Abstract
Economic suppression of Panonychus ulmi (Koch) has been realized during the first 2 years of an integrated control study on 10 acres of apple trees in central Ohio. Naturally occurring insect predators have reduced mites during the summer and have also reduced numbers of overwintering eggs. Conversely, low predation has permitted high mite populations on scattered experimental trees, with subsequent high overwintering egg deposition resulting in high mite densities the following year. The association with low and high mite densities is reported for these predators: Leptothrips mali (Fitch), Orius insidiosus (Say), Plagiognathus politus Uhler, Chrysopa rufilabris Burmeister, C. carnea Stephens, and Stethorus punctum (LeConte). Ryania and lead arsenate were without effect on L. mali, O. insidiosus and the chrysopids. Azinophosmethyl destroyed all nymphs of L. mali and O. insidiosus , but only 45–65% of the chrysopid larvae; carbaryl eliminated L. mali nymphs.
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