Search Results (599)

Herbivore-induced plant volatiles (HIPVs) are well known for their roles in herbivore deterrence and attraction of natural enemies, but their direct impact on insect reproduction remains largely unexplored. In this study, we provide novel evidence that two representative HIPVs, 2-heptanol and α-cedrene, exert opposing effects on the reproduction of Chilo suppressalis, a major rice pest. While both volatiles repelled adults, α-cedrene unexpectedly enhanced oviposition, whereas 2-heptanol significantly suppressed egg laying. To examine these effects, we conducted oviposition assays, preoviposition and longevity tests, combined with qPCR and transcriptome analyses to explore underlying molecular responses. Mechanistically, α-cedrene upregulated Kr-h1, a gene linked to juvenile hormone signaling and vitellogenesis, promoting reproductive investment. Transcriptomic profiling revealed divergent molecular responses: α-cedrene activated reproductive pathways, whereas 2-heptanol induced stress- and immune-related genes, suggesting a trade-off between stress defense and reproduction. These findings demonstrate that HIPVs can exert compound-specific reproductive effects beyond repellency. This work fills a key knowledge gap and highlights the potential of HIPVs as precision tools in pest management strategies that exploit behavioral and physiological vulnerabilities beyond repellency. Full article

Pardosa pseudoannulata plays an important role in the biological control of insect pests. The inclusion of yeast in the culture medium is very important for the growth, development, and reproduction of Drosophila melanogaster, but there have been few studies on the influence of nutrients in the culture medium on spider development. In order to explore the effects of different yeast treatments on the growth and development of D. melanogaster and as a predator, P.  pseudoannulata, three treatments (no yeast, active yeast added, and inactivated yeast added) were adopted to modify the conventional D. melanogaster culture medium. The addition of yeast to the medium shortened the development time from larva to pupation in D. melanogaster. The emergence and larval developmental times of D. melanogaster reared with activated yeast were shorter than those of the group without yeast addition, which promoted D. melanogaster emergence and increased body weight. The addition of yeast to the medium increased the fat, protein, and glucose content in D. melanogaster. The addition of activated yeast shortened the developmental time of P.  pseudoannulata at the second instar stage but had no effect on other instars. Different yeast treat-ments in the medium had no effect on the body length or body weight of P.  pseudoannulata. Adding yeast to D. melanogaster culture medium can increase the total fat content in P.  pseudoannulata, but it has no effect on glucose and total protein in P.  pseudoannulata. Our study shows the importance of yeast to the growth and development of fruit flies. Full article

Chrysomya megacephala, as one of the common blowflies, displays biological characteristics, such as ovoviviparity and carrion-feeding adaptation. Thus, this species is generally considered of significant ecological, medical, and forensic importance. However, without a high-quality pseudo-chromosome genome for C. megacephala, elucidating its evolutionary trajectory proved difficult. Herein, we assembled and analyzed a high-quality chromosome-level genome assembly of the C. megacephala, combined with PacBio HiFi long reads, Hi-C data, and Illumina reads. The pseudo-chromosomes assembly of C. megacephala spans 629.44 Mb, with 97.05% anchored to five chromosomes. Final assembly includes 1056 contigs (N50 = 1.68 Mb), and 97 scaffolds (N50 = 121.37 Mb), achieving 98.90% BUSCO completeness (n = 1367). Gene annotation predicted 17,071 protein-coding genes (95.60% BUSCO completeness), while repeat masking identified 244.26 Mb (38.82%) as repetitive elements. Additionally, 3740 non-coding RNAs were characterized. Gene family analyses resulted in 10,579 gene families, containing 151 gene families that experienced rapid evolution. Comparative genomic analyses showed that the expanded genes are related to reproduction and necrophagous habits. In addition, we annotated the gene family P450s, CCEs, IRs, GRs, and ORs, all of which represent remarkable expansion, playing a crucial role in the mechanism of locating the hosts for forensic insects. Our research establishes a high-quality genome sequence to facilitate subsequent molecular investigations into significant species within forensic entomology. Full article

Carbon nanotubes are promising in agriculture for improving crop resilience and delivering agrochemicals. However, their effects on insect pests, especially chewing pests such as the fall armyworm (Spodoptera frugiperda), remain underexplored. In this study, we investigated how two types of functionalized multi-walled carbon nanotubes—hydroxylated (MWCNTs-OH) and carboxylated (MWCNTs-COOH), both obtained from Jiangsu Xianfeng Nano (Nanjing, China)—affect the pest’s development and reproduction. Using an age-stage two-sex life table approach, we fed larvae diets containing 0.04, 0.4, or 4 mg/g of these nanomaterials. Both types of MWCNTs exhibited concentration-dependent inhibitory effects. At the highest dose (4 mg/g), larval development was significantly prolonged, adult pre-oviposition periods increased, and fecundity (egg production) sharply declined, especially with MWCNTs-OH. Population growth parameters were also suppressed: net reproductive rate (R₀), intrinsic rate of increase (r), and finite rate of increase (λ) were reduced at 4 mg/g, particularly with MWCNTs-OH, while mean generation time (T) was extended with MWCNTs-COOH. Overall, MWCNTs-OH demonstrated a greater inhibitory impact compared to MWCNTs-COOH. These findings suggest that functionalized MWCNTs could serve as potential novel pest control agents against S. frugiperda by impeding its development and reproduction. Full article

Ecdysterone controls moulting and reproduction in insects, crustaceans, and helminths. It is also produced by many plants, probably as an insect deterrent. The steroid is not made by vertebrates but has anabolic effects in mammals and could be useful for treating sarcopenia in aged horses. However, ecdysterone is banned in horseracing and equestrian sports, and with no limit of reporting, the risk of unintended exposure to this naturally occurring prohibited substance is a concern. To explore this risk, pasture plants and hay samples were analysed for ecdysterone content, as well as samples of blood, faeces, and intestinal mucosa from horses (euthanized for non-research purposes) with varying degrees of endo-parasite infestation. The variability in serum ecdysterone concentrations between different horses after administering a fixed dose was also examined. Ecdysterone was detected in 24 hay samples (0.09 to 3.74 µg/g) and several weeds, with particularly high concentrations in Chenopodium album (244 µg/g) and Solanum nigrum (233 µg/g). There was a positive correlation between faecal ecdysterone and faecal egg counts, but no effect of anthelmintic treatment and no relation to the number of encysted cyathostome larvae in the large intestine mucosa. Certain horses maintained an unusually high serum ecdysterone concentration over several weeks and/or displayed an abnormally large response to oral ecdysterone administration. Thus, the risk of environmental exposure to ecdysterone is apparent, and several factors must be considered when determining an appropriate dosage for clinical studies or setting a reporting threshold for equine sports. Full article

(1) Background: The insect male accessory gland (MAG) produces seminal fluid components crucial for male reproduction, analogous to the mammalian prostate. While some insect MAGs exhibit binucleate epithelial cells for luminal volume plasticity, the diversity of cellular arrangements and their functional implications across insects remain largely unknown. (2) Methods: We investigated the cellular architecture of MAG epithelia in various shore bug species (infraorder Leptopodomorpha, Hemiptera) and their mechanisms of multinucleation and potential MAG volume regulation. (3) Results: The MAG epithelia of shore bugs comprise a small number of large, plastic syncytial cells with varying nuclear numbers. We hypothesize that these syncytia facilitate effective MAG volume expansion post-eclosion. Uniquely, MAG shrinkage involves the localized contraction of limited muscle fibers, unlike the systematic contraction of circular muscles in most other insects. We further describe sequential cell fusion during the nymphal stage as the mechanism of multinucleation. (4) Conclusions: The unique syncytial organization of Leptopodomorpha MAG epithelia represents an evolutionary divergence from typical binucleate or mononucleate structures in other insects; it is likely that this enables distinct mechanisms for reproductive fluid storage and evacuation. This study highlights the evolutionary diversity of male reproductive organ morphology and function within insects. Full article

Essential oils have emerged as promising alternatives for pest insect control. However, sublethal effects on insect reproduction and development are rarely explored, despite their relevance to integrated pest management (IPM). This study evaluated the sublethal effects of Piper hispidivervum C. DC. essential oil (EOPH) on the development and population growth of four populations of Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), as well as the persistence of safrole residue in treated corn grains. Population development rates were determined using emergence curves and total emerged adults, while population growth was assessed by counting live insects in the feeding substrate at different storage intervals. Safrole residue persistence was analyzed using solid-phase microextraction in headspace mode (SPME-HS). Sublethal exposure to EOPH significantly reduced the development rate, total emergence, and growth in three of the four populations. The population from Crixás, GO, showed no significant reduction, with a population curve overlapping the control. The lethal dose was reduced by 98.20%, indicating low persistence and potential food safety. The EOPH exhibited sublethal effects on S. zeamais populations, reducing both development rates and population growth. This reduction varied among the populations studied. Further research is encouraged to explore its effects on different insect populations and under broader environmental conditions. Full article

Lipids play vital roles in insect physiology, functioning as energy reserves, membrane constituents, and cuticular protectants. However, few studies have examined the anatomical distribution of lipids in blood-feeding Diptera and compared the compositions of the cuticular and internal compartments. This study analyzes the qualitative and quantitative profiles of free fatty acids (FFAs) in the female Tabanus bovinus, a hematophagous horsefly species, across different anatomical regions, including the head, wings, legs, thorax, and abdomen. The surface and internal lipid fractions were isolated using petroleum ether/dichloromethane extraction followed by sonication. GC-MS revealed the presence of 21 FFAs, including 16 saturated (C7:0, C8:0, C9:0, C10:0, C11:0, C12:0, C13:0, C14:0, C15:0, C16:0, C17:0, C18:0, C19:0, C20:0, C22:0, C24:0) and five unsaturated (C16:1, C18:2, C18:1, C20:5, C20:4). The head and wings showed the highest concentrations of cuticular FFAs. At the same time, internal lipid stores were most prominent in the thorax and abdomen (but four times lower than in the head cuticle), reflecting their role in energy storage and reproduction. All cuticular and internal extracts were dominated by C16:0, C18:0, and C18:1. Notably, several FFAs were undetected in specific compartments: C10:0 from inside the head, C11:0 and C13:0 from inside all examined body parts, C19:0 was absent from inside the head, wings and legs, while C20:5 and C20:4 were absent from both the cuticular and internal lipid pools of the wings. Interestingly, our analysis of the cuticle on the thorax and abdomen together revealed that both C13:0 and C19:0 were present only on the dorsal side, i.e., absent from the ventral side. These absences suggest a selective lipid metabolism tailored to the functional and ecological demands of T. bovinus females. Our findings suggest that the absence of specific compounds from individual body parts may serve as an indicator of physiological specialization. This work provides new insights into lipid compartmentalization in Tabanidae and offers a framework for future comparative and ecological lipidomics studies in insects. Full article

Corazonin (Crz) is widely found in insects and crustaceans. In insects, Crz participates in the regulation of various physiological activities, including heartbeat, body color change, molting, and reproduction. However, the physiological effects of Crz in crustaceans remain largely unclear. In this study, the cDNAs encoding Crz and its putative receptor were isolated from the mud crab Scylla paramamosain. Tissue distribution analysis revealed that Sp-Crz was predominantly expressed in neural tissues, while its receptor (Sp-CrzR) was widely expressed in S. paramamosain, with a high expression level in the Y-organ. During ovarian development, Sp-Crz expression in the eyestalk ganglion was upregulated at the early and late vitellogenic stages, whereas its expression level in the cerebral ganglion displayed an initial downregulation at the early stage, followed by a remarkable upregulation at the late vitellogenic stage. The expression level of Sp-CrzR mRNA in the ovary increased significantly at the late vitellogenic stage. However, an opposite expression pattern was observed in the hepatopancreas and Y-organ. The immunohistochemistry result showed that Sp-Crz was distributed in the cells of the lamina ganglionaris, the medulla interna, and the X-organ of the eyestalk ganglion. It was revealed that the level of Sp-Vg in the hepatopancreas was not affected by the addition of Sp-Crz in vitro. However, the expression of Sp-VgR in ovarian explants was significantly induced by 6 h treatment with Sp-Crz at a concentration of 1 nM. In addition, the level of Sp-VgR in the ovary was significantly upregulated by 12 h injection of Sp-Crz. After long-term administration of Sp-Crz, the expression of Sp-VgR in the ovary, the E₂ content in hemolymph, the oocyte diameter, and the gonadosomatic index of S. paramamosain were significantly increased. In summary, these findings collectively indicate that the Sp-Crz signaling system participates in regulating the ovarian development of the mud crab. This study provides a new insight into the biological function of Crz during the ovarian development of the mud crab, which is of great significance for the sustainable development and utilization of mud crab resources. Full article

Cytoplasmic polyadenylation element-binding proteins (CPEBs) are critical regulators of maternal mRNA translation during oogenesis, yet their roles in insect reproduction remain underexplored. Here, we characterized CmCPEB2, a CPEB homolog in the rice leaf roller Cnaphalocrocis medinalis, a destructive lepidopteran pest insect, and elucidated its role in mating-induced oviposition. The CmCPEB2 protein harbored conserved RNA recognition motifs and a ZZ-type zinc finger domain and was phylogenetically clustered with lepidopteran orthologs. Spatiotemporal expression profiling revealed CmCPEB2 was predominantly expressed in ovaries post-mating, peaking at 12 h with a 6.75-fold increase in transcript levels. Liposome-mediated RNA interference targeting CmCPEB2 resulted in a 52% reduction in transcript abundance, leading to significant defects in ovarian maturation, diminished vitellogenin deposition, and a 36.7% decline in fecundity. The transcriptomic analysis of RNAi-treated ovaries identified 512 differentially expressed genes, with downregulated genes enriched in chorion formation and epithelial cell development. Tissue culture-based hormonal assays demonstrated the juvenile hormone-dependent regulation of CmCPEB2, as JH treatment induced its transcription, while knockdown of the JH-responsive transcription factor CmKr-h1 in the moths suppressed CmCPEB2 expression post-mating. These findings established CmCPEB2 as a juvenile hormone-dependent regulator of mating-induced oviposition that orchestrates vitellogenesis through yolk protein synthesis and ovarian deposition and choriogenesis via transcriptional control of chorion-related genes. This study provides novel evidence of CPEB2-mediated reproductive regulation in Lepidoptera, highlighting its dual role in nutrient allocation and structural eggshell formation during insect oogenesis and oviposition. Full article

Among various plants, corn is the primary host damaged by Spodoptera frugiperda J. E. Smith (Lepidoptera: Noctuidae). After long-term regional colonization, its larvae feed on sweet waxy corn and fresh corn for extended periods. A question arises: Does long-term feeding on different corn varieties affect their rhythms? Currently, there are no reports addressing these issues. To facilitate the formulation of effective prevention and control measures, Zhengdan 958 and Zhenghuangnuo were selected as representative varieties of normal and sweet waxy corn, respectively, for laboratory experiments. S. frugiperda were fed the leaves of these two corn types over nine consecutive generations, thereby establishing distinct S. frugiperda strains associated with each corn variety. Additionally, a strain fed an artificial diet served as the control group. Through a comparative analysis of the emergence, movement, nutritional foraging, dormancy, mating, and oviposition behaviors of adult fall armyworms from different populations, differences in the six behavioral peak times among the strains were identified. RT-qPCR analysis indicated significant differences in the expression levels of four circadian clock genes across different populations and tissues of the fall armyworm. Feeding on different host plants influenced the expression of circadian clock genes and their associated behavioral rhythms. Our study showed that sweet corn is more conducive to pupation, mating, and oviposition. Because of these differences in adult insect rhythms, sweet corn may have an impact on the reproduction of fall armyworms in the Huang–Huai–Hai corn-planting region. Full article

Blueberry is a high-value fruit crop in the United States, with Georgia and Florida serving as important early-season production regions. In these areas, several thrips species (Thysanoptera: Thripidae), including Frankliniella tritici (Fitch), Frankliniella bispinosa (Morgan), and Scirtothrips dorsalis (Hood), have emerged as economically significant pests. While F. tritici and F. bispinosa primarily damage floral tissues, S. dorsalis targets young foliage. Their rapid reproduction, high mobility, and broad host range contribute to rapid population buildup and complicate the management programs. Species identification is often difficult due to overlapping morphological features and requires the use of molecular diagnostic tools for accurate identification. Although action thresholds, such as 2–6 F. tritici per flower cluster, are used to guide management decisions, robust economic thresholds based on yield loss remain undeveloped. Integrated pest management (IPM) practices include regular monitoring, cultural control (e.g., pruning, reflective mulch), biological control using Orius insidiosus (Say) and predatory mites, and chemical control. Reduced-risk insecticides like spinetoram and spinosad offer effective suppression while minimizing harm to pollinators and beneficial insects. However, the brief flowering period limits the establishment of biological control agents. Developing species-specific economic thresholds and phenology-based IPM strategies is critical for effective and sustainable thrips management in blueberry cropping systems. Full article

Trichoderma spp., Metarhizium spp., and Bacillus spp. are commonly used as biocontrol microorganisms domestically and internationally. However, microbial pesticides currently prepared from single living microorganisms have problems such as a short shelf life, particularly under stressful environment conditions. Secondary metabolites produced from biocontrol microorganisms are comparatively stable when used under field conditions. This study screened the optimal combination of biocontrol metabolites, referred to as TMB, composed of culture filtrates from certain isolates of Trichoderma asperellum 10264, Bacillus subtilis S4-4-10, and Metarhizium anisopliae 3.11962 (1:4:1 (v/v)). RNA-seq analysis and transmission electron microscope observations were carried out to identify the major functions of the most effective culture filtrates against Magnaporthe oryzae (the pathogen causing rice blast disease) and Chilo suppressalis (an insect pest in rice cultivation). TMB was found to disrupt the midgut subcellular structure of C. suppressalis larvae and inhibit the expression of genes related to immunity, membrane components, protein synthesis, and other functions in C. suppressalis larvae and M. oryzae, thereby interfering with their normal growth, reproduction, and infection potential in rice. In addition, TMB was also able to promote rice growth and trigger host defense responses against infections by the target pests and pathogens. In summary, TMB generated different inhibitory activities against multiple targets in C. suppressalis and M. oryzae and induced plant immunity in rice. Therefore, it can be used as a new environmentally friendly agent or alternative to control rice pests and diseases. Full article

MicroRNAs (miRNAs) are key post-transcriptional regulators involved in a wide range of biological processes in insects, yet little is known about their roles in stingless bees. Here, we present the first characterization of miRNAs in Melipona quadrifasciata using small RNAs (sRNAs) deep sequencing. A total of 193 high-confidence mature miRNAs were identified, including 106 M. quadrifasciata-exclusive sequences. Expression profiling revealed that mqu-miR-1 and mqu-miR-276 together accounted for over 70% of all miRNA reads, suggesting their central roles in development and reproduction. Comparative analyses showed a higher conservation of M. quadrifasciata miRNAs with other Hymenopterans, especially Apis mellifera and Bombus spp. Putative target genes were predicted using a consensus approach, and functional annotation indicated their involvement in diverse biological regulatory pathways. This work represents the first comprehensive identification of the miRNA repertoire in stingless bees using sRNAs and provides a valuable foundation for understanding miRNA-mediated gene regulation in this ecologically and economically important pollinator. Full article

Chlorfenapyr is a widely used insecticide known to harm non-target insects, but its effects on reproductive development in the silkworm (Bombyx mori L.) remain incompletely understood. In this study, we investigated the histopathological and transcriptional changes in the gonads (ovaries and testes) of newly molted fifth-instar silkworm larvae exposed to chlorfenapyr. Histopathological analysis revealed delayed gonadal development, a reduction in oogonia and oocytes in the ovaries, and decreased numbers of spermatocytes in the testes. Transcriptome analysis identified significant differentially expressed genes (DEGs), mainly enriched in pathways such as “Drug metabolism—cytochrome P450”, “Insect hormone biosynthesis”, and “Ribosome”. Key up-regulated genes included members of the cytochrome P450 family (CYP6B5, CYP9f2, CYP6B6), glutathione S-transferases (GSTT1, GST1), and juvenile hormone-related enzymes (JHAMT, JHEH), indicating active detoxification and hormonal regulation responses. Several transcription factor families, particularly C2H2, HB-other, and TRAF, exhibited altered expression, suggesting roles in stress adaptation. Protein–protein interaction (PPI) network analysis identified hub genes such as EcR, Kr-h1, and various ribosomal proteins, highlighting their potential involvement in reproductive development. Quantitative PCR (qPCR) validated the transcriptomic data, confirming the reliability of the results. Overall, these findings enhance our understanding of chlorfenapyr’s impact on silkworm reproductive development and the underlying molecular mechanisms, providing valuable insights for sustainable pest management and ecological risk assessment of insecticides. Full article