Foraging patterns for protein baits by South African fruit fly pests (Diptera: Tephritidae)

Abstract

In sub-Saharan Africa, three fruit fly pests, Bactrocera dorsalis (Hendel), Ceratitis capitata (Wiedemann) and Ceratitis cosyra (Walker), are among those of economic significance for a number of commercially grown fruit and vegetable crops. Their presence leads to high yield losses and restricted access to export markets, and limits the economic and social value derived from these commodities. Protein baits are extensively used for monitoring and control of these and other fruit fly species. Control of fruit flies using protein baits or bait application technique (BAT- an attract and kill tactic) requires a sound understanding of their foraging patterns for protein so that application of baits leads to maximum response. The main aim of this project was to improve fruit fly control using tactics that incorporate protein baits. The spatial and temporal foraging patterns of Bactrocera dorsalis, Ceratitis capitata and Ceratitis cosyra for protein baits within a citrus tree with regard to fly age, sex and nutritional status were established in field cages. This was followed by the a study that determined the response of the three pest species to protein baits applied at two different densities. Results showed that bait location in the canopy affects response by B. dorsalis, C. capitata, and C. cosyra with more flies foraging for protein in the middle to upper canopy heights of the tree compared to protein bait positioned on the lower canopy and directly on the ground. The first study also revealed that nutritional status, age and sex influenced protein bait response, with 1 day-old flies with prior access to protein showing a lower response to protein bait, while 10-day-old protein-deprived flies intensely foraged for protein regardless of sex or species. Females responded more to protein baits than males, and foraging for protein peaked in the warmest part of the day when temperatures were between 20-30℃ at a relative humidity ranging between 40-80%. Furthermore, the second study showed that species, diet history and bait density had a significant effect on the response to protein bait. Ceratitis capitata females were more attracted to the bait followed by B. dorsalis, and C. cosyra with the lowest response. Similar to results obtained in the first study, protein deprived females were most responsive to the bait regardless of species and bait density. Additionally, females were more attracted to 10 droplets of 200 µL protein bait applied in 10 traps than a single 2000 µL droplet applied in one trap regardless of diet and species. Based on the results, protein baits should be applied between the mid and upper canopy heights and should be evenly distributed on the tree canopy for increased effectiveness of