Grains Research and Development

Date: 01.11.2001

Wanted: Mitey predator

Wanted: Predator for red-legged earth mite.

IN SEARCH of a bio-control for the dreaded red-legged earth mite (RLEM), scientists are looking particularly closely at the performance of a number of exotic predatory mites.

In a recent survey of RLEM predators in Australia and South Africa, the research team uncovered 49 species of predatory mite including 20 species that do not occur in Australia.

In recent feeding tri als, the predatory mite Chaussieria capensis (Anystidae) showed promise by destroying RLEM at the rate of one per predator per day, according to Michael Keller of the University of Adelaide.

"However, this mite is not a specific predator and at thi s stage we can't say whether or not it will cause ecological damage in Australia."

Related research in Queensland and South Australia showed that some exotic non-specific predatory mites do not pose an ecological threat to non-target organisms because they don't colonise native vegetation.

"If we can show the same thing for C. capensis then we may be able to import it, but this is more of a long-term prospect," Dr Keller said.

"c. capensis was conspicuous and abundant during our search for predators throughout the range of the target mite in its native South Africa."

Discovery of a non-chemical method of controlling RLEM could help save the grain industry millions of doll ars currently lost through crop damage, reduced yields and pesticide use each year. RLEM damages canola, lupins, grain legumes, some cereals and broad-leafed pastures, and requires extensive pesticide use for effective control.

Given the magnitude of the problem, Dr Keller and colleagues see a natural predator as a valuable part of an integrated approach to RLEM pest management.

Program 2.7.1 Contact: Dr Michael Keller 08 8383 72

Region North