Control of the Two-Spotted Mite in a Victorian Peach Orchard With an Introduced Insecticide-Resistant Strain of the Predatory Mite Typhlodromus Occidentalis Nesbitt (Acarina: Phytoseiidae).

Abstract

A strain of the phytoseiid mite Typhlodromus occidentalis, introduced from North America and known to be resistant to azinphos-methyl and various other pesticides, was released into a commercial peach orchard at Undera, Vic., in December 1974. Its effect on the two-spotted mite, Tetranychus urticae, was studied under various spraying programs for three successive seasons. The predator quickly established itself on the release trees and controlled T. urticae in each season under spray programs which included azinphos-methyl or phosmet for controlling Oriental fruit moth, pirimicarb for aphids, ziram for leaf curl and rust, mancozeb for rust, captan and triforine for brown rot, and ethephon for promoting even fruit ripening. However, it did not establish on trees treated with benomyl for the control of brown rot. The predator rapidly spread throughout the orchard and only one acaricide application was required on non-release trees during the three seasons. Native coccinellids (Stethorus spp.) were important predators of T. urticae in the early part of the second season but not in the other two seasons.