Effects of Mediterranean Fruit Fly Malathion Bait Spray on the Longevity and Oviposition of Parasitoids of Linden and Tuliptree Aphids (Homoptera: Aphididae)

Abstract

The longevity of two primary aphid parasitoids, Aphidius liriodendrii Liu and Trioxys curvicaudus (MacKauer), was severely reduced when they were exposed in the laboratory to a malathion bait spray used to eradicate the Mediterranean fruit fly, Ceratitis capitata (Wiedemann). The longevity of several hyperparasites of A. liriodendrii and T. curvicaudus also was reduced. Oviposition of A. liriodendrii was severely reduced on plants that received field applications of malathion bait spray. The parasitoids appeared neither attracted to nor repelled by the malathion bait. Pesticide contact occurred during apparently random searching by the parasitoids. As T. curvicaudus is reportedly responsible for the biological control of its aphid host, Eucallipterus tiliae (L.), malathion bait sprays used for Mediterranean fruit fly control may cause an increase in aphid populations by reducing the effectiveness of primary parasitoids.