Piñero et al.: Residual Attractiveness of Spinosad Fruit Fly Bait 1077 RESIDUAL ATTRACTIVENESS OF A SPINOSAD-CONTAINING PROTEIN- BASED BAIT AGED UNDER VARIABLE CONDITIONS TO BACTROCERA DORSALIS AND B. CUCURBITAE (DIPTERA: TEPHRITIDAE) WILD FEMALES IN HAWAII

Key to the effectiveness of fruit fly (Diptera: Tephritidae) suppression efforts using insecticidal bait sprays is the determination of how long the bait remains attractive to adult flies after application. Using a comparative approach, field studies were conducted in commercial papaya (Carica papaya L.; Brassicales: Caricaceae) orchards in Hawaii with the goal of quantifying the response of Bactrocera dorsalis (Hendel) and Bactrocera cucurbitae (Coquillett) wild females to yellow bait stations treated with 2 dilutions (40% and 20%) of GF-120 NF Naturalyte Fruit Fly Bait that had been aged either outdoors (for 3 and 7 days) or indoors (for 1, 2, 3, and 7 days). Important variations in the level of female response to the baits were documented between these 2 fruit fly species, and the response levels were modulated by bait dilution, duration of aging and aging conditions. For B. dorsalis wild females, the attractiveness of 40% GF-120 and aged outdoors for either, 3 or 7 days did not differ significantly from the fresh bait, whereas for B. cucurbitae wild females a significant reduction (48 %) in bait attractiveness was recorded within 1 day of aging indoors independent of percent dilution of the bait. Environmental conditions, in particular mean temperature and relative humidity, prevailing during bait aging outdoors differed significantly from those recorded indoors, and these differences appeared to have influenced the attractiveness of GF-120. The types of variations in the level of responses to the aged baits documented in this study between fruit fly species within a genus, and potentially across genera need to be considered when developing suppression programs for fruit flies that involve the use of bait sprays.