Fluctuations in the Protein and Carbohydrate Content of the Crop Correlated to Periodicities in Ovarian Development of the Female Face Fly (Diptera: Muscidae)

Abstract

A significant cyclic fluctuation occurred between physiological age and total protein in crop contents of face flies, Musca autumnalis De Geer, fed separately and ad lib. egg protein, sugar, and water, and of flies intermittently exposed to the bovine host as the only available source of protein. Females in early and middle physiological ages, plus age 1 (age before vitellogenesis), had significantly more protein per crop on the average than flies at mature egg ages. This cyclic fluctuation was not observed when total crop sucrose was assayed instead of protein in flies exposed to a 0.5 M sucrose solution. Periodicity of crop filling and emptying, investigated with radiographic analysis and by tracing dyes through the digestive tract, indicated that crop protein and sucrose contents adequately reflected protein and sucrose appetite. Females that recently fed on protein or sucrose had significantly more protein or sucrose in their crops than females that had not fed. The observed fluctuations are believed to be a behavioral expression of the shifting physiological demands for protein within each gonotrophic cycle. Results indicate that female flies at early and middle physiological ages (plus age 1) have recently fed on protein to fulfill metabolic demands for vitellogenesis, and in females at mature egg ages, protein hunger has diminished or stopped. Flies appear to seek sugar for basic metabolic survival, regardless of the progress of ovarian development