Journal of Insect Science最新文献

Bactrocera dorsalis (Hendel, 1912), a major invasive pest, survives under extreme climates through molecular and tissue-specific cold stress adaptations. In this study, we investigated the tissue-specific impacts of cold stress on the survival and molecular response of B. dorsalis. Results showed that cold stress had a significant effect on survival rates. The Kyoto Encyclopedia of Genes and Genomes pathway analysis indicated that signaling and metabolic pathways were activated by cold stress in the head and fat body during a transcriptome analysis. Under cold stress, 184 and 365 genes were differentially expressed in the head and fat body, respectively. RNA interference (RNAi)-mediated knockdown of transposon Ty3-I Gag-Pol polyprotein (Ty3-I) and Ty3-G Gag-Pol polyprotein (Ty3-G) in the head and fat body, significantly reduced the larval survival. Relative expression analysis revealed that expression of the Ty3-I and Ty3-G Gag-Pol polyprotein was greatly reduced in the head of cold treated larvae relative to controls (dsGFP) and that the expression level of Ty3-I Gag-Pol polyprotein in the fat body was not significantly reduced by cold stress. These results highlight the tissue-specific response of Ty3-I and Ty3-G Gag-Pol polyproteins in mediating cold stress responses and aid in understanding their importance in survival and stress adaptation. Additionally, the identification of important stress-responsive genes provides a foundation for the development of RNAi-based strategies for pest control using the targeted disruption of stress adaptation gene pathways for more effective control of B. dorsalis populations.

Thripidae, a member of the order Thysanoptera, has more than 2,200 existing species in the world. Many species of this family are economic pests for agriculture, horticulture, and forestry, whereas the distribution patterns of species diversity at large spatial scales remain poorly understood. We studied the species diversity of Thripidae and the distribution patterns of this family in China, as well as its environmental determinants and geographic determinants, on the basis of 376 species. As a result, 76 endemic species were examined, and Dendrothripinae has the highest percentage of endemic species among 4 subfamilies. The distribution patterns of Thripidae in China are mainly in the Oriental realm; only a few were distributed in the Palaearctic realm. High species richness was concentrated in the South China region, Southwest region, and Central China region. Six of 19 environmental factors were obtained for the relation between species richness and environmental factors. Our study showed that the species distributions of Thripidae in China were mainly influenced by monthly mean diurnal temperature range, Isothermality, SD of temperature seasonal change, Precipitation of the driest month, Precipitation of the wettest month, and Precipitation variation coefficient. The linear relationship between longitude, latitude of the distribution of Thripidae species, and climate factors were explored. Our study analyzed the diversity and distribution of Thripidae in China and provided basic data support for evolutionary biology and conservation of biodiversity.

Spodoptera litura (F.) infests over 380 plant species. Insecticide resistance and ecological risks underscore the need for biological alternatives. The entomopathogenic fungus Metarhizium anisopliae (Metsch.) Sorokin offers effective, sustainable pest control. We isolated entomopathogenic fungi (EPF) from diverse soils and evaluated the effects of temperature and media on their growth and sporulation. We also assessed their pathogenicity against S. litura. Fungal infection stages in S. litura were analyzed using scanning electron microscopy (SEM). Based on morphological and molecular analyses, five fungal isolates (PT-01, PT-03, PT-04, PT-05, and PT-06) were identified as M. anisopliae. Optimal fungal growth and sporulation occurred at 25 ± 1 °C on Sabouraud dextrose agar (SDA) medium. All isolates were pathogenic, causing mortality ranging from 23.33 ± 2.11% to 70 ± 8.21%, depending on the conidial concentration. The LC50 values ranged from 5.55 × 106 to 2.01 × 1013 spores/ml, while LT50 values varied from 4.01 to 18.71 d. Of these isolates, PT-01 showed the lowest LT50 and highest mortality and was selected for evaluation on developmental stages and greenhouse bioassays. Exposure of S. litura from eggs to fifth larval instars to 1 × 108 spores/ml of PT-01 revealed stage-specific susceptibility, with first instars exhibiting the greatest mortality and fifth instars the least. Greenhouse trial on the third larval instar showed reduced mortality. Fungal infection stages were confirmed via SEM. These findings show strong biocontrol potential of PT-01 against S. litura and support further evaluation in field trials, formulation and integration into Integrated Pest Management (IPM) programs.

Subject Editor: Karen Poh While locomotion in adult fleas has been thoroughly documented, the mechanics of larval flea movement are not well described. Efficient independent movement is essential in the larval stage, as fleas must acquire food, avoid predation, and seek out preferred environmental conditions. Herein, we use high-speed videography and scanning electron microscope imaging to investigate and describe the mechanics of larval movement in the cat flea Ctenocephalides felis (Bouché). Cat flea larvae move by extending their heads, leading with their maxillary palps, and pulling the rest of their body forward in a crawl. This locomotory behavior is used across all 3 larval instars while moving across flat and through 3-dimensional substrates, moving up to 1.14 body lengths per second. Beyond projecting from the head, we find no evidence of locomotory-specific anatomical features of the maxillary palps. More generally, this is an example of behavioral co-option of non-locomotory body parts to enable larval movement, a strategy that can be found across many insect orders.

Phoresy, the passive transport of an organism by another, is a well-documented strategy among flightless arthropods, particularly in species that exploit patchily distributed resources. While phoresy among parasitic lice has been frequently recorded between avian-associated ischnoceran species riding on louse flies, reports of phoretic lice parasitic on mammals are exceedingly rare. Here, we report a case of phoresy of the chewing louse Damalinia (Cervicola) meyeri (Taschenberg) hitchhiking attached to the legs of the snipe fly Symphoromyia immaculata (Diptera: Ragionidae) (Meigen), collected while feeding on a human in central Italy. This represents the first case of phoresy on a rhagionid fly, increasing the known diversity of phoretic carriers of chewing lice.

The gut microbiome plays a fundamental role in host ecophysiology. Numerous studies have examined microbiome composition and functionality to understand the ecological and evolutionary factors shaping host-microbe interactions. However, the consequences of these patterns for animal ecology remain poorly understood. Here, we examined how variations in the gut microbiome influence fitness differences among Drosophila species sharing a common dietary niche. Using 16S rRNA gene sequencing, we analyzed the gut microbial taxonomy and predicted functional profiles of 4 Drosophila species collected in central Chile. Our results revealed a strong signal of phylosymbiosis in the microbial taxonomy, while functionality was highly redundant across the studied fly species. Functional biomarkers analysis indicated that the gut microbiome supports the nutritional requirements of D. simulans (Sturtevant), D. hydei (Sturtevant), and D. repleta (Wollaston); whereas, this was less evident in D. melanogaster (Meigen). To assess the potential contribution of the microbiome to host performance, we compared egg-to-adult viability between 2 species with the greatest physiological divergence: D. simulans and D. hydei. Notably, D. simulans exhibited significantly higher egg viability and shorter development time than D. hydei. Strikingly, the D. simulans microbiome contained more taxonomic and functional biomarkers previously demonstrated to enhance fly fitness, whereas the D. hydei microbiome harbored taxa and functions potentially detrimental to host performance. These findings suggest that the gut microbiome contributes to host fitness and may shape the evolutionary ecology of Drosophila species, with broader implications for community dynamics, including interspecific competition and species displacement.

Thrips are small, cosmopolitan pests that attack a wide variety of crops, including avocado (Persea americana Mill.), where they feed on the fruit surface, hindering export quality. In Colombia, 7 thrips species have been identified in avocado where Frankliniella gardeniae (Fg) (Moulton, 1948), F. panamensis (Fp) (Hood, 1925), and Scirtothrips hansoni (Sh) (Mound and Hoddle, 2016) are the most abundant. Despite their economic importance, limited genomic and transcriptomic data are available for these pests. Here, we present the first draft genomes of these species and compare them to the reference genome of Frankliniella occidentalis. The mitochondrial genomes (mitogenomes) of the 3 species differ in size and gene order, with F. gardeniae exhibiting the largest mitochondria. Phylogenetic analysis clustered F. gardeniae and F. panamensis together and S. hansoni with S. dorsalis. Genome assembly revealed differences in genome sizes: 397 Mbp (Fp), 454 Mbp (Sh), and 601 Mbp (Fg), with F. gardeniae having the largest genome. Coverage was 118× for S. hansoni and 35× for the other 2 species. S. hansoni showed the highest sequence count and N50 values. BUSCO analysis estimated genome completeness between 96% and 97.95%. Annotated genes shared among these species included insecticide resistance and metabolism, particularly P450 and CYP family genes, as well as chemosensory genes (Ir). They are promising targets for RNA interference-based studies to enhance pest management strategies thus further studies are required in this issue.

Arma chinensis (Fallou) (a predatory insect) and Halyomorpha halys (Stål) (a phytophagous insect) exhibit distinct feeding ecologies. This contrast provides a model system to investigate metabolic divergence in insects, which remains insufficiently characterized. To address this, we employed untargeted metabolomics for comparing the global metabolic profiles of these 2 species. Significant differences were detected between A. chinensis and H. halys, with 194 and 195 differentially abundant metabolites identified in females and males, respectively. The metabolic profile of A. chinensis was characterized by an enrichment of lipids and lipid-like molecules. In contrast, H. halys exhibited an enrichment of organic acids, their derivatives, and plant-derived secondary metabolites, consistent with its phytophagous diet. Sex-specific metabolic patterns were also observed: females showed higher lipid accumulation, a pattern often associated with reproductive investment in insects, whereas males displayed a relative increase in metabolites related to protein synthesis. This study elucidates the distinct metabolomic signatures associated with different feeding habits for 2 closely related insect species. These findings provide a foundation for further investigation into the physiological correlates of dietary ecology and may inform future research into pest management strategies.

Invasive species pose a critical threat to biodiversity, often endangering ecologically naive endemic fauna. The avian vampire fly, Philornis downsi Dodge & Aitken, 1968 (Diptera: Muscidae), a semi-hematophagous ectoparasite introduced to the Galápagos Islands, has caused severe declines in endemic and native bird populations, including Darwin's finches. Yet, the physiological mechanisms enabling its ecological success remain largely unexplored. Here, we describe the first metabolome study of P. downsi, identifying 806 metabolites (78% confirmed by standards) across 2 developmental stages (larvae and adults) and from 2 ecological contexts (collected from natural habitats and reared under laboratory conditions). Global metabolomics analysis revealed pronounced stage- and sex-specific metabolic reprogramming in response to ecological context. Wild females showed enriched pathways linked to reproductive investment and environmental resilience, including α-linolenic acid, nicotinamide, and ascorbate metabolism. Wild males exhibited elevated lipid signaling, one-carbon metabolism, and phosphonate pathways, suggesting adaptations to reproductive demands and environmental variability. In contrast, lab-reared adults displayed more constrained metabolic profiles dominated by carbohydrate and vitamin metabolism, indicative of physiological canalization under nutrient-rich conditions. Larvae exhibited the most extensive metabolic divergence. Wild larvae were enriched in pathways related to amino acid turnover, antioxidant defenses, and membrane lipid remodeling, patterns reflecting developmental plasticity under fluctuating ecological pressures. Lab-reared larvae, conversely, exhibited upregulation in fructose and mannose metabolism, phenylalanine metabolism, and starch and sucrose metabolism, likely reflecting metabolic optimization for growth efficiency. These findings provide molecular insight into the physiological plasticity and invasion success of P. downsi, informing refinements in mass rearing for control strategies.

Sensitivity to double-stranded RNA (dsRNA)-induced gene silencing has been observed in multiple coleopterans. Initial work with mountain pine beetle, Dendroctonus ponderosae Hopkins, determined that specific ubiquitously expressed essential genes can cause mortality when silenced by carefully designed dsRNAs. However, current dsRNA production methods are not economically feasible for production at scale. Therefore, identifying the minimum efficacious dose is a critical step to deployment. To investigate the relationship between dsRNA dose and subsequent gene expression, adult mountain pine beetles were fed either a target or control dsRNA across a gradient of concentrations, including 2.5, 1.0, 0.25, and 0.025 µg/µl, and relative gene expression of the target gene was computed between dsRNA treatments of the same concentration. Differences in relative gene expression were detected along the dsRNA concentration gradient. Interestingly, higher doses of dsRNA caused significant overexpression of the target gene, heat shock protein 70 kDa, while the more miniscule doses showed no statistically significant upregulation. Overexpression of target mRNA levels in the presence of exogenous dsRNA has been demonstrated in multiple other coleopterans, but the mechanism is not yet clear. The interplay between dsRNA dose, target sequence, and other factors will likely vary by target organism, and as such, rigorous optimization assays will be necessary to understand the unique factors necessary for consistent gene silencing.