Increasing pesticide use is changing the profile of insect and other pests that Australian farmers must contend with, and GM crops are set to bring their own changes, say experts.

Ecological geneticist Dr Andrew Weeks from the University of Melbourne and colleagues report their findings in the Australian Journal of Experimental Agriculture.

In the first study of its kind, Weeks and colleagues compared recent reports of winter grain pests with those dating back as far as 1980.

In both Victoria and Western Australia they found pests such as armyworms and pea weevils have declined, but other pests such as mites and lucerne fleas have been on the rise.

"One of the big things that we found was that a couple of species of mites, which weren't even really recorded early on, had become quite prevalent now," says Weeks, who is based at the Centre for Environmental Stress and Adaptation Research.