Grain growers have been reluctant to embrace the use of beneficial insects as part of an integrated pest management system, despite the success of such programs in the cotton and citrus industries.
According to the Grains Research and Development Corporation, growers still need to be convinced of the merits of the bio-control methods.
Dr Joanne Holloway, of the NSW Department of Primary Industries, says beneficial invertebrates can make significant contributions to the suppression of insect pests in grain crops, but there is a need for more data to quantify their potential contribution and to help overcome constraints to adoption of integrated pest management.
She says interest in IPM has increased, but a major constraint to adoption by growers is the lack of information about the benefits.
"We don't know the exact extent to which beneficial invertebrates – predators and parasitoids – contribute to IPM," Dr Holloway said.
"We don't know how many beneficials are needed for effective control, and advisers don't have enough information to confidently advise growers on IPM."
Dr Holloway is examining IPM in overseas grain production and other Australian agricultural industries such as citrus and cotton.
Her project is part of the National Invertebrate Pest Initiative, which is supported by growers and the Australian Government through the GRDC.
She said growers also wanted to see that IPM works before adopting it.
"The cost of chemicals, growers' concerns about the natural environment and the industry's increasing need for traceability has generated greater interest in IPM, but growers need to see that it works," Dr Holloway said.
"These industries are being innovative in their approach to IPM.
"Cotton growers are planting strips of lucerne near their crops to provide a habitat for beneficial invertebrates, from which they can move into the crops and prey on pests when they emerge.
"This is also happening in the United Kingdom, where they use 'beetle banks' – areas of natural vegetation on the farm – to promote more beneficial invertebrates."
Dr Holloway said this technique could also be used by Australian grain growers, but more data was needed about what sort of vegetation was best to harbour populations of beneficial invertebrates, and how best to ensure they disperse and enter crops to do their job.
"Other measures growers can take include using selective insecticides instead of broad-spectrum chemicals, as the former is softer on beneficial invertebrates," she said.
"IPM is not all about beneficial invertebrates – I don't think there will ever be a time when chemicals won't be needed in some way, particularly when infestations are severe.
"Minimum tillage systems, in addition to conferring other advantages, are another way growers can promote greater activity by beneficial invertebrates, but such systems can sometimes promote pest species too.
"Beneficial invertebrates are able to control pest insects to an extent, and growers can reduce their reliance on spraying and their impact on the environment by adopting IPM."
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