Unlike controls, Obp59a¹ adults placed in a space with two separate regions of high and low humidity fail to show the expected hygrotaxis behavior towards the higher humidity region; a similar behavior is observed if flies are desiccated prior to the experiment, although flies start showing a muted hygrotaxis behavior towards the end of the experiment time period. Desiccated Obp59a¹ adults also show a decrease in proboscis extension response to water vapor emanating from a moistened cotton swab, as compared to controls. Counterintuitively, these flies show increased resistance (i.e. survival) to desiccation, but no changes in lifespan under 70% humidity conditions, as compared to controls.

These flies do not show any obvious defects in the hygrosensitive neurons in the second chamber of the sacculus (i.e. IR93a-, IR25a- or IR68a-GAL4-positive neurons), nor significant changes in odor avoidance behavior or climbing ability, as compared to controls.