Integrated Pest Management (IPM) was developed in the 1970s in response to concern over using broad-spectrum insecticides like DDT. By adding biological and physical pest control methods to their arsenal, farmers found they could minimize pesticide use. IPM gained interest particularly as a cost-cutting measure by non-organic fruit growers.
IPM approaches pest control from several different angles. It starts by trying to prevent pest damage. Then, if pest numbers climb, you can, for example, release beneficial organisms to attack the pests while also removing the pests’ habitat. If that isn’t enough, you might strategically apply a biopesticide that targets the most vulnerable stage of the pest.
Several Organic Science Cluster 4 (OSC4) research activities explore ways to control pests that are cost-effective and have a minimal environmental impact. In this article, we’ll describe how IPM works using examples of OSC4 research.
Components of an IPM Strategy
Learning
To develop an IPM strategy, growers need to identify pests at different life stages so you can implement a strategy at the right time – for example, when you see eggs rather than waiting until those become voracious caterpillars. It helps to also learn about the pest’s diet, habitat, and life cycle, and what its predators are. This information enables the development of a fine-tuned pest management strategy.
Set action threshold
The goal of IPM is to find a balance where pests are kept in check so they don’t cause significant economic damage. In IPM, growers decide what losses can be absorbed and then calculate when pest numbers are high enough to take action.
Monitoring
IPM relies on monitoring to evaluate when pest numbers require a response and, later, to assess whether the strategy is effective or needs modification.
OSC4: Mapping Spotted wing drosophila
At UBC, Drs. Juli Carrillo and Claire Kremen plan to expand “bio-surveillance” to better understand how populations of pests and their natural enemies change over time. They will gather data to “create an interactive insect map relating species occurrence with environmental factors and landscape features.” Their focus is on Spotted-wing drosophila (SWD), Drosophila suzukii, but their research may serve as a template for dealing with other pests.
Prevention
Prevention can start with creating less hospitable habitat for the pests. This can take many forms, such as increasing row spacing to improve air flow if fungal diseases are a problem. You can also create habitat for the enemies of the pests – the predators, parasites, and parasitoids. This way, your pest control efforts will be amplified by a legion of other organisms, such as ground beetles, tachinid flies, parasitic wasps, and lady beetles.
OSC4: Providing habitat for beneficials in vineyards
Dr. Liette Vasseur at Brock University is using native plants as cover crops in vineyards. In addition to protecting the soil, the cover crops might provide habitat for insects that attack pests. She is also looking at the impact of perennial plants, such as trees and shrubs, along the perimeter of vineyards. These can provide habitat for beneficial organisms that attack pests while also increasing on-farm carbon storage.
OSC4: Ecological intensification of perennial berry farms
Drs. Carrillo and Kremen are investigating “ecological intensification” of the perennial berry farm-scape. One aspect of their research evaluates how growers can support the wild organisms that attack pests.
On organic farms, non-organic farms, and experimental research stations, the researchers will evaluate how the abundance and diversity of such beneficial organisms are influenced by floral strips, cover crops, and grassy field margins. They will then develop best management practices for creating and maintaining habitat for beneficial organisms.
Image: Phacelia floral strips are planted between blueberry rows. In the background, a technician uses a “bug vacuum” to survey for parasitoids. [Photo credit, Hannah Anderson, UBC]
Improving crop resistance
Imagine two fields with the same number of pests -one has minimal yield loss and the other is devasted by the pests. Crop resistance plays a role in how much pests can damage crops. Crop genetics can boost resistance but other factors such as soil quality and moisture levels can also come into play. When a plant is stressed, whether it be due to drought, nutrient imbalance or pressure from other pests, it is more susceptible to pest damage.
OSC4: Pest resistance in dry beans
At the AAFC Research Station in Harrow, Ontario, Drs. Robert Nurse and Jamie Larsen are working to improve dry bean genetics. They aim to release varieties with genetic resistance to pests, particularly the following which can all result in significant yield losses: potato leafhopper (Empoasca fabae), which attacks bean seedlings; two fungal diseases that affect foliage, anthracnose (Colletotrichum lindemuthianum) and white mold (Sclerotinia sclerotiorum).
This activity highlights the need for research focused on organic production. For example, plant breeders are aware of genes for resistance to fungal diseases. However, there has been little incentive to develop resistant cultivars given that most production is non-organic, and these diseases are controlled by chemical fungicides on non-organic farms.
Biological control
Biological pest control relies on using other organisms (like parasitic wasps) to attack pests or disrupting the life cycle of pests by using chemicals produced by other organisms (such as pheromones). A few forms of biological control are described below.
Releasing organisms to attack pests
In addition to providing habitat for wild populations of beneficial organisms, farmers can release organisms that will prey upon or parasitize pests. Timing can be critical – this works best if the beneficials can multiply and become established before the pest cycle peaks; this requires understanding the life cycles of pests and beneficials. For example, tachinid flies lay eggs in the larvae of certain pests (e.g., cabbage looper). After hatching, the larvae eat the caterpillar from the inside out. If you release the flies too early, they might not find enough caterpillars to lay eggs in. Release too late and your crop might be consumed by caterpillars and allow a second generation of loopers before the flies have an effect.
With introduced beneficial organisms, just like wild ones, it helps to provide habitat to sustain the populations between releases and possibly enable them to become established.
Mating disruption
Many insects use pheromones to communicate, including sex pheromones to attract or detect members of the opposite sex. If a grower releases pheromones, this communication is disrupted. Mates might not be able to find or attract each other. The result: less mating and fewer offspring.
Herbivory Induced Plant Volatiles (HIPV)
Just as insects and animals use pheromones to communicate within their species, plants release chemicals as a form of communication. The release of Herbivory Induced Plant Volatiles (HIPV) is a bit like sending out an SOS. For example, when an insect chews a leaf, its saliva triggers the plant’s defense system to release HIPV into the air. The insects that prey upon or parasitize the pest are drawn by the HIPV to the injured plant (and the pest, their food).
Scientists have found ways to produce HIPV so it can be released into crops. This will, ideally, attract surrounding predators and parasitoids of the pest and lead to biological pest control without introducing new species into the environment.
OSC4: A multi-pronged approach to biological control of cranberry insect pests
Didier Labarre at the Cranberry Research and Innovation Centre (CRIC) and Dr. Éric Lucas at l’Université du Québec à Montréal, are evaluating a multi-pronged approach to pest control. While they focus on organic cranberry production, as with other OSC4 activities, their research results may have broader applications in other organic and non-organic crops.
The OSC4 research activity is evaluating four ways to control the blackheaded fireworm (Rhopobota naevana) and cranberry fruitworm (Acrobasis vaccinii). These two pests can cause between 60% and 95% yield loss in organic cranberries.
- Parasitic wasps – Trichogramma are tiny wasps (about ¼ the size of a pinhead). The wasps lay eggs in the eggs of other species. The wasp larvae consume the eggs and emerge as adults. The OSC4 researchers will assess existing populations of Trichogramma and develop cost-effective ways to introduce more Trichogramma if needed.
- Viruses and bacteria – The scientists will identify viruses and bacteria (specifically Baculovirus and Bacillus thuringiensis) that naturally control cranberry pests. They will then multiply the microbes within the bodies of pests and release them back into the crop to infect more pests.
- Mating disruption – The researchers will compare various forms of mating disruption, such as the release of pheromones by microencapsulated (MEC) formulation into the air, fixed pheromone dispensers, and MEC by chemigation (through irrigation).
- Herbivory Induced Plant Volatiles (HIPV) – The researchers will evaluate the cost-effectiveness of releasing HIPV with the goal of attracting predators and parasitoids of cranberry pests.
Physical control
Pests can be controlled by physical and mechanic means, such as traps to capture pests, netting to exclude pests, or mulch to prevent pests from reaching crops.
Sticky traps
Sticky traps are often used in IPM to monitor insect pest populations. The traps can also, however, be used as pest control, particularly in enclosed spaces such as greenhouses. In the field, sticky traps are less effective but may complement other forms of pest control. They should be used cautiously however, as the traps can attract beneficial organisms, such as parasitoids and spiders, that would otherwise attack the pests.
One colour does not fit all. Many pests, including aphids, leaf miners and whiteflies, appear to prefer the yellow sticky traps but, for example, Western flower thrips seem to prefer blue traps and blunt-nosed leafhoppers seem to prefer green. Even within a species, there can be a range of preferences: in several species of leafhoppers, males are more attracted to the yellow sticky cards than females. This is unfortunate because it is more critical to kill the females that are capable of laying eggs rather than the males (because one male can fertilize many females).
OSC4: Different colours of sticky traps
Dr. Vasseur is comparing the effectiveness of yellow, green, and blue sticky traps and various colours of sticky cards in vineyards to attract pests, for both monitoring and pest control. The research team will record the number and type of pests and beneficials captured on the sticky cards.
OSC4: Sticky cards + AI = Automated insect ID
Researchers at UBC and AAFC-Agassiz are developing automatic insect identification with a focus on Spotted Wing-Drosophila (SWD) and their natural enemy, figitid parasitoids. The researchers scanned and digitized sticky cards collected from partners’ fields across Canada. These images were used to refine artificial intelligence (AI) protocols towards the development of an automated monitoring system.
Image: A scanned yellow sticky card dotted with insects is used to train the algorithm that will automatically identify insects. [Photo credit, Quentin Geissmann, UBC].
OSC4 researchers are contributing to the future of pest control in organic and non-organic farms by exploring innovative multi-pronged approaches across crop types and regions. The future of IPM envisioned by the OSC4 researchers is effective pest control with minimal environmental costs.
Published November 29, 2024
Organic Science Cluster 4 is an industry-led research and development endeavour co-managed by the Organic Federation of Canada and the Organic Agriculture Centre of Canada at Dalhousie University and supported by the AgriScience Program under Agriculture and Agri-Food Canada’s Sustainable Canadian Agricultural Partnership together with over 80 funding partners.
