Fig. 5: Summary illustrating the divergent effects of a gustatory polymorphism on survival and sexual behavior.

Maltose and maltotriose contained in the male’s nuptial secretion (upper left) stimulate the female’s mouthparts (lower left) and lure the female to mount the courting male. Initially, both WT and GA females accept the secretion and commence nuptial feeding because oligosaccharides stimulate sugar-sensitive GRNs. However, during nuptial feeding saliva is secreted, salivary alpha-glucosidases hydrolyze the oligosaccharides, and free glucose is released. Glucose stimulates deterrent-sensitive GRNs of GA females, resulting in interrupted nuptial feeding. In contrast, glucose is highly appetitive to WT females, and they continue to feed on the nuptial secretion; longer nuptial feeding enables the male to grasp the female’s genitalia and copulate. Thus, the GA trait is highly adaptive for cockroach survival in the presence of glucose-containing toxic baits, but it interferes with sexual signaling by the male and results in lower mating success of GA females, especially with WT males.