After being acclimatized to feeding on fruit flies, the Asian house gecko, Hemidactylus frenatus Duméril & Bibron (Gekkonidae:Squamata), consumed fewer methyl eugenol (ME) fed male fruit flies, Bactrocera papayae Drew & Hancock (Tephritidae: Diptera) than when offered ME-deprived males. After one-day exposure to only ME-fed males, the geckos avoided feeding on female flies when in the presence of ME-fed males. When mechanically disturbed, the ME-fed males spontaneously ejaculated a rectal secretion which contains phenyl propanoids that deter the predator.
The ME-fed males also competed significantly better than normal (ME-deprived) males for virgin females. Male B. papayae converts ME to three other phenyl propanoids which act in concert as a sex pheromone to attract females during courtship and as an allomone to the gecko.