of China Australia Food Security Cooperation Initiative (CAFSCI)

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Phosphine resistance in insect pests of stored grain

Overview of Project

Insecticides and fumigants are the most effective and flexible means of controlling pest activity in grain storage and handling, with phosphine being used as the main fumigant of grain in Australia, China and India. However, resistance to phosphine fumigation is emerging among many major pest species in Australia, China, India and many other countries. The aim of this project is to develop and implement management practices which limit the current problem of phosphine-resistant pest species and delay the further development of phosphine resistance.

Key Outcomes of Project

The project established that resistance within several major pest species posed a serious threat to the safe storage of grain in some situations. In China and India laboratory and field experiments led to formulations for dosage requirements for successful fumigation of resistant insects and provided a better understanding of resistance development and its management.

Very high levels of phosphine resistance were detected in several Chinese strains of stored grain pests (especially Rhizopertha dominicina and Cryptolestes). Field evaluations of phosphine use in China indicated that fumigation failures (i.e. incomplete control of pests leading to selection of phosphine-resistant strains) were inevitable while the prevailing practices persisted. A similar pattern emerged in India, while low-level resistance was detected amongst Australian isolates.

In Australia, scientists completed genetic studies on Chinese phosphine-resistant strains of three species. Results showed that two or more genes were apparently responsible for controlling phosphine resistance. Meanwhile studies in China provided information on the genetics and ecological fitness of resistance, and on cross-resistance to other chemicals, all of which help in understanding the evolution of resistance and in designing measures to counter it.

Studies in Australia showed that fumigations according to the protocols recommended for the CSIRO-patented Siroflo fumigation process (and similar procedures in Australia) did not control two resistant strains from China, therefore these protocols required urgent revision.

In China, field experiments in grain warehouses identified deficiencies in current practices, largely associated with inadequate storage sealing and gas-tightness. Modifications of fumigation techniques have led to improved maintenance of lethal dose (a higher concentration for longer) and compliance with agreed standards for fumigation success. The information on fumigation practices and modifications have helped the project team to formulate new recommendations for phosphine use in China to minimise the impact of phosphine-resistant strains.

In India the scientists formulated recommendations to improve fumigation performance and reduce development of resistance. Further research was recommended to show that a slow-release phosphine formulation could be used as a significant means of improving fumigation performance.

As a result of the project findings concerning phosphine resistance, Queensland and New South Wales authorities doubled the recommended dose for phosphine fumigation of grain."

Project Dates

01 Jan 1995 - 31 Dec 1999


State Administration of Grain Reserves - Department of Storage - China
State Internal Trade Bureau - Dept of International Co-Operation - China
Central Food Technological Research Institute - Infestation Control and Protectants Department - India


Dr Greg Daglish



07 3896 9415

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