Locust killer

CSIRO scientists have successfully used a rare Australian native fungus – Metarhizium – to produce an environmentally friendly 'bioinsecticide' spray, Green Guard, which has proven effective in controlling one of the world's major agricultural scourges, plague locusts.

Green Guard has already been used in Australia to control locust outbreaks, but only under a special licence. Now it will be available to all rural producers.

CSIRO recently signed a commercial agreement with the agricultural biotechnology firm, Becker Underwood and soon Green Guard will be available worldwide.

Managing Director of Becker Underwood Australia, Richard Waterworth, said that Green Guard had now been granted full registration by the Australian Pesticides and Veterinary Medicines Authority and will be made available to farmers through agricultural resellers and government bodies involved in locust control such as the Australian Plague Locust Commission and the NSW Rural Lands Protection Boards.

'We have also had promising discussions with groups around the world and will be pursuing these,” Waterworth said. ”Our first aim is registration of Green Guard in China. Africa, Mexico, Canada, USA and South America will be targeted in the longer term.”

It took Dr. Richard Milner and his team at CSIRO Entomology a decade to produce a usable product.

“When Metarhizium was discovered it didn't seem to be a likely candidate for controlling plague locusts,” Dr. Milner said. “Locusts like it dry and the fungus likes it moist. However, the need for a 'green' alternative to insecticides for locust control encouraged us to persevere.”

Metarizhium spores infect locusts by literally boring into their cuticle (skin). Once inside they use up water and nutrients and grow tiny tubes which eventually kill the insect.

Early attempts to produce a water-based spray failed and Dr. Milner's team spent years developing a mix of vegetable and mineral oils in which Metarhizium spores can be delivered with maximum efficiency.

“In an oil suspension, Metarhizium can be sprayed under very hot conditions and won't dry out,” Dr. Milner said. “In fact, the fungus will infect and kill locusts in conditions where we would not normally expect it to be active,” he said.

After spraying, Green Guard does not persist in the environment for more than two to four weeks and, while it is effective against a wide range of grasshoppers and locusts, it does not affect even close relatives like crickets. Aquatic life and birds are also safe.

The research was conducted by CSIRO Entomology with assistance from the Australian Plague Locust Commission (APLC), the Queensland Department of Natural Resources and NSW Agriculture.