Predictive thresholds for forecasting the compatibility of Forficula auricularia and Aphelinus mali as biological control agents against woolly apple aphid in apple orchards
The woolly apple aphid (WAA), Eriosoma lanigerum (Hausmann) (Hemiptera: Aphididae) is a well-known pest of apple orchards world-wide. Several studies have demonstrated variable control of WAA populations by the European earwig, Forficula auricularia (L.) (Dermaptera: Forficulidae) and the WAA parasitoid Aphelinus mali (Halderman) (Hymenoptera: Aphelinidae). We examine whether a beneficial interaction between F. auricularia and A. mali exists and calculate optimal numbers for each species to maintain WAA infestations below acceptable levels. We demonstrate that trees possessing >14 earwigs per trunk trap per week within the first seven weeks post-blossom contained WAA infestations well below acceptable levels. Where these earwig thresholds were not met, a first generation of A. mali greater than 0.5 wasps per tree was required. If these beneficial insect targets were not met, severe WAA infestations occurred. Our findings suggest that if F. auricularia and A. mali numbers exceed these thresholds chemical intervention may not be required.
History
Publication title
BioControl
Volume
62
Pagination
243-256
ISSN
1386-6141
Department/School
Tasmanian Institute of Agriculture (TIA)
Publisher
Kluwer Academic Publ
Place of publication
Van Godewijckstraat 30, Dordrecht, Netherlands, 3311 Gz
Rights statement
Copyright 2017 International Organization for Biological Control (IOBC)