Management of resistance in horticultural pests and beneficial species in New Zealand

Abstract

AbstractTwo related insecticide resistance management programmes are under way in New Zealand horticulture. The first aims to limit the spread and impact of azinphos‐methyl resistant lightbrown apple moth (LBAM) in an applegrowing district. In the second, the introduction of pyrethroid (SP) resistance in organophosphate‐resistant (OP) Typhlodromus pyri makes it possible to undertake biological control of the European red mite that is compatible with SP and OP control of orchard pests.In the LBAM programme the resistant zone, which includes alternative host‐plant reservoirs, has been delineated by detailed resistance monitoring with topical application of males caught using female sex pheromone. In that zone, chlorpyrifos, to which the azinphos‐methyl resistant LBAM has low cross‐resistance, is used in the short term to control resistant moths, while alternative measures (e. g. other insecticides and mating disruption) are investigated. Recognition of the importance of immigration from alternative host plant reservoirs has led to specific tactics such as the application of pyrethroids to non‐crop areas. This resulted in a significant decrease of the resistant population. So far, however, SPs have not been registered in apple orchards because they kill OP‐resistant predatory mites which control the European red mite, and also because of the lack of residue tolerances for SPs in some overseas markets.Following the assessment of the potential value of pyrethroids in pipfruit, DSIR started field selection for pyrethroid resistance in predatory mites, which was later expanded to include laboratory selection. The successful development of pyrethroid‐resistant predators which retain organophosphate resistance is permitting the introduction of biological control of European red mite compatible with the use of these two classes of insecticides for control of other pests.In future, the lepidopterous pests on New Zealand apples may be controlled by pyrethroids, scales and other minor pests by organophosphates, and European red mite by multi‐resistant predatory mites.