The discovery of another species of wheat curl mite, the organism primarily responsible for transmitting the wheat streak mosaic virus, is causing researchers to re-think strategies for studying the pest.

Wheat streak mosaic virus was first confirmed in Australia in 2003, not only causing significant yield losses in parts of New South Wales but also forcing wheat breeding programs across the country to destroy many promising breeding lines.

The wheat curl mite (Aceria tosichella) is a wingless cigar-shaped mite about 0.2mm long that also carries the high plains virus, another damaging wheat disease. The wheat curl mite acquires the wheat streak mosaic virus when it feeds on infected plants.

“This latest discovery has opened a Pandora’s box in relation to what we now know about the wheat curl mite and the transmission of wheat streak mosaic virus,” CESAR director Professor Ary Hoffmann said. 

Using novel DNA-based approaches in a project funded by the Grains Research and Development Corporation (GRDC), the Centre for Environmental Stress and Adaptation Research (CESAR) at the University of Melbourne has not only found that there are two species of wheat curl mite in Australia, but that both are widespread across the wheat belt (although only one species has been collected in Queensland).

“Only one of these species is ultimately likely to carry the name Aceria tosichella – the other may yet prove to be a new, undescribed species,” Professor Hoffmann said. A new diagnostic test has been developed to distinguish the species.

“We have now detected one of the species on grasses and volunteer wheat, which enables survival over summer between wheat crops,” Professor Hoffmann said.

Further research is underway at CESAR to determine if one or both species of wheat curl mite transmit the wheat streak mosaic virus and to also better understand the underlining cause of the 2005 wheat streak mosaic virus epidemic.