摘要: Insects produce silk to form cocoons, nests, and webs, which are important for their survival and reproduction. However, little is known about the molecular mechanism of silk protein synthesis at the translation level. The solute carrier family 7 (SLC7) genes are involved in activating the target of rapamycin complex 1 (TORC1) signaling pathway and protein translation process, but the physiological roles of SLC7 genes in silk-producing insects have not been reported. Here, we found that amino acid signaling regulates silk protein synthesis and larval development via the L-type amino acid transporter 1 (LAT1; also known as SLC7A5) in Bombyx mori. A total of 12 SLC7 homologs were identified in the silkworm genome, among which BmSLC7A5 was found to be a silk gland-enriched gene and may be involved in leucine transport. Bioinformatics analysis indicated that SLC7A5 displays high homology and a close phylogenetic relationship in silk-producing insects. Subsequently, we found that leucine treatment significantly increased silk protein synthesis by improving the transcription and protein levels of silk genes. Furthermore, systemic and silk gland-specific knockout of BmSLC7A5 led to decreased silk protein synthesis by inhibiting TORC1 signaling, and somatic mutation also resulted in arrested development from the 5th instar to the early pupal stage. Altogether, our study reveals that BmSLC7A5 is involved in regulating silk protein synthesis and larval development by affecting the TORC1 signaling pathway, which provides a new strategy and target for improving silk yield.

摘要: Understanding the genetic basis of adaptive evolution following habitat expansion can have important implications for pest management. The pink rice borer (PRB), Sesamia inferens (Walker), is a destructive pest of rice that was historically restricted to regions south of 34(degrees) N latitude in China. However, with changes in global climate and farming practices, the distribution of this moth has progressively expanded, encompassing most regions in North China. Here, 3 highly differentiated subpopulations were discovered using high-quality single-nucleotide polymorphism and structural variant datasets across China, corresponding to northern, southern China regions, and the Yunnan-Guizhou Plateau, with significant patterns of isolation by geographic and environmental distances. Our estimates of evolutionary history indicate asymmetric migration with varying population sizes across the 3 subpopulations. Selective sweep analyses estimated strong selection at insect cuticle glycine-rich cuticular protein genes which are associated with enhanced desiccation adaptability in the northern group, and at the histone-lysine-N-methyltransferase gene associated with range expansion and local adaptation in the Shandong population. Our findings have significant implications for the development of effective strategies to control this pest.

摘要: Sex pheromones are considered to play critical roles in partner communication of most parasitic Hymenoptera. However, the identification of sex pheromone components remains limited to a few families of parasitoid wasps. In this study, we functionally characterized a candidate sex pheromone component in Microplitis mediator (Hymenoptera: Braconidae), a solitary parasitoid of Noctuidae insects. We found that the body surface extract from female wasps could significantly stimulate courtship behavior of males. Gas chromatography-electroantennographic detection (GC-EAD) analysis revealed that a candidate semiochemical from extract triggered significant electrophysiological response of antennae of males. By performing gas chromatography-mass spectrometer (GC-MS) measurement, GC-EAD active compound was identified as n-octyl acrylate, a candidate sex pheromone component in female M. mediator. In electroantennogram (EAG) tests, antennae of male wasps showed significantly higher electrophysiological responses to n-octyl acrylate than those of females. Y-tube olfactometer assays indicated that male wasps significantly chose n-octyl acrylate compared with the control. Furthermore, male wasps showed a remarkable preference for n-octyl acrylate in a simulated field condition behavioral trial; simultaneously, n-octyl acrylate standard could also trigger significant courtship behavior in males. We propose that n-octyl acrylate, as a candidate vital sex pheromone component, could be utilized to design behavioral regulators of M. mediator to implement the protection and utilization of natural enemies.

摘要: Juvenile hormone (JH) acts in the regulation of caste differentiation between queens and workers (i.e., with or without reproductive capacity) during vitellin synthesis and oogenesis in social insects. However, the regulatory mechanisms have not yet been elucidated. Here, we identified a highly expressed microRNA (miRNA), miR-1175-3p, in the red imported fire ant, Solenopsis invicta. We found that miR-1175-3p is prominently present in the fat bodies and ovaries of workers. Furthermore, miR-1175-3p interacts with its target gene, broad-complex core (Br-C), in the fat bodies. By utilizing miR-1175-3p agomir, we successfully suppressed the expression of the Br-C protein in queens, resulting in reduced vitellogenin expression, fewer eggs, and poorly developed ovaries. Conversely, decreasing miR-1175-3p levels led to the increased expression of Br-C and vitellogenin in workers, triggering the re-development of the ovaries. Moreover, when queens were fed with JH, the expression of miR-1175-3p decreased, whereas the expression of vitellogenin-2 and vitellogenin-3 increased. Notably, the suppression of fertility in queens caused by treatment with agomir miR-1175-3p was completely rescued by the increased vitellogenin expression induced by being fed with JH. These results suggest the critical role of miR-1175-3p in JH-regulated reproduction, shedding light on the molecular mechanism underlying miRNA-mediated fecundity in social insects and providing a novel strategy for managing S. invicta.

摘要: Insulin receptors (InR) are an integral component of the insulin/insulin-like growth factor signaling pathway, which plays a vital role in insect development, lifespan, reproduction, and olfactory sensitivity. However, whether InR participate in the peripheral olfactory system of insects remains unclear. Recently, we found that 2-heptanone (2-HT) affects AcerInR expression, the gene for an InR protein, in Apis cerana cerana. We then examined the spatiotemporal expression profile of the gene in A. cerana cerana. The mRNA of AcerInR was primarily expressed in the antennae, wings, and legs of forager bees, which are probable chemosensory tissues. The results of fluorescence competitive binding assays, combined with site-directed mutagenesis, demonstrated that AcerOBP6 and AcerOBP14 exhibit strong binding affinities to 2-HT. Furthermore, after foragers were fed with double-stranded AcerInR, the expression levels of AcerOBP6 and AcerOBP14 decreased significantly, as did the electroantennogram responsiveness to 2-HT and some other odorants. In conclusion, our findings provide a foundation for understanding the involvement of AcerInR in the odor perception of A. cerana cerana. Moreover, they offer novel insights into the olfactory recognition mechanism in insects.