Effects of Surface Residues of Azinphosmethyl on Apple Maggot Behavior, Oviposition, and Mortality1

Abstract

Two types of laboratory bioassays were conducted to determine the quantitative effects of surface residues of azinphosmethyl on the behavior, oviposition, and mortality of the apple maggot (AM), Rhagoletis pomonella (Walsh). In one bioassay, groups of AM females were continuously exposed to uniform residues for various time periods by confining them in a glass sphere coated with azinphosmethyl. At the recommended rate (313 ppm AI), 39% of the flies died after only 5 min of exposure, and 92% mortality occurred after 20 min. The results of this test were fit to a dynamic model of insecticide effectiveness. In a second bioassay, single females were caged for 48 h on apples coated with the insecticide. The insects were observed less frequently on fruit with increasing residues, and oviposition was reduced even on apples with sublethal levels of insecticide. Equations were developed from these two studies to predict AM mortality and oviposition inhibition resulting from different residues of azinphosmethyl on apples.