Ken Bullen* explains how insect resistance is building, and the steps being taken to keep science and on-farm practices on top of the problem
Insect resistance to phosphine and protectant insecticides is emerging as a serious threat to Australia"s grains industry.
The GRDC has been sponsoring an Australia-wide program monitoring this resistance to ensure the industry is not caught without adequate means of dealing with storage insects.
The GRDC "Resistance Monitoring" project is led by Dr Pat Collins, Queensland Department of Primary Industries and Fisheries, Brisbane (northern region), Dr Rob Emery, WA Department of Agriculture (western region), and Dr Joanne Holloway, NSW Department of Primary Industries, Wagga Wagga (southern region).
The project covers Australia"s grain regions in a cooperative program that is resistance-testing insect populations in grain storages on farms, in merchants" premises and in bulk-handling facilities.
Dr Collins says the development of insect resistance has been caused by several factors:
Each year, researchers visit hundreds of farms, grain merchants and bulk-handling sites in each grain region. insect specimens are taken at each site and the insects are then bred under controlled conditions in a laboratory. These insects are then exposed to a battery of protectant insecticide and phosphine tests. The program has been running since the early 1990s.
Based on Australian and overseas experience, resistances can be expected to become more serious and widespread. scientists are trying to improve their understanding of the mechanism of resistance development using the latest biotechnology. With grains industry support through GRDC, the University of Queensland"s Dr Paul Ebert ("Markers for Phosphine Resistance" project UQ00010) is searching for a "rapid test" for phosphine resistance.
We would like to retain phosphine as a principal fumigant for the foreseeable future because of its low cost, its ease of use and its acceptance by all markets. There is no ready alternative. We will see wider investment by the grains industry in sealed, aeratable silos to improve the effectiveness of phosphine use.
The Australian grains industry will adopt a "Food production" ethos in the management of grain production and marketing. There is a already a widespread trend overseas towards "identity preservation" and Quality Assurance. We will continue to investigate and develop new fumigants and protectant insecticides for industry adoption. For example, the biological insecticide compound spinosad has been recently researched and developed as a new "green" protectant insecticide for the control of LGB. A new fumigant, "Vapormate" (ethyl formate and Co² mix) is under development by BOC and CSIRO. other fumigants are also being investigated, but are expected to be more expensive and more complex to apply than phosphine products.
* Ken Bullen, Queensland Department of Primary Industries and Fisheries, Toowoomba.
[Photo: Phillip Taylor carries out laboratory testing of grain storage insects for pesticide resistance from hundreds of sites, as part of a GRDC-funded project "Resistance Monitoring"
[Photo - Department of Agriculture WA: rust-red flour beetle]
[Photo - Department of Agriculture WA: lesser grain borer]
[Photo - Department of Agriculture WA: sawtooth grain beetle]
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