Insects

17 pages, 1416 KiB

Open AccessArticle

Combination of Chitosan and Essential Oils for Tomatoes Protection Against the Insect Pest Spodoptera littoralis (Lepidoptera: Noctuidae)

by Thomas Drozdz, Philippe Couzi, Manuel Massot, Barbara Conti, Roberta Ascrizzi and David Siaussat

Insects 2025, 16(7), 718; https://doi.org/10.3390/insects16070718 (registering DOI) - 12 Jul 2025

Abstract

Tomatoes are one of the most popular vegetables. The high level of production in the world is often offset by numerous losses that occur during production in the field or in the post-production stages. Preservation in its fresh form is a challenge, particularly [...] Read more.

Tomatoes are one of the most popular vegetables. The high level of production in the world is often offset by numerous losses that occur during production in the field or in the post-production stages. Preservation in its fresh form is a challenge, particularly due to pest attacks on stored food. A promising natural and inexpensive solution to protect against pests is the use of chitosan (CH), which can be associated with essential oils (EOs) with repellent effects. In previous studies, some protective effects have been demonstrated using chitosan films coated with EOs. In this study, we tested CH-EOs associations on tomato fruits to evaluate their efficacy against attacks by the pest Spodoptera littoralis (Boisduval, 1833), taking into account parameters such as age and body mass of the larvae and the effect over time (10 days) of the treatments. Our study highlights the potential of the combination of CH and cinnamon EO as an environmentally friendly solution to protect tomatoes from S. littoralis attack. Here we found a repellent effect of cinnamon EO combined with CH on S. littoralis larvae, with no effect on larval attractiveness or repellence for CH alone and the four other EOs tested. The main compound in cinnamon EO, (E)-cinnamaldehyde, had no overall repellent effect on larvae, but had specific effects when larval age, body mass, and post-treatment time were taken into account. Full article

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

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14 pages, 1323 KiB

Open AccessArticle

Impact of Temperature and Soil Moisture on the Life Cycle of the Strawberry Pest Priophorus fulvostigmatus and Its Control

by Juan Cui, Jingxu Yin, Lihuan Dong, Yu Gao, Shusen Shi, Jingzhu Zou, Wenbo Li and Yu Wang

Insects 2025, 16(7), 717; https://doi.org/10.3390/insects16070717 (registering DOI) - 12 Jul 2025

Abstract

Priophorus fulvostigmatus, a species of leaf-cutter wasp, is an important leaf-feeding pest on strawberries. We investigated the effects of temperature and soil moisture content on key life cycle parameters of P. fulvostigmatus. The development time, survival, fecundity, and life table parameters [...] Read more.

Priophorus fulvostigmatus, a species of leaf-cutter wasp, is an important leaf-feeding pest on strawberries. We investigated the effects of temperature and soil moisture content on key life cycle parameters of P. fulvostigmatus. The development time, survival, fecundity, and life table parameters of P. fulvostigmatus were observed at five temperatures. Pupal development and survival under five moisture contents (8%, 12%, 16%, 20%, and 24%) and four durations of water immersion (0, 1, 3, and 5 d) were recorded. P. fulvostigmatus could complete its life cycle at a constant temperature range of 16–28 °C. The duration of the immature stage first decreased and then increased with rising temperature, being longest at 16 °C and shortest at 25 °C. Female longevity and female fecundity did not differ between the temperature range of 16–25 °C. However, survival rates at all developmental stages decreased with increasing temperature. At 28 °C, both fecundity and survival rates of P. fulvostigmatus were significantly reduced compared to other temperatures. Compared with that at the constant temperature of 22 °C, the developmental duration of each stage was similar at a fluctuating temperature of 22 °C. The number of eggs laid per female, the longevity of male adults, and the eclosion rate were all significantly reduced. The net reproductive rate (R₀) under constant temperature conditions was significantly higher than under fluctuating temperature conditions, and the mean generation period (T), intrinsic rate of increase (r), and finite rate of increase (λ) differed significantly. The soil moisture content significantly impacted the pupation and eclosion of P. fulvostigmatus. Differences in soil moisture content had no significant effect on the duration of development; a moisture content of 8–16% was more suitable for their pupation and eclosion. Pupal development differed significantly between different periods of water immersion after the mature larvae were immersed in the soil. The longer the larvae remained in the soil, the lower their emergence rate after immersion. Thus, environmental temperature affected the growth, reproduction, and survival of P. fulvostigmatus. The optimal soil moisture for pupation of mature larvae was 12% to 16%. After the larvae were immersed in soil, the emergence rate was significantly reduced. These findings expand our understanding of the biological characteristics of P. fulvostigmatus and can facilitate the development of prevention and control strategies. Full article

(This article belongs to the Collection Integrated Pest Management Strategies for Horticultural Crops)

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14 pages, 1826 KiB

Open AccessArticle

Combination of the Parasitoid Spalangia endius Walker and Chemical Pesticides for the Control of Zeugodacus cucurbitae (Coquillett)

by Lei Li, Dongyin Han, Jing Zhao, Haiyan Qiu, Fangping Zhang, Zhengpei Ye and Yueguan Fu

Insects 2025, 16(7), 716; https://doi.org/10.3390/insects16070716 (registering DOI) - 12 Jul 2025

Abstract

Spalangia endius Walker, a pupal parasitoid of the alien invasive pest Zeugodacus cucurbitae (Coquillett), causes 33% host mortality. This study assessed whether combining S. endius with insecticides (abamectin, thiamethoxam, nitenpyram, emamectin benzoate, or beta-cypermethrin)—all effective against Z. cucurbitae—could enhance control efficacy. Among [...] Read more.

Spalangia endius Walker, a pupal parasitoid of the alien invasive pest Zeugodacus cucurbitae (Coquillett), causes 33% host mortality. This study assessed whether combining S. endius with insecticides (abamectin, thiamethoxam, nitenpyram, emamectin benzoate, or beta-cypermethrin)—all effective against Z. cucurbitae—could enhance control efficacy. Among these, abamectin was the least toxic to adult S. endius. Surface contact treatments with 12 and 15 mg a.i./kg of abamectin did not significantly increase S. endius mortality. However, mixing 12 mg a.i./kg of abamectin into a honey solution to encourage ingestion decreased the survival, parasitism, and fecundity of S. endius. In olfactometer assays, S. endius adults avoided abamectin-treated host pupae, though prior exposure to abamectin mitigated this avoidance. The timing of abamectin soil application relative to host pupation and S. endius release affects host mortality. The most effective timing is spraying abamectin before host pupation (to expose Z. cucurbitae larvae) and then releasing S. endius. Field trials confirmed that combining abamectin (12 mg a.i./kg) with S. endius increased host mortality more than either treatment alone. In conclusion, abamectin (12 mg a.i./kg) is a suitable insecticide for combination with S. endius to control Z. cucurbitae. The application sequence should be spraying abamectin before hosts pupate and, only after that, releasing the parasitoid. Full article

(This article belongs to the Special Issue Advances in Research on Parasitoids for Biological Control of Agricultural Pests)

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17 pages, 3641 KiB

Open AccessArticle

Enhancing Biological Control of Drosophila suzukii: Efficacy of Trichopria drosophilae Releases and Interactions with a Native Parasitoid, Pachycrepoideus vindemiae

by Nuray Baser, Charbel Matar, Luca Rossini, Abir Ibn Amor, Dragana Šunjka, Dragana Bošković, Stefania Gualano and Franco Santoro

Insects 2025, 16(7), 715; https://doi.org/10.3390/insects16070715 - 11 Jul 2025

Abstract

The spotted wing drosophila, Drosophila suzukii is an injurious polyphagous pest threatening worldwide soft fruit production. Its high adaptability to new colonized environments, short life cycle, and wide host range are supporting its rapid spread. The most common techniques to reduce its significant [...] Read more.

The spotted wing drosophila, Drosophila suzukii is an injurious polyphagous pest threatening worldwide soft fruit production. Its high adaptability to new colonized environments, short life cycle, and wide host range are supporting its rapid spread. The most common techniques to reduce its significant economic damage are based on multiple insecticides applications per season, even prior to the harvest, which reduces agroecosystem biodiversity and affects human and animal health. Environmental concerns and regulatory restrictions on insecticide use are driving the need for studies on alternative biological control strategies. This study aimed to assess the effect of T. drosphilae in controlling D. suzukii infestations and its interaction with P. vindemiae, a secondary parasitoid naturally present in Apulia (South Italy). Field experiments were carried out in organic cherry orchards in Gioia del Colle (Bari, Italy) to test the efficacy and adaptability of T. drosphilae following weekly releases of artificially reared individuals. Additionally, the interaction between P. vindemiae and T. drosphilae was studied under laboratory conditions. Results from field experiments showed that D. suzukii populations were significantly lower when both parasitoids were present. However, T. drosophilae was less prone to adaptation, so its presence and parasitism were limited to the post-release period. Laboratory experiments, instead, confirmed the high reduction of D. suzukii populations when both parasitoids are present. However, the co-existence of the two parasitoids resulted in a reduced parasitism rate and offspring production, notably for T. drosophilae. This competitive disadvantage may explain its poor establishment in field conditions. These findings suggest that the field release of the two natural enemies should be carried out with reference to their natural population abundance to not generate competition effects. Full article

(This article belongs to the Special Issue Advances in Insect Pest Management: Innovative Approaches to Enhance Plant Protection)

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10 pages, 863 KiB

Open AccessArticle

FlowerPatch: New Method to Measure Nectar Volume in Artificial Flowers

by Edwin Lara-Perez, Jose Agosto Rivera, Tugrul Giray, Remi Megret Laboye and Edwin Flórez Gómez

Insects 2025, 16(7), 714; https://doi.org/10.3390/insects16070714 - 11 Jul 2025

Abstract

This article proposes a new Flower Patch Nectar Sensor to address the problem of detecting and measuring nectar in artificial flowers used in experiments on pollinator behavior. Traditional methods have focused mainly on recording the visits of pollinators to the flowers, without addressing [...] Read more.

This article proposes a new Flower Patch Nectar Sensor to address the problem of detecting and measuring nectar in artificial flowers used in experiments on pollinator behavior. Traditional methods have focused mainly on recording the visits of pollinators to the flowers, without addressing the dynamic variations in nectar in terms of volume and concentration. The proposed approach provides more detailed information about the nectar consumption by bees and allows for the determination of the optimal time to refill the flowers. This study introduces an innovative method that uses electrodes and an oscillator circuit to measure the volume of nectar present in the flower. The system correlates the concentration of nectar with a frequency signal that can be processed by a microcontroller. It was evaluated using initial volumes ranging from 1

μ

L to 4

μ

L, demonstrating its ability to accurately detect variations in nectar, even up to the point where the frequency approaches zero. The results confirm that this method allows us to identify how the reward offered to pollinators (represented by nectar) varies over time, in terms of concentration, under both controlled and natural conditions. Additionally, graphs are presented that show the relationship between an initial volume of 4

μ

L and variations in the frequency signal over a period of 25 min, highlighting the influence of these factors on nectar dynamics. This work not only introduces an innovative approach for the dynamic monitoring of nectar in artificial flowers but also lays the groundwork for future studies on the physical and chemical modeling of nectar in response to environmental conditions. Full article

(This article belongs to the Special Issue Current Advances in Pollinator Insects)

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15 pages, 2036 KiB

Open AccessArticle

What Is the Relationship Between Efficacy of Seed Treatment with Insecticides Against Dalbulus maidis (Delong and Wolcott) (Hemiptera: Cicadellidae) Healthy and Infected with Spiroplasm in the Corn Stunt Control?

by Ana Carolina M. Redoan, Vinicius M. Marques, Poliana S. Pereira, Ivênio R. de Oliveira, Dagma D. Silva-Araújo, Luciano V. Cota, Marcos Antonio M. Fadini, Charles M. Oliveira, Diego D. Rafael and Simone Mendes

Insects 2025, 16(7), 713; https://doi.org/10.3390/insects16070713 - 11 Jul 2025

Abstract

Seed treatments with insecticides are important tools for managing corn stunting disease complex (CSDC) transmitted by Dalbulus maidis (Hemiptera: Cicadellidae) by reducing the initial leafhoppers’ population and, consequently, the risk of pathogen transmission. We evaluated the effect of insecticides used in seed treatment [...] Read more.

Seed treatments with insecticides are important tools for managing corn stunting disease complex (CSDC) transmitted by Dalbulus maidis (Hemiptera: Cicadellidae) by reducing the initial leafhoppers’ population and, consequently, the risk of pathogen transmission. We evaluated the effect of insecticides used in seed treatment on both healthy and spiroplasma-infected leafhoppers, the persistence of the seed treatment effect on disease symptom severity, and its impact on corn productivity. At the V2 stage, imidacloprid/thiodicarb was the most effective, resulting in 100% mortality of healthy leafhoppers and 85.7% mortality of infective ones, thus preventing spiroplasma transmission. Thiamethoxam and methomyl + fipronil/thiamethoxam showed a high total mortality after 72 h, but only for the infective leafhoppers, with a total mortality of healthy leafhoppers around 40%, reducing the number of plants with symptoms by 80% and 90%, respectively. Our results prove that there is a difference between the chemical molecules and that the infected leafhoppers are more susceptible. Insecticide seed treatment was effective until the V2 growth stage, and imidacloprid/thiodicarb was the most effective product tested. Infective leafhoppers were more susceptible to insecticide seed treatments, and the infestation by the corn leafhopper carrying spiroplasma in the early stages of plant development heavily reduced corn yield. Full article

(This article belongs to the Special Issue Corn Insect Pests: From Biology to Control Technology)

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15 pages, 754 KiB

Open AccessArticle

Effect of Volatile Organic Compounds from Branches of Healthy and Unhealthy Araucaria araucana (Molina) K. Koch Trees on Host Selection by Bark Beetle Sinophloeus porteri (Coleoptera: Curculionidae)

by Washington Aniñir, Leonardo Bardehle, Cristian Montalva, Andrés Quiroz and Javier Espinoza

Insects 2025, 16(7), 712; https://doi.org/10.3390/insects16070712 - 10 Jul 2025

Abstract

Araucaria araucana is one of the longest-living Chilean trees. Recently, Araucaria Leaf Damage disease, which causes damage to branches and crowns, was detected. Sinophloeus porteri, a bark beetle affecting A. araucana, could be associated with foliar damage. However, little is known [...] Read more.

Araucaria araucana is one of the longest-living Chilean trees. Recently, Araucaria Leaf Damage disease, which causes damage to branches and crowns, was detected. Sinophloeus porteri, a bark beetle affecting A. araucana, could be associated with foliar damage. However, little is known about their ecological and chemical interactions. This study examined the olfactory response of S. porteri to volatiles emitted from A. araucana. Branches and weevils were collected from a national park, and volatiles were trapped from both healthy and unhealthy branches. Thirty terpenes were identified, some of which were reported for the first time in A. araucana. Healthy branches emitted large amounts of myrcene (>360 ng g⁻¹ day⁻¹), and unhealthy branches showed high hibaene emanations (>140 ng g⁻¹ day⁻¹). Olfactory assays verified that S. porteri was attracted to the volatile blends of branches, regardless of the health condition of the branches, but preferred the blend of unhealthy branches. Moreover, myrcene was repellent to these weevils, and hibaene acted as an attractant, suggesting that A. araucana might use myrcene for defense against S. porteri, and hibaene could stimulate host selection by beetles. Full article

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

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20 pages, 3517 KiB

Open AccessArticle

Diversity and Functional Potential of Gut Bacteria Associated with the Insect Arsenura armida (Lepidoptera: Saturniidae)

by María Griselda López-Hernández, Reiner Rincón-Rosales, Clara Ivette Rincón-Molina, Luis Alberto Manzano-Gómez, Adriana Gen-Jiménez, Julio Cesar Maldonado-Gómez and Francisco Alexander Rincón-Molina

Insects 2025, 16(7), 711; https://doi.org/10.3390/insects16070711 - 10 Jul 2025

Abstract

Insects are often associated with diverse microorganisms that enhance their metabolism and nutrient assimilation. These microorganisms, residing in the insect’s gut, play a crucial role in breaking down complex molecules into simpler compounds essential for the host’s growth. This study investigates the diversity [...] Read more.

Insects are often associated with diverse microorganisms that enhance their metabolism and nutrient assimilation. These microorganisms, residing in the insect’s gut, play a crucial role in breaking down complex molecules into simpler compounds essential for the host’s growth. This study investigates the diversity and functional potential of symbiotic bacteria in the gut of Arsenura armida (Lepidoptera: Saturniidae) larvae, an edible insect from southeastern Mexico, using culture-dependent and metagenomic approaches. Bacterial strains were isolated from different gut sections (foregut, midgut, and hindgut) and cultured on general-purpose media. Isolates were identified through 16S rRNA gene sequencing and genomic fingerprinting. Metagenomics revealed the bacterial community structure and diversity, along with their functional potential. A total of 96 bacterial strains were isolated, predominantly Gram-negative bacilli. Rapidly growing colonies exhibited enzymatic activity, cellulose degradation, and sugar production. Phylogenetic analysis identified eight genera, including Acinetobacter, Bacillus, Enterobacter, Pseudomonas, and others, with significant cellulose-degrading capabilities. Metagenomics confirmed Bacillota as the most abundant phylum. These complementary methods revealed abundant symbiotic bacteria with key metabolic roles in A. armida, offering promising biotechnological applications in enzymatic bioconversion and cellulose degradation. Full article

(This article belongs to the Section Insect Behavior and Pathology)

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61 pages, 30208 KiB

Open AccessArticle

New Amber Fossils Indicate That Larvae of Dermestidae Had Longer Defensive Structures in the Past

by Jéhan Le Cadre, Joshua Gauweiler, Joachim T. Haug, Sofía I. Arce, Viktor Baranov, Jörg U. Hammel, Carolin Haug, Uwe Kaulfuss, Christine Kiesmüller, Ryan C. McKellar, Patrick Müller, Marie K. Hörnig and Ana Zippel

Insects 2025, 16(7), 710; https://doi.org/10.3390/insects16070710 - 10 Jul 2025

Abstract

Representatives of Dermestidae (skin, larder, and carpet beetles) play a crucial role as decomposers in global ecosystems, facilitating the recycling of animal and plant biomass to sustain nutrient cycling. Despite their widespread ecological presence and functional importance, the fossil record of their larval [...] Read more.

Representatives of Dermestidae (skin, larder, and carpet beetles) play a crucial role as decomposers in global ecosystems, facilitating the recycling of animal and plant biomass to sustain nutrient cycling. Despite their widespread ecological presence and functional importance, the fossil record of their larval stages has remained sparse, with previous documentation limited to occasional discoveries. This study significantly expands the larval fossil record by identifying 36 amber-preserved specimens from the Cretaceous, Eocene, and Miocene time slices, obtained from deposits distributed globally. By challenging the historical view of larval fossil rarity, we reveal morphological changes in defensive setae over geological time, demonstrating that Cretaceous and later fossil larvae possess significantly longer absolute and relative setal lengths compared to their extant counterparts. These findings, bolstered by quantitative comparisons of setal and body dimensions across fossil and extant representatives, indicate evolutionary adaptations in defensive structures dating back at least 100 million years. Our results offer new insights into the paleobiology of the group Dermestidae, highlighting how the morphology of larvae potentially reflects historical ecological pressures and resources availability. This study emphasizes the importance of integrating fossil evidence with comparative morphology to elucidate the evolutionary trajectories and functional roles of larvae in ancient terrestrial ecosystems. Full article

(This article belongs to the Special Issue Revival of a Prominent Taxonomy of Insects)

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10 pages, 2050 KiB

Open AccessArticle

Inheritance Mode of a Red-Eye Mutation in Macrolophus pygmaeus (Hemiptera: Miridae)

by María del Carmen Reche, Carolina Grávalos, Virginia Balanza, Ana Belén Abelaira, Amador Rodríguez-Gómez and Pablo Bielza

Insects 2025, 16(7), 709; https://doi.org/10.3390/insects16070709 - 10 Jul 2025

Abstract

A mutation affecting eye color was discovered in Macrolophus pygmaeus (Rambur) (Hemiptera: Miridae). This species is an important biological control agent used to manage whiteflies and other arthropod pests in greenhouse crops. Typically, these predators exhibit a dark eye coloration, ranging from garnet [...] Read more.

A mutation affecting eye color was discovered in Macrolophus pygmaeus (Rambur) (Hemiptera: Miridae). This species is an important biological control agent used to manage whiteflies and other arthropod pests in greenhouse crops. Typically, these predators exhibit a dark eye coloration, ranging from garnet to black. However, individuals with bright red eyes have been identified within wild populations, making them easily distinguishable. The objective of this study was to study the mode of inheritance of the red eye color mutation observed. Additionally, a comparative analysis of key biological traits was conducted between individuals carrying the mutation and those from a wild-type population. From these specimens, a population carrying this eye color mutation, referred to as ruby, was established. Genetic analyses revealed that the red coloration is controlled by a single recessive allele located on an autosomal chromosome. Red-eyed individuals exhibited superior performance in biological traits, including greater body size in both males and females, as well as increased fecundity and longevity in females. The utilization of this red-eyed variant could be valuable as a visual marker in ecological and biological studies of population dynamics. Full article

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

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17 pages, 4288 KiB

Open AccessArticle

Evaluation of Pupal Parasitoids Trichomalopsis ovigastra and Pachycrepoideus vindemiae as Potential Biological Control Agents of Bactrocera dorsalis

by Ziwen Teng, Yiting Wang, Minghao Jiang, Yikun Zhang, Xintong Wang, Fanghao Wan and Hongxu Zhou

Insects 2025, 16(7), 708; https://doi.org/10.3390/insects16070708 - 10 Jul 2025

Abstract

Parasitoid wasps are vital for biological control, and while new species continue to be discovered, evaluating their biological characteristics is crucial for realizing their potential for pest management. Pachycrepoideus vindemiae (Rondani) (Hymenoptera: Pteromalidae) is a well-studied parasitoid of dipteran pests, while Trichomalopsis ovigastra [...] Read more.

Parasitoid wasps are vital for biological control, and while new species continue to be discovered, evaluating their biological characteristics is crucial for realizing their potential for pest management. Pachycrepoideus vindemiae (Rondani) (Hymenoptera: Pteromalidae) is a well-studied parasitoid of dipteran pests, while Trichomalopsis ovigastra Sureshan & Narendran (Hymenoptera: Pteromalidae) has been only morphologically described. To assess its biocontrol potential, we compared the biological traits of T. ovigastra and P. vindemiae using Drosophila melanogaster Meigen (Diptera: Drosophilidae) and Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) as hosts. T. ovigastra showed significantly higher parasitism rates, especially against B. dorsalis, where T. ovigastra achieved nearly 50% parasitism, compared to less than 0.3% by P. vindemiae. When using D. melanogaster as the host, no significant differences were observed between T. ovigastra and P. vindemiae in offspring sex ratio or adult longevity; however, T. ovigastra exhibited a shorter developmental duration and greater tolerance to temperature extremes, starvation, and desiccation. Notably, B. dorsalis has expanded its range from southern to northern China; however, no native parasitoids of this pest have been reported in the newly invaded northern regions. T. ovigastra, collected from northern orchards and capable of parasitizing B. dorsalis, thus shows promise as a biocontrol agent. These findings highlight the potential of locally occurring parasitoids, although field validation is still required. Full article

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

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15 pages, 2434 KiB

Open AccessArticle

Proteomic Responses of the Springtail Folsomia candida to Drought

by Yang Wang, Stine Slotsbo, Steffen Y. Bak, Christopher J. Martyniuk and Martin Holmstrup

Insects 2025, 16(7), 707; https://doi.org/10.3390/insects16070707 - 9 Jul 2025

Abstract

Springtails are adapted to life in the pore space of soil, where humidity in moist soil is close to saturation. Drought is the most important limiting factor for springtails; however, their molecular and physiological adaptations to low humidity are not well understood. The [...] Read more.

Springtails are adapted to life in the pore space of soil, where humidity in moist soil is close to saturation. Drought is the most important limiting factor for springtails; however, their molecular and physiological adaptations to low humidity are not well understood. The present study explored the global proteomic drought response of the springtail, Folsomia candida (Isotomidae, Collembola). In relatively dry soil (−360 kPa), adult springtails initially lost body water but re-established the normal body water content over the following two weeks. Nano LC–MS/MS analysis identified a total of 1729 unique proteins. Proteomic analysis and pathway enrichment found that the proteome generally did not show a dramatic induction of proteins in response to drought stress. After an initial down-regulation of pathways related to metabolism and growth, these pathways gradually returned to the same levels as in moist soil. Other pathways such as the cytoskeleton pathway, which is important in cell proliferation and differentiation, were predominantly down-regulated throughout the experiment in drought-exposed animals, which correlated with essentially no somatic growth of the springtails in dry soil. This study facilitates the understanding of the consequences of climate change on soil functioning and fertility. Full article

(This article belongs to the Special Issue Research on Insect Molecular Biology)

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13 pages, 1328 KiB

Open AccessArticle

Biocontrol of Fall Armyworm Larvae by Selected Mexican Metarhizium rileyi Isolates Under Greenhouse and Small-Scale Field Conditions in Maize

by Yordanys Ramos, Samuel Pineda-Guillermo, Patricia Tamez-Guerra, Javier Francisco Valle-Mora, José Isaac Figueroa-de la Rosa, Selene Ramos-Ortiz, Luis Jesús Palma-Castillo and Ana Mabel Martínez-Castillo

Insects 2025, 16(7), 706; https://doi.org/10.3390/insects16070706 - 9 Jul 2025

Abstract

The efficacy of two selected Metarhizium rileyi Mexican isolates (T9-21 and L8-22) against Spodoptera frugiperda was evaluated under greenhouse conditions. To this end, a suspension (1 × 10⁸ conidia/mL) of these isolates was sprayed on maize plants previously infested with six second-instar [...] Read more.

The efficacy of two selected Metarhizium rileyi Mexican isolates (T9-21 and L8-22) against Spodoptera frugiperda was evaluated under greenhouse conditions. To this end, a suspension (1 × 10⁸ conidia/mL) of these isolates was sprayed on maize plants previously infested with six second-instar larvae. No significant differences were observed between the survival curves of the T9-21 and L8-22 isolates. Cadaver sporulation was significantly higher, and the lethal time was significantly lower with the T9-21 isolate compared with those of the L8-22 isolate (97% and 8 days vs. 70% and 10 days, respectively). Based on these results, a small-scale field trial on maize was performed to evaluate the degree of pest control achieved by the T9-21 isolate and compare it with the insecticide spinetoram, applied at a rate of 1 × 10¹³ conidia/ha and 75 mL/ha, respectively. No significant differences were observed in the proportion of larval mortality between the T9-21 isolate (0.49) and spinetoram (0.72). However, spinetoram significantly reduced natural enemies and phytophagous insect populations compared with the fungus and the control. In conclusion, M. rileyi T9-21 isolate could be a promising alternative for the control of S. frugiperda larvae. Full article

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

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17 pages, 1598 KiB

Open AccessArticle

Comparative Analysis of Diel and Circadian Eclosion Rhythms and Clock Gene Expression Between Sexes in the Migratory Moth Spodoptera frugiperda

by Changning Lv, Yibo Ren, Viacheslav V. Krylov, Yumeng Wang, Yuanyuan Li, Weidong Pan, Gao Hu, Fajun Chen and Guijun Wan

Insects 2025, 16(7), 705; https://doi.org/10.3390/insects16070705 - 9 Jul 2025

Abstract

The circadian clock orchestrates behavioral and molecular processes such as eclosion. Understanding eclosion timing may offer insights into circadian mechanisms underlying migratory timing. Here, we characterize the diel and circadian patterns of eclosion and core clock gene expression in the fall armyworm (FAW), [...] Read more.

The circadian clock orchestrates behavioral and molecular processes such as eclosion. Understanding eclosion timing may offer insights into circadian mechanisms underlying migratory timing. Here, we characterize the diel and circadian patterns of eclosion and core clock gene expression in the fall armyworm (FAW), Spodoptera frugiperda, a globally distributed migratory moth. Using a custom-designed eclosion monitoring system under 14 h light: 10 h dark (L14: D10) and constant darkness (DD) conditions, we observed robust diel eclosion rhythms peaking shortly after lights-off under L14: D10, which became delayed and damped over three consecutive days in DD. Males showed a tendency toward more dispersed emergence patterns and exhibited statistically distinguishable eclosion distributions from females under both conditions. Expression of five canonical clock genes (cyc, clk, tim, per, cry2) displayed significant 24 h rhythmicity, with generally higher mesors in males. However, sex-specific differences in amplitude and phase were detected only for clk and cyc under L14: D10, not in DD. These findings suggest that sex-specific differences in circadian regulation are limited. Nonetheless, subtle variations in clock gene output and emergence timing in the FAW population established in China may contribute to sex-specific ecological strategies in the novel migratory arena. Full article

(This article belongs to the Special Issue Travelers on the Wind: Migratory Insects as Emerging Research Models)

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14 pages, 7445 KiB

Open AccessArticle

CRISPR/Cas9-Mediated Knockout of the Corazonin Gene Indicates Its Regulation on the Cuticle Development of Desert Locusts (Schistocerca gregaria)

by Yingying He, Qiang Yan, Yong Bi, Guosheng Liu, Shuang Hou, Xinyi Chen, Xiaoming Zhao, Xueyao Zhang, Min Zhang, Jianzhen Zhang, Binbin Ma, Benjamin Warren, Siegfried Roth and Tingting Zhang

Insects 2025, 16(7), 704; https://doi.org/10.3390/insects16070704 - 9 Jul 2025

Abstract

The desert locust (Schistocerca gregaria) represents one of the most destructive agricultural pests globally, renowned for its ability to form massive swarms that can devastate crops and threaten food security across vast regions. Despite the widespread application of the CRISPR/Cas9 gene-editing [...] Read more.

The desert locust (Schistocerca gregaria) represents one of the most destructive agricultural pests globally, renowned for its ability to form massive swarms that can devastate crops and threaten food security across vast regions. Despite the widespread application of the CRISPR/Cas9 gene-editing system in several insect orders, its utilization in locusts, particularly in the desert locust, has remained relatively unexplored. We established a CRISPR/Cas9-mediated gene-editing workflow for the desert locust using gene encoding for neuropeptide corazonin (Crz) as a target. We also analyzed the phenotypic and physiological characteristics of the mutant using paraffin sectioning, HE staining, and chitin staining techniques. Our findings revealed that while Crz knockout desert locusts were viable and maintained normal fertility, they exhibited striking phenotypic alterations, including albinism and a significant reduction in cuticle thickness. These observations not only highlight the functional role of Crz in pigmentation and cuticle development but also underscore the potential of CRISPR/Cas9 as a powerful tool for dissecting gene function in locusts. Furthermore, the successful application of CRISPR/Cas9 in desert locusts also paves the way for similar genetic studies in other non-model insects, expanding the scope of functional genomics in entomology. Full article

(This article belongs to the Section Insect Molecular Biology and Genomics)

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16 pages, 3429 KiB

Open AccessArticle

Effects of Endosymbionts on the Nutritional Physiology and Biological Characteristics of Whitefly Bemisia tabaci

by Han Gao, Xiang-Jie Yin, Zhen-Huai Fan, Xiao-Hang Gu, Zheng-Qin Su, Bing-Rui Luo, Bao-Li Qiu and Li-He Zhang

Insects 2025, 16(7), 703; https://doi.org/10.3390/insects16070703 - 9 Jul 2025

Abstract

Insects and their endosymbionts have a close mutualistic relationship. However, the precise nature of the bacterial endosymbiont-mediated interaction between host plants and whitefly Bemisia tabaci MEAM1 is still unclear. In the present study, six populations of Bemisia tabaci MEAM1 sharing the same genetic [...] Read more.

Insects and their endosymbionts have a close mutualistic relationship. However, the precise nature of the bacterial endosymbiont-mediated interaction between host plants and whitefly Bemisia tabaci MEAM1 is still unclear. In the present study, six populations of Bemisia tabaci MEAM1 sharing the same genetic background were established by rearing insects for ten generations on different host plants, including poinsettia, cabbage, cotton, tomato, and tobacco, and an additional population was reared on cotton and treated with antibiotics. The physiological and nutritional traits of the insects were found to be dependent on the host plant on which they had been reared. Systematic analysis was conducted on the endosymbiont titers, the amino acid molecules and contents, as well as developmental and oviposition changes in the MEAM1 populations reared on each host plant tested. The results indicate that B. tabaci contained the primary symbiont Portiera and the secondary symbionts Hamiltonella and Rickettsia. In addition, the titer of endosymbiotic bacteria in females is higher than that in males. Among the MEAM1 populations reared on each host plant, the variation pattern of Portiera titer generally corresponded with changes in biological characteristics (body length, weight and fecundity) and AA contents. This suggests that changes in the amino acid contents and biological characteristics of different B. tabaci populations may be due to changes in the Portiera content and the differences in the nutrition of the host plants themselves. Our findings were further confirmed by the reduction in Portiera with antibiotic treatment. The amino acids, body size, body weight, and fecundity of B. tabaci were all reduced with the decrease in the Portiera titer after antibiotic treatment. In summary, our research revealed that host plants can affect the content of symbiotic bacteria, particularly Portiera, and subsequently affect the nutrition (i.e., the essential amino acids content) of host insects, thus changing their biological characteristics. Full article

(This article belongs to the Section Insect Behavior and Pathology)

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19 pages, 2061 KiB

Open AccessArticle

Determining the Effectiveness of Saccharomyces cerevisiae as a Postbiotic in Mass-Reared Acheta domesticus (House Cricket)

by Kimberly L. Boykin, Erik Neff and Mark A. Mitchell

Insects 2025, 16(7), 702; https://doi.org/10.3390/insects16070702 - 9 Jul 2025

Abstract

Pre-, pro-, and post-biotics have been used with success in several commercially grown insect species to increase yields and improve health outcomes. However, few studies have been published evaluating the use of nutritional supplements in Acheta domesticus. For this study, we fed [...] Read more.

Pre-, pro-, and post-biotics have been used with success in several commercially grown insect species to increase yields and improve health outcomes. However, few studies have been published evaluating the use of nutritional supplements in Acheta domesticus. For this study, we fed day-old, farm-raised, A. domesticus a Saccharomyces cerevisiae postbiotic product at one of three different inclusion rates (0, 0.25, and 0.5%) for 32 days. Crickets were analyzed for differences in average weights, total biomass, percent survival, nutritional analyses, viral qPCR, and 16S/18S microbiomes. Crickets receiving the 0.5% inclusion feed trended towards having a higher total biomass (F = 3.823, p = 0.052) and a higher percent survival per bin (F = 3.667, p = 0.057) than the crickets receiving lower inclusion feeds. No significant differences were found in viral prevalences or loads. Significant changes to the microbiomes were mostly defined by increased abundances of presumed beneficial bacteria (Akkermansia, Catenibacillus, and Odoribacter) in the groups receiving postbiotics rather than by losses of harmful bacteria. For the 18S results, there was an increased abundance of a Gregarian apicomplexan, Leidyana erratica in the treatment groups. Overall, the 0.5% inclusion feed appeared to be beneficial and further study investigating other forms of feed additives is warranted. Full article

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

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10 pages, 361 KiB

Open AccessArticle

Effects of Photoperiod on the Developmental Duration and Reproduction of Sclerodermus sichuanensis

by Kui Kang, Lina Wang, Zhongjiu Xiao, Shaobo Wang, Ke Wei, Xiaoyi Wang, Yanlong Zhang and Yanlong Tang

Insects 2025, 16(7), 701; https://doi.org/10.3390/insects16070701 - 8 Jul 2025

Abstract

Sclerodermus sichuanensis, a parasitic wasp, plays a significant role in wood-boring forest pest control in China. Research has shown that the photoperiod significantly affects the development and reproduction of parasitic wasps. However, the effects of the photoperiod on S. sichuanensis have not [...] Read more.

Sclerodermus sichuanensis, a parasitic wasp, plays a significant role in wood-boring forest pest control in China. Research has shown that the photoperiod significantly affects the development and reproduction of parasitic wasps. However, the effects of the photoperiod on S. sichuanensis have not yet been reported. This study investigates the impact of different photoperiods on the developmental duration and reproduction of S. sichuanensis. The wasps were reared under four photoperiod conditions: 0L:24D, 8L:16D, 16L:8D, and 24L:0D. The results show that increased light duration shortened the egg, larval, and pupal stages, with the total developmental period decreasing by up to 17 days. The number of offspring was highest in the 8L:16D and 16L:8D treatments, while constant light (24L:0D) led to a significant decrease in offspring numbers. The parasitism rate and pre-oviposition period were also affected by light exposure, with the longest pre-oviposition period observed in complete darkness. These findings indicate that the photoperiod plays a crucial role in regulating the development and reproductive efficiency of S. sichuanensis, suggesting that appropriate light conditions could enhance the efficiency of its use in pest control. Full article

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

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14 pages, 5582 KiB

Open AccessArticle

Silencing Miniature Gene Disrupts Elytral and Hindwing Structures in Leptinotarsa decemlineata

by Man-Hong Cheng, Kai-Yun Fu, Wei Zhou, Ji-Feng Shi and Wen-Chao Guo

Insects 2025, 16(7), 700; https://doi.org/10.3390/insects16070700 - 8 Jul 2025

Abstract

The Colorado potato beetle (Leptinotarsa decemlineata, CPB) is a major pest in potato crops, notorious for its rapid dispersal and insecticide resistance, which are enabled by its robust elytra and flight-capable hindwings. The Miniature (Mi) gene, encoding a protein [...] Read more.

The Colorado potato beetle (Leptinotarsa decemlineata, CPB) is a major pest in potato crops, notorious for its rapid dispersal and insecticide resistance, which are enabled by its robust elytra and flight-capable hindwings. The Miniature (Mi) gene, encoding a protein with a zona pellucida (ZP) domain, is involved in wing development and cuticle integrity, yet its functional role in beetles remains underexplored. In this study, we cloned and characterized the LdMi gene in the CPB and investigated its function using RNA interference (RNAi), morphological analyses, and spectroscopy. LdMi encodes a 146.35 kDa transmembrane protein with a conserved ZP domain, clusters with coleopteran homologs, and exhibits relative conservation across insect species. Expression profiling showed high LdMi transcript levels in the hindwings, the elytra, and the pupal stages. RNAi knockdown in fourth-instar larvae resulted in severe eclosion defects, including malformed wings and reduced adult weight. Scanning electron microscopy (SEM) revealed disrupted elytral patterns and deformed hindwing veins in knockdown individuals. Spectroscopic analyses using Fourier-transform infrared (FTIR) and Raman spectroscopy indicated a reduction in protein–chitin crosslinking and diminished hydrogen bonding, suggesting compromised cuticular integrity. These results highlight the essential role of LdMi in cuticle formation and the surface morphology of the elytra and hindwings, offering new insights into ZP domain proteins in insects. Full article

(This article belongs to the Special Issue RNAi in Insect Physiology)

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