Responses of fruit flies (Diptera: Tephritidae) to protein bait: Effects of tree canopy, species, physiological state and weather

The application of protein baits forms the core of fruit fly (Diptera: Tephritidae) control measures in many orchard environments. Protein baits target adult fruit flies, which need protein for reproductive maturation. A proper understanding of the factors influencing fruit fly responses to protein is required to optimise control outcomes. In this study, responses to protein bait by three fruit fly species, Ceratitis capitata (Wiedemann), C. cosyra (Walker), and Bactrocera dorsalis (Hendel), were investigated. This was done in two field cages erected over lemon trees within an orchard. The response of each species to protein bait presented as a station and positioned at different heights within the tree canopy was evaluated. For each species, effects of fly age, sex, and nutritional status were evaluated under conditions of varying temperature and relative humidity. The highest response occurred when protein baits were placed in the middle to upper tree canopy. Species, nutritional status, sex and age also affected protein foraging. Ceratitis capitata responded more to bait compared to B. dorsalis and C. cosyra. The lowest response to protein bait was by one-day-old protein fed flies, while 10-day-old protein-deprived flies were most responsive. Protein deprived females were more attracted to protein than males fed the same diet. Flies responded to bait when temperatures were between 20 and 30°C. Based on the results, the success of protein baits in controlling fruit flies in a tree canopy is height dependent and can be lower in areas with alternative protein sources.