Insects

14 pages, 5097 KiB

Open AccessArticle

Potentially Suitable Habitat for the Pest Histia rhodope Based on Its Host Plant Bischofia polycarpa and Climatic Factors in China

by Huicong Du, Jingxin Shen, Wenping Luo, Zi Yang, Daizhen Zhang and Xiangbo Kong

Insects 2025, 16(6), 627; https://doi.org/10.3390/insects16060627 (registering DOI) - 13 Jun 2025

Abstract

Histia rhodope is a defoliating pest that feeds mainly on the ornamental garden plant Bischofia polycarpa. Recently, frequent outbreaks of H. rhodope in Southern China have severely affected cityscapes and people’s lives. To provide a predictive early-warning program for the spread risk [...] Read more.

Histia rhodope is a defoliating pest that feeds mainly on the ornamental garden plant Bischofia polycarpa. Recently, frequent outbreaks of H. rhodope in Southern China have severely affected cityscapes and people’s lives. To provide a predictive early-warning program for the spread risk of H. rhodope in China and reduce damage to B. polycarpa, we used the MaxEnt model to investigate the potentially suitable spread characteristics of H. rhodope and its host B. polycarpa under different climate scenarios for the years 2050 and 2070. The results showed that the potentially suitable habitat of H. rhodope under the SSP5-8.5 scenario will reach an area of 3174.55 × 10³ km² in the 2070s, an increase of 1010 × 10³ km² from the current distribution. The potentially suitable habitat of B. polycarpa under the SSP5-8.5 scenario will reach 2618.01 × 10³ km² in the 2070s (an increase of 464 × 10³ km²). The potentially suitable habitats of H. rhodope and B. polycarpa are expected to shift to higher elevations under future climate scenarios. We also identified ten key environmental factors, of which Precipitation of Warmest Quarter (bio18) had the greatest influence on the probability of moth and host plant occurrence. Our results highlight the risk of further expansion of the potentially suitable area for H. rhodope and the important role of the host plant in this process, and provide a firm scientific basis for the monitoring and management of H. rhodope and B. polycarpa. Full article

(This article belongs to the Special Issue Effects of Environment and Food Stress on Insect Population)

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14 pages, 3023 KiB

Open AccessArticle

Distribution Pattern and Change Prediction of Luprops orientalis (Coleoptera: Tenebrionidae) Suitable Area in East Asia Under Climate Change

by Jieqiong Wang, Shuangyi Wang, Yunchun Li, Shuangmei Ding, Zhonghua Wei, Aimin Shi and Ding Yang

Insects 2025, 16(6), 626; https://doi.org/10.3390/insects16060626 - 13 Jun 2025

Abstract

Luprops orientalis (Motschulsky, 1868) is an economically important pest in traditional Chinese medicines, widely distributed in East Asia. However, the primary limiting factors affecting its distribution, potential suitable areas, as well as its response to global warming, remain largely unknown. Utilizing 295 filtered [...] Read more.

Luprops orientalis (Motschulsky, 1868) is an economically important pest in traditional Chinese medicines, widely distributed in East Asia. However, the primary limiting factors affecting its distribution, potential suitable areas, as well as its response to global warming, remain largely unknown. Utilizing 295 filtered distribution points and 10 environmental variables (9 climate variables and 1 land cover type), this study uses the MaxEnt model to predict the potential distribution of L. orientalis under near-current and future environmental change scenarios. The results indicated that precipitation of the warmest quarter (bio18), temperature seasonality (bio04), and precipitation of the wettest month (bio13) were the most significant environmental variables affecting the distribution of suitable habitats for L. orientalis, while the contribution of average variation in daytime temperature (bio2) was the smallest. Under the near-current climate, the areas of low, moderate, and high suitability for L. orientalis are approximately 1.02 × 10⁶ km², 1.65 × 10⁶ km², and 8.22 × 10⁵ km², respectively. The suitable areas are primarily located in North China, Central China, the Korean Peninsula, and Central and Southern Japan. Under future climate conditions, the potential suitable areas are expected to expand significantly, especially in Central China. However, the high-suitability areas in North China are predicted to experience a slight reduction. With the increase in carbon emission concentrations, the suitable area shows an increasing trend in the 2050s, followed by a declining trend in the 2090s. The centroids of suitable areas will shift to the northeast in the future. These findings enhance our understanding of how climate change affects the distribution of L. orientalis and will assist governments in formulating effective pest control strategies, including widespread monitoring and stringent quarantine measures. Full article

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

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24 pages, 14728 KiB

Open AccessArticle

Death-Leading Envenomization of Rabbits with Snake Versus Scorpion Venoms: A Comparative Forensic Investigation of Postmortem Decomposition and Beetle Succession

by Afnan Saleh Al-Qurashi, Mohammed Saleh Al-Khalifa, Hathal Mohammed Al Dhafer, Mahmoud Saleh Abdel-Dayem, Hossam Ebaid and Ashraf Mohamed Ahmed

Insects 2025, 16(6), 625; https://doi.org/10.3390/insects16060625 - 13 Jun 2025

Abstract

Background:Envenomation by poisonous creatures is a major global cause of mortality. Its concomitant impact on the postmortem corpse decomposition and associated insect succession pattern is still poorly understood. Purpose of the study: This study comparatively investigates the impact of envenomization with [...] Read more.

Background:Envenomation by poisonous creatures is a major global cause of mortality. Its concomitant impact on the postmortem corpse decomposition and associated insect succession pattern is still poorly understood. Purpose of the study: This study comparatively investigates the impact of envenomization with the venoms of the snake Walterinnesia aegyptia L. versus the scorpion, Androctonus crassicauda L., on rabbit corpse decomposition and beetle succession. Methods: Three groups of rabbits (five animals each) were injected with the snake venom, the scorpion venom, or 0.9% saline (control) prior to euthanasia with CO₂. The corpse decomposition stages and beetle succession were monitored over 11 days. Results: Four stages of decomposition with venom-dependent duration variation were observed. The scorpion-envenomized corpses showed a longer decay stage and a delayed dry stage. A total of 1094 beetles belonging to 27 species of 14 families were reported. Histeridae, Dermestidae, Scarabaeidae, and Tenebrionidae were the most diversified and prevalent families. Chrysomelidae, Elateridae, Hybosoridae, and Ptinidae were incidentally attracted to control corpses, while Nitidulidae and Zopheridae were only found on control and snake-envenomized ones. Four species belonging to the families Anthicidae, Histeridae, Scarabaeidae, and Tenebrionidae were predominant on all corpses. Four species belonging to the families Chrysomelidae, Curculionidae, Elateridae, and Hybosoridae were distinctively associated with the control corpses. Conclusions: These findings provided evidence that envenomation impacted the decomposition process and beetle succession in a venom-dependent manner, which could be significant for forensic investigations. Full article

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

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17 pages, 2226 KiB

Open AccessArticle

Transcriptome-Wide Identification of Neuropeptides and Neuropeptide Receptors in the Twenty-Eight-Spotted Ladybird Henosepilachna vigintioctopunctata

by Quanxing Lei, Ziming Wang, Shuangyan Yao, Aili Lin, Yunhui Zhang, Chengxian Sun, Xiaoguang Liu, Mengfang Du, Xiaoming Liu and Shiheng An

Insects 2025, 16(6), 624; https://doi.org/10.3390/insects16060624 - 13 Jun 2025

Abstract

The ladybird beetle, Henosepilachna vigintioctopunctata, is an oligophagous pest with significant economic impact. This pest causes considerable economic damage on numerous Solanaceae crops. Neuropeptides, along with their designated receptors, play a pivotal role in regulating diverse biological processes in insects, presenting a [...] Read more.

The ladybird beetle, Henosepilachna vigintioctopunctata, is an oligophagous pest with significant economic impact. This pest causes considerable economic damage on numerous Solanaceae crops. Neuropeptides, along with their designated receptors, play a pivotal role in regulating diverse biological processes in insects, presenting a promising avenue for innovative pest management strategies. Herein, the transcriptome of the central nervous system (CNS) of H. vigintioctopunctata was sequenced. Overall, our analysis identified 58 neuropeptide precursor genes, from which 98 diverse mature peptides were predicted. Furthermore, 31 neuropeptide receptor genes belonging to three distinct classes were discovered, along with predictions for their potential ligands. Moreover, the expression patterns of these 58 neuropeptide genes across larval brain tissue, ventral nerve cord, and gut were evaluated using quantitative real-time PCR. Collectively, these findings will significantly contribute to future research focused on understanding the physiological functions and pharmacological characteristics of neuropeptides and their receptors in H. vigintioctopunctata. Ultimately, these insights may facilitate the development of targeted neuropeptide-based solutions for managing this pest affecting solanaceous plants. Full article

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

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15 pages, 4822 KiB

Open AccessArticle

Predicting the Current and Future Habitat Distribution for an Important Fruit Pest, Grapholita dimorpha Komai (Lepidoptera: Tortricidae), Using an Optimized MaxEnt Model

by Li Huang, Shichao Zuo, Yiqi Huo, Lizong Hu, Zhengbing Wang, Jiahui Zhang, Jin Liu, Weili Ding, Keshi Ma and Mingsheng Yang

Insects 2025, 16(6), 623; https://doi.org/10.3390/insects16060623 - 12 Jun 2025

Abstract

The Grapholita dimorpha is one of the significant borer pests that primarily damage plum, pear, and apple trees, often resulting in substantial economic losses in fruit production. However, the potential distribution range of this economically important pest remains poorly understood. In this study, [...] Read more.

The Grapholita dimorpha is one of the significant borer pests that primarily damage plum, pear, and apple trees, often resulting in substantial economic losses in fruit production. However, the potential distribution range of this economically important pest remains poorly understood. In this study, we simulated an optimized maximum entropy (MaxEnt) model to predict the spatiotemporal distribution pattern of G. dimorpha and identified its underlying driving factors. The results indicate that suitable habitats, under current bioclimatic conditions, are mainly distributed in eastern China, northeastern China, Korea, and Japan, covering a total of 273.5 × 10⁴ km². The highly suitable habitats are primarily located in Korea and parts of central Japan, with a total area of 19.8 × 10⁴ km². In future projections, the suitable area is expected to increase by 17.74% to 62.10%, and the suitable habitats are predicted to shift northward overall. In particular, there are more highly suitable habitats for G. dimorpha in China and Japan compared to their predominance in Korea under current climatic conditions. The bio9 and bio18 contribute 51.9% and 20.7% to the modeling, respectively, indicating that the distribution of G. dimorpha may be shaped mainly by the mean temperature of the driest quarter and precipitation of the warmest quarter. In summary, the distribution range predicted, particularly for regions with highly suitable habitats, poses a high risk of G. dimorpha outbreaks, emphasizing the priority of pest monitoring and management. Furthermore, the key bioclimatic variables identified could also provide crucial reference for pest monitoring. Full article

(This article belongs to the Special Issue Tortricid Moths (Lepidoptera: Tortricidae): Biology, Ecology and Integrated Pest Management)

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10 pages, 3033 KiB

Open AccessArticle

Glycosidase Isoforms in Honey and the Honey Bee (Apis mellifera L.): Differentiating Bee- and Yeast-Derived Enzymes and Implications for Honey Authentication

by Ratko Pavlović, Sanja Stojanović, Marija Pavlović, Nenad Drulović, Miroslava Vujčić, Biljana Dojnov and Zoran Vujčić

Insects 2025, 16(6), 622; https://doi.org/10.3390/insects16060622 - 12 Jun 2025

Abstract

The enzymes in honey can originate not only from bees and the plants from which the bees collect pollen and nectar but also from feed provided by beekeepers. Enzymes that hydrolyze sucrose—present in honey (α-glucosidase) or honey adulterated with invert syrup (β-fructofuranosidase)—can be [...] Read more.

The enzymes in honey can originate not only from bees and the plants from which the bees collect pollen and nectar but also from feed provided by beekeepers. Enzymes that hydrolyze sucrose—present in honey (α-glucosidase) or honey adulterated with invert syrup (β-fructofuranosidase)—can be distinguished using zymography, where enzymatic bands are detected with nitroblue tetrazolium (NBT) after sugar removal via ultrafiltration. This method enables the identification of honey produced in hives that have been improperly fed with invert syrup, leading to the mixture of natural honey and syrup, and offers a practical tool to detect indirect adulteration. The NBT assay, in combination with ultrafiltration, was used to determine the isoelectric point of honey bee α-glucosidases. The pI value of 6.63 for isoforms found in the head, midgut, and natural honey extracts during winter can be attributed to α-glucosidase III. Two additional isoforms with isoelectric points of 5.20 and 5.77 were observed in the midgut extract and may correspond to α-glucosidase I and II. The difference between α-glucosidase and β-fructofuranosidase was confirmed using a substrate specificity test, followed by thin-layer chromatography, where it was confirmed that α-glucosidase from natural honey, bee head, and bee midgut does not hydrolyze raffinose, in contrast to yeast β-fructofuranosidase. Full article

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

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12 pages, 1087 KiB

Open AccessArticle

Activation of BmToll9-1 in Silkworm (Bombyx mori) Larval Midgut by Escherichia coli and Regulation of Growth

by Jisheng Liu, Weijian Chen, Minchun Lai, Jiahua Chen and Luc Swevers

Insects 2025, 16(6), 621; https://doi.org/10.3390/insects16060621 - 11 Jun 2025

Abstract

Insects rely on their innate immune system to defend against pathogens, and the Toll signaling pathway plays an important role in immune regulation. Our previous studies have shown that BmToll9-1 functions as a positive regulator in the Toll pathway. This study seeks to [...] Read more.

Insects rely on their innate immune system to defend against pathogens, and the Toll signaling pathway plays an important role in immune regulation. Our previous studies have shown that BmToll9-1 functions as a positive regulator in the Toll pathway. This study seeks to elucidate the role of BmToll9-1, as a sensor to bacterial challenge, in modulating larval development and downstream Toll signaling pathways. Silkworm larvae were subjected to infection with either Gram-negative Escherichia coli or Gram-positive Staphylococcus aureus bacteria following silencing of BmToll9-1 by RNA interference (RNAi). This bacterial challenge triggered a compensatory re-induction of BmToll9-1 expression, which resulted in the recovery of larval weight and size to levels observed in untreated controls. Furthermore, upon bacterial infection of BmToll9-1-silenced larvae, there was an up-regulation in the expression of both signaling genes in the Toll pathway and downstream effector genes, with a marked preference for Gram-negative bacteria. These results highlight the involvement of BmToll9-1 in the Toll signaling pathway as a positive regulator, influencing silkworm development. Additionally, BmToll9-1 and BmToll9-2 were cross-validated to be genetically distinct genes, even though they were confirmed to be functionally analogous in the silkworm. Full article

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

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12 pages, 1284 KiB

Open AccessArticle

Invasion Dynamics and Migration Patterns of Fall Armyworm (Spodoptera frugiperda) in Shaanxi, China

by Zhanfeng Yan, Xiaojun Feng, Xing Wang, Xiangqun Yuan, Yongjun Zhang, Daibin Yang, Kanglai He, Feizhou Xie, Zhenying Wang and Yiping Li

Insects 2025, 16(6), 620; https://doi.org/10.3390/insects16060620 - 11 Jun 2025

Abstract

The fall armyworm (Spodoptera frugiperda) is a highly invasive agricultural pest that has caused significant damage to maize and other crops since its initial detection in China in 2019. Understanding its invasion dynamics, migration patterns, genetic diversity, and overwintering capacity is [...] Read more.

The fall armyworm (Spodoptera frugiperda) is a highly invasive agricultural pest that has caused significant damage to maize and other crops since its initial detection in China in 2019. Understanding its invasion dynamics, migration patterns, genetic diversity, and overwintering capacity is crucial for developing effective pest management strategies. This study investigates these aspects in Shaanxi Province, a critical transitional zone between northern and southern climates in China, from 2019 to 2023. We conducted field surveys in six cities across Shaanxi to monitor the initial infestation of FAW. Migration trajectories were simulated using the HYSPLIT model, integrating pest occurrence data and meteorological information. Genetic analyses were performed on 113 FAW individuals from 12 geographical populations using mitochondrial COI and nuclear Tpi genes. Additionally, an overwintering experiment was conducted to assess the survival of FAW pupae under local winter conditions. The first detection dates of FAW in Shaanxi showed significant interannual variation, with a trend of delayed infestation each year. Three primary migration routes into Shaanxi were identified, originating from Sichuan, Hubei-Chongqing, and Henan. Genetic analysis revealed a predominance of the rice-strain FAW in Shaanxi, with some corn-strain variants in northern regions. The overwintering experiment indicated that FAW pupae could not survive the winter in Shaanxi, suggesting that the region does not support year-round breeding of this pest. This study provides comprehensive insights into the spatiotemporal dynamics and migration patterns of FAW in Shaanxi. The findings highlight the importance of integrated pest management approaches, including monitoring migration routes and genetic diversity, to develop targeted control measures. The inability of FAW to overwinter in Shaanxi suggests that regional climate conditions play a significant role in limiting its year-round presence, which is valuable information for designing early warning systems and sustainable pest management strategies. Full article

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

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16 pages, 3031 KiB

Open AccessArticle

Histopathological and Transcriptional Changes in Silkworm Larval Gonads in Response to Chlorfenapyr Exposure

by Tao Li, Changxiong Hu, Zenghu Liu, Qiongyan Li, Yonghui Fan, Pengfei Liao, Min Liu, Weike Yang, Xingxing Li and Zhanpeng Dong

Insects 2025, 16(6), 619; https://doi.org/10.3390/insects16060619 - 11 Jun 2025

Abstract

Chlorfenapyr is a widely used insecticide known to harm non-target insects, but its effects on reproductive development in the silkworm (Bombyx mori L.) remain incompletely understood. In this study, we investigated the histopathological and transcriptional changes in the gonads (ovaries and testes) [...] Read more.

Chlorfenapyr is a widely used insecticide known to harm non-target insects, but its effects on reproductive development in the silkworm (Bombyx mori L.) remain incompletely understood. In this study, we investigated the histopathological and transcriptional changes in the gonads (ovaries and testes) of newly molted fifth-instar silkworm larvae exposed to chlorfenapyr. Histopathological analysis revealed delayed gonadal development, a reduction in oogonia and oocytes in the ovaries, and decreased numbers of spermatocytes in the testes. Transcriptome analysis identified significant differentially expressed genes (DEGs), mainly enriched in pathways such as “Drug metabolism—cytochrome P450”, “Insect hormone biosynthesis”, and “Ribosome”. Key up-regulated genes included members of the cytochrome P450 family (CYP6B5, CYP9f2, CYP6B6), glutathione S-transferases (GSTT1, GST1), and juvenile hormone-related enzymes (JHAMT, JHEH), indicating active detoxification and hormonal regulation responses. Several transcription factor families, particularly C2H2, HB-other, and TRAF, exhibited altered expression, suggesting roles in stress adaptation. Protein–protein interaction (PPI) network analysis identified hub genes such as EcR, Kr-h1, and various ribosomal proteins, highlighting their potential involvement in reproductive development. Quantitative PCR (qPCR) validated the transcriptomic data, confirming the reliability of the results. Overall, these findings enhance our understanding of chlorfenapyr’s impact on silkworm reproductive development and the underlying molecular mechanisms, providing valuable insights for sustainable pest management and ecological risk assessment of insecticides. Full article

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

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22 pages, 12796 KiB

Open AccessArticle

The Thoracic Anatomy of Two Flightless Chrysolina Species (Coleoptera: Chrysomelidae)

by Sipei Liu, Xiaokun Liu, Xieshuang Wang, Wenjie Li, Xin Liu and Siqin Ge

Insects 2025, 16(6), 618; https://doi.org/10.3390/insects16060618 - 11 Jun 2025

Abstract

Flight loss has independently evolved across nearly all winged insect orders. Comparing the thoracic structures of flightless insects with those of their flight-capable relatives can reveal key characteristics linked with flight. Although flight loss has been widely studied in beetles, exploration of this [...] Read more.

Flight loss has independently evolved across nearly all winged insect orders. Comparing the thoracic structures of flightless insects with those of their flight-capable relatives can reveal key characteristics linked with flight. Although flight loss has been widely studied in beetles, exploration of this phenomenon has been limited to taxonomic and geographic distribution studies in the species-rich family Chrysomelidae, with little analysis of thoracic anatomical structures. This study employs a suite of morphological techniques to examine the thoracic structures of two flightless beetle species Chrysolina: sulcicollis and Chrysolina virgata, originating from desert and temperate regions, respectively. A comparison between the two flightless species reveals that C. sulcicollis has fewer tergo-pleural muscles involved in elytral movement likely to save water, but more muscles that contribute to stabilizing larger body structures. Meanwhile, differences are also observed in the elytral base, the anterior corner of the mesal suture, and the setae on the meso-inner region of the epipleuron. Compared to other flight-capable chrysomelid beetles, apart from the absence of flight-related muscles, the two flightless beetles exhibit similar thoracic skeletal structures. The absence of lateral cervical sclerites, along with the presence of muscles Idvm4, 5 and Itpm5, could enhance head mobility as a compensatory adaptation doe the loss of flight capability. Additionally, the greater number of tergo-pleural muscles in the mesothorax of C. virgata could suggest that its elytra serve a specialized function. Compared to other flightless beetles, aside from the similarly reduced flight muscles, these two species have relatively intact thoracic skeletons. Further data on habitat, functional compensation and other related factors are needed to compare their evolutionary processes with those of other flightless beetles. Full article

(This article belongs to the Special Issue Beetles in Integrative Entomology: Biology, Taxonomy, and Conservation)

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18 pages, 1392 KiB

Open AccessReview

Environmental Impacts and Behavioral Adaptations of Honeybees in Algeria: A Review of Apis mellifera intermissa and Apis mellifera sahariensis Characteristics

by Yamina Haider, Noureddine Adjlane and Nizar Haddad

Insects 2025, 16(6), 617; https://doi.org/10.3390/insects16060617 - 11 Jun 2025

Abstract

Honeybees are vital for pollination and the overall health of ecosystems. Since the 18th century, the intricate biology of honeybees has been a subject of scientific inquiry. Understanding their biological and behavioral characteristics is essential for effective beekeeping, honey production, and ecosystem sustainability. [...] Read more.

Honeybees are vital for pollination and the overall health of ecosystems. Since the 18th century, the intricate biology of honeybees has been a subject of scientific inquiry. Understanding their biological and behavioral characteristics is essential for effective beekeeping, honey production, and ecosystem sustainability. This review examines the environmental impact and management practices on the health of local honeybees in Algeria, focusing on Apis mellifera intermissa and Apis mellifera sahariensis. We summarize research findings on genetic diversity, morphometric traits, behavioral characteristics, and adaptation of local honeybees. Additionally, we discuss the threats posed by abiotic and biotic stressors and highlight the importance of conservation and sustainable management. The reviewed studies indicate that environmental factors significantly influence the behavioral characteristics and adaptation of local honeybees. Notably, the hygienic behavior of A. m. intermissa contributes to their resistance against diseases and the Varroa destructor mite. Further research in these areas is important for enhancing our understanding of honeybee health and population dynamics in Algeria, thereby informing strategies for sustainable beekeeping practices. Full article

(This article belongs to the Special Issue Impact of Environmental Factors and Management Practices on Bee Health)

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13 pages, 1435 KiB

Open AccessArticle

Development of an Experimental Method Using a Portable Photosynthesis-Monitoring System to Measure Respiration Rates in Small-Sized Insects

by Bi-Yue Ding, Qin-Qin Xu, Yu-Jing Liu, Yu-Hong Zhong and Yan Zhou

Insects 2025, 16(6), 616; https://doi.org/10.3390/insects16060616 - 10 Jun 2025

Abstract

Respiration rates in insects are critical for survival and environmental adaptation, being influenced by developmental stages, environmental conditions, and the regulation of mitochondrial protein-coding genes. However, methods for field-based measurements in small-sized insects remain limited. In this study, we established a portable photosynthesis [...] Read more.

Respiration rates in insects are critical for survival and environmental adaptation, being influenced by developmental stages, environmental conditions, and the regulation of mitochondrial protein-coding genes. However, methods for field-based measurements in small-sized insects remain limited. In this study, we established a portable photosynthesis system to quantify respiration rates in five small-sized insects (body length < 8 mm): Acyrthosiphon pisum, Aphis citricidus, Tuta absoluta, Tribolium castaneum, and Bactrocera dorsalis. We tested its effectiveness across life stages and under diverse treatments, including light/dark cycles, insecticides, temperature shifts, starvation, mitochondrial inhibitors, and RNA interference. The system exhibited high sensitivity and reproducibility rates, revealing stage-specific respiration patterns. Various treatments, as well as expression changes in mitochondrial protein-coding genes, significantly affected respiration rates. This study validates the portable system as a reliable tool for insect respiration studies and highlights regulatory networks associated with respiratory plasticity. These findings enhance experimental methodologies and advance our understanding of insect adaptation to environmental stressors and pest control strategies. Full article

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

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14 pages, 645 KiB

Open AccessReview

Overview and Recent Advances in Bioassays to Evaluate the Potential of Entomopathogenic Fungi Against Ambrosia Beetles

by Jesús Enrique Castrejón-Antonio and Patricia Tamez-Guerra

Insects 2025, 16(6), 615; https://doi.org/10.3390/insects16060615 - 10 Jun 2025

Abstract

Ambrosia beetles, known for their symbiotic relationship with fungi cultivated within the tissues of host trees, have become significant pests, particularly when they serve as vectors for pathogenic fungi such as Raffaelea lauricola. Given the regulatory and environmental constraints for chemical application [...] Read more.

Ambrosia beetles, known for their symbiotic relationship with fungi cultivated within the tissues of host trees, have become significant pests, particularly when they serve as vectors for pathogenic fungi such as Raffaelea lauricola. Given the regulatory and environmental constraints for chemical application as a tool for their control, entomopathogenic fungi (EPF) represent a promising pest management alternative. This review presents an overview of bioassays assessing the pathogenicity and virulence of EPF against ambrosia beetles. Most studies have been performed in vivo (artificial diet) under laboratory conditions, focusing on exotic species and testing EPF genera such as Beauveria, Metarhizium, Isaria, and Purpureocillium. However, variations in inoculation methods, environmental conditions, and fungal formulations, have led to diverse results. In addition, the complex biology of these insects, particularly their dependence on symbiotic fungi, represents significant methodological challenges. Field trials (in situ bioassays) are still scarce, and there is a need to move toward standardized protocols and more objective experimental models that consider not only insects’ behavior but also ecological factors. Bridging this gap is essential for successfully implementing EPF-based strategies to assess ambrosia beetles’ biocontrol. 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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15 pages, 1181 KiB

Open AccessArticle

Effects of Orally Delivered Double-Stranded RNA of Trehalose-6-Phosphate Synthase on the Population of Frankliniella occidentalis

by Tao Lin, Xiaoyu Chen, Ying Chen, Ting Chen, Xueyi Liang, Hui Wei and Guang Yang

Insects 2025, 16(6), 614; https://doi.org/10.3390/insects16060614 - 10 Jun 2025

Abstract

The invasive pest Frankliniella occidentalis (western flower thrip, WFT) severely impacts agricultural production. RNA interference (RNAi) has emerged as a viable alternative to chemical control methods. Trehalose-6-phosphate synthase (TPS) is an important enzyme for the synthesis of trehalose in insects. The TPS gene [...] Read more.

The invasive pest Frankliniella occidentalis (western flower thrip, WFT) severely impacts agricultural production. RNA interference (RNAi) has emerged as a viable alternative to chemical control methods. Trehalose-6-phosphate synthase (TPS) is an important enzyme for the synthesis of trehalose in insects. The TPS gene is a potential target for RNAi-based pest control; however, its efficacy against WFTs remains unclear. Feeding with the synthesized dsFoTPS to WFT significantly increased the mortalities of first- and second-instar nymphs and adults and significantly decreased the number of eggs laid by adults within 72 h; the expression of FoTPS was significantly down-regulated in 24, 48, and 72 h. Ingestion of WFTs on Escherichia coli expressing dsFoTPS led to a marked increase in the total pre-reproductive period; reductions in survival rate, adult longevity, oviposition days, fecundity, peak reproduction value, the intrinsic rate of increase, the finite rate of increase, and the net reproductive rate; and an extension of the mean generation time. TPS gene expression was significantly down-regulated on days 7 and 28. A population simulation of WFTs fed with E. coli expressing dsFoTPS indicated that the population suppression was reduced to 1/34 of the control in 100 d. Oral delivery of E. coli expressing dsFoTPS effectively inhibited the survival, fecundity, and population growth of WFTs, offering a novel approach and rationale for the prevention and control of WFTs. Full article

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

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23 pages, 2291 KiB

Open AccessArticle

Mating Behavior of Cyclocephala barrerai Martínez (Coleoptera: Melolonthidae)

by Abraham Sanchez-Cruz, Patricia Villa-Ayala and Alfredo Jiménez-Pérez

Insects 2025, 16(6), 613; https://doi.org/10.3390/insects16060613 - 10 Jun 2025

Abstract

Our study aimed to characterize mating behavior in virgin and once-mated males and females of Cyclocephala barrerai. We reared the specimens under laboratory conditions and recorded the age at which the organisms began their reproductive activity and the time they remained active. [...] Read more.

Our study aimed to characterize mating behavior in virgin and once-mated males and females of Cyclocephala barrerai. We reared the specimens under laboratory conditions and recorded the age at which the organisms began their reproductive activity and the time they remained active. We characterized behavioral acts during mating in two groups—virgin and once-mated organisms. Transitions between behaviors were analyzed using Markov chains and the generated ethograms. The duration of behaviors and the percentage of transitions were compared between the two groups. To characterize the mating behavior of C. barrerai, we adopted a framework commonly used in the literature, dividing mating behavior into three phases: premating, mating, and postmating. (A) Premating: Males search for females and mount and stimulate them, which the females resist through fighting behaviors. (B) Mating: The male mounts the female, which moves around and then stops; the male performs specific movements of the antennae and head and inserts his aedeagus into the female. (C) Postmating: Males exhibit guarding behavior over females. Although differences in pre- and postmating behaviors were observed between virgin and once-mated organisms, the duration of the acts did not show significant differences. These results provide key information on the reproductive behavior of C. barrerai, contributing to a better understanding of their biology and sexual interaction patterns. Full article

(This article belongs to the Special Issue Arthropod Reproductive Biology)

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20 pages, 4156 KiB

Open AccessArticle

Reproductive Senescence in the Pollinator, Megachile rotundata

by Jacob B. Pithan, Brooke L. Kohler, Arun Rajamohan and Kendra J. Greenlee

Insects 2025, 16(6), 612; https://doi.org/10.3390/insects16060612 - 10 Jun 2025

Abstract

The disposable soma theory posits that organisms allocate limited resources between reproduction, maintenance, and growth, resulting in trade-offs, particularly as they age. In this study, we examined age-related reproductive senescence in Megachile rotundata, a solitary bee and important agricultural pollinator. We hypothesized [...] Read more.

The disposable soma theory posits that organisms allocate limited resources between reproduction, maintenance, and growth, resulting in trade-offs, particularly as they age. In this study, we examined age-related reproductive senescence in Megachile rotundata, a solitary bee and important agricultural pollinator. We hypothesized that, similarly to social bees, aging females would show declines in foraging behavior and reproductive fitness. Contrary to this hypothesis, we found no evidence of reproductive senescence in M. rotundata within the timeframe observed. Instead, older females increased their foraging rate, leading to larger provisions and offspring. We also observed that older bees exhibited improved foraging efficiency, likely due to learning and muscle physiology changes. Furthermore, ovarian development showed no decline with age, indicating that reproductive capacity remains stable throughout the observed timeframe. Our results challenge conventional assumptions about reproductive senescence in solitary bees and suggest that older M. rotundata may contribute to more efficient pollination, with implications for pollinator management. This study provides new insights into the aging process in solitary bees, emphasizing the need for further research into the mechanisms behind age-related behavioral and reproductive changes. Full article

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

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13 pages, 1070 KiB

Open AccessArticle

Laboratory Test Indirectly Reveals the Unreliability of RNA-Dependent 16S rRNA Amplicon Sequences in Detecting the Gut Bacterial Diversity of Delia antiqua

by Miaomiao Li, Xin Cao, Linfeng Xu, Luyao Lin, Xiaoqing Wu, Susu Fan, Xinjian Zhang and Fangyuan Zhou

Insects 2025, 16(6), 611; https://doi.org/10.3390/insects16060611 - 10 Jun 2025

Abstract

In insect–microbe symbiosis, understanding the diversity of associated bacteria is crucial. DNA-dependent sequence methods are widely used to assess microbial diversity in insects, but they cannot distinguish between live and dead microbes. In contrast, RNA-dependent sequencing can identify alive bacterial communities, making them [...] Read more.

In insect–microbe symbiosis, understanding the diversity of associated bacteria is crucial. DNA-dependent sequence methods are widely used to assess microbial diversity in insects, but they cannot distinguish between live and dead microbes. In contrast, RNA-dependent sequencing can identify alive bacterial communities, making them more suitable for evaluating alive microbiota diversity. However, its practical reliability in insect–microbe symbiosis remains poorly validated. This study investigated larval gut bacteria diversity of Delia antiqua, a major pest of Liliaceae crops, by employing both DNA- and RNA-dependent 16S rRNA amplicon sequencing. The reliability of both sequencing methods was evaluated by comparing the effects of synthetic communities (SynComs, constructed according to DNA- or RNA-dependent sequencing) and bacterial communities from wild larvae on axenic larvae. Results revealed significant differences in bacterial community between DNA- and RNA-dependent sequence samples. Compared to bacterial communities from wild larvae, the SynCom constructed based on RNA-dependent sequencing exhibited inhibition effects on D. antiqua larvae survival and body weight, while DNA-dependent SynCom did not, suggesting that DNA-dependent methods were superior for assessing symbiotic microbiota in D. antiqua. This work will provide insights into microbial diversity detection in D. antiqua and offer a framework for other insect–microbe studies. Full article

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

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20 pages, 5993 KiB

Open AccessArticle

High-Precision Stored-Grain Insect Pest Detection Method Based on PDA-YOLO

by Fuyan Sun, Zhizhong Guan, Zongwang Lyu and Shanshan Liu

Insects 2025, 16(6), 610; https://doi.org/10.3390/insects16060610 - 10 Jun 2025

Abstract

Effective stored-grain insect pest detection is crucial in grain storage management to prevent economic losses and ensure food security throughout production and supply chains. Existing detection methods suffer from issues such as high labor costs, environmental interference, high equipment costs, and inconsistent performance. [...] Read more.

Effective stored-grain insect pest detection is crucial in grain storage management to prevent economic losses and ensure food security throughout production and supply chains. Existing detection methods suffer from issues such as high labor costs, environmental interference, high equipment costs, and inconsistent performance. To address these limitations, we proposed PDA-YOLO, an improved stored-grain insect pest detection algorithm based on YOLO11n which integrates three key modules: PoolFormer_C3k2 (PF_C3k2) for efficient local feature extraction, Attention-based Intra-Scale Feature Interaction (AIFI) for enhanced global context awareness, and Dynamic Multi-scale Aware Edge (DMAE) for precise boundary detection of small targets. Trained and tested on 6200 images covering five common stored-grain insect pests (Lesser Grain Borer, Red Flour Beetle, Indian Meal Moth, Maize Weevil, and Angoumois Grain Moth), PDA-YOLO achieved an mAP@0.5 of 96.6%, mAP@0.5:0.95 of 60.4%, and F1 score of 93.5%, with a computational cost of only 6.9 G and mean detection time of 9.9 ms per image. These results demonstrate the advantages over mainstream detection algorithms, balancing accuracy, computational efficiency, and real-time performance. PDA-YOLO provides a reference for pest detection in intelligent grain storage management. Full article

(This article belongs to the Special Issue Artificial Intelligence (AI) and Insect Pests Management: Securing Food Security, Human Health, and Natural Resources)

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26 pages, 3528 KiB

Open AccessArticle

Synergistic Insecticidal Activity of Plant Volatile Compounds: Impact on Neurotransmission and Detoxification Enzymes in Sitophilus zeamais

by Leidy J. Nagles Galeano, Juliet A. Prieto-Rodríguez and Oscar J. Patiño-Ladino

Insects 2025, 16(6), 609; https://doi.org/10.3390/insects16060609 - 9 Jun 2025

Abstract

Sitophilus zeamais, a major pest of stored grains, causes significant post-harvest losses and challenges effective control. While synthetic insecticides pose risks of resistance and toxicity, essential oils (EOs) offer a safer alternative. However, the insecticidal potential of their individual volatile constituents (VCs) [...] Read more.

Sitophilus zeamais, a major pest of stored grains, causes significant post-harvest losses and challenges effective control. While synthetic insecticides pose risks of resistance and toxicity, essential oils (EOs) offer a safer alternative. However, the insecticidal potential of their individual volatile constituents (VCs) remains largely unexplored. This study evaluated the insecticidal activity of 51 EO-derived volatile compounds (VCs) against S. zeamais, identifying the most toxic ones, optimizing 15 synergistic mixtures, and assessing their effects on key insect enzymes. A structure–activity relationship (SAR) analysis determined functional groups associated with insecticidal activity, while a cluster analysis pre-selected 29 ternary mixtures, later refined using response surface methodology (RSM). Additionally, enzymatic assays explored their impact on detoxification and nervous system enzymes, providing insights into potential mechanisms of action. Among the 51 VCs tested, 37 exhibited significant toxicity, with 11 acting as fumigants and 13 displaying contact toxicity. Monocyclic monoterpenoids with ketone or alcohol functional groups and exocyclic unsaturation demonstrated the highest insecticidal activity via both exposure routes. Notably, pulegone enantiomers were particularly effective (LC₅₀ < 0.1 mg/L, LD₅₀ < 7.5 µg/adult). Among the optimized mixtures, 10 displayed strong insecticidal effects, 8 were active through both routes, and 5 exhibited synergistic fumigant interactions. The most effective formulations were M2 (R-pulegone + S-pulegone + S-carvone, LC₅₀ 0.48 mg/L) and M20 (isopulegone + δ-3-carene, LC₅₀ 2.06 mg/L), showing the strongest fumigant and synergistic effects, respectively. Enzymatic assays revealed that while some compounds mildly inhibited GST and CAT, others, such as δ-3-carene (IC₅₀ 0.19 mg/L), significantly inhibited AChE. Five mixtures exhibited synergistic neurotoxicity, with M20 (IC₅₀ 0.61 mg/L) and M12 (IC₅₀ 0.81 mg/L) emerging as the most potent AChE inhibitors. These findings highlight the potential of plant-derived volatile compounds as bioinsecticides, leveraging synergistic interactions to enhance efficacy, disrupt enzymatic pathways, and mitigate resistance. Full article

(This article belongs to the Collection Stored-Product Pests: Biology, Ecology, Behavior and Integrated Management)

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