Insects

17 pages, 1593 KiB

Open AccessReview

Conservation of Apis mellifera mellifera L. in the Middle Ural: A Review of Genetic Diversity, Ecological Adaptation, and Breeding Perspectives

by Olga Frunze, Alexander V. Petukhov, Anna Z. Brandorf, Mikhail K. Simankov, Hyunjee Kim and Hyung-Wook Kwon

Insects 2025, 16(5), 512; https://doi.org/10.3390/insects16050512 (registering DOI) - 11 May 2025

Abstract

The European dark bee is well adapted to cold winters and short summers. However, threats from habitat loss, pests, and hybridization with southern bees pose significant challenges to its populations. The Perm region (Middle Ural, Russia) hosts a distinct population of Apis mellifera [...] Read more.

The European dark bee is well adapted to cold winters and short summers. However, threats from habitat loss, pests, and hybridization with southern bees pose significant challenges to its populations. The Perm region (Middle Ural, Russia) hosts a distinct population of Apis mellifera mellifera, known as Prikamskaya. Despite extensive local research, a comprehensive analysis remains lacking. This review presents an analysis based on selected historical, ecological, genetic, and regulatory sources relevant to honey bee populations in northern climates. Inclusion criteria prioritized peer-reviewed scientific literature, regional monographs, institutional reports, and expert contributions published from the 20th century onward. Preference was given to studies addressing environmental conditions, queen-rearing practices, population structure, and conservation strategies. At the northern limit of honey bee distribution, the region has diverse forest zones and a growing season of 145–190 days, influencing nectar availability from lime, honeysuckle, and willow. Although the region’s potential honey yield is estimated at 390,919,300 kg, only 6.7% of its 3,007,200 colonies are commercially utilized, largely due to the low number of apiaries specializing in local honey bees. Distinct northern and southern types of A. m. mellifera have been identified based on morphological (cubital index) and physiological (cold resistance) traits, although links to genetic diversity remain underexplored. This study underscores the importance of regional conservation efforts in preserving the genetic diversity of A. m. mellifera, emphasizing the need for targeted breeding strategies to address climate change and hybridization, ensuring the sustainability of agriculture and natural ecosystems worldwide Full article

(This article belongs to the Section Social Insects and Apiculture)

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22 pages, 10806 KiB

Open AccessArticle

Rare Chromosomal Uniformity in Black Flies of the Simulium striatum Species Group (Diptera: Simuliidae)

by Peter H. Adler, Sergey Vlasov, Yao-Te Huang, Upik K. Hadi, Khamla Inkhavilay, Banchai Malavong, Varvara Topolenko, Bhuvadol Gomontean, Waraporn Jumpato, Ronnalit Mintara, San Namtaku, Isara Thanee, Wannachai Wannasingha, Komgrit Wongpakam, Chavanut Jaroenchaiwattanachote and Pairot Pramual

Insects 2025, 16(5), 511; https://doi.org/10.3390/insects16050511 (registering DOI) - 10 May 2025

Abstract

We conducted a comparative chromosomal analysis of 10 nominal species and 3 unidentified species in the Simulium striatum group from six countries. A total of 66 chromosomal rearrangements were found, of which 78.8% were inversions. The group is defined by 11 fixed inversions, [...] Read more.

We conducted a comparative chromosomal analysis of 10 nominal species and 3 unidentified species in the Simulium striatum group from six countries. A total of 66 chromosomal rearrangements were found, of which 78.8% were inversions. The group is defined by 11 fixed inversions, of which 6 are unique, supporting the monophyletic status previously indicated by morphological and molecular characters. Only 1 of the 13 taxa had a unique fixed chromosomal rearrangement. Although the group demonstrates significant macrogenomic reorganization, subsequent speciation occurred largely without chromosomal rearrangement. The results conflict with the pattern seen in all other species groups of Simuliidae, in which one or more diagnostic rearrangements are typically expressed among species in the same group. The chromosomes provide limited evidence that four entities are valid species but no evidence for the nine others. The weight of evidence from combined chromosomal, molecular, and morphological data, in addition to the practical considerations made for insular species, supports the species status of seven of these nominal species; the remaining taxa require further study. The S. striatum group, accordingly, is either over-divided into nominal species or deficient in chromosomal discriminators. If most or all nominal species and unnamed species are valid, all but one are homosequential, an unprecedented condition in Simuliidae. This group illustrates the need for the integration of multiple character sets for discovering and delimiting species. Full article

(This article belongs to the Special Issue Diptera Diversity: Systematics, Phylogeny and Evolution)

13 pages, 2841 KiB

Open AccessArticle

An Optimized Bioassay System for the Striped Flea Beetle, Phyllotreta striolata

by Liyan Yao, Xinhua Pu, Yuanlin Wu, Ke Zhang, Alexander Berestetskiy, Qiongbo Hu and Qunfang Weng

Insects 2025, 16(5), 510; https://doi.org/10.3390/insects16050510 (registering DOI) - 10 May 2025

Abstract

The striped flea beetle (SFB), Phyllotreta striolata, is a major pest of Brassicaceae crops, causing substantial yield losses worldwide. Effective biocontrol strategies, particularly the development of mycoinsecticides, require the identification of virulent entomopathogenic fungi (EPF) and the establishment of reliable bioassay systems. [...] Read more.

The striped flea beetle (SFB), Phyllotreta striolata, is a major pest of Brassicaceae crops, causing substantial yield losses worldwide. Effective biocontrol strategies, particularly the development of mycoinsecticides, require the identification of virulent entomopathogenic fungi (EPF) and the establishment of reliable bioassay systems. However, establishing reliable bioassay systems for SFB has been particularly challenging, especially for larval stages due to their recalcitrant rearing requirements. This study aimed to establish a standardized bioassay protocol to evaluate EPF efficacy against SFB. A specialized larval collection apparatus was developed, and the virulence of three EPF strains (Beauveria bassiana BbPs01, Metarhizium robertii MrCb01, and Cordyceps javanica IjH6102) was assessed against both adult and larval stages using a radish slice-based rearing system. Intriguingly, BbPs01 and MrCb01 exhibited significantly higher LT₅₀ values in larvae than in adults, contrary to the typical pattern of greater larval susceptibility observed in most insect systems. We hypothesized that isothiocyanate—specifically sulforaphane, a compound abundant in radish tissues—exerts fungistatic effects that impair fungal growth and virulence. Follow-up experiments confirmed that radish-derived sulforaphane inhibited fungal activity. Through alternative host plant screening, Chinese flowering cabbage (Brassica campestris L. ssp. chinensis var. utilis) was identified as an optimal larval diet that minimally interferes with EPF bioactivity, enabling reliable virulence assessments. This study presents critical methodological advancements for SFB biocontrol research, providing a robust framework for standardized larval bioassay and novel insights into plant secondary metabolite interactions with entomopathogens. The optimized system supports the development of targeted mycoinsecticides and contributes to a deeper understanding of tri-trophic interactions in crucifer pest management. Full article

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

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13 pages, 616 KiB

Open AccessReview

Strategies to Mitigate the Adverse Impacts of Viral Infections on Honey Bee (Apis mellifera L.) Colonies

by Ivana Tlak Gajger, Hossam F. Abou-Shaara and Maja Ivana Smodiš Škerl

Insects 2025, 16(5), 509; https://doi.org/10.3390/insects16050509 (registering DOI) - 10 May 2025

Abstract

Honey bees (Apis mellifera) play a crucial role in global food production through the pollination of various crops. These vital insects are susceptible to a range of viral pathogens that can disrupt their normal behavior and physiology, ultimately affecting colony dynamics [...] Read more.

Honey bees (Apis mellifera) play a crucial role in global food production through the pollination of various crops. These vital insects are susceptible to a range of viral pathogens that can disrupt their normal behavior and physiology, ultimately affecting colony dynamics and survival. There are diverse viruses that infect honey bees at different life stages, with a year-round prevalence. There are multiple pathways through which viruses can be transmitted among colonies. Notably, there is also a lack of commercial treatments against viral infections in bees, but some promising strategies exist to mitigate their negative effects, including vector control, and the implementation of good beekeeping practices and biosecurity measures. While methods for treating infected colonies have garnered attention, they receive less focus compared to aspects like transmission methods and seasonal prevalence of viruses. This article aims to review the aforementioned strategies in light of the available literature. It presents succinct and practical approaches categorized based on their potential direct or indirect effects on viruses, providing beekeepers and researchers with an overview of both fully established and still-developing methods. Controlling the ectoparasitic Varroa destructor mite population, which significantly impacts viral prevalence and virulence in bees, is crucial for reducing infections. Practical approaches such as selectively breeding honey bee populations resistant to viruses and ensuring proper nutrition are important strategies. Moreover, genetic methods have also been proposed and tested. The article not only emphasizes these methods but also discusses knowledge gaps and suggests future solutions to improve the health and productivity of honey bee colonies. Full article

(This article belongs to the Section Social Insects and Apiculture)

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20 pages, 725 KiB

Open AccessArticle

Bioconversion of Meat and Fish-Based Former Foodstuffs by Black Soldier Fly Larvae: A Sustainable Pathway for Reducing Food Waste, Enhancing Nutrient Recovery, with a Circular Economy Approach

by Antonio Franco, Valentina Pucciarelli, Seyed Ali Hosseini, Eric Schmitt, Fulvia Bovera, Carmen Scieuzo and Patrizia Falabella

Insects 2025, 16(5), 508; https://doi.org/10.3390/insects16050508 - 9 May 2025

Abstract

Food waste containing meat and fish presents a considerable environmental challenge due to regulatory constraints preventing its use in industrial insect farming. Although substrates derived from meat and fish are not currently approved for industrial insect feed production due to regulatory constraints, this [...] Read more.

Food waste containing meat and fish presents a considerable environmental challenge due to regulatory constraints preventing its use in industrial insect farming. Although substrates derived from meat and fish are not currently approved for industrial insect feed production due to regulatory constraints, this study explores their potential in bioconversion through Hermetia illucens larvae. In this study, five different former foodstuffs containing meat and/or fish were tested to evaluate their suitability for BSFL rearing. The substrates included pizza with salami (PIZZA), cheeseburger (CHB), pasta Bolognese with meat (PASTA), chicken salad (CHISA), and fish salad (FISA). Results showed that BSFL successfully developed on all tested substrates. The highest performance was observed for FISA, with a total larval weight of 35.21 ± 3.91 g, dry matter yield of 11.21 ± 0.45 g, survival rate of 96.63 ± 0.40%, and the most efficient feed conversion ratio (FCR, 4.11 ± 0.59). Heavy metal analysis revealed substantial bioaccumulation of lead (Pb) and cadmium (Cd) in larvae. In particular, larvae reared on PIZZA showed a Pb concentration of 4.68 μg/100 g, with a corresponding bioaccumulation factor (BAF) of approximately 1.5. Cadmium accumulation was most notable in larvae fed CHB, with a Cd concentration of 0.41 ± 0.33 μg/100 g and a BAF of about 2.1. Despite this bioaccumulation, all detected concentrations remained well below the regulatory limits set by the European Union for animal feed, indicating not only the feasibility of H. illucens larvae in sustainable waste management but also its use as a safe protein source in animal feed. This research highlights the viability of integrating such food waste into insect bioconversion systems. With appropriate risk management, this practice could significantly improve nutrient recycling, waste management, and the circular economy, urging a regulatory review to allow broader substrate utilization. These positive outcomes underscore the potential of integrating currently restricted animal-derived food waste streams into H. illucens-based bioconversion systems, unlocking additional value for the circular economy and contributing to more efficient waste management practices. Full article

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

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17 pages, 6171 KiB

Open AccessArticle

Low-Frequency Ultrasound Assisted in Improvement in Cell Development and Production of Parasporal Crystals from Bacillus thuringiensis HD1

by Sufen Cui, Kaihui Shen, Shiqi Xiong, Xiao Li, Yue Wang, Xueqing Geng and Yujie Lu

Insects 2025, 16(5), 507; https://doi.org/10.3390/insects16050507 - 9 May 2025

Abstract

Bacillus thuringiensis is widely utilized as a microbial insecticide due to its production of parasporal crystals during the spore-forming stage. However, lower fermentation efficiency coupled with elevated production costs limit its broad application. Low-frequency ultrasound (LFU) has been employed in the fermentation industry [...] Read more.

Bacillus thuringiensis is widely utilized as a microbial insecticide due to its production of parasporal crystals during the spore-forming stage. However, lower fermentation efficiency coupled with elevated production costs limit its broad application. Low-frequency ultrasound (LFU) has been employed in the fermentation industry to enhance microbial growth and metabolism. In this study, the effect of LFU on the growth of B. thuringiensis HD1 and the yields of parasporal crystals was investigated. The maximum biomass accumulation of Bacillus thuringiensis and parasporal crystal production yield were achieved following low-frequency ultrasonic (LFU) treatment applied during the logarithmic growth phase (18 h of cultivation) under optimized parameters: a frequency of 40 kHz, a power output of 176 W, and an irradiation duration of 45 min. Under optimal conditions, LFU significantly increased the cell membrane permeability and secretory inositol, favoring cell growth and parasporal crystal production. FESEM/CLSM and TEM analyses visually displayed the changes in cell morphology. In addition, the germination rate of spores was increased after LFU treatment, which further confirmed the positive effect of LFU on the growth of B. thuringiensis. Compared to the control, parasporal crystals harvested under LFU exhibited significant modifications in their physicochemical characteristics; the particle size increased, the surface electronegativity intensified, and there was a morphological transition from spherical to cubic geometry. Importantly, the parasporal crystals exhibited strong insecticidal activity against S. zeamais adults, a typical stored-product insect pest, with an LC₅₀ of 10.795 mg/g on day 14 and a Kt₅₀ of 4.855 days at a concentration of 30 mg/g. These findings will provide new insights into the product development and application of B. thuringiensis in the future. Full article

(This article belongs to the Special Issue Recent Advances in Bacillus thuringiensis (Bt) Insecticides and Bt Crops: Challenges and Opportunities)

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26 pages, 1848 KiB

Open AccessReview

Insect Mating Behaviors: A Review of the Regulatory Role of Neuropeptides

by Alfayo Ombuya, Jianyang Guo and Wanxue Liu

Insects 2025, 16(5), 506; https://doi.org/10.3390/insects16050506 - 8 May 2025

Abstract

Insect mating behaviors are complex, diverse, and primarily regulated by neuropeptides and their receptors. Neuropeptides are peptide signaling molecules mainly secreted by insects’ central nervous system (CNS) to reach target organs. A substantial body of research on the role of neuropeptides in regulating [...] Read more.

Insect mating behaviors are complex, diverse, and primarily regulated by neuropeptides and their receptors. Neuropeptides are peptide signaling molecules mainly secreted by insects’ central nervous system (CNS) to reach target organs. A substantial body of research on the role of neuropeptides in regulating mating behaviors in insects has been undertaken. This review aims to (1) synthesize existing knowledge on insect mating behaviors, (2) elucidate the neuropeptidergic mechanisms governing these behaviors, and (3) identify knowledge gaps and propose future research directions. The mating process, covering mate attraction, courtship rituals, copulation, and post-mating behaviors, was elucidated with appropriate examples. Additionally, specific neuropeptides involved at each stage of the mating process, their functions, and mechanistic aspects were discussed as demonstrated in research. The review highlights that insects display behavioral dimorphism in the mating process driven by a complex underlying neuropeptidergic mechanism. While previous publications have generally addressed the role of neuropeptides in insect behavior, none has intensively and methodically examined their role in mating behaviors. In this review, we synthesized 18 neuropeptides that we found to regulate mating behaviors in insects. We note that some of the neuropeptides are malfunctional in their regulatory roles, while others are specific. We also note that these neuropeptides execute their regulatory functions through the G protein-coupled receptor (GPCR) signaling pathway but may take different routes and messengers downstream to effect behavioral change. Neuropeptides also interact with other regulatory systems, such as the endocrine system, to discharge their functions. Given their significance in mediating mating and reproduction, targeted manipulation of the signaling system of neuropeptides could serve as viable targets in the production of ecologically friendly pest management tools. Tools that could disrupt the mating process would be applied in crop production systems to reduce the population pressure of destructive pests, consequently reducing the urge to use chemical pesticides that are ecologically unfriendly. Our findings not only advance the understanding of neuropeptide-mediated mating regulation but also highlight their potential as eco-friendly pest control targets. Full article

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

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19 pages, 1403 KiB

Open AccessArticle

Effects of Three Different Bee Pollen on Digestion, Immunity, Antioxidant Capacity, and Gut Microbes in Apis mellifera

by Xin-Meng Li, Ying Wang, Li Lei, Ge Zhang and Bao-Hua Xu

Insects 2025, 16(5), 505; https://doi.org/10.3390/insects16050505 - 8 May 2025

Abstract

The nutritional value of pollen for honeybees varies significantly depending on its source. This study examines the nutrient composition of three types of bee-collected pollen—Maize bee-collected pollen (MBP), Lotus bee-collected pollen (LBP), and Sunflower bee-collected pollen (SBP)—and their effects on honeybee digestion, immunity, [...] Read more.

The nutritional value of pollen for honeybees varies significantly depending on its source. This study examines the nutrient composition of three types of bee-collected pollen—Maize bee-collected pollen (MBP), Lotus bee-collected pollen (LBP), and Sunflower bee-collected pollen (SBP)—and their effects on honeybee digestion, immunity, and gut microbiota. Nutritional analysis revealed no significant differences in moisture, protein, and carbohydrate content among the three pollen types. However, sunflower bee-collected pollen exhibited a significantly lower crude fat content than maize bee-collected pollen and lotus bee-collected pollen, while lotus bee-collected pollen had a significantly higher crude ash content than the other pollen types. Additionally, notable differences in amino acid composition were observed across the three pollen types. Feeding assays demonstrated that honeybees consumed significantly more sunflower bee-collected pollen than maize bee-collected pollen or lotus bee-collected pollen. Honeybees fed sunflower bee-collected pollen exhibited reduced lipid deposition, enhanced immune enzyme activity, and increased expression of immune-related genes. Protein digestibility was highest in honeybees fed lotus bee-collected pollen, whereas protease and lipase activities were significantly lower in those consuming sunflower bee-collected pollen. Notably, honeybees fed sunflower bee-collected pollen had thinner midgut intestinal walls. Furthermore, the microbial structure of the honeybee gut was altered depending on the type of different pollen. In summary, honeybees had the worst digestibility of Sunflower bee-collected pollen; sunflower bee pollen had a greater effect on antioxidant and immune functions, and intestinal flora of honeybees. These findings underscore the influence of different types of pollen on honeybee nutrition, immunity, and gut microbiota, offering a foundation for optimizing pollen diets to support honeybee health. Full article

(This article belongs to the Section Social Insects and Apiculture)

19 pages, 2449 KiB

Open AccessArticle

Transcriptome Analysis and Identification of Chemosensory Membrane Proteins in the Head of Euplatypus parallelus

by Qi Wu, Xiang Zhou, Zheyuan Xu, Xufeng Zhang, Hongchao Yuan and Jixing Guo

Insects 2025, 16(5), 504; https://doi.org/10.3390/insects16050504 - 7 May 2025

Abstract

Euplatypus parallelus is a polyphagous pest capable of harming multiple plant species. Adult beetles invade tree trunks by boring holes, which negatively impacts the trees’ growth and may result in tree death. E. parallelus depends on plant volatiles to identify and locate appropriate [...] Read more.

Euplatypus parallelus is a polyphagous pest capable of harming multiple plant species. Adult beetles invade tree trunks by boring holes, which negatively impacts the trees’ growth and may result in tree death. E. parallelus depends on plant volatiles to identify and locate appropriate hosts for feeding or reproduction, with its olfactory system playing a vital role in volatile detection. In this work, we applied transcriptomics, phylogenetic analysis, and expression analysis to investigate four chemosensory membrane protein gene families that play a role in olfaction in E. parallelus. Based on the annotation analysis, 41 odorant receptors (ORs), 12 gustatory receptors (GRs), 14 ionotropic receptors (IRs), and 4 sensory neuron membrane proteins (SNMPs) were identified in the head. We used differential gene expression (DGE) and fragments per kilobase per million (FPKM) values to compare the transcription levels of chemosensory membrane protein gene families between males and females. The data indicate that the chemosensory membrane protein gene families in E. parallelus exhibit different expression levels in male and female heads, with some genes showing significant differences and displaying sex-biased expression. These results offer a basis for future exploration of the functions of chemosensory membrane protein gene families in E. parallelus and offer a theoretical framework for designing innovative eco-friendly control technologies. Full article

(This article belongs to the Special Issue Bark and Wood-Boring Insects: Past and Present Research and Essential Future Knowledge—2nd Edition)

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23 pages, 4901 KiB

Open AccessArticle

Multi-Omics Analysis of Curculio dieckmanni (Coleoptera: Curculionidae) Larvae Reveals Host Responses to Steinernema carpocapsae Infection

by Bin Wang, Fanyu Meng, Shiqi Song, Bin Xie, Shuxia Jia, Dongying Xiu and Xingpeng Li

Insects 2025, 16(5), 503; https://doi.org/10.3390/insects16050503 - 7 May 2025

Abstract

The hazelnut weevil larvae (Curculio dieckmanni) is a major pest of nut weevils, spending part of its life cycle in the soil and causing significant damage to hazelnut crops. Moreover, its concealed feeding behavior complicates effective control with chemical insecticides. The [...] Read more.

The hazelnut weevil larvae (Curculio dieckmanni) is a major pest of nut weevils, spending part of its life cycle in the soil and causing significant damage to hazelnut crops. Moreover, its concealed feeding behavior complicates effective control with chemical insecticides. The entomopathogenic nematode Steinernema carpocapsae, which efficiently kills weevil larvae, offers a promising biological control agent. To investigate the molecular responses of hazelnut weevil larvae to nematode infection, we employed integrated transcriptomic and proteomic analyses following infection by S. carpocapsae. Our results revealed substantial alterations in gene expression, particularly the upregulation of immune-related transcripts such as antimicrobial peptides (AMPs) and stress-responsive proteins like heat shock protein 70 (HSP70). Furthermore, significant metabolic reprogramming occurred, marked by the downregulation of carbohydrate metabolic pathways and activation of energy conservation mechanisms. Although we observed an overall correlation between mRNA and protein expression levels, notable discrepancies highlighted the critical roles of post-transcriptional and post-translational regulatory processes. Collectively, these findings advance our understanding of the molecular interaction between insect hosts and pathogenic nematodes and contribute valuable knowledge for enhancing the effectiveness of EPN-based pest management strategies. Full article

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

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15 pages, 1997 KiB

Open AccessArticle

Genomic Analysis Reveals the Role of New Genes in Venom Regulatory Network of Parasitoid Wasps

by Bo Zhang, Yifan Bu, Jiqiang Song, Bo Yuan, Shan Xiao, Fang Wang, Qi Fang, Gongyin Ye, Yi Yang and Xinhai Ye

Insects 2025, 16(5), 502; https://doi.org/10.3390/insects16050502 - 7 May 2025

Abstract

New genes play a critical role in phenotypic diversity and evolutionary innovation. Parasitoid wasps, a highly abundant and diverse group of insects, parasitize other arthropods and exhibit remarkable evolutionary adaptations, such as evading host immune responses and exploiting host resources. However, the specific [...] Read more.

New genes play a critical role in phenotypic diversity and evolutionary innovation. Parasitoid wasps, a highly abundant and diverse group of insects, parasitize other arthropods and exhibit remarkable evolutionary adaptations, such as evading host immune responses and exploiting host resources. However, the specific contributions of new genes to their unique traits remain poorly understood. Here, we identified 480 new genes that emerged after the Nasonia-Pteromalus divergence. Among these, 272 (56.7%) originated through DNA-mediated duplication, representing the largest proportion, followed by 77 (16.0%) derived from RNA-mediated duplication and 131 (27.3%) that arose de novo. Comparative analysis revealed that these new genes generally have shorter coding sequences and fewer exons compared to single-copy older genes conserved in the seven parasitoid wasps. These new genes are predominantly expressed in the reproductive glands and exhibit venom gland-biased expression. Notably, gene co-expression network analysis further identified that a new gene may act as a hub by interacting with older genes to regulate venom-related networks rather than directly encoding venom proteins. Together, our findings provide novel insights into the role of new genes in driving venom innovation in parasitoid wasps. Full article

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

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17 pages, 1992 KiB

Open AccessArticle

Environmental Factors Determining the Distribution Pattern of Chironomidae in Different Types of Freshwater Habitats

by Nataša Popović, Jelena Đuknić, Nikola Marinković, Bojana Tubić, Ana Atanacković, Djuradj Milošević and Maja Raković

Insects 2025, 16(5), 501; https://doi.org/10.3390/insects16050501 - 7 May 2025

Abstract

Chironomidae are characterised by cosmopolitan distribution, high abundance and diversity in different aquatic environments, which makes them ideal for studying changes in freshwater ecosystems. To understand the environmental factors influencing chironomid communities, we analysed how altitude and waterbody type (hydromorphological features) affect their [...] Read more.

Chironomidae are characterised by cosmopolitan distribution, high abundance and diversity in different aquatic environments, which makes them ideal for studying changes in freshwater ecosystems. To understand the environmental factors influencing chironomid communities, we analysed how altitude and waterbody type (hydromorphological features) affect their composition at 75 study sites from 49 watercourses. A total of 110 chironomid taxa from five subfamilies were identified, with Prodiamesa olivacea, Rheocricotopus fuscipes and Cricotopus bicinctus being the most frequent species. The lowest values of all alpha diversity components were recorded in communities collected from watercourses at altitudes up to 500 m a.s.l., while the highest values were observed in small mountainous rivers and streams. Beta diversity showed that taxa turnover was the dominant component in all situations analysed. Communities in large rivers with fine substrate were characterised by the lowest taxa turnover and the highest levels of nestedness, indicating the existence of an ecological gradient that reduces the number of taxa from one site to another. We identified indicator taxa for different altitudes, as well as groups of taxa that are typical for different waterbody types. Furthermore, the combination of four water parameters (oxygen saturation, conductivity, concentration of ammonium and nitrates) had the strongest influence on the chironomid community composition in the studied watercourses. Full article

(This article belongs to the Special Issue Aquatic Insects: Ecology, Diversity and Conservation)

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21 pages, 2701 KiB

Open AccessArticle

Development of Quantitative Real-Time PCR Tests for the Identification of Biting Midge Species and Clades (Diptera: Ceratopogonidae) of the Obsoletus Group (Subgenus Avaritia), Including Important Viral Vectors in Europe

by Oliver Dähn, Bernd Hoffmann, Doreen Werner, Bruno Mathieu and Helge Kampen

Insects 2025, 16(5), 500; https://doi.org/10.3390/insects16050500 - 7 May 2025

Abstract

Species of the widespread Obsoletus Complex (Culicoides subgenus Avarita Fox, 1955) have been implicated as potential key vectors during the bluetongue and Schmallenberg epidemics in Central Europe in 2006 and 2012. Although extensive efforts have been made to clarify vector–pathogen relationships, one [...] Read more.

Species of the widespread Obsoletus Complex (Culicoides subgenus Avarita Fox, 1955) have been implicated as potential key vectors during the bluetongue and Schmallenberg epidemics in Central Europe in 2006 and 2012. Although extensive efforts have been made to clarify vector–pathogen relationships, one of the most important steps in this process—correct species identification—remains difficult, due to the presence of isomorphic species within the Obsoletus Group. To overcome the difficulties in morphological species identification, several PCR tests were developed. With the aim of developing a high-throughput PCR, capable of differentiating all putative vector species and newly described haplotypes of the subgenus Avaritia present in Europe, a dataset of 4407 published sequences of the mitochondrial (mt) cytochrome c oxidase subunit I (COI) was used to develop specific primers and probes, which can either be applied in a singleplex PCR or in different multiplex PCR approaches. The real-time PCR achieved very high diagnostic sensitivity (100%) and specificity (91.7%) and reliably detected the three clades of C. obsoletus sensu stricto (s.s.) in a pool of specimens. Thus, the new real-time PCR approach will provide an excellent tool for large-scale monitoring, which could improve the understanding of the biology, geographical distribution, and habitat preference of European biting midge species involved in the transmission of bluetongue, Schmallenberg, and epizootic hemorrhagic disease viruses. Full article

(This article belongs to the Special Issue Approaches to Diseases Control Centered on Arthropod Vectors of Animal and Human Pathogens)

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22 pages, 1872 KiB

Open AccessArticle

Survey of ‘Candidatus Liberibacter solanacearum’ and Its Potential Psyllid Vectors in Northwestern Italy

by Ahmed Y. S. Oraby, Valentina Candian and Rosemarie Tedeschi

Insects 2025, 16(5), 499; https://doi.org/10.3390/insects16050499 - 7 May 2025

Abstract

Psyllids (Hemiptera: Psylloidea) are the main vectors of various phloem-limited plant pathogens, including ‘Candidatus Liberibacter’ species. ‘Candidatus Liberibacter solanacearum’ (CLso) has been associated with various plant disorders and economic losses in plants from the Solanaceae and Apiaceae families. Recently, it has [...] Read more.

Psyllids (Hemiptera: Psylloidea) are the main vectors of various phloem-limited plant pathogens, including ‘Candidatus Liberibacter’ species. ‘Candidatus Liberibacter solanacearum’ (CLso) has been associated with various plant disorders and economic losses in plants from the Solanaceae and Apiaceae families. Recently, it has been reported in Europe, primarily linked to carrots and celery. This situation presents a significant threat, prompting the need for a survey to assess the presence of the bacterium and its potential vectors. Plant and psyllid samples were collected from potato (Solanum tuberosum), carrot (Daucus carota) and other wild weed species in commercial fields and urban areas over two consecutive years (2022 and 2023). DNA was extracted from the samples, followed by conventional PCR and the sequencing of positive samples. The psyllid species Bactericera nigricornis was the dominant species in potato fields, while Bactericera trigonica was the most abundant in carrot fields, followed by Heterotrioza chenopodii, ranking as the second most abundant species in both cases. CLso-positive samples were found in D. carota, B. trigonica, H. chenopodii, B. nigricornis, and Trioza urticae. The sequencing results suggest the detected haplotypes are D and U. These findings raise concerns about the potential spread of CLso and the associated risk of significant economic losses. Full article

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

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24 pages, 7113 KiB

Open AccessArticle

Species Richness and Distribution of Calliphoridae Along an Elevation Gradient in Sicily (Italy) and Ecuador

by Maria Denise Gemmellaro, Gail Scott Anderson, George Craig Hamilton, Mariela Domínguez-Trujillo and Lauren Marie Weidner

Insects 2025, 16(5), 498; https://doi.org/10.3390/insects16050498 - 6 May 2025

Abstract

Blow flies (Diptera: Calliphoridae) are among the first insects to arrive on a corpse, and so they are particularly important in forensic entomology. To use blow flies in forensic investigations, there must be information available on their species diversity, abundance, and distribution in [...] Read more.

Blow flies (Diptera: Calliphoridae) are among the first insects to arrive on a corpse, and so they are particularly important in forensic entomology. To use blow flies in forensic investigations, there must be information available on their species diversity, abundance, and distribution in the areas where investigations are conducted. Several factors can contribute to species distribution, and elevation is one of those factors. The purpose of this study was to document the distribution of Calliphoridae across four elevational gradients in Sicily and Ecuador, where little information is available. Baited traps were placed at elevations ranging from 20 m to 1552 m in Sicily (a major island and region of Italy and a distinct ecoregion) and 561 m to 3336 m in Ecuador. Species richness, relative abundance, and diversity were calculated, as well as the ratio of female to male blow flies and community assemblage. Twelve species were collected in Sicily, and seventeen species were collected in Ecuador. In Sicily, the most abundant species was Lucilia sericata (Johann Wilhelm Meigen, 1826) (68.50% of the total capture), while in Ecuador, it was Compsomyiops verena (Walker) (51.67% of the total capture). In Sicily, significant differences were only observed in the relative abundance of L. sericata across elevations. In Ecuador, significant differences were observed in the relative abundance of Calliphora nigribasis (Macquart), Chrysomya albiceps (Wiedemann), C. verena, Hemilucilia semidiaphana (Rondani), Lucilia ibis (Shannon), L. purpurascens (Walker), and Paralucilia sp. across elevations. These data can help build a checklist of blow fly species in these two regions and can be instrumental in environmental and forensic investigations. Full article

(This article belongs to the Special Issue Diptera Diversity: Systematics, Phylogeny and Evolution)

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15 pages, 929 KiB

Open AccessArticle

Assessing Wine Grape Cultivar Susceptibility to Spotted Wing Drosophila and Melanogaster-Type Drosophila in Hungarian Vineyards: Effects of Berry Integrity and Insights into Larval Interactions

by Abir Ibn Amor, Ágnes Kukorellyné Szénási, Csaba Németh, Ferenc Deutsch and Balázs Kiss

Insects 2025, 16(5), 497; https://doi.org/10.3390/insects16050497 - 5 May 2025

Abstract

The invasive spotted wing Drosophila (SWD) represents new challenges for European and North American fruit producers. The aim of our study was to examine wine grape cultivar susceptibility to this pest and melanogaster-type Drosophila (MTD) by surveying drosophilid populations using field traps and [...] Read more.

The invasive spotted wing Drosophila (SWD) represents new challenges for European and North American fruit producers. The aim of our study was to examine wine grape cultivar susceptibility to this pest and melanogaster-type Drosophila (MTD) by surveying drosophilid populations using field traps and conducting emergence tests. We assessed fly development from intact and artificially injured berries collected from four cultivars. Berries were incubated individually and in pooled samples to evaluate infestation patterns and potential larval interactions. Although grapes are generally considered less favorable hosts for SWD, the pest was consistently present across all vineyard plots. Infestation levels differed significantly among cultivars, with the Hungarian white cultivar Furmint being the most susceptible, while French-origin red cultivars Cabernet Franc and Cabernet Sauvignon, along with the other Hungarian cultivar Rózsakő, were less susceptible. Berry integrity played a crucial role: intact berries showed minimal infestation, whereas physical injuries led to a substantial and significant increase in infestation rates and fly emergence. In contrast to SWD-dominated trap catches and the nearly equal proportions of SWD and MTD observed in intact berries, injured berries were predominantly colonized by MTD. This dominance became even more pronounced in pooled samples, suggesting that larval competition in shared environments favors MTD over SWD. These findings underscore the importance of grape cultivar traits and berry condition in shaping Drosophila infestation dynamics. Further research into the chemical and ecological drivers of host selection and interspecific interactions is warranted to improve vineyard pest management strategies. Full article

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

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14 pages, 606 KiB

Open AccessReview

The Role of Chemosensory Proteins in Insecticide Resistance: A Review

by Angeliki Tsouri and Vassilis Douris

Insects 2025, 16(5), 496; https://doi.org/10.3390/insects16050496 - 5 May 2025

Abstract

Chemosensory proteins (CSPs) are small soluble proteins found predominantly in insects, with a conserved structure that contains a hydrophobic cavity. While originally associated with chemosensation, they were soon implicated to several other functions related to their ability to bind hydrophobic molecules. Research in [...] Read more.

Chemosensory proteins (CSPs) are small soluble proteins found predominantly in insects, with a conserved structure that contains a hydrophobic cavity. While originally associated with chemosensation, they were soon implicated to several other functions related to their ability to bind hydrophobic molecules. Research in the last decade has shown that CSPs may play a role in insecticide resistance. Several CSP genes are upregulated upon induction by sublethal insecticide doses or are highly expressed in resistant populations. RNA interference of CSP genes can restore susceptibility to insecticides. In vitro binding assays and molecular docking simulations suggest that CSPs can strongly bind to insecticides and can accommodate even large molecules in their hydrophobic cavities. Some cases of CSP overexpression in transgenic insects conferring insecticide resistance are reported. Taken together, these results indicate a role for CSPs in insecticide resistance, presumably through a sequestration mechanism, perhaps in combination with other mechanisms like metabolic resistance. This article reviews the evidence for CSP involvement in resistance and discusses ongoing research in the field. Full article

(This article belongs to the Special Issue Chemical Toxicology and Insecticide Resistance on Insect Pests)

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17 pages, 4171 KiB

Open AccessArticle

Sexual Development of Silba adipata (Diptera: Lonchaeidae): Effects of Diet, Ultraviolet Light and Fig Latex

by Ricardo Díaz-del-Castillo, Guadalupe Córdova-García, Diana Pérez-Staples, Andrea Birke, Trevor Williams and Rodrigo Lasa

Insects 2025, 16(5), 495; https://doi.org/10.3390/insects16050495 - 5 May 2025

Abstract

The black fig fly, Silba adipata McAlpine (Diptera: Lonchaeidae), is a monophagous invasive pest of fig crops. Its recent detection in Mexico has highlighted the urgent need for control strategies. However, efforts to study and manage this pest are constrained by a limited [...] Read more.

The black fig fly, Silba adipata McAlpine (Diptera: Lonchaeidae), is a monophagous invasive pest of fig crops. Its recent detection in Mexico has highlighted the urgent need for control strategies. However, efforts to study and manage this pest are constrained by a limited understanding of its basic biology and an inability to rear this insect in the laboratory. Some species of flies are reproductively immature at adult emergence and require specific nutrients for the development of reproductive structures. Given this, we examined the development of ovaries and testes in response to different adult diets, ovary maturation in relation to access to figs and ultraviolet (UV) light exposure and behavioral responses to fig latex. Dietary protein (hydrolyzed yeast) was essential for egg maturation. The highest prevalence of sexual maturity in females was observed at age 21 days and was not influenced by UV light or access to figs. Male testes size decreased over time irrespective of the adult diet. The consumption of latex increased when protein was not available, although the sexes differed in their response to latex over time. These findings help overcome a critical barrier to the laboratory colonization of S. adipata by demonstrating that protein-supplemented diets are essential for sexual maturation. However, the lack of information on the specific role of fig latex in the diet and the absence of sexual behavior during the experiments highlight key knowledge gaps. Future research should focus on identifying those stimuli that promote copulation and oviposition to understand the complete life cycle of this pest under controlled conditions. Full article

(This article belongs to the Special Issue Fly Biology, Ecology, Behavior and Management—2nd Edition)

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14 pages, 4013 KiB

Open AccessArticle

Imidacloprid Resistance Challenges in Brazilian Strains of Drosophila suzukii (Diptera: Drosophilidae)

by Felipe Andreazza, Flávio Roberto Mello Garcia, Pedro Bento da Silva, Lucas Bretas Barbosa, Joel Marques de Oliveira, Gabriel Netto Araújo and Eugenio E. Oliveira

Insects 2025, 16(5), 494; https://doi.org/10.3390/insects16050494 - 5 May 2025

Abstract

Drosophila suzukii (Matsumura) is a relevant pest affecting berries and stone fruits globally, including in the Neotropical region, where its invasion was reported about a decade ago. Despite chemical control being the main management method for D. suzukii, data on insecticide susceptibility [...] Read more.

Drosophila suzukii (Matsumura) is a relevant pest affecting berries and stone fruits globally, including in the Neotropical region, where its invasion was reported about a decade ago. Despite chemical control being the main management method for D. suzukii, data on insecticide susceptibility in Neotropical D. suzukii populations are scarce. Here, we assessed the susceptibility of three field-collected Brazilian D. suzukii populations to four insecticides (i.e., deltamethrin, permethrin, spinetoram, imidacloprid) and contrasted this with a standard insecticide-susceptible population. Using the discriminating concentration (LC₉₀) from the standard susceptible population, we identified resistant populations. Synergist exposure (piperonyl butoxide, triphenyl phosphate, diethyl maleate) indicated the role of detoxification enzymes in resistance. Our results showed that deltamethrin was the most toxic, followed by spinetoram, permethrin, and imidacloprid. While all field populations were similarly susceptible to pyrethroids and spinosyns, one population from Minas Gerais (i.e., Paula Candido) had significantly lower imidacloprid susceptibility, with only 53.4 ± 5.2% mortality at 10.0 g/L (the equivalent of 10-fold the estimated imidacloprid LC₉₀). Only piperonyl butoxide increased the imidacloprid susceptibility of Paula Candido flies. Our findings indicate the occurrence of cytochrome P450 enzyme-based imidacloprid resistance in the state of Minas Gerais, which can challenge the management of D. suzukii in Brazil. Full article

(This article belongs to the Special Issue Fly Biology, Ecology, Behavior and Management—2nd Edition)

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