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Insecticides and Environmental Impact | |
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Insecticides have the potential to impact the environment by destroying beneficial insects, entering water through drift or runoff, or depositing on vegetation that may be contacted or eaten by wildlife. These potential effects of insecticides have been recognized for many decades and the use of insecticides is carefully controlled through federal and provincial legislation and through industry standards.
Wildlife
Annual field crops such as canola are temporary monocultures without complex ecological interactions. They are less important to wildlife than permanent habitat and foraging areas. The noise and activity of pesticide application equipment reduces the direct spraying of wildlife. Birds and other wildlife tend to move out of fields being sprayed.
The insecticides used to control the Lygus bug are excreted from the body rather than accumulated in the body fat. This prevents the phenomenon known as "biomagnification" which results in pesticides stored in body fats that can be ingested by animals (including humans) higher up the food chain.
Beneficial Insects
Most insecticides will have an effect on some beneficial insects: predators and parasites of insect pests; pollinators; and the food source for other species. Any insects in the upper crop canopy at the time of spraying will be exposed to a potentially lethal dose of insecticide at the time of application, depending on insect species and insecticide. Insects entering treated fields can be harmed if re-entry occurs shortly after application.
The mortality of beneficial insects is an important consideration when spraying complex ecosystems such as forests or agricultural crops that are established over a period of years (e.g. alfalfa). Insecticide applications made to agricultural monocultures once within the growing season will not result in long-term suppression of beneficial insect populations. Re-population can occur from untreated fields, roadsides, forage fields and other unsprayed areas.
Insecticide spraying when crops are in bloom and used by bee populations can have significant consequences for commercial bee production if appropriate steps are not taken to protect the bees. The fact sheet "How To Reduce Bee Poisonings From Pesticides" will be of assistance to beekeepers and canola producers in areas of commercial bee production. The same precautions used to protect commercial bees will help other pollinators.
Insecticide Breakdown
The insecticides used in Alberta today tend to have a relatively short period of insecticidal activity - several days to several weeks. Persistence in soil or in water can be longer than the activity period, depending on the chemical and environmental conditions. Insecticides break down through chemical reactions triggered by exposure to sunlight and moisture. They are also broken down in soil by microbes that use insecticide molecules as a food source.
Spraying a mature crop canopy will substantially reduce the amount of insecticide that enters the soil. Insecticides tend to bind to leaf surfaces and are not readily washed off with rainfall once dry. Where an insecticide has low water solubility or binds strongly to organic matter, surface or groundwater contamination is further minimized.
Water Protection
Anyone applying any insecticide, herbicide, fungicide or other pesticide to field crops must be extremely careful to ensure that these products do not drift into water sources. Many insecticides can affect aquatic life at concentration levels far less than those that affect humans.
It is illegal to apply pesticides in a manner that could cause an adverse effect.
This information has been developed and supported by:
The above contributors are able to supple more detailed information on insecticides and their impact on the environment.
Alberta Environment maintains a 24 hour toll-free line for environmental complaints and emergencies: phone 1-800-222-6514.
For more information, contact Janet McLean
The contents of this page are no longer available.
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For more information about the content of this document, contact Scott Meers.
This document is maintained by Shelley Barkley.
This information published to the web on November 9, 2001.
Last Reviewed/Revised on November 17, 2006.
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