responding to honeydew, will counter the nitrogen-induced enhancement of planthopper fitness on resistant rice. Full article

(This article belongs to the Collection Biology and Management of Sap-Sucking Pests)

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13 pages, 1778 KiB

Open AccessEditor’s ChoiceArticle

Designing a Pest and Disease Outbreak Warning System for Farmers, Agronomists and Agricultural Input Distributors in East Africa

by Molly E. Brown, Stephen Mugo, Sebastian Petersen and Dominik Klauser

Insects 2022, 13(3), 232; https://doi.org/10.3390/insects13030232 - 26 Feb 2022

Cited by 7 | Viewed by 4322

Abstract

Early warnings of the risks of pest and disease outbreaks are becoming more urgent, with substantial increases in threats to agriculture from invasive pests. With geospatial data improvements in quality and timeliness, models and analytical systems can be used to estimate potential areas [...] Read more.

Early warnings of the risks of pest and disease outbreaks are becoming more urgent, with substantial increases in threats to agriculture from invasive pests. With geospatial data improvements in quality and timeliness, models and analytical systems can be used to estimate potential areas at high risk of yield impacts. The development of decision support systems requires an understanding of what information is needed, when it is needed, and at what resolution and accuracy. Here, we report on a professional review conducted with 53 professional agronomists, retailers, distributors, and growers in East Africa working with the Syngenta Foundation for Sustainable Agriculture. The results showed that respondents reported fall armyworm, stemborers and aphids as being among the most common pests, and that crop diversification was a key strategy to reduce their impact. Chemical and cultural controls were the most common strategies for fall armyworm (FAW) control, and biological control was the least known and least used method. Of the cultural control methods, monitoring and scouting, early planting, and crop rotation with non-host crops were most used. Although pests reduced production, only 55% of respondents were familiar with early warning tools, showing the need for predictive systems that can improve farmer response. Full article

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16 pages, 1535 KiB

Open AccessEditor’s ChoiceArticle

Comparative Screening of Mexican, Rwandan and Commercial Entomopathogenic Nematodes to Be Used against Invasive Fall Armyworm, Spodoptera frugiperda

by Patrick Fallet, Lara De Gianni, Ricardo A. R. Machado, Pamela Bruno, Julio S. Bernal, Patrick Karangwa, Joelle Kajuga, Bancy Waweru, Didace Bazagwira, Thomas Degen, Stefan Toepfer and Ted C. J. Turlings

Insects 2022, 13(2), 205; https://doi.org/10.3390/insects13020205 - 16 Feb 2022

Cited by 16 | Viewed by 3533

Abstract

The fall armyworm (FAW), Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) is an important pest of maize originating from the Americas. It recently invaded Africa and Asia, where it causes severe yield losses to maize. To fight this pest, tremendous quantities of synthetic insecticides are [...] Read more.

The fall armyworm (FAW), Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) is an important pest of maize originating from the Americas. It recently invaded Africa and Asia, where it causes severe yield losses to maize. To fight this pest, tremendous quantities of synthetic insecticides are being used. As a safe and sustainable alternative, we explore the possibility to control FAW with entomopathogenic nematodes (EPN). We tested in the laboratory whether local EPNs, isolated in the invasive range of FAW, are as effective as EPNs from FAW native range or as commercially available EPNs. This work compared the virulence, killing speed and propagation capability of low doses of forty EPN strains, representing twelve species, after placing them with second-, third- and sixth-instar caterpillars as well as pupae. EPN isolated in the invasive range of FAW (Rwanda) were found to be as effective as commercial and EPNs from the native range of FAW (Mexico) at killing FAW caterpillars. In particular, the Rwandan Steinernema carpocapsae strain RW14-G-R3a-2 caused rapid 100% mortality of second- and third-instar and close to 75% of sixth-instar FAW caterpillars. EPN strains and concentrations used in this study were not effective in killing FAW pupae. Virulence varied greatly among EPN strains, underlining the importance of thorough EPN screenings. These findings will facilitate the development of local EPN-based biological control products for sustainable and environmentally friendly control of FAW in East Africa and beyond. Full article

(This article belongs to the Special Issue Entomopathogenic Nematodes: Lethal Parasites of Insects)

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8 pages, 1411 KiB

Open AccessEditor’s ChoiceArticle

The Effect of Resistance to Bt Corn on the Reproductive Output of Spodoptera frugiperda (Lepidoptera: Noctuidae)

by Natália de Souza Ribas, Jeremy N. McNeil, Hernane Dias Araújo, Bruna de Souza Ribas and Eraldo Lima

Insects 2022, 13(2), 196; https://doi.org/10.3390/insects13020196 - 14 Feb 2022

Cited by 2 | Viewed by 2837

Abstract

The fall armyworm (FAW) Spodoptera frugiperda is the most significant lepidopteran corn pest in South American countries. Transgenic Bt corn, producing the Cry1Fa toxins, has been used to control this pest, but there is clear evidence that some FAW populations have developed resistance. [...] Read more.

The fall armyworm (FAW) Spodoptera frugiperda is the most significant lepidopteran corn pest in South American countries. Transgenic Bt corn, producing the Cry1Fa toxins, has been used to control this pest, but there is clear evidence that some FAW populations have developed resistance. To determine if there are costs associated with resistance, we compared the mass of adults, the duration of mating, and the mass of the first spermatophore produced, as well as the lifetime fecundity and fertility of once-mated susceptible (SS) and resistant (RR) females. Adult mass was affected by both sex and strain, with SS females being significantly larger than RR ones, while the inverse was true for males. RR pairs took significantly longer to mate than SS pairs, yet the mass of spermatophores produced by RR males was significantly less than those of SS males. The total number of eggs laid did not differ but the fertility of eggs from once-mated RR pairs was significantly lower than that of SS pairs. Our data provided clear evidence that the development of Bt resistance affected the reproductive capacity of resistant FAW. Full article

(This article belongs to the Special Issue Applied Insect Reproductive Biology)

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14 pages, 825 KiB

Open AccessEditor’s ChoiceArticle

Imported Dengue Case Numbers and Local Climatic Patterns Are Associated with Dengue Virus Transmission in Florida, USA

by Caroline Stephenson, Eric Coker, Samantha Wisely, Song Liang, Rhoel R. Dinglasan and John A. Lednicky

Insects 2022, 13(2), 163; https://doi.org/10.3390/insects13020163 - 3 Feb 2022

Cited by 8 | Viewed by 3617

Abstract

Aedes aegypti mosquitoes are the main vector of dengue viruses globally and are present throughout much of the state of Florida (FL) in the United States of America. However, local transmission of dengue viruses in FL has mainly occurred in the southernmost counties; [...] Read more.

Aedes aegypti mosquitoes are the main vector of dengue viruses globally and are present throughout much of the state of Florida (FL) in the United States of America. However, local transmission of dengue viruses in FL has mainly occurred in the southernmost counties; specifically Monroe and Miami-Dade counties. To get a better understanding of the ecologic risk factors for dengue fever incidence throughout FL, we collected and analyzed numerous environmental factors that have previously been connected to local dengue cases in disease-endemic regions. We analyzed these factors for each county-year in FL, between 2009–2019, using negative binomial regression. Monthly minimum temperature of 17.5–20.8 °C, an average temperature of 26.1–26.7 °C, a maximum temperature of 33.6–34.7 °C, rainfall between 11.4–12.7 cm, and increasing numbers of imported dengue cases were associated with the highest risk of dengue incidence per county-year. To our knowledge, we have developed the first predictive model for dengue fever incidence in FL counties and our findings provide critical information about weather conditions that could increase the risk for dengue outbreaks as well as the important contribution of imported dengue cases to local establishment of the virus in Ae. aegypti populations. Full article

(This article belongs to the Special Issue Vector-Borne Infections: From Ecology to Vector-Microbe-Host Interactions)

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10 pages, 461 KiB

Open AccessEditor’s ChoiceArticle

Could Sterile Aedes albopictus Male Releases Interfere with Aedes aegypti Population in Reunion Island?

by Harilanto Felana Andrianjakarivony, David Damiens, Lucie Marquereau, Benjamin Gaudillat, Nausicaa Habchi-Hanriot and Louis-Clément Gouagna

Insects 2022, 13(2), 146; https://doi.org/10.3390/insects13020146 - 29 Jan 2022

Cited by 2 | Viewed by 2355

Abstract

In Reunion Island, the feasibility of an Aedes albopictus control program using the Sterile Insect Technique (SIT) is studied. Because, in some regions, Ae. albopictus is living in sympatry with Aedes aegypti, the impact of releasing millions of sterile male Ae. albopictus [...] Read more.

In Reunion Island, the feasibility of an Aedes albopictus control program using the Sterile Insect Technique (SIT) is studied. Because, in some regions, Ae. albopictus is living in sympatry with Aedes aegypti, the impact of releasing millions of sterile male Ae. albopictus on female Ae. aegypti reproduction needs to be assessed. Thus, to study the potential heterospecific matings, a marking technique using rhodamine B has been used. Rhodamine is given in solution to male mosquitoes to be incorporated into the male body and seminal fluid and transferred during mating into the bursa inseminalis and spermathecae of females. The presence of rhodamine in females occurred in 15% of cases when Ae. aegypti females were offered non-irradiated Ae. albopictus males, 5% when offered irradiated Ae. albopictus males and 18% of cases in the inverse heterospecific matings. Moreover, our results also showed that these matings gave few eggs but were not viable. Finally, the results showed that whatever the type of mating crosses, females in cages previously crossed with males of another species can re-mate with males of their species and produce an equivalent amount of egg compared to females only mated with conspecific males. Despite the promiscuity of the males and females in small cages for three days, heterospecific mating between sterile male Ae. albopictus and female Ae aegypti, 95% of the females have not been inseminated suggesting that in the field the frequency satyrization would be very low. Full article

(This article belongs to the Special Issue Mosquito Handling, Transport, Release and Male Trapping Methods)

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0 pages, 2904 KiB

Open AccessEditor’s ChoiceArticle

Quick Spreading of Populations of an Exotic Firefly throughout Spain and Their Recent Arrival in the French Pyrenees

by Marcel Koken, José Ramón Guzmán-Álvarez, Diego Gil-Tapetado, Miguel Angel Romo Bedate, Geneviève Laurent, Lucas Ezequiel Rubio, Segimon Rovira Comas, Nicole Wolffler, Fabien Verfaillie and Raphaël De Cock

Insects 2022, 13(2), 148; https://doi.org/10.3390/insects13020148 - 29 Jan 2022

Cited by 4 | Viewed by 5866

Abstract

In August 2018, a firefly (Coleoptera: Lampyridae) of American origin was observed in several localities in Girona (Catalonia, Spain) and was described as Photinus immigrans by Zaragoza-Caballero and Vinolas, 2018. Here, we show that this species dispersed very quickly throughout northeastern [...] Read more.

In August 2018, a firefly (Coleoptera: Lampyridae) of American origin was observed in several localities in Girona (Catalonia, Spain) and was described as Photinus immigrans by Zaragoza-Caballero and Vinolas, 2018. Here, we show that this species dispersed very quickly throughout northeastern Spain and was, in 2020, observed in the French Pyrenees. The animal’s quick progress is documented, and part of its biology is described (dispersion speed, land use, phenology, identification of all life stages). An additional population was localized in Extremadura, and its special status is discussed. We were able to determine its Argentinian–Uruguayan origin and propose, therefore, to consider Photinus immigrans as a synonym of Photinus signaticollis (Blanchard, 1846) (=Photinus immigrans Zaragoza-Caballero and Viñolas, 2018, syn. nov.). Our data clearly show that at least the Catalan and French populations are spreading very quickly and are able to settle permanently if adequate ecosystems are found. The species is highly expansive and may well be invasive; our citizen science platforms are ideally suited to monitor their progress throughout Spain and France. This is important for avoiding future ecological problems with diverse native faunas, such as glow-worms, fireflies and earthworms. If no ways are found to stop the species’ progression, the animals will quite probably invade substantial areas of France, Spain and the rest of Europe in the years to come. Full article

(This article belongs to the Special Issue Reproductive Behaviour in Insects and other Non-Marine Arthropods)

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26 pages, 821 KiB

Open AccessEditor’s ChoiceArticle

Temperature-Specific and Sex-Specific Fitness Effects of Sympatric Mitochondrial and Mito-Nuclear Variation in Drosophila obscura

by Pavle Erić, Aleksandra Patenković, Katarina Erić, Marija Tanasković, Slobodan Davidović, Mina Rakić, Marija Savić Veselinović, Marina Stamenković-Radak and Mihailo Jelić

Insects 2022, 13(2), 139; https://doi.org/10.3390/insects13020139 - 28 Jan 2022

Cited by 5 | Viewed by 20848

Abstract

The adaptive significance of sympatric mitochondrial (mtDNA) variation and the role of selective mechanisms that maintain it are debated to this day. Isofemale lines of Drosophila obscura collected from four populations were backcrossed within populations to construct experimental lines, with all combinations of [...] Read more.

The adaptive significance of sympatric mitochondrial (mtDNA) variation and the role of selective mechanisms that maintain it are debated to this day. Isofemale lines of Drosophila obscura collected from four populations were backcrossed within populations to construct experimental lines, with all combinations of mtDNA Cyt b haplotypes and nuclear genetic backgrounds (nuDNA). Individuals of both sexes from these lines were then subjected to four fitness assays (desiccation resistance, developmental time, egg-to-adult viability and sex ratio) on two experimental temperatures to examine the role of temperature fluctuations and sex-specific selection, as well as the part that interactions between the two genomes play in shaping mtDNA variation. The results varied across populations and fitness components. In the majority of comparisons, they show that sympatric mitochondrial variants affect fitness. However, their effect should be examined in light of interactions with nuDNA, as mito-nuclear genotype was even more influential on fitness across all components. We found both sex-specific and temperature-specific differences in mitochondrial and mito-nuclear genotype ranks in all fitness components. The effect of temperature-specific selection was found to be more prominent, especially in desiccation resistance. From the results of different components tested, we can also infer that temperature-specific mito-nuclear interactions rather than sex-specific selection on mito-nuclear genotypes have a more substantial role in preserving mtDNA variation in this model species. Full article

(This article belongs to the Special Issue Selected Papers from the 1st International Electronic Conference on Entomology)

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17 pages, 2046 KiB

Open AccessEditor’s ChoiceArticle

Peering into the Darkness: DNA Barcoding Reveals Surprisingly High Diversity of Unknown Species of Diptera (Insecta) in Germany

by Caroline Chimeno, Axel Hausmann, Stefan Schmidt, Michael J. Raupach, Dieter Doczkal, Viktor Baranov, Jeremy Hübner, Amelie Höcherl, Rosa Albrecht, Mathias Jaschhof, Gerhard Haszprunar and Paul D. N. Hebert

Insects 2022, 13(1), 82; https://doi.org/10.3390/insects13010082 - 12 Jan 2022

Cited by 26 | Viewed by 8403

Abstract

Determining the size of the German insect fauna requires better knowledge of several megadiverse families of Diptera and Hymenoptera that are taxonomically challenging. This study takes the first step in assessing these “dark taxa” families and provides species estimates for four challenging groups [...] Read more.

Determining the size of the German insect fauna requires better knowledge of several megadiverse families of Diptera and Hymenoptera that are taxonomically challenging. This study takes the first step in assessing these “dark taxa” families and provides species estimates for four challenging groups of Diptera (Cecidomyiidae, Chironomidae, Phoridae, and Sciaridae). These estimates are based on more than 48,000 DNA barcodes (COI) from Diptera collected by Malaise traps that were deployed in southern Germany. We assessed the fraction of German species belonging to 11 fly families with well-studied taxonomy in these samples. The resultant ratios were then used to estimate the species richness of the four “dark taxa” families (DT families hereafter). Our results suggest a surprisingly high proportion of undetected biodiversity in a supposedly well-investigated country: at least 1800–2200 species await discovery in Germany in these four families. As this estimate is based on collections from one region of Germany, the species count will likely increase with expanded geographic sampling. Full article

(This article belongs to the Special Issue Diptera Diversity in Space and Time)

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22 pages, 2861 KiB

Open AccessEditor’s ChoiceArticle

Changes in Alpine Butterfly Communities during the Last 40 Years

by Simona Bonelli, Cristiana Cerrato, Francesca Barbero, Maria Virginia Boiani, Giorgio Buffa, Luca Pietro Casacci, Lorenzo Fracastoro, Antonello Provenzale, Enrico Rivella, Michele Zaccagno and Emilio Balletto

Insects 2022, 13(1), 43; https://doi.org/10.3390/insects13010043 - 30 Dec 2021

Cited by 16 | Viewed by 4409

Abstract

Our work aims to assess how butterfly communities in the Italian Maritime Alps changed over the past 40 years, in parallel with altitudinal shifts occurring in plant communities. In 2019, we sampled butterflies at 7 grassland sites, between 1300–1900 m, previously investigated in [...] Read more.

Our work aims to assess how butterfly communities in the Italian Maritime Alps changed over the past 40 years, in parallel with altitudinal shifts occurring in plant communities. In 2019, we sampled butterflies at 7 grassland sites, between 1300–1900 m, previously investigated in 2009 and 1978, by semi-quantitative linear transects. Fine-scale temperature and precipitation data elaborated by optimal interpolation techniques were used to quantify climate changes. The changes in the vegetation cover and main habitat alterations were assessed by inspection of aerial photographs (1978–2018/1978–2006–2015). The vegetation structure showed a marked decrease of grassland habitats and an increase of woods (1978–2009). Plant physiognomy has remained stable in recent years (2009–2019) with some local exceptions due to geomorphic disturbance. We observed butterfly ‘species substitution’ indicating a general loss in the more specialised and a general gain in more tolerant elements. We did not observe any decrease in species richness, but rather a change in guild compositions, with (i) an overall increased abundance in some widespread and common lowland species and (ii) the disappearance (or strong decrease) of some alpine (high elevation) species, so that ‘resilience’ could be just delusive. Changes in butterfly community composition were consistent with predicted impacts of local warming. Full article

(This article belongs to the Collection Insects in Mountain Ecosystems)

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21 pages, 7037 KiB

Open AccessEditor’s ChoiceArticle

Anatomy of the Nervous System in Chelifer cancroides (Arachnida: Pseudoscorpiones) with a Distinct Sensory Pathway Associated with the Pedipalps

by Torben Stemme and Sarah E. Pfeffer

Insects 2022, 13(1), 25; https://doi.org/10.3390/insects13010025 - 24 Dec 2021

Cited by 7 | Viewed by 4203

Abstract

Many arachnid taxa have evolved unique, highly specialized sensory structures such as antenniform legs in Amblypygi (whip spiders), for instance, or mesosomal pectines in scorpions. Knowledge of the neuroanatomy as well as functional aspects of these sensory organs is rather scarce, especially in [...] Read more.

Many arachnid taxa have evolved unique, highly specialized sensory structures such as antenniform legs in Amblypygi (whip spiders), for instance, or mesosomal pectines in scorpions. Knowledge of the neuroanatomy as well as functional aspects of these sensory organs is rather scarce, especially in comparison to other arthropod clades. In pseudoscorpions, no special sensory structures have been discovered so far. Nevertheless, these animals possess dominant, multifunctional pedipalps, which are good candidates for being the primary sensory appendages. However, only little is known about the anatomy of the nervous system and the projection pattern of pedipalpal afferents in this taxon. By using immunofluorescent labeling of neuronal structures as well as lipophilic dye labeling of pedipalpal pathways, we identified the arcuate body, as well as a comparatively small mushroom body, the latter showing some similarities to that of Solifugae (sun spiders and camel spiders). Furthermore, afferents from the pedipalps terminate in a glomerular and a layered neuropil. Due to the innervation pattern and structural appearance, we conclude that these neuropils are the first integration centers of the chemosensory and mechanosensory afferents. Within Arthropoda, but also other invertebrates or even vertebrates, sensory structures show rather similar neuronal arrangement. Thus, these similarities in the sensory systems of different evolutionary origin have to be interpreted as functional prerequisites of the respective modality. Full article

(This article belongs to the Collection Insect Senses: From Perception to Cognition)

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18 pages, 35930 KiB

Open AccessEditor’s ChoiceArticle

Weeds Enhance Pollinator Diversity and Fruit Yield in Mango

by Blaire M. Kleiman, Suzanne Koptur and Krishnaswamy Jayachandran

Insects 2021, 12(12), 1114; https://doi.org/10.3390/insects12121114 - 13 Dec 2021

Cited by 9 | Viewed by 12852

Abstract

Agriculture is dependent on insect pollination, yet in areas of intensive production agriculture, there is often a decline in plant and insect diversity. As native habitats and plants are replaced, often only the weeds or unwanted vegetation persist. This study compared insect diversity [...] Read more.

Agriculture is dependent on insect pollination, yet in areas of intensive production agriculture, there is often a decline in plant and insect diversity. As native habitats and plants are replaced, often only the weeds or unwanted vegetation persist. This study compared insect diversity on mango, Mangifera indica, a tropical fruit tree dependent on insect pollination, when weeds were present in cultivation versus when they were removed mechanically. The pollinating insects on both weeds and mango trees were examined as well as fruit set and yield in both the weed-free and weedy treatment in South Florida. There were significantly more pollinators and key pollinator families on the weedy mango trees, as well as significantly greater fruit yield in the weedy treatment compared to the weed-free treatment. Utilizing weeds, especially native species, as insectary plants can help ensure sufficient pollination of mango and increase biodiversity across crop monocropping systems. Full article

(This article belongs to the Special Issue Pollinator Diversity in Sustainable Agroecosystems)

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11 pages, 1292 KiB

Open AccessEditor’s ChoiceArticle

Body Size Variation in a Social Sweat Bee, Halictus ligatus (Halictidae, Apoidea), across Urban Environments

by Rachel A. Brant and Gerardo R. Camilo

Insects 2021, 12(12), 1086; https://doi.org/10.3390/insects12121086 - 3 Dec 2021

Cited by 4 | Viewed by 3423

Abstract

High morphological variation is often associated with species longevity, and it is hypothesized that urban-dwelling species may require more plasticity in functional traits such as body size in order to maximize fitness in heterogeneous environments. There has been published research regarding the functional [...] Read more.

High morphological variation is often associated with species longevity, and it is hypothesized that urban-dwelling species may require more plasticity in functional traits such as body size in order to maximize fitness in heterogeneous environments. There has been published research regarding the functional trait diversity of urban bee pollinators. However, no two cities are identical, so the implementation of multi-city studies is vital. Therefore, we compared body size variation in female Halicus ligatus sweat bees from May–October 2016 from three distinct Midwestern United States cities: Chicago, Detroit, and Saint Louis. Additionally, to elucidate potentially influential environmental factors, we assessed the relationship between temperature and measured body size. We collected bees in community gardens and urban farms and measured their head width and intertegular distance as a proxy for overall body size. We utilized an ANCOVA to determine whether body size variation differed significantly across the three surveyed cities. Results indicated that H. ligatus females in Chicago, Detroit, and Saint Louis had significantly different body size ranges. These findings highlight the importance of intraspecific body size variation and support our prediction that bees from different urban environments will have distinct ranges in body size due to local ecological factors affecting their populations. Additionally, we found a significant influence of temperature, though this is probably not the only important ecological characteristic impacting bee body size. Therefore, we also provided a list of predictions for the future study of specific variables that are likely to impact functional trait diversity in urban bees. Full article

(This article belongs to the Section Insect Ecology, Diversity and Conservation)

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27 pages, 3853 KiB

Open AccessEditor’s ChoiceArticle

The Ant-like Tachydromia Complex in the Iberian Peninsula—Insights from Habitat Suitability Modelling for the Conservation of an Endemism (Diptera: Hybotidae)

by Ana Rita Gonçalves, Carlos Vila-Viçosa and João Gonçalves

Insects 2021, 12(12), 1068; https://doi.org/10.3390/insects12121068 - 29 Nov 2021

Viewed by 3124

Abstract

Ant-like flies comprise nine Iberian endemic species of flightless Tachydromia. Severe knowledge gaps on distribution and ecological requirements hinder conservation assessments. Species distribution models were applied to unveil habitat suitability and to provide guidelines for future studies. An ensemble modeling approach combining [...] Read more.

Ant-like flies comprise nine Iberian endemic species of flightless Tachydromia. Severe knowledge gaps on distribution and ecological requirements hinder conservation assessments. Species distribution models were applied to unveil habitat suitability and to provide guidelines for future studies. An ensemble modeling approach combining ten different techniques was implemented with the biomod2 package. Occurrence data was partitioned into six sets, including two multi-species groups and four species. The most relevant drivers of habitat suitability are climate-related, followed by forest type and structure, according to well-defined biogeographic gradients. T. lusitanica and T. ebejeri are adapted to mild temperatures and high-humidity environments. Their distribution is connected to the Temperate–Eurosiberian life zone. T. semiaptera and T. iberica are adapted to progressively drier and hotter central and southern parts of the Iberian Peninsula, connected to transitional Temperate–submediterranean areas. Ant-like fly’ ranges overlap with deciduous/marcescent oak species, acting as suitable indicators of their presence in Iberia. Southern marcescent forests emerge as “islands” with particular interest for future prospections. Ant-like flies are threatened by several factors such as climate change and habitat destruction, including urbanization and forest fires. This study provides vital tools to better assess the ant-like flies’ conservation status and to manage their habitat. Full article

(This article belongs to the Special Issue Systematics, Evolution, and Diversity of Dance Flies (Diptera, Empidoidea))

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15 pages, 1687 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Condition-Specific Competitive Effects of the Invasive Mosquito Aedes albopictus on the Resident Culex pipiens among Different Urban Container Habitats May Explain Their Coexistence in the Field

by Paul T. Leisnham, Shannon L. LaDeau, Megan E. M. Saunders and Oswaldo C. Villena

Insects 2021, 12(11), 993; https://doi.org/10.3390/insects12110993 - 4 Nov 2021

Cited by 7 | Viewed by 2794

Abstract

Condition-specific competition, when environmental conditions alter the outcome of competition, can foster the persistence of resident species after the invasion of a competitively superior invader. We test whether condition-specific competition can facilitate the areawide persistence of the resident and principal West Nile virus [...] Read more.

Condition-specific competition, when environmental conditions alter the outcome of competition, can foster the persistence of resident species after the invasion of a competitively superior invader. We test whether condition-specific competition can facilitate the areawide persistence of the resident and principal West Nile virus vector mosquito Culex pipiens with the competitively superior invasive Aedes albopictus in water from different urban container habitats. (2) Methods: We tested the effects of manipulated numbers of A. albopictus on C. pipiens’ survival and development in water collected from common functional and discarded containers in Baltimore, MD, USA. The experiment was conducted with typical numbers of larvae found in field surveys of C. pipiens and A. albopictus and container water quality. (3) Results: We found increased densities of A. albopictus negatively affected the survivorship and development of C. pipiens in water from discarded containers but had little effect in water from functional containers. This finding was driven by water from trash cans, which allowed consistently higher C. pipiens’ survival and development and had greater mean ammonia and nitrate concentrations that can promote microbial food than other container types. (4) Conclusions: These results suggest that the contents of different urban containers alter the effects of invasive A. albopictus competition on resident C. pipiens, that trash cans, in particular, facilitate the persistence of C. pipiens, and that there could be implications for West Nile virus risk as a result. Full article

(This article belongs to the Special Issue Urban Pests and Vectors: Interdisciplinary Links between Arthropod–Human Systems)

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12 pages, 1254 KiB

Open AccessEditor’s ChoiceArticle

Crude Extracts and Alkaloids Derived from Ipomoea-Periglandula Symbiotic Association Cause Mortality of Asian Citrus Psyllid Diaphorina citri Kuwayama (Hemiptera: Psyllidae)

by Xue-Dong Chen, Navneet Kaur, David R. Horton, W. Rodney Cooper, Jawwad A. Qureshi and Lukasz L. Stelinski

Insects 2021, 12(10), 929; https://doi.org/10.3390/insects12100929 - 12 Oct 2021

Cited by 4 | Viewed by 2637

Abstract

Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is an important economic pest of citrus crops because it vectors the causal pathogen of huanglongbing (HLB; aka citrus greening). Population suppression of D. citri with insecticides has been disproportionally relied on for HLB management [...] Read more.

Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is an important economic pest of citrus crops because it vectors the causal pathogen of huanglongbing (HLB; aka citrus greening). Population suppression of D. citri with insecticides has been disproportionally relied on for HLB management and a greater diversity of more sustainable tools is needed. Periglandula spp. is a fungal endosymbiont (family Clavicipitaceae) that forms a mutualistic relationship with members of plants in family Convolvulaceae. This association results in the production of ergot alkaloids that were previously documented as having psyllicidal properties. We investigated the mortality and behavior of D. citri exposed to crude extracts from morning glories in the plant family Convolvulaceae, as well as synthetic ergot alkaloids. Nymphs and adults were exposed to the crude plant extracts from Periglandula positive species of Convolvulaceae, as well as five synthetic ergot alkaloids. Treatments were prepared by exposing clippings of citrus to 100 ng/µL of crude extract from Periglandula-positive species of Ipomoea (I. imperati, I. leptophylla, I. pandurata and I. tricolor), and Turbina corymbosa, and from one Periglandula-negative species (I. alba) (100 ng/µL). Mortality of adult and nymphal D. citri was significantly higher than the control after exposure to extracts from I. tricolor and I. imperati. The synthetic ergot alkaloids, lysergol (10–100 ng/µL), ergonovine maleate (100 ng/µL), agroclavine (10–100 ng/µL), and ergosine (10–100 ng/µL) increased mortality of D. citri nymphs, while ergosine (100 ng/µL) and agroclavine (100 ng/µL) increased mortality of adults compared to water controls. Fewer D. citri adults settled on plants treated with crude extracts or synthetic ergot alkaloids than on water controls at 48 h after release. D. citri that fed on citrus leaves treated with 10 ng/μL solution of crude extract from the Periglandula-positive species Ipomoea (I. imperati, I. leptophylla, I. pandurata, I. tricolor), and Turbina corymbosa excreted significantly less honeydew compared with a negative water control and extract from Periglandula-negative species (I. alba). Our results indicate that crude extracts and ergot alkaloids exhibit toxic and sub-lethal effects on D. citri that could be useful for management of this pest. Full article

(This article belongs to the Collection Psyllid Vectors: From Genetics to Pest Integrated Management)

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18 pages, 1060 KiB

Open AccessEditor’s ChoiceArticle

Adaptation by the Brown Planthopper to Resistant Rice: A Test of Female-Derived Virulence and the Role of Yeast-like Symbionts

by Finbarr G. Horgan, Ainara Peñalver Cruz, Arriza Arida, Jedeliza B. Ferrater and Carmencita C. Bernal

Insects 2021, 12(10), 908; https://doi.org/10.3390/insects12100908 - 6 Oct 2021

Cited by 8 | Viewed by 2694

Abstract

The adaptation by planthoppers to feed and develop on resistant rice is a challenge for pest management in Asia. We conducted a series of manipulative experiments with the brown planthopper (Nilaparvata lugens (Stål)) on the resistant rice variety IR62 (BPH3/ [...] Read more.

The adaptation by planthoppers to feed and develop on resistant rice is a challenge for pest management in Asia. We conducted a series of manipulative experiments with the brown planthopper (Nilaparvata lugens (Stål)) on the resistant rice variety IR62 (BPH3/BPH32 genes) to assess behavioral and bionomic changes in planthoppers exhibiting virulence adaptation. We also examined the potential role of yeast-like symbionts (YLS) in virulence adaptation by assessing progeny fitness (survival × reproduction) following controlled matings between virulent males or females and avirulent males or females, and by manipulating YLS densities in progeny through heat treatment. We found virulence-adapted planthoppers developed faster, grew larger, had adults that survived for longer, had female-biased progeny, and produced more eggs than non-selected planthoppers on the resistant variety. However, feeding capacity—as revealed through honeydew composition—remained inefficient on IR62, even after 20+ generations of exposure to the resistant host. Virulence was derived from both the male and female parents; however, females contributed more than males to progeny virulence. We found that YLS are essential for normal planthopper development and densities are highest in virulent nymphs feeding on the resistant host; however, we found only weak evidence that YLS densities contributed more to virulence. Virulence against IR62 in the brown planthopper, therefore, involves a complex of traits that encompass a series of behavioral, physiological, and genetic mechanisms, some of which are determined only by the female parent. Full article

(This article belongs to the Collection Biology and Management of Sap-Sucking Pests)

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13 pages, 1664 KiB

Open AccessEditor’s ChoiceArticle

Aposematic Coloration of Moths Decreases Strongly along an Elevational Gradient in the Andes

by Konrad Fiedler and Gunnar Brehm

Insects 2021, 12(10), 903; https://doi.org/10.3390/insects12100903 - 3 Oct 2021

Cited by 2 | Viewed by 6027

Abstract

On tropical mountains, predation pressure decreases with elevation. Accordingly, one expects an elevational decay in the prevalence of costly defensive traits such as aposematic coloration. Using light-trap catches of Arctiinae moths (353 species, 4466 individuals), assembled along a forested gradient in the megadiverse [...] Read more.

On tropical mountains, predation pressure decreases with elevation. Accordingly, one expects an elevational decay in the prevalence of costly defensive traits such as aposematic coloration. Using light-trap catches of Arctiinae moths (353 species, 4466 individuals), assembled along a forested gradient in the megadiverse tropical Andes of southern Ecuador, we show that the incidence of aposematic coloration decreases strongly between 1040 and 2670 m asl. While over 60% of Arctiinae moths were warningly colored at lowest sites, this fraction decreased to less than 20% in montane forest, yet increased slightly again at the highest sites in the very open Purdiaea nutans forest. In parallel, the incidence of hymenopteran mimics and of species that mimic chemically defended beetles decreased with elevation. Hymenopteran mimics accounted for less than 5% of Arctiinae moths at sites above 2100 m, and beetle mimics were essentially lacking at high elevations. These patterns coincide with a change in gross taxonomic composition of Arctiinae ensembles and with an increase in average body size towards higher elevations. Representatives of Euchromiina and Ctenuchina became scarce with altitude, whereas the prevalence of Lithosiinae increased. Our findings suggest that the variable selective pressures along the elevational gradient favor warning coloration primarily at lower sites, whereas cryptic appearance of adult moths dominates in the tropical upper montane forest. Full article

(This article belongs to the Section Insect Ecology, Diversity and Conservation)

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13 pages, 446 KiB

Open AccessEditor’s ChoiceArticle

Metabolic Resistance in Permethrin-Resistant Florida Aedes aegypti (Diptera: Culicidae)

by Sierra M. Schluep and Eva A. Buckner

Insects 2021, 12(10), 866; https://doi.org/10.3390/insects12100866 - 24 Sep 2021

Cited by 11 | Viewed by 2417

Abstract

Aedes aegypti is the principal mosquito vector for many arthropod-borne viruses (arboviruses) including dengue, chikungunya, and Zika. In the United States, excessive permethrin use has led to a high frequency of resistance in mosquitoes. Insecticide resistance is a significant obstacle in the struggle [...] Read more.

Aedes aegypti is the principal mosquito vector for many arthropod-borne viruses (arboviruses) including dengue, chikungunya, and Zika. In the United States, excessive permethrin use has led to a high frequency of resistance in mosquitoes. Insecticide resistance is a significant obstacle in the struggle against vector-borne diseases. To help overcome metabolic resistance, synergists that inhibit specific metabolic enzymes can be added to formulated pyrethroid products. Using modified CDC bottle bioassays, we assessed the effect of three inhibitors (piperonyl butoxide (PBO), which inhibits oxidase activity; S.S.S-tributyl phosphorotrithioate (DEF), which inhibits esterase activity; and diethyl maleate (DM), which inhibits glutathione transferase activity) + permethrin. We performed these against 20 Florida Ae. aegypti populations, all of which were resistant to permethrin. Our data indicated that 11 out of 20 populations (55%) exhibited metabolic resistance. Results revealed 73% of these populations had significant increases in mortality attributed to DEF + permethrin, 64% to PBO + permethrin, and 55% to DM + permethrin compared to permethrin alone. Currently, PBO is the only metabolic enzyme inhibitor added to formulated pyrethroid products used for adult mosquito control. Our results suggest that the DEF and DM inhibitors could also be useful additives in permethrin products, especially against metabolically resistant Ae. aegypti mosquitoes. Moreover, metabolic assays should be conducted to better inform mosquito control programs for designing and implementing integrated vector management strategies. Full article

(This article belongs to the Section Insect Pest and Vector Management)

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12 pages, 1207 KiB

Open AccessEditor’s ChoiceArticle

Developmental Temperature Affects Life-History Traits and Heat Tolerance in the Aphid Parasitoid Aphidius colemani

by Mey Jerbi-Elayed, Vincent Foray, Kévin Tougeron, Kaouthar Grissa-Lebdi and Thierry Hance

Insects 2021, 12(10), 852; https://doi.org/10.3390/insects12100852 - 22 Sep 2021

Cited by 7 | Viewed by 2716

Abstract

Developmental temperature plays important roles in the expression of insect traits through thermal developmental plasticity. We exposed the aphid parasitoid Aphidius colemani to different temperature regimes (10, 20, or 28 °C) throughout larval development and studied the expression of morphological and physiological traits [...] Read more.

Developmental temperature plays important roles in the expression of insect traits through thermal developmental plasticity. We exposed the aphid parasitoid Aphidius colemani to different temperature regimes (10, 20, or 28 °C) throughout larval development and studied the expression of morphological and physiological traits indicator of fitness and heat tolerance in the adult. We showed that the mass decreased and the surface to volume ratio of parasitoids increased with the development temperature. Water content was not affected by rearing temperature, but parasitoids accumulated more lipids when reared at 20 °C. Egg content was not affected by developmental temperature, but adult survival was better for parasitoids reared at 20 °C. Finally, parasitoids developed at 20 °C showed the highest heat stupor threshold, whereas parasitoids developed at 28 °C showed the highest heat coma threshold (better heat tolerance CTmax1 and CTmax2, respectively), therefore only partly supporting the beneficial acclimation hypothesis. From a fundamental point of view, our study highlights the role of thermal plasticity (adaptive or not) on the expression of different life history traits in insects and the possible correlations that exist between these traits. From an applied perspective, these results are important in the context of biological control through mass release techniques of parasitoids in hot environments. Full article

(This article belongs to the Special Issue Thermal Plasticity and Adaptation in Insects)

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11 pages, 1114 KiB

Open AccessEditor’s ChoiceArticle

Evolution of Adaptive Variation in the Mosquito Culex pipiens: Multiple Independent Origins of Insecticide Resistance Mutations

by Valentina Mastrantonio, Daniele Porretta, Valentina Lucchesi, Nurper Güz, Naciye Sena Çağatay, Romeo Bellini, John Vontas and Sandra Urbanelli

Insects 2021, 12(8), 676; https://doi.org/10.3390/insects12080676 - 27 Jul 2021

Cited by 6 | Viewed by 2296

Abstract

Insecticide resistance is an informative model for studying the appearance of adaptive traits. Simultaneously, understanding how many times resistance mutations originate is essential to design effective resistance management. In the mosquito Culex pipiens, target–site resistance to the insecticide diflubenzuron (DFB) has been [...] Read more.

Insecticide resistance is an informative model for studying the appearance of adaptive traits. Simultaneously, understanding how many times resistance mutations originate is essential to design effective resistance management. In the mosquito Culex pipiens, target–site resistance to the insecticide diflubenzuron (DFB) has been recently found in Italian and Turkish populations. Three point mutations confer it at the codon 1043 of the chitin synthase 1 gene (chs-1): I1043L, I1043M, and I1043F. Whether the resistant mutations originated independently from different susceptible alleles or sequentially from resistant alleles and whether resistant alleles from Italy and Turkey have originated once or multiple times remain unresolved. Here, we sequenced a fragment of the chs-1 gene carrying the resistant mutations and inferred the phylogenetic relationships among susceptible and resistant alleles. Confirming previous findings, we found the three mutations in Italy and the I1043M in Turkey. Notably, the I1043F was also found for the first time in Turkish samples, highlighting the need for extensive monitoring activities. Phylogenetic analyses are consistent with an independent origin of the I1043F, I1043M, and I1043L mutations from different susceptible alleles and with multiple independent origins of the Italian and Turkish I1043M and I1043F alleles. Full article

(This article belongs to the Section Insect Pest and Vector Management)

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30 pages, 2130 KiB

Open AccessEditor’s ChoiceArticle

Investigating Virus–Host Interactions in Cultured Primary Honey Bee Cells

by Alexander J. McMenamin, Fenali Parekh, Verena Lawrence and Michelle L. Flenniken

Insects 2021, 12(7), 653; https://doi.org/10.3390/insects12070653 - 17 Jul 2021

Cited by 7 | Viewed by 5522

Abstract

Honey bee (Apis mellifera) health is impacted by viral infections at the colony, individual bee, and cellular levels. To investigate honey bee antiviral defense mechanisms at the cellular level we further developed the use of cultured primary cells, derived from either [...] Read more.

Honey bee (Apis mellifera) health is impacted by viral infections at the colony, individual bee, and cellular levels. To investigate honey bee antiviral defense mechanisms at the cellular level we further developed the use of cultured primary cells, derived from either larvae or pupae, and demonstrated that these cells could be infected with a panel of viruses, including common honey bee infecting viruses (i.e., sacbrood virus (SBV) and deformed wing virus (DWV)) and an insect model virus, Flock House virus (FHV). Virus abundances were quantified over the course of infection. The production of infectious virions in cultured honey bee pupal cells was demonstrated by determining that naïve cells became infected after the transfer of deformed wing virus or Flock House virus from infected cell cultures. Initial characterization of the honey bee antiviral immune responses at the cellular level indicated that there were virus-specific responses, which included increased expression of bee antiviral protein-1 (GenBank: MF116383) in SBV-infected pupal cells and increased expression of argonaute-2 and dicer-like in FHV-infected hemocytes and pupal cells. Additional studies are required to further elucidate virus-specific honey bee antiviral defense mechanisms. The continued use of cultured primary honey bee cells for studies that involve multiple viruses will address this knowledge gap. Full article

(This article belongs to the Special Issue Advances in the Use of Insect Cell Culture and Biotechnology)

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24 pages, 3058 KiB

Open AccessEditor’s ChoiceArticle

Mosquito-Textile Physics: A Mathematical Roadmap to Insecticide-Free, Bite-Proof Clothing for Everyday Life

by Kun Luan, Andre J. West, Marian G. McCord, Emiel A. DenHartog, Quan Shi, Isa Bettermann, Jiayin Li, Nicholas V. Travanty, Robert D. Mitchell III, Grayson L. Cave, John B. Strider, Yongxin Wang, Florian Neumann, Tobias Beck, Charles S. Apperson and R. Michael Roe

Insects 2021, 12(7), 636; https://doi.org/10.3390/insects12070636 - 13 Jul 2021

Cited by 10 | Viewed by 33670

Abstract

Garments treated with chemical insecticides are commonly used to prevent mosquito bites. Resistance to insecticides, however, is threatening the efficacy of this technology, and people are increasingly concerned about the potential health impacts of wearing insecticide-treated clothing. Here, we report a mathematical model [...] Read more.

Garments treated with chemical insecticides are commonly used to prevent mosquito bites. Resistance to insecticides, however, is threatening the efficacy of this technology, and people are increasingly concerned about the potential health impacts of wearing insecticide-treated clothing. Here, we report a mathematical model for fabric barriers that resist bites from Aedes aegypti mosquitoes based on textile physical structure and no insecticides. The model was derived from mosquito morphometrics and analysis of mosquito biting behavior. Woven filter fabrics, precision polypropylene plates, and knitted fabrics were used for model validation. Then, based on the model predictions, prototype knitted textiles and garments were developed that prevented mosquito biting, and comfort testing showed the garments to possess superior thermophysiological properties. Our fabrics provided a three-times greater bite resistance than the insecticide-treated cloth. Our predictive model can be used to develop additional textiles in the future for garments that are highly bite resistant to mosquitoes. Full article

(This article belongs to the Special Issue Insecticides for Mosquito Control: Strengthening the Evidence Base)

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14 pages, 1280 KiB

Open AccessEditor’s ChoiceArticle

Complementary Contribution of Wild Bumblebees and Managed Honeybee to the Pollination Niche of an Introduced Blueberry Crop

by Marcos Miñarro and Daniel García

Insects 2021, 12(7), 595; https://doi.org/10.3390/insects12070595 - 30 Jun 2021

Cited by 7 | Viewed by 2955

Abstract

The entomophilous pollination niche (abundance, phenotypic traits, foraging behaviours and environmental tolerances of insect pollinators) helps to understand and better manage crop pollination. We apply this niche approach to assess how an entomophilous crop (blueberry, Vaccinium ashei) can be expanded into new [...] Read more.

The entomophilous pollination niche (abundance, phenotypic traits, foraging behaviours and environmental tolerances of insect pollinators) helps to understand and better manage crop pollination. We apply this niche approach to assess how an entomophilous crop (blueberry, Vaccinium ashei) can be expanded into new territories (i.e., northern Spain) far from their original area of domestication (North America). Insect visits to blueberry flowers were monitored in a plantation on 12 different days, at 8 different times during day and covering various weather conditions. Abundance, visitation rate, pollen gathering behaviour, and frequency of inter-plant and inter-row movements were recorded. The pollinator assemblage was basically composed of one managed honeybee species (50.8% of visits) and three native bumblebee species (48.3%). There was a marked pattern of seasonal segregation throughout bloom, with bumblebees dominating the early bloom and honeybee the late bloom. Pollinators also segregated along gradients of daily temperature and relative humidity. Finally, the two pollinator types differed in foraging behaviour, with bumblebees having a visitation rate double that of honeybee, collecting pollen more frequently and changing plant and row more frequently. The spatio-temporal and functional complementarity between honeybee and bumblebees suggested here encourages the consideration of an integrated crop pollination strategy for blueberries, based on the concurrence of both wild and managed bees. Full article

(This article belongs to the Special Issue Pollinator Diversity in Sustainable Agroecosystems)

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19 pages, 3268 KiB

Open AccessEditor’s ChoiceArticle

Biology of an Adventive Population of the Armored Scale Rhizaspidiotus donacis, a Biological Control Agent of Arundo donax in California

by Charles A. Braman, Adam M. Lambert, A. Zeynep Özsoy, Ellen N. Hollstien, Kirsten A. Sheehy, Tara McKinnon, Patrick Moran, John F. Gaskin, John A. Goolsby and Thomas L. Dudley

Insects 2021, 12(7), 588; https://doi.org/10.3390/insects12070588 - 29 Jun 2021

Cited by 2 | Viewed by 2556

Abstract

Arundo donax (giant reed) is invasive in Mediterranean, sub-, and tropical riparian systems worldwide. The armored scale Rhizaspidiotus donacis is approved for biocontrol in North America, but an adventive population was recently discovered in southern California. We documented this population’s distribution, phylogeny, phenology, [...] Read more.

Arundo donax (giant reed) is invasive in Mediterranean, sub-, and tropical riparian systems worldwide. The armored scale Rhizaspidiotus donacis is approved for biocontrol in North America, but an adventive population was recently discovered in southern California. We documented this population’s distribution, phylogeny, phenology, potential host spillover to Phragmites spp., and potential for parasitism by a common biocontrol parasitoid of citrus scale. The adventive scale was found within a single watershed and is genetically closest to Iberian scale genotypes. Rhizaspidiotus donacis developed on Phragmites haplotypes but at much lower densities than Arundo. The adventive population is univoltine, producing crawlers from March-June. Aphytis melinus parasitoids exhibited sustained interest in R. donacis during choice and no-choice trials and oviposition resulted in a small second generation. Rhizaspidiotus donacis appears limited in distribution by its univoltinism and sessile adult females. This presents challenges for broad biocontrol implementation but allows for targeted application. The genetic differentiation between imported biocontrol samples and adventive populations presents an opportunity for exploring benefits of hybrids and/or alternative genotypes where establishment has been difficult. While unlikely to occur in situ, spillover to vulnerable endemic Phragmites or deleterious parasitoid effects on scale biocontrol agents warrants consideration when planning use of R. donacis. Full article

(This article belongs to the Special Issue Biological Control of Invasive Plants Using Arthropods)

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14 pages, 2189 KiB

Open AccessEditor’s ChoiceArticle

Molecular Evolution of Phototransduction Pathway Genes in Nocturnal and Diurnal Fireflies (Coleoptera: Lampyridae)

by Gavin J. Martin, Sarah E. Lower, Anton Suvorov and Seth M. Bybee

Insects 2021, 12(6), 561; https://doi.org/10.3390/insects12060561 - 18 Jun 2021

Cited by 2 | Viewed by 3648

Abstract

Most organisms are dependent on sensory cues from their environment for survival and reproduction. Fireflies (Coleoptera: Lampyridae) represent an ideal system for studying sensory niche adaptation due to many species relying on bioluminescent communication; as well as a diversity of ecologies. Here; using [...] Read more.

Most organisms are dependent on sensory cues from their environment for survival and reproduction. Fireflies (Coleoptera: Lampyridae) represent an ideal system for studying sensory niche adaptation due to many species relying on bioluminescent communication; as well as a diversity of ecologies. Here; using transcriptomics; we examine the phototransduction pathway in this non-model organism; and provide some of the first evidence for positive selection in the phototransduction pathway beyond opsins in beetles. Evidence for gene duplications within Lampyridae are found in inactivation no afterpotential C and inactivation no afterpotential D. We also find strong support for positive selection in arrestin-2; inactivation no afterpotential D; and transient receptor potential-like; with weak support for positive selection in guanine nucleotide-binding protein G(q) subunit alpha and neither inactivation nor afterpotential C. Taken with other recent work in flies; butterflies; and moths; this represents an exciting new avenue of study as we seek to further understand diversification and constraint on the phototransduction pathway in light of organism ecology. Full article

(This article belongs to the Special Issue Systematics, Phylogeny, Evolution and Diversity of Elateridae (Coleoptera) and Their Relatives)

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19 pages, 6886 KiB

Open AccessEditor’s ChoiceArticle

Species Identification of Wireworms (Agriotes spp.; Coleoptera: Elateridae) of Agricultural Importance in Europe: A New “Horizontal Identification Table”

by Lorenzo Furlan, Isadora Benvegnù, María Fabiana Bilò, Jörn Lehmhus and Enrico Ruzzier

Insects 2021, 12(6), 534; https://doi.org/10.3390/insects12060534 - 8 Jun 2021

Cited by 9 | Viewed by 4132

Abstract

Wireworms are yellowish soil-dwelling larvae that damage a wide range of arable crops. The most common wireworms found in European cultivated fields (except for the Caucasus) belong to the genus Agriotes (Coleoptera: Elateridae). In several European countries, environment-impacting insecticides are applied on a [...] Read more.

Wireworms are yellowish soil-dwelling larvae that damage a wide range of arable crops. The most common wireworms found in European cultivated fields (except for the Caucasus) belong to the genus Agriotes (Coleoptera: Elateridae). In several European countries, environment-impacting insecticides are applied on a prophylactic basis to control them. However, before any treatment can be applied, European legislation requires that an assessment is done when pest population levels exceed a damage threshold. The threshold substantially depends on wireworm species, thus quick reliable larval identification is needed to implement the appropriate integrated pest management practices. Furthermore, research into non-chemical strategies involves carrying out tests with live and identified wireworms. Thus, thousands of wireworms were observed in a bid to identify live larvae so that larval density could be assessed and compared with species-specific thresholds before sowing, and laboratory experiments were carried out. This work led to a horizontal identification table that allows for quick and accurate identification of live larvae. This key, unlike traditional dichotomous keys, simultaneously considers a set of multiple discriminating morphological characters in order of stability. The key can be reliably used by less experienced users and, once minimum familiarity is acquired, most larvae can be identified rapidly, with high precision. Full article

(This article belongs to the Special Issue Systematics, Phylogeny, Evolution and Diversity of Elateridae (Coleoptera) and Their Relatives)

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16 pages, 805 KiB

Open AccessEditor’s ChoiceArticle

Short-Term Selection to Diflubenzuron and Bacillus thuringiensis Var. Israelensis Differentially Affects the Winter Survival of Culex pipiens f. Pipiens and Culex pipiens f. Molestus (Diptera: Culicidae)

by Charalampos S. Ioannou, Christos Hadjichristodoulou, Maria A. Kyritsi and Nikos T. Papadopoulos

Insects 2021, 12(6), 527; https://doi.org/10.3390/insects12060527 - 6 Jun 2021

Cited by 8 | Viewed by 2591

Abstract

The Culex pipiens (Diptera: Culicidae) mosquito is of high medical importance as it is considered the prime vector of West Nile virus. In Europe, this species consists of two forms, named pipiens and molestus, that exhibit substantial differences in their overwintering biology. [...] Read more.

The Culex pipiens (Diptera: Culicidae) mosquito is of high medical importance as it is considered the prime vector of West Nile virus. In Europe, this species consists of two forms, named pipiens and molestus, that exhibit substantial differences in their overwintering biology. Diflubenzuron (DFB) and Bacillus thuringiensis var. israelensis (Bti) are two of the most used larvicides in mosquito control, including that of Culex pipiens. The high dependency on these two larvicides poses major concerns for resistance development. The evolution and stability of resistance to insecticides has been associated with fitness costs that may be manifested under stressful conditions, such as the winter period. This study investigated how short-term selection of pipiens and molestus forms to both larvicides affect their overwintering success. Larvae from each form were subjected to the same selective pressure (80% mortality) for three successive generations with DFB and Bti. At the end of this process, the winter survival between the selected populations and the controls (colonies without selection) was determined for each form. Selection to both larvicides significantly reduced the winter survival rates of molestus but not of pipiens form, indicating potential differences in the persistence of the selected individuals from year to year between the two forms. Full article

(This article belongs to the Section Insect Pest and Vector Management)

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20 pages, 1708 KiB

Open AccessEditor’s ChoiceArticle

Body Size and Behavioural Plasticity Interact to Influence the Performance of Free-Foraging Bumble Bee Colonies

by Jacob G. Holland, Shinnosuke Nakayama, Maurizio Porfiri, Oded Nov and Guy Bloch

Insects 2021, 12(3), 236; https://doi.org/10.3390/insects12030236 - 10 Mar 2021

Cited by 12 | Viewed by 2821

Abstract

Specialisation and plasticity are important for many forms of collective behaviour, but the interplay between these factors is little understood. In insect societies, workers are often developmentally primed to specialise in different tasks, sometimes with morphological or physiological adaptations, facilitating a division of [...] Read more.

Specialisation and plasticity are important for many forms of collective behaviour, but the interplay between these factors is little understood. In insect societies, workers are often developmentally primed to specialise in different tasks, sometimes with morphological or physiological adaptations, facilitating a division of labour. Workers may also plastically switch between tasks or vary their effort. The degree to which developmentally primed specialisation limits plasticity is not clear and has not been systematically tested in ecologically relevant contexts. We addressed this question in 20 free-foraging bumble bee (Bombus terrestris) colonies by continually manipulating colonies to contain either a typically diverse, or a reduced (“homogeneous”), worker body size distribution while keeping the same mean body size, over two trials. Pooling both trials, diverse colonies produced a larger comb mass, an index of colony performance. The link between body size and task was further corroborated by the finding that foragers were larger than nurses even in homogeneous colonies with a very narrow body size range. However, the overall effect of size diversity stemmed mostly from one trial. In the other trial, homogeneous and diverse colonies showed comparable performance. By comparing behavioural profiles based on several thousand observations of individuals, we found evidence that workers in homogeneous colonies in this trial rescued colony performance by plastically increasing behavioural specialisation and/or individual effort, compared to same-sized individuals in diverse colonies. Our results are consistent with a benefit to colonies of large and small specialists under certain conditions, but also suggest that plasticity or effort can compensate for reduced (size-related) specialisation. Thus, we suggest that an intricate interplay between specialisation and plasticity is functionally adaptive in bumble bee colonies. Full article

(This article belongs to the Special Issue Behavioural Variability)

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14 pages, 2078 KiB

Open AccessEditor’s ChoiceArticle

Effect of the Genotypic Variation of an Aphid Host on the Endosymbiont Associations in Natural Host Populations

by Francisca Zepeda-Paulo and Blas Lavandero

Insects 2021, 12(3), 217; https://doi.org/10.3390/insects12030217 - 4 Mar 2021

Cited by 4 | Viewed by 2445

Abstract

Understanding the role of facultative endosymbionts on the host’s ecology has been the main aim of the research in symbiont–host systems. However, current research on host–endosymbiont dynamics has failed to examine the genetic background of the hosts and its effect on host–endosymbiont associations [...] Read more.

Understanding the role of facultative endosymbionts on the host’s ecology has been the main aim of the research in symbiont–host systems. However, current research on host–endosymbiont dynamics has failed to examine the genetic background of the hosts and its effect on host–endosymbiont associations in real populations. We have addressed the seasonal dynamic of facultative endosymbiont infections among different host clones of the grain aphid Sitobion avenae, on two cereal crops (wheat and oat) and whether their presence affects the total hymenopteran parasitism of aphid hosts at the field level. We present evidence of rapid seasonal shifts in the endosymbiont frequency, suggesting a positive selection of endosymbionts at the host-level (aphids) through an agricultural growing season, by two mechanisms; (1) an increase of aphid infections with endosymbionts over time, and (2) the seasonal replacement of host clones within natural populations by increasing the prevalence of aphid clones closely associated to endosymbionts. Our results highlight how genotypic variation of hosts can affect the endosymbiont prevalence in the field, being an important factor for understanding the magnitude and direction of the adaptive and/or maladaptive responses of hosts to the environment. Full article

(This article belongs to the Collection Insect Symbionts: Evolution and Application)

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15 pages, 1961 KiB

Open AccessEditor’s ChoiceArticle

Organic Farming and Cover-Crop Management Reduce Pest Predation in Austrian Vineyards

by Jo Marie Reiff, Sebastian Kolb, Martin H. Entling, Thomas Herndl, Stefan Möth, Andreas Walzer, Matthias Kropf, Christoph Hoffmann and Silvia Winter

Insects 2021, 12(3), 220; https://doi.org/10.3390/insects12030220 - 4 Mar 2021

Cited by 23 | Viewed by 3894

Abstract

Habitat simplification and intensive use of pesticides are main drivers of global arthropod declines and are, thus, decreasing natural pest control. Organic farming, complex landscapes, and local vineyard management practices such as implementation of flower-rich cover-crop mixtures may be a promising approach to [...] Read more.

Habitat simplification and intensive use of pesticides are main drivers of global arthropod declines and are, thus, decreasing natural pest control. Organic farming, complex landscapes, and local vineyard management practices such as implementation of flower-rich cover-crop mixtures may be a promising approach to enhance predator abundance and, therefore, natural pest control. We examined the effect of organic versus integrated management, cover-crop diversity in the vineyard inter-rows, and landscape composition on the natural pest control of Lobesia botrana eggs and pupae. Predation of L. botrana pupae was reduced by organic farming and species-poor cover-crops by about 10%. Predation rates of L. botrana eggs did not differ significantly in any of the studied management options. Dominant predators were earwigs (Forficulidae), bush crickets (Tettigoniidae), and ants (Formicidae). Negative effects of organic viticulture are most likely related to the negative nontarget effects on arthropods related to the frequent sulfur and copper applications in combination with the avoidance of strongly damaging insecticides by integrated winegrowers. While a 10% difference in predation rates on a single pest stage is unlikely to have strong practical implications, our results show that the assumed effectiveness of environmentally friendly agriculture needs to be evaluated for specific crops and regions. Full article

(This article belongs to the Special Issue Improving Functional Biodiversity in Vineyards)

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16 pages, 2020 KiB

Open AccessEditor’s ChoiceArticle

The Eco-Bio-Social Factors That Modulate Aedes aegypti Abundance in South Texas Border Communities

by Jose G. Juarez, Selene M. Garcia-Luna, Matthew C. I. Medeiros, Katherine L. Dickinson, Monica K. Borucki, Matthias Frank, Ismael Badillo-Vargas, Luis F. Chaves and Gabriel L. Hamer

Insects 2021, 12(2), 183; https://doi.org/10.3390/insects12020183 - 21 Feb 2021

Cited by 9 | Viewed by 3347

Abstract

Aedes aegypti control requires dedicated resources that are usually scarce, limiting the reach and sustainability of vector control programs. This generates a need to focus on areas at risk of disease transmission and also understand the factors that might modulate local mosquito abundance. [...] Read more.

Aedes aegypti control requires dedicated resources that are usually scarce, limiting the reach and sustainability of vector control programs. This generates a need to focus on areas at risk of disease transmission and also understand the factors that might modulate local mosquito abundance. We evaluated the eco-bio-social factors that modulate indoor and outdoor relative abundance of female Ae. aegypti in communities of South Texas. We conducted housing quality and Knowledge Attitudes and Practices surveys in households that were part of a weekly mosquito surveillance program in November of 2017 and 2018. Our results showed widespread knowledge of mosquitoes and Zika virus by our participants. However, less than 35% considered them as serious problems in this region. The presence of window-mounted air conditioning units increased the risk of female mosquito relative abundance indoors. An increase in outdoor relative abundance was associated with larger properties and a higher number of children between 6 to 17 years of age. Interestingly, we observed that an increasing number of children <5 years of age modulated both indoor and outdoor relative abundance, with a 52% increase indoors and 30% decrease outdoors. The low perception of mosquito and disease risk highlights engagement needs for vector-borne disease prevention in this region. The identified risk factors can help guide public health officials in their efforts to reduce human and vector contact. Full article

(This article belongs to the Special Issue Urban Pests and Vectors: Interdisciplinary Links between Arthropod–Human Systems)

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24 pages, 5212 KiB

Open AccessEditor’s ChoiceArticle

Further Insights on the Migration Biology of Monarch Butterflies, Danaus plexippus (Lepidoptera: Nymphalidae) from the Pacific Northwest

by David G. James and Linda Kappen

Insects 2021, 12(2), 161; https://doi.org/10.3390/insects12020161 - 14 Feb 2021

Cited by 11 | Viewed by 4997

Abstract

The fall migration of monarch butterflies, Danaus plexippus (L.), in the Pacific Northwest was studied during 2017–2019 by tagging 14,040 captive-reared and 450 wild monarchs. One hundred and twenty-two captive-reared monarchs (0.87%) were recovered at distances averaging 899.9 ± 98.6 km for Washington-released [...] Read more.

The fall migration of monarch butterflies, Danaus plexippus (L.), in the Pacific Northwest was studied during 2017–2019 by tagging 14,040 captive-reared and 450 wild monarchs. One hundred and twenty-two captive-reared monarchs (0.87%) were recovered at distances averaging 899.9 ± 98.6 km for Washington-released and 630.5 ± 19.9 km for Oregon-released monarchs. The greatest straight-line release to recovery distance was 1392.1 km. A mean travel rate of 20.7 ± 2.2 km/day and maximum travel of 46.1 km/day were recorded. Recovery rates were greater for Oregon-released monarchs (0.92%) than Washington-released (0.34%) or Idaho-released monarchs (0.30%). Most monarchs (106/122) were recovered SSW-S-SSE in California, with 82 at 18 coastal overwintering sites. Two migrants from Oregon were recovered just weeks after release ovipositing in Santa Barbara and Palo Alto, CA. Two migrants released in central Washington recovered up to 360.0 km to the SE, and recoveries from Idaho releases to the S and SE suggests that some Pacific Northwest migrants fly to an alternative overwintering destination. Monarchs released in southern Oregon into smoky, poor quality air appeared to be as successful at reaching overwintering sites and apparently lived just as long as monarchs released into non-smoky, good quality air. Migration and lifespan for monarchs infected with the protozoan parasite, Ophryocystis elektroscirrha (McLaughlin and Myers), appeared to be similar to the migration and survival of uninfected monarchs, although data are limited. Our data improve our understanding of western monarch migration, serving as a basis for further studies and providing information for conservation planning. Full article

(This article belongs to the Collection Butterfly Diversity and Conservation)

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13 pages, 1420 KiB

Open AccessEditor’s ChoiceArticle

Host-Parasite Co-Evolution in Real-Time: Changes in Honey Bee Resistance Mechanisms and Mite Reproductive Strategies

by Arrigo Moro, Tjeerd Blacquière, Delphine Panziera, Vincent Dietemann and Peter Neumann

Insects 2021, 12(2), 120; https://doi.org/10.3390/insects12020120 - 29 Jan 2021

Cited by 17 | Viewed by 7389

Abstract

Co-evolution is a major driving force shaping the outcome of host-parasite interactions over time. After host shifts, the lack of co-evolution can have a drastic impact on novel host populations. Nevertheless, it is known that Western honey bee (Apismellifera) populations [...] Read more.

Co-evolution is a major driving force shaping the outcome of host-parasite interactions over time. After host shifts, the lack of co-evolution can have a drastic impact on novel host populations. Nevertheless, it is known that Western honey bee (Apismellifera) populations can cope with host-shifted ectoparasitic mites (Varroa destructor) by means of natural selection. However, adaptive phenotypic traits of the parasites and temporal variations in host resistance behavior are poorly understood. Here, we show that mites made adaptive shifts in reproductive strategy when associated with resistant hosts and that host resistance traits can change over time. In a fully-crossed field experiment, worker brood cells of local adapted and non-adapted (control) A.mellifera host colonies were infested with mites originating from both types of host colonies. Then, mite reproduction as well as recapping of cells and removal of infested brood (i.e., Varroa Sensitive Hygiene, VSH) by host workers were investigated and compared to data from the same groups of host colonies three years earlier. The data suggest adaptive shifts in mite reproductive strategies, because mites from adapted hosts have higher probabilities of reproduction, but lower fecundity, when infesting their associated hosts than mites in treated colonies. The results confirm that adapted hosts can reduce mite reproductive success. However, neither recapping of cells nor VSH were significantly expressed, even though the latter was significantly expressed in this adapted population three years earlier. This suggests temporal variation in the expression of adaptive host traits. It also appears as if mechanisms not investigated here were responsible for the reduced mite reproduction in the adapted hosts. In conclusion, a holistic view including mite adaptations and studies of the same parasite/host populations over time appears overdue to finally understand the mechanisms enabling survival of V.destructor-infested honey bee host colonies. Full article

(This article belongs to the Special Issue Honeybees and Wild Bees Health)

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12 pages, 3133 KiB

Open AccessEditor’s ChoiceArticle

Reproductive Soldier Development Is Controlled by Direct Physical Interactions with Reproductive and Soldier Termites

by Yudai Masuoka, Keigo Nuibe, Naoto Hayase, Takateru Oka and Kiyoto Maekawa

Insects 2021, 12(1), 76; https://doi.org/10.3390/insects12010076 - 15 Jan 2021

Cited by 5 | Viewed by 4634

Abstract

In eusocial insects (e.g., ants, bees, and termites), the roles of different castes are assigned to different individuals. These castes possess unique phenotypes that are specialized for specific tasks. The acquisition of sterile individuals with specific roles is considered a requirement for social [...] Read more.

In eusocial insects (e.g., ants, bees, and termites), the roles of different castes are assigned to different individuals. These castes possess unique phenotypes that are specialized for specific tasks. The acquisition of sterile individuals with specific roles is considered a requirement for social evolution. In termites, the soldier is a sterile caste. In primitive taxa (family Archotermopsidae and Stolotermitidae), however, secondary reproductives (neotenic reproductives) with their mandibles developed into weapons (so-called reproductive soldiers, also termed as soldier-headed reproductives or soldier neotenics) have been reported. To understand the developmental mechanism of this unique caste, it is necessary to understand the environmental cues and developmental processes of reproductive soldiers under natural conditions. Here, we established efficient conditions to induce reproductive soldiers in Zootermopsis nevadensis. Male reproductive soldiers frequently developed after the removal of both the king and soldiers from an incipient colony. Similarly, high differentiation rates of male reproductive soldiers were observed after king-and-soldier separation treatment using wire mesh. However, no male reproductive soldiers were produced without direct interaction with the queen. These results suggest that male reproductive soldier development is repressed by direct physical interactions with both the king and soldiers and facilitated by direct physical interaction with the queen. Full article

(This article belongs to the Section Insect Physiology, Reproduction and Development)

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22 pages, 2368 KiB

Open AccessEditor’s ChoiceArticle

The Genetic Basis for Salivary Gland Barriers to Arboviral Transmission

by Irma Sanchez-Vargas, Ken E. Olson and William C. Black

Insects 2021, 12(1), 73; https://doi.org/10.3390/insects12010073 - 15 Jan 2021

Cited by 20 | Viewed by 3709

Abstract

Arthropod-borne viruses (arboviruses) infect mosquito salivary glands and then escape to saliva prior to virus transmission. Arbovirus transmission from mosquitoes can be modulated by salivary gland infection barriers (SGIBs) and salivary gland escape barriers (SGEBs). We determined the influence of SGIBs and SGEBs [...] Read more.

Arthropod-borne viruses (arboviruses) infect mosquito salivary glands and then escape to saliva prior to virus transmission. Arbovirus transmission from mosquitoes can be modulated by salivary gland infection barriers (SGIBs) and salivary gland escape barriers (SGEBs). We determined the influence of SGIBs and SGEBs by estimating the quantitative genetic contributions of Aedes aegypti half-sib families (Mapastepec, Mexico) infected with three dengue 2 (DENV2), two chikungunya (CHIKV), and two Zika (ZIKV) genotypes. We determined virus titer per salivary gland and saliva at seven days post-infection and virus prevalence in the half-sib population. CHIKV or ZIKV genotypes did not present SGIB, whereas DENV2 genotypes showed low rates of SGIB. However, virus titer and prevalence due to additive genetic factors in the half-sib family displayed a significant narrow-sense heritability (h²) for SGIB in two of the three DENV2 genotypes and one CHIKV and one ZIKV genotype. SGEBs were detected in all seven virus strains: 60–88% of DENV2 and 48–62% of CHIKV or ZIKV genotype infections. SGEB h² was significant for all CHIKV or ZIKV genotypes but not for any of the DENV2 genotypes. SGIBs and SGEBs exhibited classical gene-by-gene interaction dynamics and are influenced by genetic factors in the mosquito and the virus. Full article

(This article belongs to the Special Issue A Tribute to Bill Black: Breakthroughs in Mosquito Vector Competence and Insecticide Resistance Research)

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17 pages, 9917 KiB

Open AccessEditor’s ChoiceArticle

Darwin Returns to the Galapagos: Genetic and Morphological Analyses Confirm the Presence of Tramea darwini at the Archipelago (Odonata, Libellulidae)

by María Olalla Lorenzo-Carballa, Rosser W. Garrison, Andrea C. Encalada and Adolfo Cordero-Rivera

Insects 2021, 12(1), 21; https://doi.org/10.3390/insects12010021 - 31 Dec 2020

Cited by 7 | Viewed by 3071

Abstract

The status of the Tramea species present in the Galapagos Islands (Odonata, Libellulidae) has been the subject of a long-standing debate among odonatologists. Here, we use molecular and morphological data to analyze a series of specimens from this genus collected in 2018 from [...] Read more.

The status of the Tramea species present in the Galapagos Islands (Odonata, Libellulidae) has been the subject of a long-standing debate among odonatologists. Here, we use molecular and morphological data to analyze a series of specimens from this genus collected in 2018 from the Islands of San Cristobal, Isabela, and Santa Cruz, with the aim of determining their relationship with Tramea calverti Muttkowski and with their currently considered senior synonym T. cophysa Hagen. We combined sequencing of mitochondrial and nuclear DNA with morphological examination of several specimens of Tramea, including representatives of continental T. cophysa and T. calverti. Our molecular analyses place the Tramea from Galapagos in the same clade as T. calverti, with T. cophysa as a closely related species. The morphological analyses found only one consistent difference between T. cophysa and T. calverti: the presence of an accessory lobe in the male vesica spermalis of T. cophysa that is absent in T. calverti and in the Tramea from Galapagos. In agreement with our genetic results, the overall morphological differences documented by us indicate that the Galapagos material examined is conspecific with T. calverti. In light of this, and following the principle of priority in taxonomic nomenclature, Tramea calverti Muttkowski, 1910 should hereafter be considered a junior synonym of Tramea darwini Kirby, 1889. Full article

(This article belongs to the Special Issue Odonates in Human Environments)

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17 pages, 609 KiB

Open AccessEditor’s ChoiceArticle

Tick Preventive Behaviors and Practices Adopted by Medical Students from Poland, Germany, and Thailand in Relation to Socio-Demographic Conditions and Their Knowledge of Ticks and Tick-Borne Diseases

by Alicja Buczek, Johanna Pilch and Weronika Buczek

Insects 2020, 11(12), 863; https://doi.org/10.3390/insects11120863 - 3 Dec 2020

Cited by 8 | Viewed by 2663

Abstract

Given the high medical importance of ticks, we analyzed the most common preventive behaviors and practices adopted by medical students from Poland, Germany, and Thailand, and the level of their knowledge of ticks and tick-borne diseases. A survey consisting of 19 questions was [...] Read more.

Given the high medical importance of ticks, we analyzed the most common preventive behaviors and practices adopted by medical students from Poland, Germany, and Thailand, and the level of their knowledge of ticks and tick-borne diseases. A survey consisting of 19 questions was conducted among 636 randomly selected students. The study showed that the Polish and German students preferred inspection of the body on their return home (86.9% and 63.5%, respectively) and wearing protective clothes (79.8% and 32.3%, respectively) as part of prophylaxis. The Thai students most often chose wearing protective clothes (54.7%) and preventive behavior in tick habitats (42.7%). Approximately 7% of the Polish medical students and as many as 22% of the German and Thai respondents did not use any means of prevention. Our analyses suggest that the use of preventive methods and respondents’ behaviors depend on socio-demographic factors and the level of health education. The insufficient practical implementation of tick prevention measures by the medical students suggests a need for verification of health education programs in schools as well as effective popularization and educational activities. It is also necessary to develop a public health protection strategy against the effects of tick bites. Full article

(This article belongs to the Section Insect Societies and Sociality)

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9 pages, 1636 KiB

Open AccessEditor’s ChoiceArticle

Optimizing Trap Characteristics to Monitor the Leaffooted Bug Leptoglossus zonatus (Heteroptera: Coreidae) in Orchards

by Houston Wilson, Jessica J. Maccaro and Kent M. Daane

Insects 2020, 11(6), 358; https://doi.org/10.3390/insects11060358 - 9 Jun 2020

Cited by 10 | Viewed by 2855

Abstract

The leaffooted bug, Leptoglossus zonatus (Heteroptera: Coreidae), has become a key pest of almonds, pistachios, and pomegranates in California. Adults and nymphs directly feed on nuts and fruits, which reduces crop yield and quality and can facilitate pathogen infections. Current monitoring strategies require [...] Read more.

The leaffooted bug, Leptoglossus zonatus (Heteroptera: Coreidae), has become a key pest of almonds, pistachios, and pomegranates in California. Adults and nymphs directly feed on nuts and fruits, which reduces crop yield and quality and can facilitate pathogen infections. Current monitoring strategies require growers to actively sample the tree canopy, with no economic thresholds being developed for this pest. To improve monitoring of L. zonatus, a three-year study was conducted to identify an optimal trap. A hanging cross-vane panel trap was identified as the best trap type in Year 1, and subsequent work in Years 1–3 focused on refining its use by modifying surface texture and color. Results indicated that coating trap surfaces with the lubricant fluon improved trap catching ability, and adults were most frequently recovered in yellow traps. A hanging cross-vane panel trap with these features could serve as the basis for the development of a new monitoring system for this pest in orchards, which could be improved further if semiochemical lures will be developed. Full article

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16 pages, 2230 KiB

Open AccessEditor’s ChoiceArticle

Hidden in Plain Sight: Comprehensive Molecular Phylogeny of Keroplatidae and Lygistorrhinidae (Diptera) Reveals Parallel Evolution and Leads to a Revised Family Classification

by Michal Mantič, Tomáš Sikora, Nikola Burdíková, Vladimir Blagoderov, Jostein Kjærandsen, Olavi Kurina and Jan Ševčík

Insects 2020, 11(6), 348; https://doi.org/10.3390/insects11060348 - 4 Jun 2020

Cited by 19 | Viewed by 4491

Abstract

We provide the first molecular phylogeny of Keroplatidae and Lygistorrhinidae, families of fungus gnats (Diptera: Bibionomorpha: Sciaroidea). Phylogenies reconstructed by Maximum Likelihood and Bayesian methods, based on four nuclear and four mitochondrial gene markers (5106 base pairs) sequenced for 75 genera and 105 [...] Read more.

We provide the first molecular phylogeny of Keroplatidae and Lygistorrhinidae, families of fungus gnats (Diptera: Bibionomorpha: Sciaroidea). Phylogenies reconstructed by Maximum Likelihood and Bayesian methods, based on four nuclear and four mitochondrial gene markers (5106 base pairs) sequenced for 75 genera and 105 species, show Keroplatidae as monophyletic only with the family Lygistorrhinidae included, herewith treated as the subfamily Lygistorrhininae stat. nov. The subfamily Arachnocampinae is retained in the family, although lowering its overall support. An early branching clade, comprising species of Platyura Meigen, 1803 and Paleoplatyura melanderi Fisher, 1941, forms subfamily Platyurinae Loew, 1850 stat. nov. The subfamilies Sciarokeroplatinae and Macrocerinae grouped together with three genera considered here as Keroplatidae incertae sedis. Subfamily Lygistorrhininae forms a sister clade to subfamily Keroplatinae, both retained monophyletic with high support. The traditional division of the subfamily Keroplatinae into the tribes Orfeliini and Keroplatini appears as outdated, resting largely on adaptive characters prone to parallel evolution. We find support for an alternative tribe corresponding to the Cloeophoromyia–Asindulum genus group, but a tribal reclassification of the Keroplatinae is left for future studies. The genus Heteropterna Skuse, 1888 is considered as identical with Ctenoceridion Matile, 1972 syn. nov. Full article

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11 pages, 1136 KiB

Open AccessEditor’s ChoiceArticle

Large- and Small-Scale Environmental Factors Drive Distributions of Ant Mound Size Across a Latitudinal Gradient

by Orsolya Juhász, Zoltán Bátori, Gema Trigos-Peral, Gábor Lőrinczi, Gábor Módra, Imola Bóni, Péter János Kiss, Dianne Joy Aguilon, Anna Tenyér and István Maák

Insects 2020, 11(6), 350; https://doi.org/10.3390/insects11060350 - 4 Jun 2020

Cited by 6 | Viewed by 3792

Abstract

Red wood ants are keystone species of forest ecosystems in Europe. Environmental factors and habitat characteristics affect the size of their nest mounds, an important trait being in concordance with a colony’s well-being and impact on its surroundings. In this study, we investigated [...] Read more.

Red wood ants are keystone species of forest ecosystems in Europe. Environmental factors and habitat characteristics affect the size of their nest mounds, an important trait being in concordance with a colony’s well-being and impact on its surroundings. In this study, we investigated the effect of large-scale (latitude and altitude) and small-scale environmental factors (e.g., characteristics of the forest) on the size of nest mounds of Formica polyctena in Central Europe. We predicted that the change in nest size is in accordance with Bergmann’s rule that states that the body size of endotherm animals increases with the higher latitude and/or altitude. We found that the size of nests increased along the latitudinal gradient in accordance with Bergmann’s rule. The irradiation was the most important factor responsible for the changes in nest size, but temperature and local factors, like the perimeter of the trees and their distance from the nest, were also involved. Considering our results, we can better understand the long-term effects and consequences of the fast-changing environmental factors on this ecologically important group. This knowledge can contribute to the planning of forest management tactics in concordance with the assurance of the long-term survival of red wood ants. Full article

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10 pages, 31939 KiB

Open AccessEditor’s ChoiceArticle

A Comparison of Morphology among Four Termite Species with Different Moisture Requirements

by John Zukowski and Nan-Yao Su

Insects 2020, 11(5), 262; https://doi.org/10.3390/insects11050262 - 25 Apr 2020

Cited by 4 | Viewed by 2645

Abstract

The thicknesses of the cuticle and rectal pads, and the spiracle morphology were compared for four termite species from different habitats, including one drywood termite, Cryptotermes brevis Walker, one “wetwood” termite, Cryptotermes cavifrons Banks, one subterranean termite, Coptotermes formosanus Shiraki, and one dampwood [...] Read more.

The thicknesses of the cuticle and rectal pads, and the spiracle morphology were compared for four termite species from different habitats, including one drywood termite, Cryptotermes brevis Walker, one “wetwood” termite, Cryptotermes cavifrons Banks, one subterranean termite, Coptotermes formosanus Shiraki, and one dampwood termite, Neotermes jouteli (Banks). Cuticle thicknesses were significantly different among all four termite species. Neotermes jouteli had the thickest cuticle, while Co. formosanus had the thinnest. The cuticle of C. brevis was thicker than that of C. cavifrons and Co. formosanus, which may reflect a comparably greater need to prevent water loss in drier habitats for C. brevis. Rectal pad widths were significantly different among all four termite species, except those of C. brevis with N. jouteli. The rectal pads of N. jouteli and C. brevis were thicker than those of C. cavifrons and Co. formosanus, and the rectal pads of C. cavifrons were thicker than those of Co. formosanus in turn. Larger rectal pads likely account for the water conservation mechanism of producing dry, pelleted frass in the kalotermitids (N. jouteli, C. brevis, and C. cavifrons). Morphological observations of the spiracles showed the presence of protuberances (atrial arms) in the three kalotermitids. The function of this protuberance is unclear, but it may serve as a sac-like structure, aiding in gas exchange, or a moisture trap aiding in the prevention of water loss through evaporation. Full article

(This article belongs to the Special Issue Insect Water Relations)

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13 pages, 2661 KiB

Open AccessEditor’s ChoiceArticle

Monitoring Dermacentor reticulatus Host-Seeking Activity in Natural Conditions

by Zbigniew Zając, Katarzyna Bartosik and Aneta Woźniak

Insects 2020, 11(5), 264; https://doi.org/10.3390/insects11050264 - 25 Apr 2020

Cited by 5 | Viewed by 2464

Abstract

Ticks are hematophagous ectoparasites of humans and animals. These arthropods employ different strategies in their host-seeking activity; most often, it is the “nest”- and “pasture-questing” behaviour. Some species, e.g., Dermacentor reticulatus, exhibit both types of activity depending on their developmental stage. The [...] Read more.

Ticks are hematophagous ectoparasites of humans and animals. These arthropods employ different strategies in their host-seeking activity; most often, it is the “nest”- and “pasture-questing” behaviour. Some species, e.g., Dermacentor reticulatus, exhibit both types of activity depending on their developmental stage. The aim of the present study was to investigate the host-seeking activity of adult D. reticulatus ticks in the eastern part of Poland. To this end, ticks were collected with the flagging method during their seasonal activity in three different types of habitat. Active specimens were marked with a permanent marker and then released. This was repeated consistently at 7-day intervals using a different colour of the marker each time, which allowed tracking the questing activity of the specimens. Most frequently, repetitive tick activity (repeated up to seven times) was noted in a locality surrounded by urban developments. In an agriculturally unused open meadow habitat, 69.9% of D. reticulatus ticks were found to undertake questing activity only once. D. reticulatus females proved to be more aggressive and determined to find a host than the males of this species. Adult D. reticulatus ticks are able to stay in the habitat for a long time and undertake multiple host-seeking activities. The greatest threat of attacks on animals, including domestic animals, and sporadically humans, by these ticks occurs in meadow habitats, which are preferred by this species. Full article

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