Resisting Resistance – Making sure insecticides continue to do their job


We’ve seen it with herbicides and it’s happening with insecticides too. Resistance development. The trouble with insecticides is, it’s harder to pick up and our alternative chemical options are very limited.

Globally, there are more than 580 documented cases of invertebrate pests evolving resistance to one or more of 325 unique chemicals. Closer to home, there have been cases of resistance in red legged earth mites in WA and SA to two of three available in crop chemical groups.

Across the southern region there has been resistance to more than one insecticide group in green peach aphid, diamondback moth and cotton bollworm, key pests to the Australian grains industry.

Like many growers have been implementing alternative practices for weed control, it is becoming increasingly important to implement an integrated pest management strategy on farm to reduce the pressure on the limited chemical options at hand for insect pests.

Integrated pest management (IPM) does not mean you never have the option of spraying an insecticide on a crop to control pests. The key to IPM is in the name, it’s about integrating a number of collaborative strategies, as simple as controlling summer weeds and encouraging predatory insects to tackle insect pests without solely relying on broad-spectrum insecticides.

“It’s easy to throw the cheap pesticide in the mix, but I feel we need to be more long term focused,” says Kelly Angel, BCG “We want to get away from this prophylactic use – this use of just in case I’ll chuck it in.

The importance of monitoring pest numbers and understanding economic thresholds will allow for more sustainable control. Considering both economic and ecological factors, such as beneficial insects and selective insecticide options when making spray decisions may be more profitable in the long term.

Parasitoid wasps, parasites, bacterial, fungal and viral diseases of insects are some biological controls of insect pests that come with no upfront cost to a grower. Beneficial insects are varied and valuable in a cropping system. Whether it be wasps laying eggs inside aphids, ladybird larvae veraciously consuming pests, hoverflies or mites, these small insects have the ability to build up in numbers and significantly reduce pest populations, potentially doing a more effective job than an insecticide. 

However, like many things in farming, it is about balance. An ‘insurance spray’ put out with a fungicide may not be necessary and could even be counterproductive as beneficial populations are likely to be wiped out at the same time if harsh chemistries are used.
Improving identification skills, understanding crop thresholds and monitoring is critical to accurately assess the need to, what to, or where to spray.

By taking a more thoughtful approach to pest management rather than throwing it in just in case will mean the products we have will be available for longer, and those occasions when they are really needed.

There is a growing number of grain producers starting to think of a more sustainable approach to managing insect pests.

Improving IPM practices across the Wimmera and Mallee will provide landholders with a greater range of insect pest-management options which can delay and potentially prevent the emergence of chemical resistance among targeted insect species. Not only that, but IPM practices can result in cost savings over time plus reduce the potential impacts of insecticides on non-target insect, and other reptilian and mammalian, species. 

BCG, with support from the Department of Agriculture and Water Resources, through funding from the Australian Government’s National Landcare Program, is running a project across 2021 and 2022 which aims to encourage the adoption of IPM practices in the Wimmera and Mallee. The project will be delivered through 12 webinars (six per year), four Landcare group meetings per Landcare consortium (two per year) and citizen science, which will be created, performed and delivered by students from Birchip P-12 and Tyrrell College (Sea Lake). 

In addition to this, a series of IPM Special Interest Groups will be formed as part of the project. These groups will provide participants access to information, tools and techniques to help them identify and implement locally relevant practices that manage insect pest populations and reduce their reliance on broad-spectrum insecticides. These groups will aim to facilitate peer-to-peer learning and encourage participant engagement with leading advisors, researchers, IPM experts and practitioners. 

If you are interested in learning more about IPM please contact BCG and register your interest in joining a BCG special interest group being put together as part of a new project being funded by the National Landcare Program.

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