Response of the fruit fly parasitoid Diachasmimorpha longicaudata (Hymenoptera: Braconidae) to host-fruit stimuli

Visual and olfactory stimuli used by adult, insectary-reared larval parasitoids, Diachasmimorpha longicaudata (Ashmead), of tephritid fruit flies were examined in the context of host microhabitat location. Mated female parasitoids used the odor of ripe, uninfested fruits to orient toward sticky traps simulating host-habitats (fruits) in field-cage studies. Females showed a significant preference for some fruits (e.g., orange, guava) over others (e.g., apple). All fruit odors tested except apple were significantly more attractive to females than odorless controls. Male parasitoids, in contrast, were not attracted to any of the fruit odors tested. Males, however, readily distinguished between traps of different colors, with preferences reflecting an interaction of the colors' hue and intensity. Females' discrimination among colors was related to the presence or absence of fruit odors.