Protein requirements of the adult Ethiopian fruit fly Dacus ciliatus

Abstract

In this study, the effects of yeast protein hydrolysate (YPH): sucrose proportions in the adult diet of the Ethiopian fruit fly Dacus ciliatus Loew on survival, pupal production, and endogenous lipid and protein contents were investigated. Small populations of the fly were fed diets containing various proportions of YPH and sucrose under low-humidity and high-humidity conditions. The YPH: sucrose proportions ranged from 20 to 50%. We monitored the patterns of survival, pupal production, and individual endogenous protein and lipid loads (only under high-humidity conditions) in flies maintained on various adult diets. The survival patterns of both males and females under high-humidity conditions were inversely proportional to the proportion of YPH in the diet. Mortality of some adult flies was related to the stickiness of the highly hygroscopic adult food mix. By contrast, the survival patterns of males and females maintained under low-humidity conditions were directly proportional to the proportion of YPH in the diet. Apparently, there was no effect of diet type on the number of pupae produced; on the sucrose-only diet, flies produced significantly fewer pupae. Protein content in the flies increased significantly as the proportion of protein in the diet increased, but lipid content was clearly not related to food constitution. Based on these results and recent evidence from studies in other fruit fly species, we concluded that a large amount of protein is deleterious to the fruit flies. Workers in rearing facilities should investigate and tailor different food-delivery systems, e.g. separate dishes for carbohydrates and the food mix, and reduce the amount of YPH used in industrial adult diets.