MANAGING INSECTICIDE RESISTANCE:

Practice Integrated Pest Management

Using insecticides appropriately can significantly reduce pest populations that threaten crop yield and quality. However, some insects can become resistant to insecticides. More than one-third of Canadian growers are concerned that insecticide resistance will increase in the next five years.

Growers can slow the development of resistance by taking three actions: evaluate the need for an insecticide; follow insecticide best practices; and practice Integrated Pest Management (IPM). This factsheet focuses on the third key action – practicing IPM.

INTEGRATED PEST MANAGEMENT

IPM includes a combination of cultural, biological, and mechanical controls.

Practice a variety of cultural control methods

Cultural pest controls are practices that make the environment less attractive to insect pests. They are very important for pest management and should be practiced every year.

Choosing a pest-resistant or pest-tolerant crop variety is a prime example of cultural control methods. Pests are less likely to attack resistant varieties, while tolerant varieties can withstand a greater amount of pest pressure than a non-tolerant variety before impacting yield. Keep in mind that varieties with built-in pest protection (e.g., Bt proteins) should be rotated for effective control of targeted pests.

As part of an IPM strategy, you should also vary planting dates to avoid peak activity times of a pest. For example, planting early can allow plants to become well established and therefore more tolerant to pest attack.

Cultural pest controls are practices that make the environment less attractive for insect pests. They are very important for pest control and should be practiced every year.

Healthy crops better withstand insect attack

Another important cultural practice that helps limit pest issues is crop rotation. Plant a host crop as far as possible from where it was grown previously or from where a neighbouring field will have a similar crop. This makes it more difficult for pest populations to build, and for pests to migrate into a crop, especially if they are walking insects or weak fliers. In addition, be careful that other crops in your rotation are not susceptible to the same pests (e.g., European corn borer on corn and potatoes).

Ensuring that your crops are healthy will also help you keep pests in check. Healthy crops establish more quickly, can out-compete weeds, and more easily withstand insect and disease attacks. As well, being aware of sources of stress such as nutrient deficiency, pests, and weather conditions is vital. Develop a sound soil fertility plan to ensure strong crop establishment and growth.

Use practices that conserve beneficial insects

Conserving natural enemies (e.g., arthropod predators and parasitic wasps) is another way to reduce pest pressure.

The best way to harness the power of these beneficial insects is to support their populations in and around your fields. Providing a habitat for natural enemies is important for keeping them close by. Maintain a habitat that includes flowering plants, shrubs, clean water and nesting sites. Minimize spray drift to reduce harmful effects on beneficial insects in existing habitats next to application sites, such as hedgerows and woodlands, when these do not harbour the target insects.

For horticultural crops, avoid peak pest pressure by delaying planting (when possible) for pests that can be monitored by pheromone traps.

Be mindful of beneficials if you do need to apply chemical control for insect pests. Choose the right insecticide for the right pest on the right crop. Apply only when damage and thresholds are met or are expected to be exceeded. Also consult the label for information about times to avoid spraying (e.g., when pollinators are foraging).

Refer to these factsheets for best practices to protect pollinators: around your fields.

IPM includes a combination of cultural, biological, and mechanical controls.

The best way to harness the power of beneficial insects is to support their populations in and around your fields.

Mechanical methods work well to control pests

Physical barriers can be effective in restricting pest movement. Some examples include: plastic mulch on raised beds to reduce damage from soilbased insect pests; row covers to minimize flying pests; and screening on greenhouses vents.

Aluminized or different colours of plastic mulch can reduce pest populations by modifying the surrounding light that flying insects use for crop recognition. The pests become confused by the light and are unable to find the crop.

An example of mechanical control in horticultural operations is physically removing and destroying infested plants and, when possible, the pest itself.

A field crop example is removing weeds that host pests such as winter annuals for cutworms or buckthorn for soybean aphids.

Consider the use of biopesticides

Biopesticides should also be considered as part of your IPM plan. These are products created from bacteria, fungi, plants, and minerals with complex modes of action (MoAs), making it difficult for pests to develop resistance.

Some examples of biopesticides include pheromones (chemicals that insects use to communicate within their own species). These are used for mating disruption or ‘attract and kill’ strategies and are commercially available for several insect species.

Microbial pesticides, which contain living organisms such as algae, viruses, fungi, and bacteria, can also be used for species-specific pest control.

Biopesticides are products created from bacteria, fungi, plants, and minerals. They have complex modes of action, making it difficult for pests to develop resistance.

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