This is a completed project  

The research outcomes from this project found:

• Resistance in grain storage insects to chemical treatments continues to be a problem throughout the southern region.
• Regional surveys have detected new sites of strong phosphine resistance, with only a few recurrences at previous sites (generally central storages).
• A new highly phosphine-resistant strain of flat grain beetle (Cryptolestes spp) was detected at several sites. The level of resistance found can not be controlled with current phosphine fumigation protocols.
• Based on data collected, phosphine resistance appears to be primarily due to improper use of the chemical, particularly repeated applications at doses lower than recommended.
• The over-reliance on methoprene for control of lesser grain borer has resulted in an extremely high proportion of resistant strains, many of which cannot be controlled at doses over six times that of the recommended label rate.
• Resistance in the lesser grain borer to the grain protectant deltamethrin has spread and is now commonly found throughout New South Wales, Victoria and South Australia.

What are the implications for future research in this area?

• If resistance to phosphine continues to develop, especially at levels similar to those recently detected in the flat grain beetle, its life will be severely limited. Either alternative chemicals will have to be developed or export restrictions on live insects in grain will have to be eased. The result from either of these options will be a reduction in profits from Australian grain. This is because any new chemical will invariably be more expensive than phosphine, combined with the added infrastructure costs required for its application. In addition, easing of export restrictions on live insects will result in the loss of Australia's competitive advantage on production of high quality, insect-free grain.
• There is an urgent need for the development of alternative protectants for on-farm use. This is especially true now that the phosphine label states that it is restricted to use in 'well-sealed structures' only, as many farms have none.
• As improper use of grain storage chemicals appears primarily responsible for the development of resistance, education and training programs need to be developed. This will help ensure that growers and others in the grain storage industry are aware of correct chemical application and fumigation procedures. Without this training and enforcement of label recommendations, resistance will continue to develop and possibly evolve to levels higher than those currently detected.