Insect Science最新文献

The embryonic pro-nymphal cuticle of hemimetabolous insects is a critical protective structure, yet the molecular mechanisms governing its formation, particularly the regulation of chitin organization, remain poorly understood. Chitin deacetylases (CDAs) are key enzymes that modify chitin physicochemical properties, prompting this study to investigate the functions of two Group I CDAs, LmCDA1 and LmCDA2, during the formation of the pro-nymphal cuticle in Locusta migratoria. We found that both LmCDA1 and LmCDA2 were highly expressed during the key period of pro-nymphal cuticle formation (E8-E11). Immunofluorescence localization revealed that LmCDA1 and LmCDA2 proteins were deposited in the apical region of the procuticle. RNA interference (RNAi)-mediated knockdown of LmCDA1 significantly reduced cuticle thickness but did not disrupt the helicoidal organization of chitin laminae. In contrast, knockdown of LmCDA2 completely abolished the laminar structure, resulting in disorganized chitin microfibrils and increased cuticle thickness. Together, these results demonstrate that LmCDA1 and LmCDA2 play distinct and complementary roles in regulating the biosynthesis and structural integrity of the pro-nymphal cuticle. Functional assays further revealed that suppression of either gene impaired the cuticular barrier, accelerated water loss under desiccating conditions, and significantly reduced egg tolerance to dryness. This study provides evidence that CDAs are essential for embryonic cuticle formation and desiccation resistance in a hemimetabolous insect. Our findings offer new insights into the evolutionary functional diversification of CDAs and suggest a potential novel strategy for locust control by targeting chitin metabolism during embryogenesis.

Heritable symbionts are key modulators of host biology, influencing reproduction and fitness. While antibiotic removal of symbionts is common, non-target effects on host fitness are often understudied. This is particularly true for Rickettsia, a widespread reproductive manipulator, and a stable, long-term (i.e., >7 generations) cured lineage in Hymenoptera has been lacking. This study aimed to fill this methodological gap by generating a cured bisexual lineage of parasitoid wasp with non-target effects of such treatments. Thus, we investigated not only the efficacy but also the non-target effects of three antibiotics: rifampicin, tetracycline, and sulfadiazine, administered at five concentrations (0.01, 0.05, 0.1, 1, and 10 mg/mL) in Rickettsia-infected thelytokous parasitoid Anastatus gansuensis (Hymenoptera: Eupelmidae). Survival, parasitism, emergence, and male rate were evaluated to determine the safety of antibiotic treatments, while Rickettsia titer reduction was used to assess elimination efficacy. Results showed that at a concentration of 0.01 mg/mL, tetracycline and rifampicin had minimal negative effects on host survival, parasitism, and emergence rates. However, prolonged exposure effectively eliminated Rickettsia, leading to the exclusive production of male offspring. Notably, short-term rifampicin feeding (0.01 mg/mL) across multi-generations successfully established a stable Rickettsia-cured bisexual line, confirmed via diagnostic PCR, quantitative PCR, and reproductive phenotyping over 10 generations. In contrast, sulfadiazine, previously effective against Wolbachia, had minimal impact on Rickettsia removal. This study provides a validated protocol for generating genetically stable aposymbiotic lines and a framework for assessing antibiotic specificity and non-target effects, enabling future studies of host adaptation and biological control in Rickettsia-cured parasitoids.

Raising atmospheric CO₂ could modify plant defenses against herbivorous insects and pathogenic microbial, by which shapes the outcomes of biotic interaction. Relative few studies, however, evaluates the effects of elevated CO₂ on the attractiveness of plant with and without virus infection to the virus-vector insects. Here, the effects of elevated CO₂ (750 ppm vs. 400 ppm), plant genotypes (a jasmonate-deficient mutant spr2 vs. its wild-type Castlemart) and TYLCV infection on the attractiveness of tomato plants to whitefly were determined in field open-top chambers. We found that elevated CO₂ increased plant photosynthetic rate and facilitated TYLCV infection on tomato plants. TYLCV infection and plant genotypes, rather than CO₂ levels, significantly affected plant attractiveness to whitefly, in that JA signaling pathway is required for virus-enhanced attractiveness to whitefly. Furthermore, TYLCV infection reduced the emission of five monoterpene volatiles, and three of them were repellent against whitefly. TYLCV infection downregulated the gene expression of JA signaling pathway and decreased JA content. The emission of monoterpenes in spr2 plants was lower than that in wild-type plants. These results suggested that TYLCV infection could reduce JA-dependent monoterpenes emission of tomato plants, thereby increasing plant attractiveness to whitefly. Our results revealed that TYLCV-enhanced olfactory attractiveness of tomato plants to whitefly was unaffected by elevated CO₂, indicating the evolutionarily chemical associations among plant-virus-insect vector remain robust and still effective under the context of climate change.

Parasitic wasps (Hymenoptera) are important biological control agents, yet studies on the function and evolution of their G protein-coupled receptors (GPCRs) remain limited. To address this gap, we systematically identified GPCRs in seven representative hymenopteran species based on evolutionary relationships, and found notable contraction compared to basal hymenopterans. Furthermore, phylogenetic analysis revealed extensive contraction in Family A GPCRs and methuselah-like (mthl) genes. Among the species analyzed, Gregopimpla kuwanae was selected for detailed experimental studies due to its relatively large size and suitability for laboratory manipulation. Temporal gene expression analysis in G. kuwanae showed that opsins and biogenic amine receptors exhibit low expression during the larval stages, likely reflecting adaptations associated with its parasitic lifestyle. Moreover, transcriptomic comparisons before and after initial host feeding in G. kuwanae showed 63 GPCRs showing higher expression before feeding, suggesting their involvement in host detection and feeding initiation. Notably, we found that short neuropeptide F (sNPF) and its receptor are highly expressed in females before their initial host-feeding experience, and RNAi knockdown of either gene significantly reduced both feeding motivation and intake, confirming their key function in parasitic feeding behavior. Together, our study elucidates how a streamlined GPCR repertoire supports essential life-history traits in parasitic wasps and provides a framework for leveraging these receptors in targeted biological-control strategies.

Unveiling the enigmatic processes underlying the rapid disappearance of arthropod corpses in nature is not only fascinating but also essential for understanding their ecological fate. Functional traits retained in freshly dead arthropods may influence their consumption by invertebrate scavengers. To validate this idea, we conducted a field trapping survey using four types of baits (arthropod corpses, yak carrion, yak dung, and horse dung) to investigate the attraction of arthropod corpses to necrophagous beetles in a Tibetan alpine meadow, complemented by a laboratory experiment to further examine the scavenging behavior of three necrophagous beetle species (i.e., Thanatophilus rugosus, Nicrophorus sinensis, and Nicrophorus investigator) on 25 species of dead arthropods. Results show that arthropod corpses can attract necrophagous beetles, albeit with lower species richness and abundance compared to yak carrion in the Tibetan alpine meadow. All the three necrophagous beetle species exhibited a preference for arthropod corpses with higher internal water content, lower exoskeleton content, and intermediate body size. In addition, the beetles preferentially consumed the abdomen with lower exoskeleton content to the thorax and head during partial consumption. These findings suggest that internal water content, exoskeleton content, and body size of arthropod corpses significantly influence the scavenging behavior of necrophagous beetles, thereby highlighting the importance of animal functional traits in shaping predator-prey interactions within scavenger communities.

The NF-κB transcription factor Relish and Cap "n" collar (Cnc) transcription factor CncC primarily regulate innate immune defense and xenobiotic response, respectively, in insects. However, the roles of Relish and CncC in insect development as well as their mutual regulation are still poorly understood. In this study, Relish was cloned from Tribolium castaneum. Spatial-temporal expression analysis revealed that TcRelish expression was highly expressed in the fat body and in 7-d-old female pupae, respectively. Knockdown of TcRelish in 15-d-old larvae resulted in failure of 95% of larvae to pupate, remaining in the larval stage until death. Mechanistically, dsTcRelish treatment led to an increase of juvenile hormone (JH) content by 30.66% concomitant with the upregulation of JH receptor gene Met and JH-responsive gene Kr-h1 by 94.16% and 57.93%, respectively. Notably, knockdown of TcRelish downregulated the expression of JH degradation enzyme genes JHEH2, JHEH3, and JHEH4 by 29.76%, 22.44%, and 23.83%, respectively. Similarly, knockdown of TcCncC resulted in failure of larval pupation, an increase of JH content, upregulation of Met and Kr-h1 as well as downregulation of JHEH2, JHEH3, and JHEH4. Further analysis revealed that the protein level of TcCncC was significantly reduced in 6 d after TcRelish RNAi, whereas stimulation with the Relish agonist NF-κB activator 2 significantly upregulated TcCncC protein levels. Additionally, a luciferase reporter assay revealed that overexpression of TcRelish significantly enhanced the promoter activity of TcCncC by 5.78 fold. These results demonstrate that TcRelish directly regulates larval development through transcriptional regulation of TcCncC, thereby altering the metabolism of JH.

Investigating the genetic basis of dietary adaptation provides insight into ecological specialization and the evolution of adaptive traits. Nutritional composition of available food sources varies substantially across ecological niches and plays an important role in shaping species distribution and adaptation. Unlike most Drosophila larvae that develop in decaying matters rich in protein and carbohydrate, the larvae of the invasive pest Drosophila suzukii thrive in fresh ripening fruits, a diet characterized by very limited protein and high carbohydrate levels. To understand the intrinsic nutritional adaptation of D. suzukii larvae, we examined its development and fitness on diets spanning a range of protein-to-carbohydrate (P : C) ratios and found that D. suzukii exhibits superior performance on low P : C diets compared to closely related D. biarmipes and D. melanogaster. Transcriptomic analyses showed that D. suzukii underwent fewer transcriptional changes on low P : C diets, with pathways associated with nutrient sensing, transport and digestion contributing to its adaptation. Functional validation in D. melanogaster confirmed that upregulating five genes-dilp3, sNPF, Oct-TyrR, Obp49a, and Dh31-enhanced larval fitness on low P : C diets, supporting their roles in D. suzukii's nutritional adaptation. Together, these results uncover intrinsic molecular mechanisms that enable D. suzukii larvae to successfully colonize a nutritionally challenging niche, and provide potential targets for its pest management strategies.

Aedes aegypti, a globally widespread mosquito, is a key public health threat due to its ability to transmit multiple deadly arboviruses. The midgut is crucial for the survival, reproduction, and disease transmission of mosquitoes. Competing endogenous RNAs (ceRNAs) regulate gene expression by competing for miRNA response elements (MREs), influencing processes like immunity, growth, and disease. While numerous studies have investigated miRNAs and lncRNAs in mosquitoes, the relationship between ceRNAs and nutrient uptake in the mosquito midgut remains largely unexplored. In this study, we employed whole transcriptome sequencing to identify differentially expressed (DE) miRNAs, mRNAs, lncRNAs, and circRNAs in the midgut of blood-fed Ae. aegypti mosquitoes. We identified 22 DEmiRNAs, 4226 DEmRNAs, 1238 DElncRNAs, and 35 DEcircRNAs, and developed regulatory networks for DE lncRNA/miRNA/mRNA and DE circRNA/miRNA/mRNA interactions. In these networks, DEmRNAs, DEmiRNA targets, and DEcircRNA host genes are enriched in processes like DNA integration, DNA metabolism, membrane lumen sealing, and RNA catalytic activity. KEGG analysis shows these genes are mainly involved in pathways such as mucin-type O-glycan biosynthesis and pantothenic acid and coenzyme A biosynthesis. Notably, miR-305-5p, miR-275-3p, miR-11-5p, miR-33, and miR-34-3p are key components of the ceRNA network, interacting with DElncRNAs, DEcircRNAs, and DEmRNAs. In conclusion, this study identified lncRNAs, mRNAs, miRNAs, and circRNAs in the midgut of Ae. aegypti that respond significantly to blood stimulation, suggesting their key roles in nutrient absorption regulation. These findings enhance our understanding of the molecular mechanisms of nutrient absorption and transformation in Ae. aegypti by clarifying RNA interactions.

Insect survival strategies exhibit significant phenotypic plasticity in response to environmental variation, yet the mechanisms driving sex-specific adaptations under habitat fragmentation remain poorly understood. To address this knowledge gap, we employed a multivariate analysis approach in structural equation modeling (SEM) to analyze long-term data collected from urban habitats. The data includes multiple body size parameters, natural environment parameters, and social environment parameters under distinct levels of intraspecific competition. Body size parameters varied significantly with environmental and social parameters. We then conducted SEM analysis to explore the relationships among four body size parameters, competitive aggression, habitat area and isolation. Our results revealed distinct sex-specific responses: males were negatively selected by natural environment parameters below-threshold and by social environment parameters above-threshold. Females were positively selected by both natural environment parameters and social environment parameters below-threshold, but negatively by social parameters above-threshold. Our findings indicate sex-specific responses to environmental changes. Furthermore, despite the higher intensity of intraspecific competition in above-threshold males compared to below-threshold males, the probability of intraspecific competitive behavior was greater in below-threshold males. We propose the Density-Dependent Competition-Alternative Strategy Trade-Off (DCAST) hypothesis to explain this paradox, wherein males reduce aggression above-threshold as the benefits of alternative strategies outweigh competitive costs. These insect science findings demonstrate how competition thresholds shape phenotypic plasticity in urban insects, providing a framework for understanding adaptive responses to anthropogenic habitat fragmentation.

Nicotinamide adenine dinucleotide (NAD⁺) is a central metabolic coenzyme that regulates redox homeostasis, DNA repair, and cellular longevity. While the role of NAD⁺ metabolism in mammalian aging has been well studied, its significance in invertebrate systems remains underexplored. Here, we establish the silkworm (Bombyx mori) as a novel model for investigating NAD⁺-dependent lifespan regulation. Through phenotypic comparisons among silkworm strains, we found that longer-lived strains exhibit higher levels of NAD⁺ and elevated expression of BmNmnat1, a key enzyme in NAD⁺ biosynthesis. CRISPR/Cas9-mediated knockout and RNAi knockdown of BmNmnat1 led to embryonic lethality, increased DNA damage, disrupted cell cycle progression, and morphological aging phenotypes. Supplementation with nicotinic acid (NA) significantly reversed these aging-associated changes both in vitro and in vivo, including improved redox balance, reduced oxidative stress markers, and prolonged adult lifespan. Our results highlight the evolutionarily conserved role of BmNmnat1-mediated NAD⁺ metabolism in aging and establish the silkworm as a valuable invertebrate model for mechanistic studies and antiaging intervention screening.