A refined palate: Manual annotation of gustatory receptors in the genome of Culex quinquefasciatus, the southern house mosquito

Culex quinquefasciatus, the Southern house mosquito, opportunistically feeds upon the blood of avian and mammalian hosts. When females bite, they may transmit pathogens to their hosts, causing diseases such as West Nile Virus, St. Louis encephalitis, and lymphatic filariasis. Host acceptance is mediated by interactions between vertebrate chemical stimuli and mosquito chemoreceptors. These chemoreceptors include gustatory receptors (GRs), transmembrane proteins that facilitate the sensation of taste in insects. In 2020, a chromosome-level reference genome of Cx. quinquefasciatus was assembled (Accession: PRJNA644878), requiring updated gene annotation. I performed manual gene annotation of the gustatory receptors in this assembly, and created a phylogeny of GRs from Cx. quinquefasciatus, Aedes aegpyti, Anopheles gambiae, and outgroup Drosophila melanogaster. Seventy-one total annotations were made, of which 65 were functional genes and 6 were pseudogenes. At least 26 GRs could be assigned to putative functional subfamilies. Other chemosensory gene families have expanded dramatically in Cx. quinquefasciatus relative to Ae. aegypti, perhaps related to their wider blood host range; the GRs showed no evidence of expansion, however. GRs are crucial not only for biting behavior, but also play a role in oviposition, plant feeding, mating, and repulsion to insect repellents. These annotations enable future analyses of gustatory receptor expression and function in Culex mosquitoes and their respective roles in aforementioned Culex behaviors and management.