Yeast Extract: Sucrose Ratio Effects on Egg Load, Survival, and Mortality Caused by GF-120 in Western Cherry Fruit Fly (Diptera: Tephritidae)

Wee L. Yee

Abstract


It is unclear which ratios of yeast extract to sucrose result in maximum egg production and survival in many tephritid fruit flies. Objectives here were to determine yeast extract:sucrose ratios that maximize egg loads without compromising survival in western cherry fruit fly, Rhagoletis indifferens Curran, and their effects on mortality caused by spinosad bait (GF-120). Yeast extract:sucrose ratios of 20:80 and 30:70 maximized egg loads without reducing survival in most cases. In 1 experiment, mortality of flies with low to high egg loads exposed to fresh GF-120 for 1 or 2 h in the absence of food did not differ. In a separate experiment, egg loads were lowest in flies fed 0:100 and 1:99 diets and highest in flies fed 20:80, 30:70, and 50:50 diets. When these flies were exposed to dried GF-120 for 6 h in presence of yeast extract and sucrose, percent mortality was lower in flies fed 20:80 and 30:70 (40%) than 0:100 (69%) and 1:99 (63%) diets. In another experiment, egg loads were lowest in flies fed 0:100 and 1:99 diet and highest in flies fed 20:80 diet. When these flies were exposed to dried GF-120 for 6 h in the presence of sucrose only, percent mortality was lower in flies fed 20:80 (39%) than 0:100 (72%) and 1:99 (62%) diets. High yeast extract:sucrose ratios result in high egg loads in R. indifferens and may reduce the fly's feeding responses to GF-120, although not to the extent that the bait is rendered completely ineffective.

View this article in BioOne

Full Text:

PDF