Mass Spectrometry–Driven Discovery of Neuropeptides Mediating Nictation Behavior of Nematodes

Neuropeptides regulate animal physiology and behavior, making them widely studied targets of functional genetics research. While the field often relies on differential -omics approaches to build hypotheses, no such method exists for neuropeptidomics. It would nonetheless be valuable for studying behaviors suspected to be regulated by neuropeptides, especially when little information is otherwise available. This includes nictation, a phoretic strategy of Caenorhabditis elegans dauers that parallels host-finding strategies of infective juveniles of many pathogenic nematodes. We here developed a targeted peptidomics method for the model organism C. elegans and show that 161 quantified neuropeptides are more abundant in its dauer stage compared with L3 juveniles. Many of these have orthologs in the commercially relevant pathogenic nematode Steinernema carpocapsae, in whose infective juveniles, we identified 126 neuropeptides in total. Through further behavioral genetics experiments, we identify flp-7 and flp-11 as novel regulators of nictation. Our work advances knowledge on the genetics of nictation behavior and adds comparative neuropeptidomics as a tool to functional genetics workflows. [Display omitted] •Using mass spectrometry for the study of neuropeptides in nictation behavior.•Novel discovery of neuropeptide genes brings the total to 97 in Steinernema carpocapsae.•Application of parallel reaction monitoring for neuropeptide quantification.•Neuropeptide genes flp-7 and flp-11 are identified as regulators of nictation. Neuropeptides are a type of signaling molecules that regulate certain behaviors. One such behavior is nictation, a strategy used by pathogenic nematodes for host finding. These pathogenic nematodes are often commercially significant, as they can be utilized as biopesticides in agriculture. Here, we have developed a method using mass spectrometry to identify and quantify neuropeptides responsible for nictation behavior. As a result, we were able to demonstrate that neuropeptide genes flp-7 and flp-11 are novel regulators of nictation.