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New Zealand Plant Protection 68 (2015): 446

An investigation of San Josť scale (Quadraspidiotus perniciosus) predation by the European earwig (Forficula auricularia)

P.W. Shaw and D.R. Wallis


The European earwig (Forficula auricularia) is a generalist predator of a wide range of insect pests in pipfruit orchards, including scale insects. Since the development of an integrated fruit production programme that uses selective pesticides and biological control of pests, earwigs are now more frequently found in commercial pipfruit orchards. San Josť scale (Quadraspidiotus perniciosus, SJS) is a diaspid species that is an important insect pest in the main apple-growing regions in New Zealand. This study investigated the potential of earwigs to feed on SJS in a non-choice laboratory trial. Individual mature earwigs were placed inside containers with small sections of apple wood infested with mixed age stages of SJS. A total of 157 SJS on the apple wood were photographically indentified and marked so that subsequent predation by earwigs over 6 nights could be recorded. Predation over this period was 12-90% (mean 56%). These results indicated that earwigs would potentially feed on scale insects, but as they are generalist predators their impact on scale infestations in orchards would depend on scale density and the availability of other prey. Very little earwig predation of SJS on fruit was recorded in a similar assessment.

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