Effect of pesticide residues on mortality of Aphytis melinus DeBach (Hym., Aphelinidae) in Munger cells and larger containers

Abstract

An experimental study was designed to test the reliability of field-usable bioassays in determining the toxicity of previously treated foliage to natural enemies. Lemon trees were treated at commercial rates with carbaryl-oil, chlorpyrifos and methidathion. Residues on leaves and twigs were quantified weekly for 50 days after treatment. Bioassays of treated and control foliage to Aphytis inelinus DeBach were conducted at similar intervals in Munger cells, 3.8 1 glass jars, and 2 1 paper cartons. Pesticide residues on twigs dissipated at approximately the same rates as residues on leaves. Bioassay mortality was high immediately following treatment. Subsequent mortality was reduced to near pretreatment and control levels quickly (3-8 days) in the cells, less quickly in the cartons, and slowest in the jars (up to 10 weeks). The mortality in the jars did not appear closely related to pesticide residue levels, but was possibly due to other contributing factors. , 1993: Residual toxicity of pesticides used for lepi-995-1 00 1.