The NPF receptor regulates larval foraging behavior and female adult oviposition-site choice in Spodoptera frugiperda

The olfactory system of insects is responsible for detecting volatile environmental chemicals and integrating this information in the brain to regulate various behaviors, including foraging and oviposition-site choice. The neuropeptidereceptor system plays a crucial role in mediating these olfactory behaviors. In this project, we investigated the involvement of the neuropeptide F (NPF) and its receptor (NPFR) in regulating larval foraging behavior and female adult oviposition site choice behavior in Spodoptera frugiperda, a globally invasive pest. First, the quantitative real-time PCR and immunohistochemistry results showed that NPF and NPFR were expressed in the antennae and antennal lobe in the brain, the tissues primarily involved in olfactory regulation. Second, we created a homozygous knockout mutant for the NPFR in S. frugiperda, and these NPFR mutant (NPFR-/-) insects needed more time to forage for their food and they also had a reduction in oviposition preference for maize, one of the most preferred plants for egg-laying for S. frugiperda. Further, in two-arm olfactometer behavioral assays and electroantennogram recording tests, the NPFR-/- insects showed a lower behavioral and electrophysiological response to the volatile compounds found in maize. The foraging ability and selection of oviposition sites are among the primary factors, contributing to the devastating impact of major invasive pests on global agricultural crops. The findings of our study enhance our understanding of the functional mechanisms underlying olfaction in non-model insects. In the future, when olfaction can be disturbed, they can potentially help to the prevention and control of important pest insects as S. frugiperda.