Risks to pest management in New Zealand's pipfruit Integrated Fruit Production programme

Abstract

Pest management in New Zealand's pipfruit Integrated Fruit Production (IFP) programme relies on selective pesticides, biological control and pheromone mating disruption. The current situation is potentially precarious and one concern, the impact of less selective pesticides, was tested. Apple trees received synthetic pyrethroid (deltamethrin) sprays during the first half of two growing seasons. Beneficial and pest species were monitored monthly from November to April. Treated trees had fewer predatory bugs (91-100% reduction), lacewings (64-100%), earwigs (80-100%), predatory mites (67-100%), spiders (20-64%) and Hymenoptera (16-49%) than untreated trees. Ladybird numbers varied depending on the assessment method. Outbreaks of phytophagous mites and woolly apple aphid occurred on treated trees, but there were fewer apple leafcurling midge, San José scale and Froggatt's apple leafhopper on untreated trees. Factors that make pest management under IFP vulnerable in the future, include a loss of biological control and the consequences of new pests establishing.