Combined Effects of Heat Stress and Food Supply on Flight Performance of Olive Fruit Fly (Diptera: Tephritidae)

The olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae), is a newly invasive pest of olives, Olea europaea L., in California. The table olive industry is located in California's Central Valley, where daily high summer temperatures can be >35.0 degrees C. This study investigated the effects of high temperatures (heat stress) and food conditions on the flight performance of B. oleae in laboratory flight mill tests. Flies were provided food (honey and hydrolyzed yeast) and water for a 1-wk preconditioning period and then subjected to 24-h preflight exposure to diurnal temperature regimes (low-high temperatures of 18.3-35.0 degrees C and 18-37.8 degrees C) and deprivation of food. Flies with the preflight stress conditions had significantly lower flight performance (1,305 in and 0.989 h at 18.3-35.0 degrees C and 1,152 in and 0.966 h at 18.3-37.8 degrees C) than control files that were held under no-stress preflight conditions (constant 23.9 degrees C, food, and water) and flew 1,982 in for 1.54 h. Flight distance and duration were further reduced when no water was provided during the 24-h preflight exposure to high temperature stress. Flight distance and duration also were decreased when the preflight exposure period was increased to 2 and 3 d. When flies were deprived of food and water during the preconditioning period, there was significant adult mortality and flight performance was poor (<50 in and <2 min) after 24-11 preflight exposure to either the 18.3-35.0 degrees C or the 18.3-37.8 degrees C temperature regime and deprivation of food. Heat stress and food deprivation also reduced postflight fecundity and adult longevity. The results are discussed with respect to the ability of B. oleae to survive summer heat and food deprivation by dispersing to refuges with food, water, and shelter.