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IPM workshop notes
Prepared by IPM Technologies
What is integrated pest management?
All of the things that we can use to control pests fit into one of three categories: biological controls (the predators, parasites and pathogens that attack pests); cultural controls (management techniques that have an impact on populations of either pests or biological control agents); and chemical controls.
Integrated pest management (IPM) simply means using all of these control options together in a compatible way, rather than just relying on chemicals. The benefits of IPM are that the three methods work together to provide sustainable pest control and in many cases far better control than if we were to use any single method on its own.
Biological control refers to the activity of natural enemies of pests. These natural enemies include predators (the beneficial insects, mites and spiders that eat invertebrate pests); parasitoids (the organisms, often flies and wasps, that feed on their hosts internally and eventually kill them); and diseases (the viral, bacterial and fungal pathogens that kill pests). In general beneficial species are naturally occurring and can be found wherever there is a suitable food source and a suitable habitat. An IPM strategy takes advantage of beneficial species by making sure that they are not disrupted by the use of pesticides and that farm or garden management practices allow the crop to become a suitable place for them to live.
Figure 1: Examples of beneficial insects include (from left to right) the larvae of brown lacewings and ladybirds, which feed on aphids and many other small soft bodied insects, and the small wasps that parasitise aphids, feeding on the aphid internally, killing the aphid and then turning the aphid’s body into its own bronze coloured cocoon!
Both pest and beneficial invertebrates can be divided into two categories, transient and resident. Transient refers to species that move into the crop from outside the farm or garden. This often happens in spring and autumn which are peak times for many species to become active. Some examples of transient beneficial species are ladybirds, brown lacewings and hoverflies. Examples of transient pests include aphids, whitefly and cabbage white butterfly. Resident species are invertebrates that are often found in the soil and live year-round on the farm or in the garden. Examples include species such as predatory ground beetles, predatory soil mites as well as pests such as slugs, snails and earwigs.
Some beneficial species are commercially available and are released into crops when naturally occurring species are not enough on their own. They are more commonly used in protected cropping and some high-value outdoor crops such as strawberries, macadamias and citrus than in vegetable production.
Figure 2: There are several companies in Australia that produce beneficial insects and mites to help manage agricultural pests. Biological control agents are reared in ’insectaries’ and are then released into crops. It is very common to use commercially produced beneficials in protected crops such as hydroponic vegetables and flowers grown in glasshouses. In field grown strawberry crops in Australia, drones are used to release predatory mites that help to control pest mites and thrips!
Cultural controls are any management methods that either enhance populations of beneficial species or disrupt populations of pest species. In some cases cultural controls can provide the most effective control of all and eliminate the need for pesticides altogether.
Some examples of cultural controls are variety selection; time of planting; weed control; crop rotation; soil management; physical barriers, sanitation and quarantine; and providing habitat and alternative food sources to attract and sustain populations of beneficials. The list of options is endless and is often determined by the individual requirements and possibilities on each farm or in each garden.
Figure 3: There are many different ways to improve the crop environment to make it more attractive and hospitable for beneficial insects. Increasing the availability of nectar and pollen supports populations of many beneficial species. For example, small wasps that parasitise aphids or caterpillars may live for several weeks or even months is they get to feed on nectar, but without a nectar feed they only survive a couple of days and their ability to help control the pests they target is dramatically reduced. Wild spaces in gardens, where a diversity of plants are allowed to go to flower; strips of flowering plants beside field crops or in the interrow in orchards and vineyards; or moveable planter boxes full of flowering plants in nurseries are all examples of practical ways to achieve an improved habitat for beneficials.
When we apply chemicals in an IPM system the choice of which pesticide to use is not only based on the efficacy on the target pest, but also on the impact the product might have on beneficial species. There are many ‘selective’ pesticides available – these are products that kill only specific groups of pests rather than targeting a wide range of invertebrates – but being ‘selective’ does not mean that they are all safe to all beneficial species.
It is important to understand the impact that each product will have on the key beneficial species for each crop type. The aim of IPM is not to eliminate all pesticide use, but to use pesticides only as support tools for when biological and cultural controls are not enough on their own. Some pesticides are not synthetic chemicals and include naturally occurring bacterial, viral and fungal pathogens that are formulated to be sprayed in the same way as chemical insecticides.
For IPM crops, the aim of monitoring is to check whether any pests are present and if so, whether they are being controlled by beneficials or cultural practices. If not, additional cultural control strategies, introduction of additional biological control agents or a pesticide application may be required.
Monitoring should always involve looking for both pest and beneficial species. The best way to do this is by direct searching and using a hand lens. Pheromone traps and sticky traps can also be useful tools under certain circumstances. The frequency and intensity of monitoring is determined by many factors including time of year, pest pressure, the value of the crop and the needs of each farm or garden.
It is important that the monitoring program is simple and practical and achievable – it is better to a do a little bit often than none at all. Time spent observing the interactions between plants, herbivores and their natural enemies is never ‘wasted’!
Invertebrates are animals without a backbone, and this includes slugs, snails, earthworms, millipedes, centipedes, insects, spiders, mites and many others. A small number of these can be pests and some are beneficial in terms of helping to control pests, but most are simply part of the food-web that involves being food for other species, nutrient cycling, pollination and decomposition processes.
Some invertebrates that originate from overseas are now important pests in Australia, and there are also biological control agents that have been deliberately introduced to help control these pests. However, the vast majority of invertebrates are native species that come from native Australian habitats. Many native invertebrates have adapted to and even flourish in various agricultural ecosystems or gardens. This includes both pest and beneficial species.
Native ecosystems are important reservoirs that contain and maintain populations of beneficial species that are valuable in agriculture and in other managed environments such as urban parks and gardens.
Knowing which species are pests, which are beneficial and which are neither in agricultural systems and gardens is essential in order to make good decisions about pest management and crop protection. However, too many farmers, gardeners, land managers and their advisors do not have the ability to correctly identify insects and other invertebrates as ‘pests’ or ‘beneficials’. This has led to a reliance on insecticides to deal with everything. There are major problems with this approach and they will be covered in this workshop.
Populations of invertebrates (both pests and beneficials) are influenced by many factors including weather, availability of food, changes in the landscape and insecticide use. These changes may occur on a small scale, such as an individual garden or farm, or across a district and beyond. Some pest insects are known to move over large distances (e.g. from Victoria to Tasmania), but populations still need to be managed on a local (farm or garden) level. Decisions will need to consider what to do in the short-term (today/this week), the medium term (this crop/this season) and the long term (next year and beyond).
- Our no. 1 book recommendation for the IPM-minded gardener: Garden Pests, Diseases and Good Bugs: The Ultimate Illustrated Guide for Australian Gardeners by Denis Crawford, published in 2015 by ABC Books
- Information about IPM Technologies Pty Ltd: www.ipmtechnologies.com.au
- Information about all biological control agents available in Australia (including links to the websites of each of the individual suppliers): www.goodbugs.org.au
- Traps and pheromone lure products: www.bugsforbugs.com.au/products/traps-and-pheromone-products/
Information about fruit fly management: www.bugsforbugs.com.au/whats-your-pest/fruit-flies/