Research fights phosphine resistance

A research team has struck a major blow in the battle against phosphine-resistant rusty grain beetle, a major pest of stored grain

Source: PBCRC

Phosphine is one of the most effective and affordable fumigants for controlling pest insects in stored grain. While other treatments are being phased out, phosphine is universally accepted as a nearly residue-free treatment around the world.

In recent years however, insects have been developing resistance to phosphine and this is emerging as a major issue for agriculture.

“Current treatment strategies are not dealing with the resistant strains,” said Dr Manoj Nayak, PBCRC Principal Research Scientist for the Queensland Department of Agriculture, Fisheries and Forestry.

“Phosphine is a vital tool for protecting grain. To keep it as an option we had to find out how to control the resistant beetle populations.”

Using all life stages (eggs, larvae, pupae and adults) of both resistant and susceptible populations, the study determined the regimes needed to kill 99.9 per cent of beetles at different concentrations and fumigation periods, confirmed after eight weeks of storage.

“By examining all the variables in the lab, the study established robust fumigation protocols that can be used in industry grain storages to control strongly resistant rusty grain beetles,” said Dr Nayak.

“Increasing phosphine concentration was highly effective, and while this means higher fumigation costs it is a worthy investment, especially for crops where alternatives to phosphine are not available.”

The role of temperature also had a major effect, with warmer temperatures significantly reducing the time required for effective control.

“Phosphine resistance is a major concern for grain storage,” said Mr Robin Reid from GrainCorp.

“The work of PBCRC is critical to sustaining the usefulness of phosphine into the foreseeable future.”

The fumigation protocols developed in the study will be used in recommending changes to the currently registered rates of phosphine in Australia where managing strongly resistant rusty grain beetle is an issue.

The paper ‘Developing effective fumigation protocols to manage strongly phosphine-resistant Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemophloeidae)’ by Ramandeep Kaur and Manoj Nayak, was published in the November issue of Pest Management Science, DOI 10.1002/ps.3926

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