Responses of Fruit Flies (Diptera: Tephritidae) to Protein Bait Applied at Different Densities

Abstract

The effectiveness of odour-based lures for insects is related to their active space, the air volume around an odour source in which an insect will detect and move towards it. This principle applies to protein baits laced with toxicants that are used as either sprays or stations to suppress pest fruit fly populations. Whilst protein bait spray droplets represent multiple odour sources distributed across a tree, a protein bait station being a device containing the bait and hung on a tree acts as a single odour source within the same arena. This study investigated responses by the females of three fruit fly pests [Bactrocera dorsalis (Hendel), Ceratitis capitata (Wiedemann) and Ceratitis cosyra (Walker) (Diptera: Tephritidae)] to protein bait applied at two densities. Unmated female flies were fed on a diet that was either protein-deficient (sugar only) or protein-rich (sugar and hydrolysed yeast) in the laboratory for 10 days. Fly responses to either 10 droplets of 200 μL each or a single droplet of 2000 μL of a protein hydrolysate solution were quantified in field cages placed in a lemon orchard. Bait density significantly affected protein response by B. dorsalis, C. capitata and C. cosyra, with the majority responding more to higher protein bait density. Additionally, dietary history significantly influenced responses across all species, with flies fed a protein-deficient diet responding more than those fed protein. These results demonstrate that protein bait may be more effective for fruit fly control when distributed as multiple points on a tree compared to a single point, and that protein food sources in an environment would reduce the efficacy of control using protein bait.