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Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 4/14/2003 Publication Date: 8/1/2003 Citation: Yee, W.L. 2003. Effects of cherries, honeydew, and bird feces on longevity and fecundity of Rhagoletis indifferens (Diptera:Tephritidae). Environmental Entomology. 32(4):726-735. Interpretive Summary: Western cherry fruit flies are the most serious pest of commercial cherries in the Pacific Northwest. A thorough knowledge of fly feeding biology is valuable in the development of management strategies designed to reduce insecticide use. Personnel at the Yakima Agricultural Research Laboratory in Wapato, WA, initiated studies in 2001 on the effects of cherries, honeydew, and bird feces, reported foods of other fruit flies, on the longevity and egg production of western cherry fruit flies. Flies were unable to survive on unripe cherries, but they were able to feed, survive, and produce eggs on a diet of ripe cherries alone, although flies fed an artificial diet of yeast and sugar had greater longevity and egg production. Honeydew increased longevity but did not contribute to egg production. Bird feces also did not contribute to egg production. The results indicate ripe cherries can be a valuable food source for flies, but other natural foods, yet to be identified, may contribute even more to longevity and egg production. When these foods are identified, they or their ingredients can potentially be incorporated into baits with traps or with sprays to manage cherry fruit flies. Technical Abstract: Females of the western cherry fruit fly, Rhagoletis indifferens Curran, are know to feed on the juice of the sweet cherry. The main objectives of this study were to determine the stage at which sweet cherries are a suitable food source for R. indifferens and how cherries compare with sucrose-yeast diets in contributing to fly longevity and fecundity. In addition, the effects of aphid honeydew and bird feces on fly longevity and fecundity were determined. Females and males did not survive on intact green to red cherries, but females survived on intact, fully ripe cherries, while both females and males survived on opened unripe and ripe cherries. Females that were exposed continuously to intact fully ripe cherries alone survived 33 d and laid 87 eggs. Females survived 20 d and laid 80 eggs when exposed to intact cherries that had been surface sterilized with bleach to reduce chances of microbial growth on fruit surfaces. Females that were exposed to dry and wet sucrose-yeast diets throughout their lives survived 48-53 d and laid 278-293 eggs, and females that had access to these sucrose-yeast diets for the first two weeks of life only and cherries alone thereafter survived 32-35 d and laid 132-155 eggs. Neither honeydew nor bird feces increased fecundity, although in one experiment, flies exposed to dried aphid honeydew with aphid exoskeletons dead aphids alone on leaves survived 36 d and laid 32 eggs, whereas those exposed to sucrose alone survived 30 d and laid only 1 egg. Despite the inability of R. indifferens to survive on unripe fruit and the moderate fecundity of flies that were exposed to intact ripe cherries alone, this is the first time any Rhagoletis has been shown capable of using its principal host fruit for both sustained survival and egg production. Results suggest cherries damaged by birds throughout the season and intact fully ripe cherries later in the season can contribute about the same as honeydew to female longevity, but that cherries contribute significantly more than either honeydew or bird feces to fly fecundity in nature. |
