EFFECT OF PESTICIDE-RESIDUES ON MORTALITY OF APHYTIS-MELINUS DEBACH (HYM, APHELINIDAE) IN MUNGER CELLS AND LARGER CONTAINERS

An experimental study was designed to test the reliability of field-us able bioassays in determining the toxicity of previously treated folia ge to natural enemies. Lemon trees were treated at commercial rates wi th carbaryl-oil, chlorpyrifos and methidathion. Residues on leaves and twigs were quantified weekly for 50 days after treatment. Bioassays o f treated and control foliage to Aphytis melinus DeBach were conducted at similar intervals in Munger cells, 3.81 glass jars, and 21 paper c artons. Pesticide residues on twigs dissipated at approximately the sa me rates as residues on leaves. Bioassay mortality was high immediatel y following treatment. Subsequent mortality was reduced to near pre tr eatment and control levels quickly (3-8 days) in the cells, less quick ly in the cartons, and slowest in the jars (up to 10 weeks). The morta lity in the jars did not appear closely related to pesticide residue l evels, but was possibly due to other contributing factors.