New DNA tests detect resistant insects – before they attack your stored grain

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Grain weevil: new DNA tests for pesticide-resistant insects promise to provide better protection against infestation for valuable stored grain.
Grain weevil: new DNA tests for pesticide-resistant insects promise to provide better protection against infestation for valuable stored grain.
Johan J.Ingles-Le Nobel, Flickr CC

Rusty grain and red flour beetles, rice weevils and lesser grain borer – as these key pests develop resistance to insecticides, eliminating them post-infestation is no longer an effective option.

Now, new research simplifying and improving insect-trapping techniques, and giving grain farmers and storage handlers the tools they need to detect problem pests pre-infestation, is set to radically change how we protect valuable stored grain from destructive insects.

NSW Department of Primary Industries (DPI) principal research scientist Mark Stevens is managing a joint DPI and Plant Biosecurity Cooperative Research Centre (CRC) project aimed at giving farmers and grain storage handlers the ability to detect problem insects before they infest grain storages.

“Until recently, grain storage was managed by eliminating pests after infestations were found,” Dr Stevens explains.

“Now, with insecticide resistance developing in at least four of the key pests, we’re focused on reducing the risk of infestations developing in the first place.”

DNA-based pest resistance test

“Rapidly developing technology will soon allow phosphine resistance to be detected using DNA analysis of individual beetles – a faster approach than we currently have,” Dr Stevens says.

“DNA-based tests are not yet available for all key pests, but they are just over the horizon.”

When the DNA technology is available, farmers and grain handlers will be able to trap beetles near grain storage facilities and send samples for laboratory analysis to identify highly resistant strains of the pests.

This information will be crucial if infestations occur, Dr Stevens notes: it will inform choices about the most effective options for control and help prevent the use of ineffective treatments that could, potentially, escalate resistance problems.

Grain silos, Newcastle Harbour: the DPI researchers are trapping insects around grain storage facilities and testing them for pesticide resistance.
Grain silos, Newcastle Harbour: the DPI researchers are trapping insects around grain storage facilities and testing them for pesticide resistance.
Tim J Keegan, Flickr CC, wwwflickrcomphotossuburbanbloke

Catch-all pheromone-based lures

“DPI entomology officer Rachael Wood and I are exploring the ecology of pest insects outside the storages – how far they can spread, what food sources they use apart from grain, and how best to monitor each pest,” says Dr Stevens.

“A central aim of this project is to simplify on-farm trapping of multiple species of pest insects, and we are testing pheromone-based lures to find how many different beetle species can be attracted to a single trap.”

So far, results have been promising, with commercial lures for lesser grain borer and red flour beetle found to be highly effective.

A new lure for rusty grain beetle, developed by the Plant Biosecurity CRC and Research Directions Pty Ltd, is being tested this spring, and researchers are hoping to improve the effectiveness of existing rice weevil lures.

The project, due to run until June 2017, has identified several organic compounds not previously used to attract rice weevil, which will be used in combination with commercial pheromone lures this season to test how well overall performance can be improved.

SOURCE: DPI NSW Media release, Nov 2015.

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