Development of an effective behavioral technology for controlling fruit flies (Diptera: Tephritidae)
Using controlled-release technology, a prototype novel biodegradable sphere, which is used for controlling apple maggot fly, Rhagoletis pomonella (Walsh), designed for long-lasting residual effectiveness of feeding stimulant and insecticide has been created. The sphere body consists of 42–50% sugar entrapped in a mixture of gelatinized corn flour and wheat flour in the presence of glycerin, and coated with a layer of latex paint containing insecticide. The sphere body serves as a slow-release sugar reservoir.
First, the lethal and sublethal toxicity and the effects of tree sprays of the new insecticide imidacloprid on apple maggot flies were investigated. Females tested in the laboratory showed great mortality and reduced fecundity regardless of whether exposure was by oral or by surface contact. However, foliar sprays resulted neither in significant mortality nor reduced fecundity over a 7-day period. Secondly, technical-grade or formulated insecticides were incorporated in sphere coating mixtures and evaluated for acute toxicity and residual effectiveness in laboratory, semi-field and field experiments. Results indicated that imidacloprid is a promising substitute for dimethoate as a fly killing agent on spheres. A wettable powder formulation of imidacloprid (Merit) proved better than a flowable formulation (Provado) in terms of residual efficacy.
Females feeding on imidacloprid-treated spheres exhibited very little tendency to forage within host plants or to lay eggs before dying, compared with females tested on dimethoate-treated spheres and control spheres.
The sucrose pH shown to stimulate maximal feeding response was 6.4, with little feeding occurring at pH values of 5.0 or less and 8.0 or greater. Males were more responsive to varying pH than females. Such information is relevant to formulation improvements of coating mixtures of sucrose and insecticide applied to lethal spheres as part of tephritid fly control programs. (Abstract shortened by UMI.)
0768: Environmental science
0480: Plant pathology