22 - 24 September 2009

Management of resistance to fumigants and contact insecticides in key stored grain pests plays a significant role in maintaining the biosecurity of Australia’s $7billion grain industry. These materials are crucial to the grain industries ability to supply the ‘insect-free’ product demanded by both domestic and export markets. A major drawback, however, with this strategy is the threat of resistance in pest species.

Two key components of managing this threat are a national resistance monitoring program and the development of treatment protocols to combat resistance. The monitoring program provides information on the frequencies and levels of resistance in time and space and also early warning of the development of new resistance. A statistically robust, nationally agreed protocol is followed, which runs concurrently at three research laboratories representing each of the grain growing regions in Australia (Northern, Southern and Western). Information gathered is used to advise industry of regional and national trends and to identify where eradication, containment or other resistance management activities can be implemented.

The other key component is the development of effective treatment protocols to control newly emerged resistant biotypes. For example, once a new phosphine resistance is detected, a purified ‘worst-case resistant strain’ is established in the laboratory and fumigation protocols (including concentration, exposure period, and temperature parameters) is developed. Close collaboration with industry ensures that the laboratory based protocols are validated through field trials before their adoption.

A successful outcome from this research program has been the management of strong resistance to phosphine in the lesser grain borer. This resistance problem was first detected in 2000 and posed a serious threat to post-harvest grain biosecurity. The latest threat is the emergence of very high-level resistance in flat grain beetle populations in central storages. Research is in progress to tackle this biosecurity problem.