Effect of pre and postblossom insecticide residues on European earwig <i>Forficula auricularia</i> in kiwifruit

Abstract

In kiwifruit orchards the European earwig Forficula auricularia L can be a useful predator of scale insects However insecticide use may reduce earwig numbers and previous work indicated that diazinon residues caused high mortality of earwigs Diazinon has been replaced by several insecticides in the crop protection programme In this study late instar earwigs which are the stages found in the canopy prior to flowering were exposed to residues of preblossom insecticides thiacloprid (Calypso) thiamethoxam (Actara) and spirotetramat (Movento) following spray applications in spring Adult earwigs were exposed to residues of chlorpyrifos (Lorsban) following an application in March when adults only are present in vines One earwig was placed in each of thirty Petri dishes three vines per treatment with two 5cm cane segments cut from sprayed vines and kept at 20C Relative to controls there was no additional mortality of earwig nymphs following exposure to preblossom insecticide residues from 115 days after spraying All adult earwigs survived one nights exposure to chlorpyrifos residues but after five successive nights mortality ranged from 10 to 90 up to 7 days after spraying suggesting an accumulative response