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By Sharon Downes Louise Thatcher Emilie Roy-Dufresne Belinda Stummer Mary Whitehouse Sandra Williams Javier Navarro Garcia 18 May 2021 8 min read

Some solutions to manage agricultural pests do not require chemicals.

A reduced reliance on agrichemicals is needed

Reduced effectiveness of agrichemicals due to resistance, fewer new products in development, and restrictions imposed by markets and new regulations are driving a chemically limited future for pest control in agriculture in Australia and abroad.

Without intervention, this will severely curtail global production of food and fibre from agriculture as agricultural pests, weeds and diseases (“agripests”) run increasingly unchecked.

However, this coincides with our reliance on chemicals to control agripests being at an all-time high. In Australia the use of agricultural chemicals such as herbicides, insecticides, miticides, fungicides, antibiotics and anthelmintics has doubled since 1992. As a country, we now use over 50,000 tonnes per annum, with Australian farmers spending around $3.1b on agrichemicals in 2017/18. This is a figure which increased by almost $1 billion since 2009/10, outstripping inflation over the same period by more than threefold.

For almost 100 years CSIRO and our partners developed alternative products and practices, and we are now delivering them across multiple scales to change thinking about how agripests interact with other parts of production systems on farms and across sectors and landscapes.

However, a key feature of lessening the reliance on chemicals must be a robust approach of measuring and monitoring the impact of changes in how agripests are controlled. In this respect, our rethinking goes beyond developing innovations to reduce the use of and replace current methods.

Our vision is a codeveloped strategic national approach that targets the future benefits of durable agripest control across sectors and landscapes and would enable evidence-based decisions to assist with achieving goals. This will require cooperation from a wide range of actors from producers to consumers including policy makers, scientists, and agribusiness to rethink the fundamental strategy behind the sustainable control of agripests. The impacts would include reduced costs of control and better management to prolong resistance to agrichemicals and hence better longevity of key products.

Our farms can be more sustainable. Improved practices and technologies already exist, but more work is still needed to implement them.

Re-designing farm systems to be less vulnerable to pests

For a low-chemical approach to be effective, CSIRO is showing how producers could re-design their farms using a wide range of Integrated Pest Management (IPM) strategies that consider impacts on the whole system over the long-term.

For example, our research has shown that farmers can enhance the services provided by beneficial insect communities - or by predators such as birds and bats - by managing natural habitats in or around the farm or planting dedicated crops that act as nurseries. Those same crops could be used to attract pests away from the main crops. Trap cropping was developed as part of an integrated control program for greyback canegrub in the Burdekin district of Australia. By manipulating the harvesting and planting sequence, the trap crops attract egg-laying beetles to specific blocks of the crops, reducing the pressure on later planted cane.

Pests could also be controlled by inoculating the field with beneficial insects (i.e., predators) which prevent populations building to economical threshold levels. Augmenting with beneficials can also reduce subsequent insecticide use, as farmers may be reluctant to kill the beneficials in which they have invested.

We have shown that soil pests and diseases can be prevented from establishing in fields by rotating crops, so that preferred hosts are not always available. Timing the planting of cereals so that they can be grazed by stock during winter and then recover to produce a harvest, produces a plant with a strong root mass going into spring which can resist soil pests and avoids late season insect attack. A current CSIRO project is investigating altering the time of lambing to reduce their exposure to parasitic diseases occurring in summer to reduce the reliance on parasiticides. We are looking to apply CSIRO’s capability to an extreme form of management change known as vertical farming that could enhance pest control. Here plants are grown inside using hydroponics in trays stacked on top of each other and provided with artificial light. This type of habitat is very suited to pest control by augmenting monitoring with beneficials in a stable environment.

Future farming to limit pesticide use could see regional groups of growers develop a process known as ‘strategic rotations’ to co-ordinate the use of refuge crops (or crops with varying resistance genes) to disrupt selection on pathogen/pest populations to develop resistance. Computer modelling demonstrates the power of these rotations when multiple farming enterprises co-ordinate at the landscape-level.

Many agripest chemicals are losing their effectiveness, and often harm the environment. However, new alternatives are being found.

Replacing chemicals with effective and sustainable alternatives

Alternatives for agripest control include naturally occurring biological organisms (microbes, predators or parasites), plant-derived biochemicals, molecular tools such as nucleic acids, vaccines or peptides, genetic breeding and physical means.

Biological options physically attack or compete for similar resources with pests. They can also act as probiotics to improve the natural immunity of livestock and crops or produce bioactive compounds that can be extracted and applied as sprays or injectables.

Genes that regulate the production of bioactive compounds can be engineered into fungi or bacteria for mass production or directly into the susceptible host for pest resistance. For instance, Monsanto, genetically inserted moth specific toxins from a soil bacteria into cotton plants to provide constant control. CSIRO developed elite cotton varieties containing these traits and together this technology enabled the industry to reduce its reliance on chemical sprays for the cotton bollworm by more than 92 per cent since the mid-1990's.

Resistance to pests can be bred into plants for example, using traditional quantitative genetic approaches or genetic modification. For example, international research led by CSIRO ‘stacked’ five rust resistance genes in wheat which is analogous to putting five deadlocks on a door to thwart an intruder. This technology is now being extended so that the ‘gene stacks’ provide durable resistance against a range of rust pathogens.

Physical technologies like irradiation, exposure to electromagnetic energy or heat and modifying atmospheres (e.g., cold-chain transport) provide alternatives for postharvest pest protection of fruit and vegetables. For example, we have shown that continuous combined microwave and hot air treatment of apples for fruit fly disinfestation shows promise as an alternative chemical free quarantine treatment.

Automated imaging systems can differentiate weeds from pastures or crops and trigger laser diodes, micro‐flames, air-blasting and capacitive coupling of electric fields for targeted control. Physically removing weeds by manual or mechanical means, such as hay making, mowing and grazing, mulching, tilling, burning or by hand are examples of common practices. Our novel research is examining virtual fencing technology as a farm automation tool that utilises livestock grazing for targeted weed control.

Reduced chemical use through informed decisions

Sound decision-making is challenging in agriculture because many integrated components of the system require timely detailed monitoring to inform the most effective management strategy.

Sensors can help identify, detect and record agripests and provide more accurate and frequent estimates of populations to enable better decisions. For instance, RapidAIM is a CSIRO-developed sensor technology which detects fruit fly in orchards and farms in real time.

Traditional pest control decisions consider fluctuations in population abundance for the pest and its natural enemies, damage levels, and the effectiveness of products based on known resistances, their application rate, and when and how they are applied.

New ecological pest forecasting models can integrate key observations with other variables such as pest breeding rates and climate to forecast outbreaks or potential losses in production. This enables pre-emptive tactics to be used such as the release of beneficial parasitoids, prediction of pest abundance when observations are lacking, and guiding biosecurity strategies that prevent the arrival of pests into Australia. One of CSIRO’s recent initiatives was to assist the Australian Plague Locust Commission develop a means by which they could daily map the abundance of the Australian Plague Locust.

Our research contributes to pest management programs in livestock that promote pre-emptive treatments, parasite monitoring schedules and non-chemical strategies such as nutrition, genetics and pasture management. Computer models of parasite epidemiology can also inform integrated management programs by predicting the effects of different approaches on worm control and anthelmintic resistance. For example, sheep producers count worm eggs in sheep faeces and monitor their reduction over time to understand the size of worm populations on their property and this method also underlies detection of resistance to drenches used to treat sheep for worms.

Chemical treatments are also used for veterinary purposes, such as against parasites that attack livestock.

A collaborative pest management innovation hub

As Australia’s national science agency, CSIRO is well placed to catalyse innovation and lead an agripest collaboration hub that brings together Australian states, industries, research disciplines, industry sectors and pest-type sectors for concerted efforts towards major pest management targets. We see this as a starting point to identify priority opportunities and targeted innovation pest management efforts to reduce agrichemical over-reliance.

By working collectively, agripest innovations can be targeted toward agricultural uses where they can bring the greatest practise shifts towards durable control and/or where interventions are likely to require alternatives to chemicals.

A codeveloped national agrichemical monitoring resource meeting international standards would be useful for industry and public use especially if was adaptable for future challenges and technological advances. This would create opportunities to maximise Australia’s food production reputation and responsiveness and could also demonstrate segments of low pesticide use (e.g. for potential market advantage) and areas where opportunities or need for reduction exist (e.g. high risk usage).

This is an opportunity to improve agripest control and agrichemical sustainability and appeal to industry by reducing the costs to farmers of chemical use. A sector wide and farm-level approach to improving agrichemical management is an important goal for underpinning future sustainability of food and fibre production.

CSIRO would like to know your thoughts on this topic. Please tell us:

1. How agrichemicals impact your day-to-day life right now

2. What you see as the biggest issue in a chemically limited future scenario

3. What you think are the highest priority research areas to focus on

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