Consider beneficial insects when spraying
- Scaddan
- Tambellup
Rob Hughes (South east Agronomy research) has found carabid beetles from Family Pterostichini, most likely from genus Simodontus, in a cereal stubble being sown to canola, near Scaddan.
Carabids, also commonly known as ground beetles, are usually dark coloured beetles that have large jaws that points forwards. They are a beneficial predator that predates on caterpillars, earwigs and other beetles. Many different species are present in paddocks.
Other beneficials may not be so obvious. A grower in Tambellup has found predatory maggots in the soil.
Predatory maggots can be easily distinguished from the onion root maggot, as they are solitary, occur in very low densities and are not found in association with plant roots. They predate on small insects in the soil.
'Beneficials' are insects and pathogens that kill crop pests. They are also referred to as 'natural enemies' or 'biological control agents' of pests. In many seasons they are important at suppressing pest populations to below damaging levels.
A range of beneficial predators can be present in crops. They include certain species of beetles, bugs, flies, lacewings, mites, spiders and wasps.
It is important that growers correctly identify beneficials and not confuse them with pests. For more information refer to DPIRD’s Know what beneficials look like in your crop page.
Insecticide impact on beneficials
Broad-spectrum insecticides such as synthetic pyrethroids and organophosphates are very toxic to beneficial insects, and removal of beneficials through these insecticides has, at times, caused pest species to build up much more rapidly than normal.
An Australian grains chemical toxicity table has been developed to help growers and advisors make informed choices about the insecticides and miticides they use in their crops. It summarises the toxicity of foliar chemical sprays on beneficial insects. This table was a collaboration between Cesar Australia and University of Melbourne, with investment from the Grains Research and Development Corporation (GRDC) as part of the Australian Grains Pest Innovation Program (AGPIP).
For more information refer to Cesar Australia’s Beneficial’s chemical toxicity table page and How to use the Grains beneficials chemical toxicity guide webinar recording.
For more information about beneficial insects contact research scientist Svetlana Micic, Albany on +61 (0)8 9892 8591.
Article authors: Cindy Webster (DPIRD Narrogin) and Svetlana Micic (DPIRD Albany).