Insect Science最新文献

Insects touch their proximal environment with their tarsi. The immediate contact with xenobiotics occurs with the tarsal cuticle surface that is covered with cuticular hydrocarbons (CHCs). In this work, we tested the hypothesis that xenobiotics entry through the tarsi depended on CHC amounts and composition. Applying RNA interference, we suppressed the expression of genes coding for the key enzymes of CHC production Cyp4G1 (total CHC), desat1 (unsaturated CHCs) and FASN2 (branched CHCs) in lipid producing oenocytes and analyzed the penetration efficiency of the insecticides DDT and chlorantraniliprole and of the inert dye Eosin Y in the respective flies. As expected, in walking experiments, reduction of CHC amounts (cyp4G1^RNAi) enhanced insecticide and dye penetration into the tarsi. In the same assay, we identified unsaturated CHCs as the main CHC component attenuating DDT and chlorantraniliprole at low concentrations. Likewise, tarsal adhesion and uptake of Eosin Y depended rather on unsaturated than on branched CHCs. Extrapolating from our data, we propose a two-step model of xenobiotics penetration through the tarsal cuticle: first, modulated by unsaturated CHCs, the molecule is repelled or adheres to the cuticle surface; upon adhesion, the molecule penetrates the cuticle and accumulates in the tarsal lumen in a second step. Whether these mechanisms apply to molecules other than Eosin Y remains to be investigated. Taken together, the tarsal cuticle constitutes a selective bipartite barrier against uncontrolled uptake of contact xenobiotics.

Farnesoic acid O-methyltransferase (FAMeT) and juvenile hormone acid O-methyltransferase (JHAMT) are key enzymes in the isoprene branch pathway, a specialized downstream biosynthetic pathway for juvenile hormone (JH). Both enzymes play crucial roles in insect egg production. While their mechanisms have been well characterized in model insects, this study aims to elucidate their specific functions in the reproductive process of the small brown planthopper (SBPH), Laodelphax striatellus. Here, we cloned the full-length cDNA encoding a putative FAMeT (LsFAMeT) from SBPH. The deduced protein sequence has a conserved Methyltransf_farnesoic acid domain and shares high identity with other insect FAMeTs. To gain further insight, we silenced LsFAMeT and LsJHAMT in SBPH and found that LsJHAMT expression increased when LsFAMeT was knocked down, and vice versa, suggesting a potential coordinated relationship between LsFAMeT and LsJHAMT in JH biosynthesis. In addition, RNAi-mediated silencing of LsFAMeT, LsJHAMT, or both genes significantly reduced female fecundity while simultaneously decreasing JH III titers. This was associated with reduced levels of total protein, cholesterol, triacylglyceride, and four carbohydrates (glucose, fructose, sucrose, and trehalose), as well as decreased ovarian cell mitosis, increased ovarian cell apoptosis, and downregulation of the JH receptor Met and its early-responsive gene Kr-h1. Together, these data suggest that LsFAMeT- and LsJHAMT-mediated JH biosynthesis regulates the reproductive capabilities of SBPH through energy mobilization, and ovarian cell activity. Our findings help elucidate the role of JH in insect reproduction and provide insights into key enzymes that may serve as potential targets for the development of selective insect growth regulators.

Feeding behavior determines insect survival and reproductive success. As insects process multimodal olfactory and gustatory cues to guide their feeding decisions, appetitive odors not only attract insects to food sources but also directly increase food ingestion. However, the mechanisms that coordinate chemosensory integration to regulate these behaviors remain poorly characterized. The silkworm mainly feeds on mulberry leaves. We previously identified GS01 as a natural mutant that consumes an expanded range of non-mulberry diets and exhibits compromised olfactory specificity for mulberry leaves. Thus, GS01 is an excellent model for studying the genetic basis of interactions between olfaction and gustation. Combining the results of molecular mapping, transcriptome sequencing, and DNA sequencing, we determined that the gustatory receptor Gr66, and odorant receptors Or39 and OrJ are involved in the euryphagous phenotype of GS01. Next, we generated a series of mutants by single or combined gene knockout using CRISPR/Cas9 and studied the interactions between the affected genes in regulating feeding behavior. We showed that a single knockout of Gr66 increases intake of an artificial diet containing no mulberry leaves, while individual or simultaneous knockouts of genes Or39 and OrJ do not increase consumption of this diet. However, the combined knockout of genes Gr66, Or39, and OrJ significantly enhances uptake of the artificial diet beyond levels exhibited by the Gr66 knockout alone. This study demonstrates the synergy between gustatory and odorant receptors in regulating silkworm feeding preference and food uptake, and sheds light on understanding the complexity of regulation of feeding behavior in insects.

The widespread use and improper disposal of polypropylene (PP) facemasks have resulted in persistent environmental pollution, posing urgent challenges for waste management. This study added bran-PP mixture, which increased the survival rate, consumption rate and removal rate of Tenebrio molitor feeding solely on PP. The average consumption of the larvae fed with the edible bran-PP mixture was 61.54% higher than those fed only PP. The removal rates were 39.26% and 36.14%, respectively. Fourier-transform infrared spectroscopy, thermal gravimetric analysis, gel permeation chromatography, and nuclear magnetic resonance confirmed the production of oxygenated compounds in the larval gut, indicating partial oxidation and degradation of PP masks within the intestinal tract. HT-GPC analysis revealed significant reductions in molecular weight parameters, with the number-average (Mn), weight-average (Mw), and Z-average (Mz) molecular weights decreasing by 51.07%, 33.60%, and 32.99%, respectively. High-throughput 16S rRNA sequencing revealed that feeding on PP enhanced gut microbiota richness and diversity. The bran-PP mixture group exhibited significantly higher relative abundances of Enterobacter and Spiroplasma, whereas the bran group was dominated by Lactobacillus. PICRUSt functional predictions indicated upregulation of plastic degradation-associated oxidases (alkane 1-monooxygenase, cyclohexanone monooxygenase) and hydrolases (chitinase, carboxylesterase) in larvae fed PP or bran-PP diets. Metabolomic profiling revealed significant enrichment in pathways related to histidine, glycerophospholipid, choline and steroid hormone metabolism in PP-fed larvae. These findings demonstrate that PP can be biodegraded in T. molitor larvae through gut microbe-mediated depolymerization involving a diverse microbial community.

We find a specialized Pachyteles-like larva from mid-Cretaceous Kachin amber, which represents a rare insight into the behavioral and morphological adaptations of early beetles. In our finding, its terminal disk morphology suggests a highly specialized ambush predation strategy, integrating both prey capture and phragmotic defense-traits that were already well developed over 99 million years ago. This fossil not only reveals the antiquity of complex larval predation and defense behaviors in Carabidae but also pushes back the evolutionary origin of phragmosis among insects. It also allows for a functional morphological interpretation of ecological interactions in Cretaceous terrestrial ecosystems. This functional approaches offer a valuable lens for decoding the ecological complexity of Mesozoic food webs, revealing that intricate predator-prey relationships were already well established in the mid-Cretaceous.

Pheromone-binding proteins (PBPs) play pivotal roles in the moth olfactory system by assisting the neuronal response to pheromone components. Thalassodes immissaria is a major notorious defoliator of lychee orchards in China. In this study, we demonstrated that (3Z,6Z,9Z,12Z)-icosa-3,6,9,12-tetraene (Z3,Z6,Z9,Z12-20:H)-a principal sex pheromone component previously identified in the Japanese population of T. immissaria-elicits significant electroantennogram (EAG) responses and robust behavioral attraction to male moths of the Chinese population. Subsequently, we identified three PBP-encoding genes, among which TimmPBP1 and TimmPBP2 were highly expressed in the antennae of adult male T. immissaria. Further fluorescence competitive binding assays revealed that recombinant TimmPBP1 and TimmPBP2 exhibited strong binding affinities to Z3,Z6,Z9,Z12-20:H. Additionally, the antennae of male moths treated with dsTimmPBP1 or dsTimmPBP2 exhibited significantly reduced EAG responses to Z3,Z6,Z9,Z12-20:H. Finally, the expression profiles of TimmPBP1 and TimmPBP2 exhibited circadian oscillations, which aligned with the diurnal rhythms of T. immissaria mating behavior and the males' EAG responsiveness to Z3,Z6,Z9,Z12-20:H. Our study elucidates the physiological roles of PBPs in the recognition of Type II sex pheromone and offers novel molecular targets for monitoring and sustainable control of T. immissaria in orchard ecosystems.

Ladybird beetles (Coleoptera: Coccinellidae) comprise over 6000 species and have been extensively studied in terms of their biology, ecology, omics, and applications in biological control. However, this knowledge is scattered across diverse publications and databases, limiting accessibility and integration. To address this gap, we developed LadybirdBase (http://www.ladybirdbase.com), a comprehensive database that compiles primarily published resources on 6872 ladybird species. It integrates five modules: Biology (taxonomy and species traits), Ecology (diet ranges and geographic distributions), Genomics (genomes, transcriptomes, and related datasets), Microbiomics (microbial amplicon and metagenome sequencing), and Lab Test (laboratory-derived biological parameters). LadybirdBase also provides analytical tools for species identification via morphology or DNA barcodes, gene and primer searches, and transcriptome-based differential expression analysis. Using Cryptolaemus montrouzieri-a representative biological control ladybird-as an example, we show that by centralizing ecological, laboratory, and multi-omics data, LadybirdBase supports efficacy evaluation, rearing and release optimization, and risk assessment, thereby advancing research and applications in evolutionary biology, ecology, and sustainable pest management.

The insect olfactory system is essential for survival, enabling the detection of chemical cues critical for feeding, reproduction, and avoiding threats. Semiochemicals, including pheromones and allelochemicals, are processed through specialized organs, primarily the antennae and maxillary palps, which contain sensilla housing olfactory receptor neurons (ORNs). Odorant-binding proteins (OBPs) transport volatile compounds to odorant receptors (ORs) on sensory neurons, initiating precise signal transduction. Rapid signal termination, vital for sensitivity, is achieved by odorant-degrading enzymes (ODEs) that prevent receptor saturation. Evolutionary adaptations optimize OBPs and ORs for species needs, such as the detection of foreign odors. Environmental factors, including temperature, nutritional state, and circadian rhythms, further modulate olfactory sensitivity. In this review article, we underline the interaction between olfactory proteins and insect immunity. Reports coming from different laboratories, point to the role of olfactory proteins in defense response, including its cellular, humoral, and behavioral aspects. Beyond chemosensitization, the olfactory system contributes to insect immunity by regulating pathogen recognition and immune signaling. OBPs interact with Toll-like receptors, regulating antimicrobial responses and gut microbiota stability. Symbiotic bacteria influence OBP expression, linking olfaction to systemic immunity. Finally, some odorant-binding proteins and chemosensory proteins possess direct antimicrobial activity. In conclusion, the insect olfactory system integrates sensory and immune functions through molecular and neuronal components, reflecting its evolutionary versatility. Blood-feeding insects, for example, Aedes aegypti or Rhodnius prolixus, exhibit heightened detection of host odors during reproductive cycles, while starved insects prioritize food-related cue.

V-ATPases are crucial for animal development and survival, but their functions in fertility are largely unknown. Here, we found that knockdown of VhaM9.7-d in germ cells induced complete sterility in male Drosophila melanogaster, but had no effects on female fertility. Depletion of VhaM9.7-d did not severely impair spermatogenesis, as the mature sperm appeared in the seminal vesicles (SVs) of the testes. However, the sperm released from the SVs of the VhaM9.7-d-knockdown males rapidly lost their motility and were unable to move over long distances. These sperm could be transferred to the female's uterus during copulation, but failed to be stored in the seminal receptacle (SR) and fertilize the egg. Tandem mass tag (TMT) proteomic analyses of SVs, including their contents, identified 434 differentially expressed proteins (DEPs) when comparing the control group to the VhaM9.7-d-knockdown group. Many downregulated proteins were enriched in phagosome and oxidative phosphorylation (OxPHOS) pathways. Subsequent experiments, encompassing the LysoSensor Probe assay, CMXRos staining, and ATP measurement, confirmed that the knockdown of VhaM9.7-d significantly disrupted phagolysosomal and mitochondrial functions, leading to diminished acidity, heightened levels of reactive oxygen species (ROS), and a decrease in both mitochondrial membrane potential and ATP contents in the SVs. These results suggest that VhaM9.7-d plays an essential role in maintaining the homeostasis of sperm energy metabolism by regulating phagolysosomal activity and mitochondrial OxPHOS. Our data provide valuable insights for the further study of the mechanisms of related diseases such as human asthenospermia.

Parasitoids often manipulate host nutritional metabolism to facilitate their own growth and survival. However, how parasitoids acquire and utilize host-derived nutrients to support embryonic development remains poorly understood. Here, we found that Trichopria drosophilae embryonic development depends on lipid nutrition from the dissociated fat bodies in its Drosophila host pupae. Untargeted metabolomics analysis revealed that host lipids, particularly glycerolipids and sphingolipids, might be important for T. drosophilae embryogenesis. We further identified eight lipophorin receptors in T. drosophilae, among which TdOGS08990 exhibited the highest expression during the egg stage. RNA interference (RNAi)-mediated knockdown of TdOGS08990 significantly disrupted embryonic development, revealing its essential role in transporting host-derived lipids for parasitoid embryogenesis. These results advance our understanding of parasitoid-host nutritional ecology, demonstrating that lipid acquisition from hosts is a fundamental requirement for embryonic development in parasitoids.