Attraction of Rhagoletis indifferens (Diptera: Tephitidae) to white light in the presence and absence of ammonia

Authors: Yee, Wee

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/17/2016
Publication Date: 3/1/2017
Citation: Yee, W.L. 2017. Attraction of Rhagoletis indifferens (Diptera: Tephitidae) to white light in the presence and absence of ammonia. Florida Entomologist. 100(1):21-28.

Interpretive Summary: Western cherry fruit fly is a quarantine pest of sweet cherry in the Pacific Northwest of the U.S. that can be detected using sticky yellow traps. Identifying factors that can increase the efficacy of traps baited with ammonia can be useful for improving fly management. Personnel at the USDA-ARS Yakima Agricultural Research Laboratory in Wapato, WA determined if flies are attracted to white light from bulbs and whether light can be used to enhance fly captures in the field. In the laboratory, it was found that flies were attracted to bright white light in the presence and absence of ammonia odor. In the field, flies were not attracted to white light when ammonia odor was present, but they were when it was absent. Results are important in that they show responses to white light could partly explain fly behaviors and efficacies of traps.

Technical Abstract: Attraction of tephritid fruit flies to light and its role in fly biology and management has 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 using 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.