搜索结果：Journal of insect physiology

Digging mammals function as ecosystem engineers by altering soil structure, influencing nutrient cycling and shaping vegetation communities. The widespread decline of these taxa globally, driven by habitat loss and introduced predators, has triggered cascading ecological effects, yet the consequences for soil-dwelling insect communities remain poorly understood. Insects, many of which have subterranean larval stages, provide essential functions such as pollination, decomposition and nutrient cycling, making them ideal indicators for evaluating the restructuring of ecological communities following mammal reintroductions. Here, we used data from a long-term experimental mammal exclusion study within a predator-free sanctuary (Scotia Wildlife Sanctuary) in south-eastern Australia to test how the reintroduction of digging mammals affects the structure and composition of insect communities emerging from soil. We sampled insects using emergence traps across replicated plots of mammal reintroduction, exclusion, and procedural control in 2010 and in 2018, 8 years after fence installation. While variation in digging activity (indexed by pit density) did not significantly affect richness or biomass of soil-emerging insect taxa, areas with digging showed reduced insect abundance. Hierarchical modelling of taxa communities revealed that parasitoid wasps (Hymenoptera) and predatory robber flies (Diptera: Asilidae) were strongly associated with plots without digging activity, likely reflecting sensitivity to direct predation or nest disturbance. No herbivorous beetle taxa showed a statistically supported association with treatment, indicating that negative associations with digging activity were restricted to specific parasitoids and predatory groups, rather than representing a consistent trophic-wide response. Our findings therefore indicate that the reintroduction of ecosystem engineers alters insect assemblages, potentially cascading through to multitrophic interactions and ecosystem functioning. This is important because it (1) suggests there may have been profound effects of the widespread loss of ecosystem engineers on ecosystems across the Australian continent; and (2) highlights that whole-of-ecosystem knowledge is critical to getting rewilding right. We emphasise the importance of thorough, long-term ecological monitoring of invertebrate assemblages to inform mammal reintroduction and restoration efforts, ensuring they align with broader ecosystem management objectives.

Global biodiversity is increasingly threatened by widespread anthropogenic impacts, which have accelerated since the First Industrial Revolution. Lowland rivers rank among the most affected ecosystems, having undergone centuries of hydromorphological modifications. The scarcity of historical data hampers precise assessments of biodiversity loss in these rivers since 1950, a critical threshold when anthropogenic pressures led to unprecedented ecological change. We compiled a comprehensive dataset of records of Ephemeroptera, Plecoptera and Trichoptera collected in time series from nine Czech lowland rivers over the past 140 years. Additionally, we integrated environmental data on water quality and hydroclimatic parameters spanning the last 60 years. Both alpha and gamma diversity declined steadily until the 1980s, followed by a partial recovery at the turn of the millennium due to water quality improvements. However, biodiversity recovery has remained limited in recent decades due to persistent pollution, climate change and potential depletion of the regional species pool. Assemblages are undergoing compositional changes driven by species turnover, rendering a return to their mid-20th-century baseline unlikely. Our results further highlight a dramatic loss of biodiversity already in the first half of the 20th century, which has not been offset by the partial recovery of rivers observed after 1990. Immediate actions are necessary to prevent further biodiversity decline and safeguard the ecosystem services of lowland rivers. Globální biodiverzita je stále více ohrožena velkoplošnými antropogenními vlivy, jejichž dopad výrazně akceleroval od dob první průmyslové revoluce po současnost. Nížinné řeky patří mezi nejvíce postižené ekosystémy, neboť prošly staletími hydromorfologických úprav. Nedostatek historických dat však ztěžuje vyhodnocení ztráty jejich biodiverzity od poloviny 20. století, což je kritický milník, kdy dopady lidské činnosti vedly k bezprecedentním ekologickým změnám. Sestavili jsme časové řady záznamů o výskytu jepic, pošvatek a chrostíků (Ephemeroptera, Plecoptera a Trichoptera) z devíti českých nížinných řek za uplynulých 140 let, které jsme doplnili environmentálními daty o kvalitě vody a hydroklimatických parametrech za posledních 60 let. Alfa i gama diverzita studovaných skupin setrvale klesala až do 80. let 20. století, poté došlo k částečnému zotavení související se zlepšením kvality vody na přelomu tisíciletí. V posledních desetiletích však zůstává zotavování omezené kvůli přetrvávajícímu znečištění, změnám klimatu a ochuzení regionálního souboru druhů. Druhové složení společenstev se mění predevším v důsledku výměny druhů, což činí návrat k jejich původnímu složení z poloviny minulého století nepravděpodobným. Naše výsledky navíc podtrhují dramatickou ztrátu biodiverzity už v první polovině 20. století, kterou však částečné zotavení řek po roce 1990 nedokázalo zmírnit. K zamezení dalšího poklesu biodiverzity a zachování ekosystémových služeb nížinných řek jsou nezbytná okamžitá opatření.

InsectMotion is a Python-based tool for analyzing video recordings of movements or muscle contractions in arthropods. It provides a simple, fast, and automated approach for semi-quantitative motion assessment by measuring "pixel activity", defined as changes in pixel intensity or colour. Unlike many existing methods, it does not require specialized equipment, chemical reagents, or expensive software. The application distinguishes active and inactive pixels within selected regions of interest (ROI) and quantifies their changes over a defined time period. InsectMotion offers two analysis modes: Graphical Analysis and Pixel Activity Analysis, both adaptable to various experimental setups. Graphical Analysis generates time-resolved plots of pixel activity, numerical outputs, and peak analysis. Pixel Activity Analysis produces binary images highlighting active pixel clusters and summary metrics describing active areas. Using immunohistochemistry, we detected calcitonin-like diuretic hormone (Bom-CT-DH) and myoinhibitory peptides (Bom-MIPs) in the innervation of digestive and reproductive organs of Bombyx mori. In vitro assays combined with InsectMotion quantified neuropeptide-induced contractions in these tissues. The tool was also applied on Ixodes ricinus in preliminary movement analyses, indicating its potential applicability beyond lepidopteran models. Our data show that InsectMotion is a reliable and accessible tool for in vitro and in vivo studies in neurobiology and physiology.

The invasive tomato leafminer, Tuta absoluta (Meyrick), is a very destructive pest that poses a major threat to tomato (Solanum lycopersicum L.) production in the Democratic Republic of Congo (DRC), causing extensive yield losses through larval feeding on leaves, stems, and fruits. Chemical insecticides remain the primary control method, but resistance development, biodiversity loss and environmental concerns necessitate alternative strategies. This study aimed at evaluating the efficacy of synthetic and botanical insecticides against T. absoluta during two consecutive cropping seasons 2023-2024 in Lubumbashi, DRC, under both dry and rainy season conditions. Two tomato seedling varieties (Tanya F1 and Tovi Star F1) were treated with four synthetic insecticides (Dudu acelamectin 5% EC, cypermethrin 200 EC, lambda-cyhalothrin 50 EC and Occasion Star 200SC) and two botanical treatments (Tephrosia vogelii extract and Nimbecidine) at the recommended doses in a randomized complete block design. Pest incidence, larval density, leaf damage, and yield were assessed over multiple intervals. Results showed that synthetic insecticides, particularly Dudu acelamectin 5% EC, lambda-cyhalothrin 50 EC, and Occasion Star 200SC, significantly reduced T. absoluta larval infestations compared to cypermethrin 200 EC, which failed to control the pest due to suspected potential resistance. Botanical insecticides were also proved effective, with T. vogelii extract reducing leaf damage by 48% and Nimbecidine by 38%. The Tovi Star F1 variety exhibited inherent resistance, with lower pest incidence and higher yields than Tanya F1. Yield losses were strongly correlated with pest incidence and larval density, emphasizing the need for timely interventions. These findings highlight the potential of integrating synthetic and botanical insecticides with resistant tomato varieties for sustainable T. absoluta management in Lubumbashi. Future research should explore long-term resistance monitoring, cost-benefit analyses for smallholder farmers, and synergetic combinations of biopesticides to enhance efficacy while minimizing environmental impacts.

Harmonia axyridis is a well-known predatory ladybird beetle renowned for its high degree of elytral pattern polymorphism. The black and yellow-red complementary areas of elytra are respectively attributed to the deposition of melanin and carotenoid pigments, while the carotenoid profiles are likely to be affected by the phenotypic plasticity of dark spots. Here, using a goldenrod-colored mutant (named gr) and a melanic mutant (named ml), we examined their elytral carotenoid profiles and compared them with those of the wild type (named wt). Moreover, we determined whether similar changes could be detected from the newly emerged stage (NE) to the 5-day post-emergence stage (PE5). The results showed that the non-oxidative carotenes accounted for over 95% of the total carotenoid pool in all the three morphs. Moreover, identical composition of carotenes was observed at both stages, with (E/Z)-phytoene and γ-carotene comprising the majority (over 70%). However, distinct profiles of carotenes were detected in ml as compared to wt and gr. Additionally, both ml and gr presented several specific xanthophylls compared to wt. Nevertheless, the three morphs showed similar changes in carotenoid composition from stage NE to PE5, i.e. the proportion of light-colored pigment (colorless (E/Z)-phytoene) decreased, while the proportion of colored pigments (lycopene and γ-carotene) increased. Our findings suggested that while different carotenoid profiles were detected in the two body color mutants, both mutants exhibited a conserved strategy for carotenoid allocation to the elytra during post-emergence development. These findings will contribute to a more comprehensive understanding of the carotenoid-based coloration in insects, particularly its correlation with the melanin-based pigmentation.

While correlative studies show worrying insect declines in recent times, the nature of insect population dynamics and the paucity of long-term data make the assessment of the status and trends of insect populations challenging and disconnected from conservation actions. The assessment of life-history dynamics, the joint responses of reproduction, survival, and other vital rates across the life cycle to environmental change, is increasingly seen as an important bridge joining underlying mechanisms to population outcomes under global change, which can substantially improve predictions of declines. However, life-history dynamics under global change have been assessed for a very biased sample of animals in the tree of life, namely mammals, birds, and, among invertebrates, species of economic or cultural significance. This hinders us from developing sound predictions and actionable conservation actions to mitigate declines for a wide range of species. Here, we review methods for assessing life-history dynamics effectively given heterogeneous data. We also argue that insects, and invertebrates more generally, have unique ecological and evolutionary niches and thus show unique life-history dynamics that are strongly linked to environmental cues. Hence, while we can learn a lot from life-history population dynamics developed for vertebrate species, this uniqueness calls for its own model development. We emphasize that such model development can advance the theory and conservation applications of life-history research more broadly.

Left-right asymmetries in brain features and behavior have long been considered unique to humans. However, they are now also recognized in vertebrates and invertebrates and exhibit similar structural lateralization across different species. For instance, the olfactory behavior and brain asymmetry of eusocial insects are evident at the population level. Certain solitary insects also exhibit behavioral asymmetry at the population level. This study examined the electroantennogram (EAG) responses, behavioral responses, and gene expression of the right and left antennae in adult diamondback moth (DBM), Plutella xylostella (lepidoptera: plutellidae). The results revealed that among the detected genes (GOBP1, GOBP2, PBP, PBP1, and ORCO), only the GOBP1 gene showed expression variance between the left and right antennae of female DBM. Also, the expressions of GOBP1 and GOBP2 in the antennae of female moths were significantly higher than that in male DBM. For male DBM, EAG responses of the left antenna were higher at differentconcentrations of Z-3-hexenol, Z-3-hexenyl acetate and allyl isothiocyanate compared to the right antenna. Marked differences were found in EAG responses between the left and right antennae of male DBM at 0.15 μg•μL-1 allyl isothiocyanate. For female DBM, EAG responses of the right antenna were higher at differentconcentrations of Z-3-hexenyl acetate and allyl isothiocyanate compared to the left antenna, but there was no statistical difference. In an olfactometer bioassay, the choice rates of male DBMs with intact left antennae were significantly higher than that of the control liquid paraffin at 1.0 μg•μL-1. Also, the choice rates of female DBM with left or right antennae to the three tested plant volatiles at 0.15 and 1.0 μg•μL-1 concentrations were significantly higher than those in liquid paraffin. Moreover, the relative choice rates of the right antennae were slightly higher than those of the left antennae in female DBM, but the results were reversed in male DBM. This study contributes to the understanding of behavioral asymmetry of the left and right antennae of DBM and provides a reference for the lateralization of olfactory behavior in other lepidoptera insects.

Sawflies (Symphyta: Hymenoptera) use specialized ovipositors to cut into soft plant tissues for egg deposition. These ovipositors employ a reciprocating sawing motion and exhibit intricate morphological and material adaptations that enable selective tissue cutting with minimal damage to surrounding structures and preservation of the mechanical integrity of the ovipositors. While wood-boring ovipositors have been widely researched in biomimetics, the structural and compositional basis of soft-tissue-cutting ovipositors remains largely unexplored. This study characterizes the hierarchical material organization of sawfly ovipositors in relation to a recently identified cutting mechanism. Using a combination of scanning electron microscopy (SEM), micro-computed tomography (μCT), confocal laser scanning microscopy (CLSM) and polarized light microscopy (PLM), we investigate the composition, microstructure, and density gradients of materials present in the ovipositor of Rhogogaster scalaris. Our results reveal multi-scale structural heterogeneity, including spatially resolved density gradients, chitin fibre-bundle arrangements, and protein composition variations suggestive of mechanical optimization. These findings suggest that cutting efficiency is supported primarily by hierarchical structure and compositional gradients, rather than requiring prominent metal-based hardening, although trace or localized metal enrichment remains to be assessed through quantitative elemental mapping. Preliminary dehydration observations support the functional significance of hydration in maintaining mechanical integrity. This study provides the first detailed compositional and structural analysis of soft-tissue-cutting ovipositors and offers a structural and compositional basis that may inform future bioinspired designs of cutting tools aiming to enhance tissue selectivity and structural preservation.

Silkworm pupae serve as an important source of protein supplementation; however, their high fat content and imbalanced essential amino acid (EAA) profile restrict efficient utilization of protein. Previous studies have demonstrated that dietary probiotic supplementation can modulate host physiology through multiple pathways, thereby enhancing nutrient quality. This study investigated the effects of dietary supplementation with Lactobacillus rhamnosus and Lactobacillus casei on gut microbiota, short-chain fatty acids (SCFAs), fat body transcriptome, and pupal nutrient composition in fifth-instar silkworm larvae. Results showed that both probiotics significantly increased the concentrations of acetic acid, butyric acid, isobutyric acid, and total SCFAs, while also modulating the composition and functional characteristics of the gut microbiota. Notably, probiotic treatment enriched the relative abundance of Bacillota, Enterococcus, and Lactobacillus, while reducing Pseudomonas and Cyanobacteria. Transcriptomic analyses revealed that supplementation of both probiotics modulated the transcription of genes (e.g., BmRad and BmLdlr) associated with key nutrient metabolic pathways, including protein synthesis, fatty acid metabolism, and carbohydrate degradation, in the fat body. Amino acid and proteomic analyses indicated that L. rhamnosus significantly inhibited the degradation of EAAs such as leucine, isoleucine, and lysine, thereby increasing their contents in silkworm pupae. Collectively, these findings lay a theoretical foundation for the application of probiotic strategies to enhance the nutrient quality of silkworm pupae and facilitate the development of high-value silkworm pupae products.

Agricultural intensification has led to many environmentally degrading practices that can cause insect biodiversity loss and a decline in ecosystem services. Local management practices and more complex landscapes can help mitigate these negative effects. The intermediate landscape complexity hypothesis suggests that local management best supports insect biodiversity in landscapes of intermediate complexity, which contain both agricultural and natural habitats. However, recent studies have also shown higher biodiversity in both simple and complex landscapes. In this review, we investigated whether certain local practices are more effective across a range of landscape complexity. Our results showed that local management or landscape complexity increases insect biodiversity or ecosystem services in about 25% of cases. We found support for the intermediate landscape complexity hypothesis in some scenarios and positive effects of local management in simple and complex landscapes in others. Future studies should more clearly define how they measure landscape complexity, which will help compare results and find patterns. These findings can begin to inform tailored local management and research directions to maximize insect biodiversity and ecosystem services in different landscape contexts.

The insect cuticle, an important protective barrier covering the body surface, is mainly composed of cuticular proteins and chitin fibers, which together form the insect exoskeleton system. Resilin, an arthropod elastic protein, has attracted attention due to its unique mechanical properties. In this study, we identified BmCPR151, a short resilin-like cuticular protein from Bombyx mori (B. mori). The gene contains a 699-bp CDS encoding a 233-amino-acid full-length protein with shortened repetitive domains, distinguishing it from Drosophila resilin and the previously reported silkworm BmCPR140. Using the CRISPR/Cas9 gene-editing tool, we successfully constructed a systemic BmCPR151 knockout homozygous mutant, and the moths of this mutant exhibited smaller wing area, a significantly thinned wing membrane, and thinner wing veins. Furthermore, based on the previously obtained BmCPR140 knockout mutant, a Double-KO (BmCPR151-KO & BmCPR140-KO) homozygous mutant was generated. Comparative analysis of the three mutants (BmCPR140-KO, BmCPR151-KO, and Double-KO) and the wild type showed that all mutants had decreased wing area and wing vein width. The wing rigidity of female moths decreased by 36.91%, 43.65%, and 45.78%, while that of male moths decreased by 26.54%, 27.08%, and 32.25%, respectively. Moreover, wing patterns were markedly faded in the Double-KO mutant. Transcriptomic analysis revealed that a large number of cuticular proteins were significantly differentially expressed in the wings of Double-KO silkworms, among which 98 cuticular proteins were down-regulated. Collectively, these results indicate that insect cuticular proteins have a relative expression balance, and the loss of resilin-like proteins disrupts the balance, thereby affecting wing development. This study provides a reference for further exploring the functions of insect resilin-like proteins.

The rapid expansion of Artificial Light at Night (ALAN), driven by anthropogenic activities, has significantly altered natural environments, affecting several taxa. ALAN is widely recognized as a significant ecological stressor, being detrimental to the behavior, physiology and reproductive fitness of insects, including Orthoptera. Based on the studies retrieved from Scopus and Web of Science, the review attempted to answer the following questions (i) Are the regions with the highest light pollution involved in studying the impact of light pollution on Orthoptera? (ii) What are the traits affected by ALAN-induced light pollution in Orthoptera? The review found that studies were largely restricted to developed nations. Countries with the highest night-time illumination have not yet studied the impact of ALAN on Orthoptera. The effect of light has been studied in only 12 species of Orthoptera, compared to the vast diversity of >29,500 species. This review highlights the physiological traits affected by ALAN such as body size, developmental time, survival rate, reproductive investment, circadian rhythm, and immune response. Behaviors affected by ALAN, such as visual orientation, locomotion, calling behavior, and mate searching, are also highlighted. It emphasizes the critical need for targeted research on their calling behavior, the efficacy of acoustic signals, mate attraction, and reproductive success for understanding the behavioural shifts as a consequence of ALAN. Given that most Orthopteran species rely on acoustic communication for mate attraction and reproductive success, it is imperative to study the impacts of ALAN on their acoustic behavior.

Although temperature is considered the most significant environmental factor influencing the survival, development and fitness of the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann) (Diptera: Teprhitidae), relative humidity also plays a crucial role in determining its performance. Phenotypic plasticity and local adaptation to a variety of climatic regions are known to lead to variation of biological traits among medfly populations. We explored the impact of hydric stress during pupal development on survival and development, as well as on the thermal performance of obtained adults of three geographically isolated C. capitata populations. Medfly pupae from Samar (Israel), Creta and Thessaloniki (Greece), that were reared for few generations in standard laboratory conditions, were exposed immediately after pupation to low (13 ± 2%), moderate (38 ± 2%), standard (56 ± 2%) and high (100%) relative humidity. Weight loss during the pupal stage, pupal developmental duration, survival rate, adult weight and sex ratio, as well as morphometric characteristics of adult size (wings, thorax and head) were recorded. Our results highlight the importance of relative humidity during pupal development. We found that low humidity levels during pupal development increased weight loss, prolonged development and resulted in the emergence of smaller sized adults. Responses to humidity were population specific, as the population originated from the xeric area of Samar had, overall, a better response to low humidity levels compared with those from the more humid areas of Creta and Thessaloniki, indicating greater phenotypic plasticity and suggesting a possible consideration for respective future experimental work.

Citrus production worldwide is severely impacted by a devastating disease known as citrus greening, or Huanglongbing (HLB). The phytopathogen causing HLB is transmitted between trees by the Asian citrus psyllid, Diaphorina citri, which acts as the primary vector. Currently, there is no cure for HLB, and management efforts primarily rely on the use of insecticides. However, there is a growing need for alternative, environmentally sustainable control methods, such as RNA interference (RNAi). We investigated the impact of gene silencing on the mortality of D. citri by targeting two genes, vacuolar-sorting protein/sucrose non-fermenting protein 7 (DcSnf7) and inhibitor of apoptosis 5 (DcIap5). Gene silencing was initially assessed by delivering synthesized double-stranded RNA (dsRNA) to D. citri through topical feeding. To further assess gene suppression in vivo, we used a virus-induced gene silencing (VIGS) approach to deliver RNAi to psyllids via citrus plants. Suppressing DcSnf7 and DcIap5 individually resulted in elevated nymph mortality; however, the combined suppression of both genes using dual dsRNA treatment did not yield an additive effect. We modified the infectious Citrus tristeza virus (CTV-T36) clone to individually and jointly carry the truncated genes, DcSnf7 and DcIap5. Over two successive generations, D. citri reared on plants inoculated with CTV-tSnf7, CTV-tIap5, or the combined construct CTV-tSnf7-tIap5 exhibited increased mortality at all life stages, as well as significantly reduced fecundity and fertility, compared to insects reared on non-infected or CTV-wt-inoculated control plants. In addition, these VIGS plants shortened the lifespan of D. citri. Notably, the dual construct CTV-tSnf7-tIap5 consistently produced the most pronounced reductions in survival, fecundity, fertility, and longevity of D. citri across all experiments, exceeding the effects observed with either single-gene construct. Our results suggest that silencing key genes of D. citri using RNAi mediated by VIGS represents a promising control strategy that could play a role in HLB management. © 2026 Society of Chemical Industry.

Substrate-borne vibrational communication is widespread in insects and spiders, yet its role in host location by bethylid ectoparasitoids remains largely unexplored. In this study, we investigated the responses of Sclerodermus domesticus Klug and Sclerodermus cereicollis Kieffer to vibrations produced by the feeding activity of their natural hosts, the longhorn beetles Hylotrupes bajulus (L.) and Trichoferus holosericeus (Rossi). Vibrations were recorded using a laser Doppler vibrometer and characterised in terms of biting frequency, damping, and spectral composition, revealing two distinct bite types with species-specific frequency profiles. A new tool, vibrational Y-shaped arena, was developed to replicate and deliver vibrations, allowing the testing of parasitoids behaviour. Choice tests demonstrated that S. domesticus was attracted to vibrations from H. bajulus, whereas S. cereicollis preferred vibrations from T. holosericeus. Behavioural observations revealed increased antennal drumming and leg rubbing in the presence of host-produced vibrations, suggesting that these behaviours are associated with vibrational detection. Our results provide the first evidence that bethylid parasitoids can detect and respond to host-emitted vibrations, highlighting the importance of substrate-borne cues in host location. These findings advance our understanding of bethylid sensory ecology and may inform novel strategies for the biological control of xylophagous pests.

Understanding how multiple stressors interact is essential for predicting insect performance under global change. Although pesticide toxicity is well-established to be temperature-dependent, the physiological mechanisms underlying these interactions remain poorly understood. Insects often display stage- and sex-specific sensitivities to environmental pressures, suggesting complex energetic trade-offs across their life cycles. Copper-based fungicides, such as Bordeaux mixture, are widely used to control fungal diseases but can stress non-target insects. Here, we experimentally examined how Bordeaux mixture exposure interacts with projected late 21st-century climatic conditions by measuring growth rate, energy reserves, standard metabolic rate (SMR), and Hsp70 concentrations across larval instars (3rd and 5th) and adult sexes in the insect pest Lobesia botrana. Our results show that larvae underwent substantial physiological adjustments to fungicide exposure (increased Hsp70 concentrations, reduced SMR and glycogen), suggesting reallocation of energy from maintenance to stress protection. Future climatic conditions strongly modulated larval responses to the fungicide, shifting the timing of metabolic adjustments across development and interacting with Hsp70 production. Adults displayed sex-specific sensitivity to fungicide exposure, without major interaction with climatic conditions. Females exposed to the fungicide emerged with depleted reserves but unchanged SMR, consistent with energy allocation to reproduction. For males, Hsp70 concentrations were increased by fungicide exposure without major energy reserve loss, suggesting preservation of flight and mate-searching performance. Thus, stress responses are not simply additive but mediated through shared physiological pathways linking Hsp70 concentrations, metabolic regulation, and energy reserve mobilization. This study provides a mechanistic framework for understanding how interacting stressors reshape insect life-history strategies.

The tobacco beetle, Lasioderma serricorne (F.) (Coleoptera: Ptinidae), is a highly adaptable generalist insect pest that inflicts billions of dollars in damage to stored food and tobacco products worldwide. Despite the neurotoxic effects of nicotine, L. serricorne thrives on tobacco, likely due to specific adaptations; however, the underlying molecular mechanisms remain uncharacterized. To investigate, we performed a comparative transcriptomic analysis of L. serricorne larvae reared on tobacco versus an artificial diet. Bioinformatic analysis revealed a significant upregulation of genes involved in metabolic detoxification in tobacco fed larvae, including 92 cytochrome P450 (CYPs), 74 ATP-binding cassette (ABC) transporters, 37 glutathione S-transferases (GSTs), 30 UDP-glycosyltransferases (UGTs) and 21 carboxylesterases (CarEs). Spatiotemporal profiling identified several ABC transporters and CYPs as midgut-enriched, indicating roles in xenobiotic metabolism. RNAi-mediated knockdown of LsCYP6TC1, a tobacco-induced CYP, reduced transcript abundance and decreased larval survival to 36.1% compared to controls. Notably, co-silencing of LsABCA1 and LsABCG1 significantly reduced larval survival (77.1%). These results indicate that both Phase I (oxidation via CYPs) and Phase III (efflux via ABC transporters) detoxification play critical roles in tobacco tolerance. Our findings offer valuable insights into insect adaptation to dietary shifts and suggest the specific detoxification genes could be targeted for developing innovative pest management strategies.

Yolk protein genes (YPs) are central to insect reproduction, yet the extent of functional divergence among members of the same gene family remains poorly understood in many pest species. Here, we identified five YP genes in Spodoptera frugiperda. Gene structure analysis showed that four YP genes are intronless, whereas YP3 possesses a two-exon structure. Conserved domain analysis revealed that all five YP proteins contain a PFM_spherulin-2a-like domain. We then examined their developmental expression profiles to assess potential stage-specific specialization. YP1 and YP2 were highly expressed in eggs, whereas YP4 and YP5 were more strongly expressed during the pupal and adult stages, with YP3 showing no marked enrichment at either targeted stage. Based on these expression patterns, four genes were selected for RNA interference assays at two developmental stages to evaluate their functions during embryogenesis and reproductive development. Knockdown of YP1 and YP2 in eggs significantly reduced hatchability, whereas pupal-stage knockdown of these genes did not affect fecundity or offspring hatchability. In contrast, knockdown of YP4 and YP5 in eggs caused little or no effect on hatchability, whereas pupal-stage knockdown reduced fecundity and offspring hatchability and impaired ovarian development. In addition, YP4 knockdown disrupted adult emergence, leading to incomplete eclosion and malformed adults. These results show that YP genes in S. frugiperda are not functionally redundant, but instead exhibit clear stage-specific specialization. YP1 and YP2 are primarily associated with embryonic development and egg viability, whereas YP4 and YP5 contribute more to later reproductive performance, with YP4 additionally affecting successful adult emergence. This study provides new evidence for stage-specific functional divergence within the YP gene family in a major agricultural pest, which may pave the ways for developing RNAi-based strategies for green pest control in S. frugiperda.

Symbiotic microbiota of insects play crucial roles in host development, metabolism, and immunity, but the molecular mechanisms underlying these interactions remain poorly understood, particularly in non-model lepidopteran pests. Traditional germ-free (GF) insect models are primarily generated using antibiotics, which may introduce confounding effects and fail to completely eliminate microbiota. Here, we present an antibiotic-free method to generate GF Spodoptera frugiperda larvae by rearing them on axenically cultured maize. The 3rd to 6th instar GF larvae exhibited significantly reduced weight and length compared to the conventionally reared (CR) larvae, and the developmental period was prolonged. Transcriptomic analysis of 3rd instar larvae revealed significant differences in gene expression between the two groups, especially in pathways related to total carbohydrate, protein, triglycerides metabolism, as well as juvenile hormone (JH) signaling pathway. In addition, three nutritional content and JH titer were tested between GF and CR larvae. Furthermore, GF groups showed lower pupation rate and eclosion rate, reduced pupal weight, and prolonged developmental period, while pupal length was not affected compare to CR groups. Additionally, the ovarian and testes sizes of GF adults were smaller than those of CR adults. Consistently, GF females laid fewer eggs with significantly lower hatching rate compared to the CR females. These findings demonstrate that microbiota profoundly influence egg, larval, pupal development and adult reproduction in S. frugiperda. This study provides a robust framework for microbiota-function research in agricultural pests and expands our understanding of lepidopteran insects and microbiota interactions.