Glossina spp. (Diptera: Glossinidae) vector trypanosomes, the causal pathogens of trypanosomiasis in humans and animals. Glossina spp. chemosensory mechanism is relevant to understanding the behavioral responses of these insects to environmental cues. Odorant binding proteins (OBPs) are involved in either olfactory or nonolfactory cue sensation depending on their spatial and temporal expression. In most insects, the OBPs are ubiquitously expressed, although the levels are higher in the antennae. This study was aimed at determining the differential gene expression patterns of OBP genes in the developmental stages (larval, pupal, teneral) and differentially starved adults of Glossina brevipalpis (Newstead) collected from Shimba Hills National Park, Kenya. Five OBP genes, GbrOBP2, GbrOBP6, GbrOBP7, GbrOBP8, and GbrOBP13, were selected for quantitative PCR expression analysis as representatives of the three OBP classes in Glossina spp. (classic, minus-C, classic-dimers). Antennal samples from the newly emerged insects (tenerals) served as the controls. GbrOBP2 was highly expressed in both larval and pupal stages, whereas GbrOBP7 was expressed in the pupal stage. GbrOBP8, GbrOBP13, and GbrOBP6 showed high expression in adult antennas. Expression of OBPs in the immature stages suggested OBP involvement in nonolfactory chemical sensation, whereas that in adult antennae was attributed to olfaction.
odorant binding proteins