Pub Date : 2025-12-01DOI: 10.1016/j.jinsphys.2025.104908
Daniel Estiven Quiroga-Murcia , Éricmar Avila dos Santos , Kristof De Schutter , Moises J. Zotti
Nuclease (RNase) activity is a major limiting factor that reduces the effectiveness of RNAi-induced gene silencing across many insect species. In Euschistus heros, dsRNA degradation occurs predominantly upon contact with saliva, while midgut fluids exhibit moderate degradative activity and the hemolymph shows minimal or no RNase activity. High expression levels of RNase genes have been confirmed in the salivary glands, and to a lesser extent, in the midgut. To assess the impact of this barrier on RNAi efficacy, a RNAi-of-RNAi-based strategy was designed, involving the microinjection of dsRNA targeting the RNase gene (dsRNase), followed by the oral delivery of dsRNA targeting the V-ATPase gene (dsVATP-ase). This approach successfully reduced RNase gene expression and significantly decreased dsRNA degradation in saliva and midgut extracts. However, RNase suppression did not result in a significant enhancement on the E. heros sensitivity to dsVATP-ase, suggesting the presence of additional barriers that limit RNAi efficacy in this species. These results highlight the importance of mitigating enzymatic degradation while also emphasizing the need for complementary approaches to overcome other physiological barriers and enhance the viability of RNAi as a control tool in E. heros.
{"title":"Euschistus heros RNase silencing: dsRNA stability and effects on RNAi susceptibility","authors":"Daniel Estiven Quiroga-Murcia , Éricmar Avila dos Santos , Kristof De Schutter , Moises J. Zotti","doi":"10.1016/j.jinsphys.2025.104908","DOIUrl":"10.1016/j.jinsphys.2025.104908","url":null,"abstract":"<div><div>Nuclease (RNase) activity is a major limiting factor that reduces the effectiveness of RNAi-induced gene silencing across many insect species. In <em>Euschistus heros</em>, dsRNA degradation occurs predominantly upon contact with saliva, while midgut fluids exhibit moderate degradative activity and the hemolymph shows minimal or no RNase activity. High expression levels of <em>RNase</em> genes have been confirmed in the salivary glands, and to a lesser extent, in the midgut. To assess the impact of this barrier on RNAi efficacy, a RNAi-of-RNAi-based strategy was designed, involving the microinjection of dsRNA targeting the <em>RNase</em> gene (ds<em>RNase</em>), followed by the oral delivery of dsRNA targeting the <em>V-ATPase</em> gene (ds<em>VATP-ase</em>). This approach successfully reduced <em>RNase</em> gene expression and significantly decreased dsRNA degradation in saliva and midgut extracts. However, RNase suppression did not result in a significant enhancement on the <em>E. heros</em> sensitivity to ds<em>VATP-ase</em>, suggesting the presence of additional barriers that limit RNAi efficacy in this species. These results highlight the importance of mitigating enzymatic degradation while also emphasizing the need for complementary approaches to overcome other physiological barriers and enhance the viability of RNAi as a control tool in <em>E. heros</em>.</div></div>","PeriodicalId":16189,"journal":{"name":"Journal of insect physiology","volume":"167 ","pages":"Article 104908"},"PeriodicalIF":2.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Diapause, which is defined as a programmed cessation of development, is considered a survival strategy in adverse seasons. However, the physiological and behavioural changes associated with diapause reduce the fitness of insects because they require greater metabolic investment and time. In many insects, diapause is induced primarily by photoperiod and temperature in a facultative manner. Furthermore, the occurrence of facultative diapause in some insects is often determined by the conditions experienced by the mother. Two species of multivoltine mirids, Trigonotylus caelestialium and Adelphocoris triannulatus (Hemiptera: Miridae), exhibit embryonic diapause induced by such a maternal effect. In this study, we evaluated the cost of diapause egg production in these two species by comparing life history traits associated with diapause and non-diapause egg production under short-day and long-day conditions, respectively. The results showed that the pre-oviposition period for adult females was significantly longer under short-day conditions for both species. Significant differences were also observed in the number of eggs laid by the two species, with approximately 30% fewer eggs being laid under short-day conditions than under long-day conditions. This implies that producing diapause eggs to ensure long-term survival incurs costs, resulting in delayed egg-laying or reduced numbers of eggs. This study is the first to focus on the costs of diapause egg production in insects.
{"title":"Cost of producing diapause eggs in two mirids, Trigonotylus caelestialium and Adelphocoris triannulatus (Hemiptera: Miridae)","authors":"Yoshinori Shintani, Ryohei Miyahara, Jun-ya Tajima","doi":"10.1016/j.jinsphys.2025.104915","DOIUrl":"10.1016/j.jinsphys.2025.104915","url":null,"abstract":"<div><div>Diapause, which is defined as a programmed cessation of development, is considered a survival strategy in adverse seasons. However, the physiological and behavioural changes associated with diapause reduce the fitness of insects because they require greater metabolic investment and time. In many insects, diapause is induced primarily by photoperiod and temperature in a facultative manner. Furthermore, the occurrence of facultative diapause in some insects is often determined by the conditions experienced by the mother. Two species of multivoltine mirids, <em>Trigonotylus caelestialium</em> and <em>Adelphocoris triannulatus</em> (Hemiptera: Miridae), exhibit embryonic diapause induced by such a maternal effect. In this study, we evaluated the cost of diapause egg production in these two species by comparing life history traits associated with diapause and non-diapause egg production under short-day and long-day conditions, respectively. The results showed that the pre-oviposition period for adult females was significantly longer under short-day conditions for both species. Significant differences were also observed in the number of eggs laid by the two species, with approximately 30% fewer eggs being laid under short-day conditions than under long-day conditions. This implies that producing diapause eggs to ensure long-term survival incurs costs, resulting in delayed egg-laying or reduced numbers of eggs. This study is the first to focus on the costs of diapause egg production in insects.</div></div>","PeriodicalId":16189,"journal":{"name":"Journal of insect physiology","volume":"168 ","pages":"Article 104915"},"PeriodicalIF":2.3,"publicationDate":"2025-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145661220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-19DOI: 10.1016/j.jinsphys.2025.104909
Weijie Yuan , Jiangkun Wei , Junkai Lian , Caiying Liao , Matthew S. Lehnert , Stanislav N. Gorb , Zhigang Wu , Jianing Wu
Nectar sources are often confined to limited amounts of liquid in the microgrooves of floral nectaries. We show that in complete darkness, bees actively tapped their antennae to detect these microgrooves, and then rapidly aligned their body axis with these structures. Mechanical measurements confirm that aligning the body with the microgrooves at θ = 0 deg. reduces the external force on the proboscis during nectar feeding. Energy calculations demonstrate that feeding with an aligned body reduces foraging costs by 53.41 % compared to feeding with a vertical body at θ = 90 deg. By demonstrating the bee’s capacity for sensory-behavioral integration and adaptation in absence of visual cues, this body alignment response, which also mitigates potential proboscis damage, provides new insights into their energy-saving strategies.
{"title":"Body alignment enhances foraging performance of honey bees in the absence of visual cues","authors":"Weijie Yuan , Jiangkun Wei , Junkai Lian , Caiying Liao , Matthew S. Lehnert , Stanislav N. Gorb , Zhigang Wu , Jianing Wu","doi":"10.1016/j.jinsphys.2025.104909","DOIUrl":"10.1016/j.jinsphys.2025.104909","url":null,"abstract":"<div><div>Nectar sources are often confined to limited amounts of liquid in the microgrooves of floral nectaries. We show that in complete darkness, bees actively tapped their antennae to detect these microgrooves, and then rapidly aligned their body axis with these structures. Mechanical measurements confirm that aligning the body with the microgrooves at <em>θ</em> = 0 deg. reduces the external force on the proboscis during nectar feeding. Energy calculations demonstrate that feeding with an aligned body reduces foraging costs by 53.41 % compared to feeding with a vertical body at <em>θ</em> = 90 deg. By demonstrating the bee’s capacity for sensory-behavioral integration and adaptation in absence of visual cues, this body alignment response, which also mitigates potential proboscis damage, provides new insights into their energy-saving strategies.</div></div>","PeriodicalId":16189,"journal":{"name":"Journal of insect physiology","volume":"167 ","pages":"Article 104909"},"PeriodicalIF":2.3,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145564256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-17DOI: 10.1016/j.jinsphys.2025.104910
Anna Zielińska
Double-stranded RNA-binding proteins (dsRBPs) are essential cofactors in insect RNA interference (RNAi), where they stabilize and process double-stranded RNA and guide small RNAs into effector complexes. While Dicer and Argonaute proteins constitute the catalytic core of RNAi, dsRBPs such as R2D2, Loquacious, and Staufen, as well as lineage-specific variants like StaufenC, determine the efficiency, specificity, and systemic spread of silencing signals. Comparative analyses across Diptera, Coleoptera, Lepidoptera, and Hemiptera reveal pronounced differences in the presence, expression, and functional specialization of these proteins, which correlate with order-specific variability in RNAi responsiveness. Coleopterans exhibit robust systemic RNAi supported by high expression of dsRBPs and SID-1-like transporters, whereas lepidopterans and hemipterans display restricted dsRBP activity, elevated nuclease degradation, and limited systemic transport, resulting in inconsistent RNAi outcomes. Structural and biochemical studies have clarified the roles of dsRBPs in Dicer-mediated processing and RISC assembly, highlighting isoform-specific mechanisms in Loquacious and cooperative interactions between R2D2 and Dicer-2. Emerging evidence also implicates lineage-specific proteins, such as StaufenC in beetles, in enhancing oral RNAi. From an applied perspective, dsRBPs represent promising molecular determinants and biomarkers of RNAi susceptibility, offering entry points for improving host-induced and spray-induced gene silencing strategies. This review provides an integrated framework for understanding the molecular causes of RNAi variability and for developing targeted approaches to enhance the reliability of RNAi-based pest management.
{"title":"Insect double-stranded RNA-binding proteins: structure, function and RNAi efficiency","authors":"Anna Zielińska","doi":"10.1016/j.jinsphys.2025.104910","DOIUrl":"10.1016/j.jinsphys.2025.104910","url":null,"abstract":"<div><div>Double-stranded RNA-binding proteins (dsRBPs) are essential cofactors in insect RNA interference (RNAi), where they stabilize and process double-stranded RNA and guide small RNAs into effector complexes. While Dicer and Argonaute proteins constitute the catalytic core of RNAi, dsRBPs such as R2D2, Loquacious, and Staufen, as well as lineage-specific variants like StaufenC, determine the efficiency, specificity, and systemic spread of silencing signals. Comparative analyses across Diptera, Coleoptera, Lepidoptera, and Hemiptera reveal pronounced differences in the presence, expression, and functional specialization of these proteins, which correlate with order-specific variability in RNAi responsiveness. Coleopterans exhibit robust systemic RNAi supported by high expression of dsRBPs and SID-1-like transporters, whereas lepidopterans and hemipterans display restricted dsRBP activity, elevated nuclease degradation, and limited systemic transport, resulting in inconsistent RNAi outcomes. Structural and biochemical studies have clarified the roles of dsRBPs in Dicer-mediated processing and RISC assembly, highlighting isoform-specific mechanisms in Loquacious and cooperative interactions between R2D2 and Dicer-2. Emerging evidence also implicates lineage-specific proteins, such as StaufenC in beetles, in enhancing oral RNAi. From an applied perspective, dsRBPs represent promising molecular determinants and biomarkers of RNAi susceptibility, offering entry points for improving host-induced and spray-induced gene silencing strategies. This review provides an integrated framework for understanding the molecular causes of RNAi variability and for developing targeted approaches to enhance the reliability of RNAi-based pest management.</div></div>","PeriodicalId":16189,"journal":{"name":"Journal of insect physiology","volume":"167 ","pages":"Article 104910"},"PeriodicalIF":2.3,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145557033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-13DOI: 10.1016/j.jinsphys.2025.104906
Haruyuki Nakano , Keiji Nakamura
The Japanese stick insect Phraortes elongatus exhibits seasonal variation in its life cycle strategy, shifting from a univoltine to a semivoltine lifecycle depending on the timing of oviposition. In the univoltine cycle, diapause occurs only at the late embryonic stage (pharate first instar), whereas in the semivoltine cycle, additional diapause is induced at an early stage. However, the environmental and maternal factors that regulate early diapause remain unclear. This study examined the influence of maternal photoperiod, maternal age, and post-oviposition temperature on early embryonic diapause in P. elongatus. Females were reared at 25 °C under long-day (16L:8D) or short-day (12L:12D) conditions, and eggs laid between 14 and 91 days after adult emergence were incubated at 25 °C under short-day conditions for 8 weeks. Under long-day conditions, the incidence of early diapause gradually increased with maternal age, reaching 100 % by day 63. In contrast, under short-day conditions, most eggs laid up to day 42 entered early diapause; however, this tendency decreased with maternal age. To assess thermal effects on the offspring generation, eggs laid 14 days after emergence under both photoperiods were incubated at 20 °C, 25 °C, or 30 °C under short-day conditions. At 20 °C, early diapause was induced regardless of maternal condition. At 30 °C, development was delayed, suggesting heat stress-induced developmental delay. These results demonstrate that early embryonic diapause in P. elongatus is regulated by the combined effects of maternal photoperiod, maternal age, and incubation temperature.
{"title":"Maternal photoperiod, age, and egg temperature regulate early embryonic diapause in the stick insect, Phraortes elongatus","authors":"Haruyuki Nakano , Keiji Nakamura","doi":"10.1016/j.jinsphys.2025.104906","DOIUrl":"10.1016/j.jinsphys.2025.104906","url":null,"abstract":"<div><div>The Japanese stick insect <em>Phraortes elongatus</em> exhibits seasonal variation in its life cycle strategy, shifting from a univoltine to a semivoltine lifecycle depending on the timing of oviposition. In the univoltine cycle, diapause occurs only at the late embryonic stage (pharate first instar), whereas in the semivoltine cycle, additional diapause is induced at an early stage. However, the environmental and maternal factors that regulate early diapause remain unclear. This study examined the influence of maternal photoperiod, maternal age, and post-oviposition temperature on early embryonic diapause in <em>P. elongatus</em>. Females were reared at 25 °C under long-day (16L:8D) or short-day (12L:12D) conditions, and eggs laid between 14 and 91 days after adult emergence were incubated at 25 °C under short-day conditions for 8 weeks. Under long-day conditions, the incidence of early diapause gradually increased with maternal age, reaching 100 % by day 63. In contrast, under short-day conditions, most eggs laid up to day 42 entered early diapause; however, this tendency decreased with maternal age. To assess thermal effects on the offspring generation, eggs laid 14 days after emergence under both photoperiods were incubated at 20 °C, 25 °C, or 30 °C under short-day conditions. At 20 °C, early diapause was induced regardless of maternal condition. At 30 °C, development was delayed, suggesting heat stress-induced developmental delay. These results demonstrate that early embryonic diapause in <em>P. elongatus</em> is regulated by the combined effects of maternal photoperiod, maternal age, and incubation temperature.</div></div>","PeriodicalId":16189,"journal":{"name":"Journal of insect physiology","volume":"167 ","pages":"Article 104906"},"PeriodicalIF":2.3,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145530616","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-13DOI: 10.1016/j.jinsphys.2025.104907
Erinç Çelik Biçer, Olga Sak, Aylin Er
Extreme temperatures, the most evident indicator of climate change, threaten the delicate balance among parasitoids, key components of the ecosystem, and their agricultural pest hosts. Understanding the effects of thermal stress on parasitoids is essential for improving the mass production of Bracon hebetor (Hymenoptera: Braconidae), and predicting how the climate change will affect host-parasitoid relationship. The immune system of the host Galleria mellonella (Lepidoptera: Pyralidae) varied with both temperature and duration of exposure. Total hemocyte count peaked at 40 °C after 24 h due to elevated granulocyte, plasmatocyte, spherulocyte, and other cell types. The mitotic index peaked at 38 °C (24 h) before dropping sharply at 40 °C. Strong encapsulation responses rose significantly at 40 °C compared to 38 °C. Re-exposing adult females of B. hebetor to thermal stress, along with its previously heat-stressed hosts, altered biological traits in both adult females and F1 offspring, especially the reduced egg fecundity. Rising temperatures initially reduced the female sex ratio, but ultimately it nearly balanced out. At 36 °C, 95 % of the 24 eggs per female developed into adults, and prolonged adult longevity increased parasitoid numbers and extended their active period, a key finding. Overall, B. hebetor displayed high thermal tolerance, yet temperature-driven changes in host immunity and parasitoid traits may reshape their interactions under future climates.
{"title":"Influence of thermal stress on the cellular immunity of Galleria mellonella F. (Lepidoptera: Pyralidae), and the biological traits of Bracon hebetor (Hymenoptera: Braconidae) in a host–parasitoid interaction: implications under climate change","authors":"Erinç Çelik Biçer, Olga Sak, Aylin Er","doi":"10.1016/j.jinsphys.2025.104907","DOIUrl":"10.1016/j.jinsphys.2025.104907","url":null,"abstract":"<div><div>Extreme temperatures, the most evident indicator of climate change, threaten the delicate balance among parasitoids, key components of the ecosystem, and their agricultural pest hosts. Understanding the effects of thermal stress on parasitoids is essential for improving the mass production of <em>Bracon hebetor</em> (Hymenoptera: Braconidae), and predicting how the climate change will affect host-parasitoid relationship. The immune system of the host <em>Galleria mellonella</em> (Lepidoptera: Pyralidae) varied with both temperature and duration of exposure. Total hemocyte count peaked at 40 °C after 24 h due to elevated granulocyte, plasmatocyte, spherulocyte, and other cell types. The mitotic index peaked at 38 °C (24 h) before dropping sharply at 40 °C. Strong encapsulation responses rose significantly at 40 °C compared to 38 °C. Re-exposing adult females of <em>B. hebetor</em> to thermal stress, along with its previously heat-stressed hosts, altered biological traits in both adult females and F<sub>1</sub> offspring, especially the reduced egg fecundity. Rising temperatures initially reduced the female sex ratio, but ultimately it nearly balanced out. At 36 °C, 95 % of the 24 eggs per female developed into adults, and prolonged adult longevity increased parasitoid numbers and extended their active period, a key finding. Overall, <em>B. hebetor</em> displayed high thermal tolerance, yet temperature-driven changes in host immunity and parasitoid traits may reshape their interactions under future climates.</div></div>","PeriodicalId":16189,"journal":{"name":"Journal of insect physiology","volume":"167 ","pages":"Article 104907"},"PeriodicalIF":2.3,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145526425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-12DOI: 10.1016/j.jinsphys.2025.104905
Cassidy Orange, Biana Qiu, Susan Villarreal
Seminal fluid proteins (SFPs), produced in the male accessory glands (MAGs) and transferred during mating, induce key post-mating changes in females, including altered feeding, reduced receptivity, and shifts in reproductive investment. In mosquitoes, these effects are well characterized in some Aedes and Anopheles species, whereas their role in Culex remains poorly understood. We tested whether MAG products alone reduce female receptivity in Culex pipiens. MAGs were dissected from virgin males, proteins extracted, and homogenates injected into virgin females, alongside saline and non-injected controls. Insemination rates were assessed under two contexts: no choice trials, where males encountered females from a single treatment group and choice trials, where all treatment types were presented simultaneously. To evaluate male mating attempts independent of sperm transfer, we also applied a fluorescent dye-transfer assay in which dye applied to male abdomens marked females during attempted copulation. MAG-injected females were significantly less likely to be inseminated than controls, implicating SFPs in inducing refractoriness. This effect was stronger in no choice trials, suggesting reduced mating reflects female rejection rather than male discrimination among female types. Dye-transfer data revealed few attempted copulations without insemination and no evidence that males preferentially courted non-injected virgin controls. Our findings confirm the conserved role of SFPs for female receptivity from an understudied species and establishes a foundation for identifying the molecular drivers of refractoriness in Culex, a key step for reproductive-based vector control strategies.
{"title":"The effect of male accessory gland extracts on female receptivity in Culex pipiens mosquitoes","authors":"Cassidy Orange, Biana Qiu, Susan Villarreal","doi":"10.1016/j.jinsphys.2025.104905","DOIUrl":"10.1016/j.jinsphys.2025.104905","url":null,"abstract":"<div><div>Seminal fluid proteins (SFPs), produced in the male accessory glands (MAGs) and transferred during mating, induce key post-mating changes in females, including altered feeding, reduced receptivity, and shifts in reproductive investment. In mosquitoes, these effects are well characterized in some <em>Aedes</em> and <em>Anopheles</em> species, whereas their role in <em>Culex</em> remains poorly understood. We tested whether MAG products alone reduce female receptivity in <em>Culex pipiens</em>. MAGs were dissected from virgin males, proteins extracted, and homogenates injected into virgin females, alongside saline and non-injected controls. Insemination rates were assessed under two contexts: no choice trials, where males encountered females from a single treatment group and choice trials, where all treatment types were presented simultaneously. To evaluate male mating attempts independent of sperm transfer, we also applied a fluorescent dye-transfer assay in which dye applied to male abdomens marked females during attempted copulation. MAG-injected females were significantly less likely to be inseminated than controls, implicating SFPs in inducing refractoriness. This effect was stronger in no choice trials, suggesting reduced mating reflects female rejection rather than male discrimination among female types. Dye-transfer data revealed few attempted copulations without insemination and no evidence that males preferentially courted non-injected virgin controls. Our findings confirm the conserved role of SFPs for female receptivity from an understudied species and establishes a foundation for identifying the molecular drivers of refractoriness in <em>Culex</em>, a key step for reproductive-based vector control strategies.</div></div>","PeriodicalId":16189,"journal":{"name":"Journal of insect physiology","volume":"167 ","pages":"Article 104905"},"PeriodicalIF":2.3,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145523632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-05DOI: 10.1016/j.jinsphys.2025.104903
Xiankun Shang , Jili Wei , Wei Liu , Chenghua Huang , Xuehong Pan
Exolontha castanea (Coleoptera: Melolonthinae) larvae are a major subterranean pest of sugarcane in China. The adults exhibit strong flight capacity and positive phototaxis. This study investigated the external morphology, internal microstructure, and light-induced adaptations of the compound eyes in both female and male E. castanea using light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The compound eyes feature a peninsula-shaped canthus that extends deeply into the basement membrane region. A marked sexual size dimorphism of the eye was observed, with females having significantly larger eyes and a greater number of facets (10,780.92 in females vs. 9,901.30 in males). The eyes were identified as being of the optical superposition type. The ommatidial length is approximately 800 μm. Moreover, the cornea was significantly thicker in female adults than in males. The crystalline cone is eucone and bullet-shaped, consisting of three to four Semper cells. Each ommatidium contains eight retinula cells (R1-R8). The cell bodies of R1-R7 form a retinular tract that traverses the clear zone, with their nuclei located in a distally swollen region. R8 is a basal cell situated beneath the rhabdom near the basement membrane. The retina was classified as the scotopic type. The proximal ends of R1-R7 extend inward to form a rhabdomere, which collectively constitute an open, seven-lobed rhabdom. The inter-rhabdom spaces are densely filled with tracheoles. Under different light conditions, including darkness, ultraviolet, violet, blue, red, and white light, the eyes demonstrate dynamic adaptations by modulating the length of the primary pigment cells (PPCs) and the migration of pigment granules. Under dark adaptation, the retinula cells are closely apposed to the crystalline cone, and pigment granules accumulate around it. Upon light exposure, the PPCs surrounding the cone elongated, the retinula cells shortened radially, and the pigment granules migrated into the elongated PPCs region beneath the cone, thereby reducing light entry. Furthermore, the degree of PPCs elongation is positively correlated with light intensity.
{"title":"Microstructural characteristics and mechanisms underlying dynamic light adaptation in the compound eyes of Exolontha castanea (Coleoptera: Melolonthinae)","authors":"Xiankun Shang , Jili Wei , Wei Liu , Chenghua Huang , Xuehong Pan","doi":"10.1016/j.jinsphys.2025.104903","DOIUrl":"10.1016/j.jinsphys.2025.104903","url":null,"abstract":"<div><div><em>Exolontha castanea</em> (Coleoptera: Melolonthinae) larvae are a major subterranean pest of sugarcane in China. The adults exhibit strong flight capacity and positive phototaxis. This study investigated the external morphology, internal microstructure, and light-induced adaptations of the compound eyes in both female and male <em>E. castanea</em> using light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The compound eyes feature a peninsula-shaped canthus that extends deeply into the basement membrane region. A marked sexual size dimorphism of the eye was observed, with females having significantly larger eyes and a greater number of facets (10,780.92 in females vs. 9,901.30 in males). The eyes were identified as being of the optical superposition type. The ommatidial length is approximately 800 μm. Moreover, the cornea was significantly thicker in female adults than in males. The crystalline cone is eucone and bullet-shaped, consisting of three to four Semper cells. Each ommatidium contains eight retinula cells (R1-R8). The cell bodies of R1-R7 form a retinular tract that traverses the clear zone, with their nuclei located in a distally swollen region. R8 is a basal cell situated beneath the rhabdom near the basement membrane. The retina was classified as the scotopic type. The proximal ends of R1-R7 extend inward to form a rhabdomere, which collectively constitute an open, seven-lobed rhabdom. The inter-rhabdom spaces are densely filled with tracheoles. Under different light conditions, including darkness, ultraviolet, violet, blue, red, and white light, the eyes demonstrate dynamic adaptations by modulating the length of the primary pigment cells (PPCs) and the migration of pigment granules. Under dark adaptation, the retinula cells are closely apposed to the crystalline cone, and pigment granules accumulate around it. Upon light exposure, the PPCs surrounding the cone elongated, the retinula cells shortened radially, and the pigment granules migrated into the elongated PPCs region beneath the cone, thereby reducing light entry. Furthermore, the degree of PPCs elongation is positively correlated with light intensity.</div></div>","PeriodicalId":16189,"journal":{"name":"Journal of insect physiology","volume":"167 ","pages":"Article 104903"},"PeriodicalIF":2.3,"publicationDate":"2025-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145467777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-04DOI: 10.1016/j.jinsphys.2025.104902
Tzvi S. Goldberg , Yuval Shalem , Daiki Fujinaga , Kerry E. Mauck , S.Hollis Woodard , Naoki Yamanaka , Guy Bloch
Juvenile hormones (JHs) are key insect endocrine signals regulating pre-adult development and adult life history strategies, physiology, and behavior. The importance of this endocrine signal has led to the development of insecticides targeting JH signaling pathways. While effective against target pests, they can also affect beneficial insects, such as pollinators and natural pest enemies, many of which are hymenopterans. Research on JH, which is crucial for understanding the physiology, behavior, and organization of social insects, requires effective means to manipulate JH signaling pathways. A common method for reducing JH titers includes applying the phytotoxin precocene-I (P-I), which abolishes JH biosynthesis in the corpora allata (CA). However, achieving consistently effective topical treatments has proven challenging. Here, we investigated the dynamics of the effect of P-I manipulations on JH titers and reproductive development in orphan worker groups of a key pollinator bumble bee. A single P-I treatment effectively reduced circulating JH levels in newly emerged workers, even after 12 days. The treatment delayed but did not prevent ovarian activation. Multiple treatments failed to further reduce JH titers or ovarian activity, and were overall less effective than surgically removing the CA. Finally, we suggest guidelines for developing P-I manipulation studies, and more generally, compare methods for reducing circulating JH levels in insects.
{"title":"Precocene-I mediated reduction of juvenile hormone titers and ovarian activity is ephemeral in a bumble bee","authors":"Tzvi S. Goldberg , Yuval Shalem , Daiki Fujinaga , Kerry E. Mauck , S.Hollis Woodard , Naoki Yamanaka , Guy Bloch","doi":"10.1016/j.jinsphys.2025.104902","DOIUrl":"10.1016/j.jinsphys.2025.104902","url":null,"abstract":"<div><div>Juvenile hormones (JHs) are key insect endocrine signals regulating pre-adult development and adult life history strategies, physiology, and behavior. The importance of this endocrine signal has led to the development of insecticides targeting JH signaling pathways. While effective against target pests, they can also affect beneficial insects, such as pollinators and natural pest enemies, many of which are hymenopterans. Research on JH, which is crucial for understanding the physiology, behavior, and organization of social insects, requires effective means to manipulate JH signaling pathways. A common method for reducing JH titers includes applying the phytotoxin precocene-I (P-I), which abolishes JH biosynthesis in the corpora allata (CA). However, achieving consistently effective topical treatments has proven challenging. Here, we investigated the dynamics of the effect of P-I manipulations on JH titers and reproductive development in orphan worker groups of a key pollinator bumble bee. A single P-I treatment effectively reduced circulating JH levels in newly emerged workers, even after 12 days. The treatment delayed but did not prevent ovarian activation. Multiple treatments failed to further reduce JH titers or ovarian activity, and were overall less effective than surgically removing the CA. Finally, we suggest guidelines for developing P-I manipulation studies, and more generally, compare methods for reducing circulating JH levels in insects.</div></div>","PeriodicalId":16189,"journal":{"name":"Journal of insect physiology","volume":"167 ","pages":"Article 104902"},"PeriodicalIF":2.3,"publicationDate":"2025-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145458975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-26DOI: 10.1016/j.jinsphys.2025.104901
Takashi Kuriwada
Many insects regulate diapause—a dormant physiological state—in response to photoperiod, with short day length typically signaling approach of winter and inducing diapause. However, artificial light at night (ALAN), often associated with urbanization, can disrupt these photoperiodic cues and inhibit diapause induction. This review examines the disruption of diapause induction by ALAN, a topic that has only recently attracted considerable attention. First, it summarizes recent empirical studies on ALAN-induced diapause inhibition. Then, it outlines the physiological and molecular genetic mechanisms involved, which remain only partially understood. Next, it discusses potential factors limiting adaptation to ALAN-induced diapause disruption. Finally, this review presents key perspectives from physiological, evolutionary, and applied entomological standpoints to guide future research, emphasizing the need to integrate existing knowledge of diapause regulation with field and laboratory studies to better understand the effects of ALAN and guide mitigation efforts.
{"title":"The age of bright nights: Photoperiodic disruption of insect diapause by artificial light at night","authors":"Takashi Kuriwada","doi":"10.1016/j.jinsphys.2025.104901","DOIUrl":"10.1016/j.jinsphys.2025.104901","url":null,"abstract":"<div><div>Many insects regulate diapause—a dormant physiological state—in response to photoperiod, with short day length typically signaling approach of winter and inducing diapause. However, artificial light at night (ALAN), often associated with urbanization, can disrupt these photoperiodic cues and inhibit diapause induction. This review examines the disruption of diapause induction by ALAN, a topic that has only recently attracted considerable attention. First, it summarizes recent empirical studies on ALAN-induced diapause inhibition. Then, it outlines the physiological and molecular genetic mechanisms involved, which remain only partially understood. Next, it discusses potential factors limiting adaptation to ALAN-induced diapause disruption. Finally, this review presents key perspectives from physiological, evolutionary, and applied entomological standpoints to guide future research, emphasizing the need to integrate existing knowledge of diapause regulation with field and laboratory studies to better understand the effects of ALAN and guide mitigation efforts.</div></div>","PeriodicalId":16189,"journal":{"name":"Journal of insect physiology","volume":"167 ","pages":"Article 104901"},"PeriodicalIF":2.3,"publicationDate":"2025-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145390368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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