Chemical use in greenhouses to be cut by half

The exotic ladybird <i>Hippodamia variegata</i> is being tested for use as a beneficial insect in greenhouses. Photo: V. Heimoana, Charles Sturt University
The exotic ladybird Hippodamia variegata is being tested for use as a beneficial insect in greenhouses. Photo: V. Heimoana, Charles Sturt University.

Chemical use in many vegetable-producing greenhouses could be halved in the next three years, according to the NSW Minister for Primary Industries, Ian Macdonald.

Mr Macdonald said NSW Department of Primary Industries (DPI) scientists have identified a number of beneficial insects and new reduced-risk chemicals in a new research project.

“These have potential for use in biologically based integrated pest management (IPM) programs”, he said.

Mr Macdonald said the project, funded by the horticulture industry, is now seeking to accelerate the research to ensure growers gain access to the technology as soon as possible.

Among the promising new biological control agents is an exotic ladybird Hippodamia variegata, noticed by Australian vegetable growers to be useful as a beneficial insect.

A range of native species is also being assessed, including the thrips predator Orius armatus, whitefly parasitoid Eretmocerus warrae and predatory brown lacewing Micromus tasmaniae.

DPI research entomologist, Dr Leigh Pilkington, said these and other targeted beneficial insects had been identified as natural enemies of key pests such as thrips, aphids, whiteflies and mites.

“We know they are useful as biocontrol agents, but we need to test how effective they will be in managing pests in commercial-scale vegetable crops.”

Pests like western flower thrips, which attack a range of vegetables, including lettuce, cucumbers, tomatoes and capsicum, are rapidly developing resistance to conventional pesticides.

Dr Pilkington said “growers now have few chemical tools left to fight these pests.”

In conjunction with commercial operators, the research will compare the effectiveness of different beneficial insects, assess their tolerance to different temperatures, work out appropriate use strategies and develop mass-rearing techniques.

New “softer” chemicals are also to be evaluated to ensure they do not affect the effectiveness of the beneficial insects.

A key product currently under development is a new biopesticide based on an insect-killing fungal disease that naturally occurs in Australia.

Dr Pilkington said “it’s important that the right chemicals are used, at the right time, which allows the beneficial insects to keep doing their job.”

He said in the future, instead of conventional or synthetic pesticides, new reduced-risk chemicals are likely to rely on novel pesticides such as the fungal biopesticide that will infect the target pest and cause its death.

“The idea is to put biocontrol in the forefront of people’s minds and to retain conventional pesticides for when the industry really needs them.”

Dr Pilkington said a range of activities designed to encourage greenhouse vegetable growers to introduce IPM techniques are already underway.

“Meetings in the Sydney Basin where the community gathers at a farm have been hugely successful, attracting up to 100 growers a day.

“It is evidence of the increasing acceptance of and enthusiasm for IPM,” he said.

Demonstration farms have also been set up so that growers can see how IPM works first hand, and are in the process of developing a web site on all facets of IPM for greenhouse vegetable growers in Australia to access.

The research is being supported by vegetable growers through Horticulture Australia Limited.