Aspects of the seasonal fluctuation of populations of Tetranychus urticae (Koch) in apple orchards in the Stanthorpe district, Queensland

Abstract

Populations of Tetranychus urticae (Koch) in a commercial orchard of Delicious apples receiving applications of broad-spectrum pesticides were determined during spring by tanglefoot traps, during summer by extraction of mites from leaf samples and during autumn by shelter traps. These showed that approximately 220 mites per tree were present during spring, 124,000 per tree during late summer and 23,000 per tree during autumn. The mites overwintered chiefly in litter near the bases of the trees and surviving individuals migrated back to the trees during spring at approximately the green-tip stage of development of the host.