A SEMIFIELD TESTING PROCEDURE USING THE LADYBIRD BEETLE, COCCINELLA-SEPTEMPUNCTATA L (COL, COCCINELLIDAE), FOR ASSESSING THE EFFECTS OF PESTICIDES ON NONTARGET LEAF-DWELLING INSECTS UNDER FIELD EXPOSURE CONDITIONS

Over a 2-year period, three research facilities examined a semi-field testing procedure to determine its usefulness in predicting potential side-effects of pesticides on non-target leaf-dwelling insects under f ield exposure conditions. The ladybird beetle Coccinella septempunctat a was chosen as an indicator species for such insects. The objectives of the research were to examine the amenability of the testing method and to evaluate the reproducibility and reliability of the results. Se cond instar larvae of the beetles were placed on aphid-infested broad bean plants and then exposed to a spray treatment with one of three in secticide formulations at different application rates. The pesticides used were ME 605 Spritzpulver (WP 30), Metasystox R (EC 250) and Pirim or Granulat (50% a.i. w/w). Larval mortalities and numbers of to succe ssful metamorphoses observed in the tests were found to be in good agr eement with observations made under agricultural field conditions. The reproductive performance of beetles which developed from the exposed larvae was highly variable between replicate groups although beetles w ere partly maintained in groups of comparable parent density and sex r atio. Overall, it is concluded that the proposed test procedure is ame nable and that the observed effects on larval survivability and the nu mber of successful metamorphoses can be used to reliably predict harmf ul effects of pesticides to ladybird beetles in the field. If used as testing endpoint, the reproductive performance should only be qualitat ively evaluated, since this sublethal endpoint is apparently subjected to a high natural variability.