Monitoring and managing phosphine resistance in Australia

Abstract

The Australian grain industry relies heavily on phosphine to meet domestic and international market demand for high-quality grain, free of insects. Phosphine usage has increased markedly over the last 10 years because of mar- ket reluctance to accept protectant chemical residues, as well as resistance in target pests to grain protectants. The threat that insects may also develop resistance to phosphine led to resistance-monitoring projects being initiated across all cereal-growing regions of Australia as a pro-active response to develop strategies to combat resistance as it evolved. With industry support, these projects have now amalgamated to form a national phosphine resistance monitoring and management program underpinned by a database of over 35,000 assays. Over the past two decades, the incidence of weak resistance has increased from 5% to 34% of strains tested along with the emergence of strong resistance in 1997. This latter resistance occurs in only 1.7% of strains from eastern states tested over the past two years, but poses the greatest threat to the industry. The Australian approach is unique in that it has drawn together primary producers, bulk handlers, chemical compa- nies, industry-funded organisations and government research institutions from across the country to combat the national threat of phosphine resistance.