A novel approach to limit the development of phosphine resistance in Western Australia

Escalating development of resistance to phosphine is of concern to grain storage operators world wide. In Western Australia 85% of grain produced is exported with a guarantee through legislation that it is free of all grain insects. Phosphine plays a vital part in shore-based fumigations to achieve this insectfree status but it is also available for unrestricted use by growers for grain stored on farms. For more than 20 years a campaign has been in place to encourage better use of phosphine. Central to the program is the preservation of phosphine for long-term use by exporters and growers. Over this period weak resistance frequency has increased to the current rate of about 48% averaged across all species. Strong resistance has been confirmed in two strains of Tribolium castaneum. The three key components of the strategy are:1. Inspection of central and farm storages for grain insects, and testing insects to discover phosphine resistance.2. Education of grain-storage managers on farms and commercial premises on effective management of grain stocks and correct use of phosphine.3. Eradication of highly resistant insect colonies found on farms and commercial premises as well as management of strains with elevated levels of tolerance to phosphine.Keywords: Farm silo, Fumigation, Phosphine resistance, Extension, Western Australia