Studies on the toxicity of insecticides to the light brown apple moth, Epiphyas postvittana Walker (Lepidoptera: Tortricidae) : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Horticultural Science in the University of Canterbury [Lincoln College]

Abstract

The introduction of the insecticide DDT as an orchard pest control material in the late 1940’s elevated the light Brown Apple moth, Epiphyas postvittana Walker, to the status of a major orchard pest requiring specific control measures. Peculiarities in the life-cycle and biology of E. Postvittana make this a difficult pest to control, and these problems were compounded by the development of resistance to the recommended insecticidal control, DDD in the Nelson area, in 1960.

Azinphos methyl then became the recommended insecticide, but after E. postivittna laboratory resistance levels to this material were demonstrated in 1961, it was not expected that the insecticide would give economic field control for very long. At the present time however, azinphos methyl has increased in Nelson Light Brown Apple moth populations during the period since 1961, by comparing the susceptibilities to the insecticide of a population from a commercial orchard, and one collected from an orchard block with a history of nil insecticide application. Secondary objectives were to investigate any variation in insecticide toxicity to the various larval stages of the pest, and to screen possible alternative insecticides to azinphos methyl for efficacy of control.