Genome-Wide Identification of Neuropeptides and Their Receptors in an Aphid Endoparasitoid Wasp, Aphidius gifuensi

SIMPLE SUMMARY: Neuropeptides and their receptors play important roles in insect physiology and behavior. Due to their specificity and importance, they have been considered as the targets for new environmentally friendly insecticides. Hence, more information on genomics and transcriptomics of neuropeptide and their receptors in more insects, especially in beneficial insects, are needed to avoid the side effects of these environmentally friendly insecticides. Aphidius gifuensis is one of the most well-known aphid parasitoids and has been successfully used to control aphids such as Myzus persicae and Sitobion avenae. In this study, we systematically identified neuropeptides and their receptors from the genome and head transcriptome of A. gifuensis. Meanwhile, we also analyzed their expression patterns in response to imidacloprid exposure and in different tissues. Our results not only laid a preliminary foundation for functional studies on neuropeptide precursors and their receptors but also provided useful information for future pesticide development. ABSTRACT: In insects, neuropeptides and their receptors not only play a critical role in insect physiology and behavior but also are the potential targets for novel pesticide discoveries. Aphidius gifuensis is one of the most important and widespread aphid parasitoids, and has been successfully used to control aphid. In the present work, we systematically identified neuropeptides and their receptors from the genome and head transcriptome of A. gifuensis. A total of 35 neuropeptide precursors and 49 corresponding receptors were identified. The phylogenetic analyses demonstrated that 35 of these receptors belong to family-A, four belong to family-B, two belong to leucine-rich repeat-containing GPCRs, four belong to receptor guanylyl cyclases, and four belong to receptor tyrosine kinases. Oral ingestion of imidacloprid significantly up-regulated five neuropeptide precursors and four receptors whereas three neuropeptide precursors and eight receptors were significantly down-regulated, which indicated that these neuropeptides and their receptors are potential targets of some commercial insecticides. The RT-qPCR results showed that dopamine receptor 1, dopamine receptor 2, octopamine receptor, allatostatin-A receptor, neuropeptides capa receptor, SIFamide receptor, FMRFamide receptor, tyramine receptor and short neuropeptide F predominantly were expressed in the head whilst the expression of ion transport peptide showed widespread distribution in various tissues. The high expression levels of these genes suggest their important roles in the central nervous system. Taken together, our study provides fundamental information that may further our understanding of neuropeptidergic signaling systems in the regulation of the physiology and behavior of solitary wasps. Furthermore, this information could also aid in the design and discovery of specific and environment-friendly insecticides.