INTEGRATED MANAGEMENT OF INSECTS AND MITES ON HOPS

Dr David G. James, Associate Professor, Department of Entomology, Washington State University, Prosser, WA

Cost-effective production of hops in the Pacific Northwest is threatened annually by insect and mite pests, primarily hop aphid, twospotted spider mite and hop looper. Control of these pests remains dependent on the use of insecticides and miticides. However, good progress has been made since 1999 in research, development and adoption of conservation biological control (recruitment and maintenance of natural enemies), as an additional management strategy enabling a measurable reduction in dependence on chemical inputs. Chemical control of hop pests is compromised by the increasing cost of chemicals and application, the ability of mites and aphids to develop resistance to chemicals and concerns over environmental and product contamination with pesticide residues. Continued development and adoption of integrated management strategies based on biological control, is needed to enhance the cost-effectiveness and sustainability of the hop industry.

Our project continues the research needed for development and adoption of practical integrated management strategies for arthropod pests of hops in the Pacific Northwest. This research is justified by the need to move away from pesticide-based control of insects and mites on hops. Continued dependence on insecticides and miticides will result in ever-increasing costs and diminished efficacy, as mites and aphids continue to develop resistance and chemical companies struggle to find replacement chemicals. Government and community pressures to reduce environmental contamination by pesticides and stricter market requirements on acceptable residue levels, will also reduce the viability of pesticide-based arthropod management on hops in the future. Our research program has produced tangible economic benefits for hop growers. Adoption of our biological control-based management recommendations has lead in some instances to substantial cost savings through reductions in miticide/aphicide use of 50-75%.

Our continuing objectives include:

1. Study of the biology and ecology of mites, aphids, hop loopers (caterpillars) and their natural enemies in the laboratory and in hop yards, with a view to increasing the practicality and efficacy of biological control. Conduct of on-farm demonstrations of biological control using endemic natural enemies, and enhancement using HIPPOs (Herbivore Induced Plant Protection Odors: e.g. methyl salicylate) to recruit/sustain predators and parasitoids Promote IPM/biological control strategies to hop growers by education and demonstration.
2. Screen and evaluate new specific miticides and insecticides in the laboratory and field for efficacy against twospotted mite, hop aphid and hop loopers and their safety to beneficial insects and mites.
3. Evaluate mite and aphid strains from hop yards and other sources for side-effects and susceptibility to currently used pesticides. Determine current levels of efficacy of miticides and aphicides to provide ‘early warning’ of pesticide resistance.
4. Evaluate the potential of ground covers/cover crops as an aid to enhancing and sustaining conservation biological control in hop yards.