Attraction ofRhagoletis indifferens(Diptera: Tephritidae) to White Light in the Presence and Absence of Ammonia

Abstract

Attraction of tephritid fruit flies to light and its role in fly biology and management have received little attention. Here, the objective was to show that western cherry fruit fly, Rhagoletis indifferens Curran (Diptera: Tephritidae), is attracted to white light in the presence and absence of ammonia, an olfactory cue used with traps. Laboratory tests were conducted inside a 0.23 m3 cage with a halogen or light-emitting diode (LED) bulb hung ~2 cm above a trap with or without an ammonium carbonate lure; flies were released in the cage opposite from the light. Fly captures on yellow or clear traps with white light from both bulb types were greater than on controls, and greater at higher than lower light intensities whether ammonia was present or not. Adding heat without additional light near traps did not increase captures, indicating light rather than heat from bulbs attracted flies. In the field, light from LED and halogen bulbs did not enhance fly captures on ammonia-baited yellow traps, but light from halogen bulbs did enhance captures when there was no ammonia, although captures were lower than when ammonia was added. Results show that bright white light is attractive to R. indifferens and suggest orientation towards it may induce behaviors that positively affect fly fitness, such as mating and foraging. However, stronger light-associated stimuli than those used here may be needed to enhance fly captures on ammonia-baited traps under field conditions.