Submitted to: Phytoparasitica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/12/2017
Publication Date: 11/22/2017
Citation: Yee, W.L. 2017. Temperature and food availability effects on spinosad and malathion against Rhagoletis indifferens (Diptera: Tephritidae) in the laboratory. Phytoparasitica. 45(5):673-682. https://doi.org/10.1007/s12600-017-0627-5.
Interpretive Summary: Western cherry fruit fly is a quarantine pest of sweet cherry in the Pacific Northwest of the U.S. that is managed using insecticides. Identifying factors that affect the efficacy of insecticides can improve fly management. Personnel at the USDA-ARS Yakima Agricultural Research Laboratory in Wapato, WA determined if temperature and food availability can affect efficacies of the insecticides spinosad and malathion against flies in the laboratory. In spinosad tests, fewer eggs were laid in cherries at 19 or 21 °C than 27 °C, especially when there was no food. For malathion, numbers of eggs laid were not significantly affected by temperature but they were by food, with lowest levels in its absence. Results suggest temperature and food availability could be factors affecting cherry fruit fly control, but whether temperature is a factor depends on the insecticide used.
Technical Abstract: Western cherry fruit fly, Rhagoletis indifferens Curran (Diptera: Tephritidae), is a quarantine pest of cherries (Prunus spp.) in western North America that is managed using insecticides. Different insecticides could vary in efficacy and ability to control flies depending on environmental factors. Here, the objective was to determine if temperature and food availability can affect efficacies of spinosad and malathion against R. indifferens in the laboratory. Fourteen to 18 day old flies were exposed to cherries that had been dipped in label rates of spinosad and malathion and then dried. Flies were then held at 19 or 21 vs. 27 ºC with or without yeast extract + sucrose food (‘food’) and deaths and oviposition recorded over 4 days. In spinosad tests, fly kill was greater at 27 °C than at lower temperatures when there was no food, but in the malathion tests, kill was greatest when there was no food irrespective of temperature. For spinosad, lower oviposition occurred at 19 or 21 °C than 27 °C, especially when there was no food. For malathion, oviposition was not significantly affected by temperature but it was by food, with lowest levels in its absence. Significantly greater oviposition occurred at 27 °C than the lower temperatures when food was present in 2 of 3 spinosad tests but not in any of 3 malathion tests. Results imply temperature and food availability could be factors affecting R. indifferens control, but whether temperature is a factor depends on the insecticide used.