Pest management is a critical component of successful crop production, but there is increasing need to promote the sustainable use of insecticides to avoid resistance issues and non-target impacts, Lilia Jenkins and Rosie Knap* write.
To support integrated pest management programs, Cesar Australia and the University of Melbourne, with the support of the GRDC, have developed a chemical use guide for growers, agronomists and farm advisers in the Beneficials Chemical Toxicity Table.
This ground-breaking resource fills a significant knowledge gap by providing an integrated and scientifically proven framework demonstrating the impact of commonly used insecticides on beneficials. The guide has already proved to be an important tool, and the team at Cesar Australia have now integrated new data and updated the table to make it an even more valuable resource.
Insecticides are a useful tool for Australian grain growers to effectively manage pests in grain production. However, beneficial insects also contribute substantially to pest suppression, and insecticides can cause substantial harm to populations of beneficial insects, particularly broad-spectrum actives such as synthetic pyrethroids and organophosphates. This disruption in natural pest suppression often paves the way for the emergence of secondary pest outbreaks where suddenly, a once-contained pest becomes problematic due to the absence of its natural predator.
To mitigate such challenges, growers can enhance the pest suppression capabilities of beneficial insects by adopting management practices that foster and sustain their populations. However, implementing such practices has been challenging as there was no integrated, scientifically proven guide to the toxicity of commonly used insecticides to beneficials. That was, until the creation of the Beneficials Chemical Toxicity Table.
The Beneficial’s Toxicity Table was first published in April 2022 and summarises the impacts of various insecticidal active ingredients on a range of beneficial insects: such as ladybird beetles, parasitoid wasps, lacewings, and hoverflies.
Developed in consultation with growers and chemical industry representatives, the table focuses on the chemicals, the field rates, growing environments, pests and beneficials specific to the grains industry. This milestone marked the first time such a comprehensive guide was developed specifically for Australian broadacre cropping.
The guide has proven instrumental in helping growers make informed management decisions on pesticides that can control pests with minimal harm to beneficial insects in situations where chemical use cannot be avoided.
Feedback so far highlights the value of the toxicity guide as a reference tool in the field.
“I work in the organic/biological space, so my recommendations are often to avoid insecticides all together, but this is not always possible,” a local agronomist said.
“So, where growers must, it is great to empower them with knowledge on what products they can use that may have less effects on beneficials.”
Since its initial publication, the Beneficial's Toxicity Table has been a dynamic and evolving resource, thanks to the ongoing efforts of lead scientist Dr Rosie Knapp and the team at Cesar Australia. The team has continued to refine the toxicity table and gather new data on important beneficial insects.
The Beneficial's Toxicity Table covers a wide array of valuable data on diverse beneficial insect species. For easy comprehension, the table presents this information in a consolidated and categorised format. For example, recent findings on snout mites, which are important predators of the red-legged earth mite and lucerne flea, have been seamlessly integrated into the broader 'predatory mites' category.
The toxicity ratings have been determined by averaging the results across chemicals and insect species and are arranged in a descending order. The least toxic chemicals begin at the top of the table and progress downward toward the more toxic chemicals.
The chemicals with a relatively low overall impact are highlighted in green, those with a moderate impact are shaded yellow. Chemicals that have a high overall impact are orange, whilst those with a very high impact are distinguished with red. In cases where a chemical's impact rating is divided, the respective cell is represented by a diagonal slash, enabling precise interpretation of its implications.
The table can assist in making targeted spray decisions that minimise harm to essential beneficial insects and maximise biological control against a specific pest. For instance, if a grower struggling with aphids has observed the presence of parasitoid wasps in their fields, they can opt for an insecticide that exhibits low toxicity towards the parasitoids.
In situations where direct monitoring of beneficial insect populations proves impractical, growers can use the table to identify pesticides that exhibit the lowest overall toxicity levels across all beneficial species, with particular mind paid to robust generalist predators such as rove beetles. This proactive approach ensures the prioritisation of pesticides that pose minimal harm to beneficial insects collectively.
The table can be accessed on the Cesar website.
This research is being undertaken as part of the Australian Grains Pest Innovation Program (AGPIP). AGPIP is a collaboration between the Pest & Environmental Adaptation Research Group at the University of Melbourne and Cesar Australia. The program is a co-investment by the Grains Research and Development Corporation (GRDC) and the University of Melbourne, together with in-kind contributions from all program partners. Assistance was provided by South Australian Research and Development Institute, Hort Innovation Australia, Crop Life Australia, Biological Services and Bugs for Bugs.
*Dr Rosie Knap is lead scientist and Lilia Jenkins is an extension scientist at Cesar Australia.
