Using biopesticides to protect crops from agricultural pests.
What are biopesticides?
Biopesticides are pest management agents and chemicals derived from natural sources such as bacteria, fungi, viruses, plants, animals and minerals. Also known as biological pesticides, they can provide an alternative to synthetic chemicals used to control pest populations in crop production and other settings. Biopesticides can be used by anyone looking for an alternative pest management approach, such as commercial growers, specialty crop growers, ornamental plant growers, or household gardeners. Like synthetic chemical pesticides, however, biopesticides must be registered by Health Canada’s Pest Management Regulatory Agency (PMRA) before becoming available for use in Canada.
Pests include diseases, insects, mites, and weeds that damage crops and reduce crop yield and quality. Many biopesticides are more environmentally friendly than synthetic pesticides. For instance, many biopesticides target specific pests and have little negative impact on the surrounding ecosystem and human health.
Types of biopesticides
In Canada three types of products are recognized as biopesticides: microbial, semiochemical and non-conventional pest control products.
Microbial Pesticides are pesticides that contain living microorganisms such as bacteria, fungi, viruses, protozoans, algae, mycoplasma, rickettsia and related organisms and associated metabolites (or by-products), that are used to control pests. Many microbials target only specific pests. For example, the Codling Moth Granulosis Virus is a microbial pesticide sprayed on apples which infects and kills only the Codling Moth larvae, one of the most serious insect pests in apples. See Pest Management Regulatory Agency (PMRA) directive: DIR2001-02.
Semiochemicals are message-bearing chemicals produced by an organism that causes a behavioural response in another organism of the same or different species. Synthetically produced equivalents of these chemicals are also considered to be semiochemical biopesticides. The most common are insect sex pheromones, which are used in monitoring traps, lure-and-kill systems or to disrupt the mating of target pests. For example, the Grape Berry Moth Pheromone, when released in large amounts, disrupts the ability of the Grape Berry Moth males to locate females. This reduces their reproductive rate and controls its populations. See directive PRO2002-02 from the Pest Management Regulatory Agency.
Non-conventional pest control products are substances used by the general public for a variety of purposes, but which can also be used as pest control products. They generally pose a low risk to humans and to the environment. Some examples include food items or preservatives such as garlic powder or table salt; vinegar; plant extracts and oils such as mineral oils; or fertilizers and plant growth supplements such as mineral salts. For example, vinegar is known to kill weeds, while mineral oil and powdered sugar is used to control mites. See PMRA directive: DIR2012-01.
Attributes of biopesticides
Biopesticides are targeted: Biopesticides frequently target a very narrow species range; meaning, they generally deter or kill only the pest damaging the crop. They rarely disturb the many surrounding organisms such as beneficial insects, microbes, vegetation and wildlife. On the other hand, many conventional chemical pesticides may not only affect the target pest, but also the surrounding ecosystem and humans, requiring careful handling to mitigate these potential impacts.
Biopesticides help prevent pesticide resistance development: Pests generally take longer to develop resistance to biopesticides, as biopesticides often have complex modes of action (a mode of action refers to how the pesticide works to kill or deter a target pest). In contrast, some synthetic pesticides have relatively simple modes of action, often related to a single gene, and this can enable pests to develop resistance more easily when these compounds are used repeatedly.
Biopesticides have short residue periods: After application, many biopesticides do not linger in the environment for a long time; they quickly det eriorate and degrade. In technical terms, they are “non-persistent” in the environment, offering less exposure and potentially less harm to humans and the environment.
Short restricted entry intervals: The majority of biopesticides have low restricted entry intervals. After application, farmers can go into the field or greenhouse immediately or within a short period of time to prune, apply irrigation, harvest, or implement other cultural practices. Many chemical pesticides, by contrast, due to their higher persistence and toxicity, require a delay in re-entry to the field to work on crops.
Integrated Pest Management (IPM): Biopesticides generally perform particularly well in IPM systems. With their lower toxicity profile, they are compatible with the use of classical biological control agents such as predatory mites and lady beetles. Because they often are most effective at low pest pressures, they are well suited to be used in combination with scouting and monitoring activities, which detect pest problems before they are out of control. As well, IPM programs which include the rotation of biopesticides with conventional chemical pesticides can reduce reliance on single chemistries and delay the development of resistance within pest populations.
Please contact the Pest Management Centre for more information on its biopesticide activities.
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