Effect of mineral oil and diazinon residues on the predator European earwig <i>Forficula auricularia</i> in kiwifruit

Abstract

The European earwig Forficula auricularia is probably a key predator of armoured scale insects in kiwifruit in New Zealand but its effectiveness may be compromised by the use of insecticides on kiwifruit vines European earwigs are nocturnal and avoid direct contact with insecticides during application but would be exposed to residues on leaves and bark Earwigs were monitored after exposure to residues of mineral oil combined with Bt (Bacillus thuringiensis) or diazinon following commercial or experimental spray applications for scale control Oil plus Bt residues caused no mortality of earwigs No earwigs survived exposure to diazinon residues for 2 nights after the commercial application while half survived for 7 nights Some mortality was recorded after exposure to diazinon residues up to 17 nights after the experimental application As there is a single generation of earwigs each year diazinon residues are likely to cause significant disruption to scale predation in conventional kiwifruit orchards