Planthopper perception: Identification and evolution of chemosensory proteins from fulgoroid transcriptome data (Hemiptera: Auchenorrhyncha)

Insects frequently use environmental odors as sources of important information such as the locations of host plants or mates. To accomplish this, they rely on a diverse suite of sense organs and chemosensory proteins. These proteins may be suitable as new targets for highly specific pesticides that reduce the risk of off-target effects, but the chemosensory protein repertoire of many pestiferous insects remains unexplored. The hemipteran superfamily Fulgoroidea (planthoppers) includes several important pest species such as the brown planthopper Nilaparvata lugens and the invasive spotted lanternfly Lycorma delicatula, but relatively little is known about chemosensory systems in this group. We used transcriptome data from 34 fulgoroid species and an iterative search strategy combining BLAST and HMMER to identify transcripts with predicted odorant binding, pheromone binding, or 7-transmembrane odorant receptor domains and to look for evidence of lineage-specific family expansions. Additionally, 2130 single copy orthologs from these species were used to conduct a species tree analysis of the fulgoroid families in order to identify events in the evolution of these gene families including duplications and losses. We have identified more than 1000 putative chemosensory proteins across all species and domains examined, with several fulgoroid-specific expansions within each protein family. The putative proteins identified in this study can serve as a foundation for additional comparative study of chemoreceptor evolution within Fulgoroidea that could facilitate development of highly targeted, evolutionarily informed pest management strategies.