Behavioral evidence for the exploitation of a novel host plant on the basis of vision in the melon fly, Bactrocera cucurbitae (Diptera: Tephritidae)

Attraction of tephritid flies to suitable host plants is known to be mediated largely by olfactory and visual cues. For nearly a century, the melon fly, Bactrocera cucurbitae (Diptera: Tephritidae), has been exploiting a novel host plant in the Hawaiian Islands, a geographical location where both the insect herbivore (native to Asia) and the plant (native to the Americas) met due to human introductions. The melon fly can locate its host plants, most of which belong to the family Cucurbitaceae (with occasional infestations occurring on tomato and eggplant (Solanaceae), green beans (Fabaceae) and other plant families) largely on the basis of olfaction. Numerous behavioral studies conducted in the Big Island of Hawaii using field cages and in papaya orchards revealed that the papaya fruit is not a chemically attractive fruit to foraging female melon flies. Rather, we demonstrate, for the first time in tephritid flies, that the exploitation of this novel host plant is largely driven by visual cues.