Ministry of Agriculture
Guidelines for Protecting the Environment from Pesticides
Protecting Bees and Beneficial Insects
Impact of Pesticides on Bees and Beneficial Insects
- "Pesticides" refers to chemicals used in controlling all pests, from weeds and fungi to rodents and insects. Insecticides are chemicals used specifically in controlling insects.
- Some broad-spectrum insecticides include highly toxic materials that may affect a wide range of insects and other invertebrates, good and bad.
- Most herbicides and fungicides have relatively low toxicity to insects.
- Beneficial insects and mites include:
- pollinators such as honeybees, bumblebees and many other solitary bees.
- insect predators such as ladybugs, wasps, predatory mites and spiders, and the larvae of lacewings and hover (syrphid) flies.
- parasitic insects such as certain wasps (brachonids, chalcids, ichneumonids) and flies (tachinids, sarcophagids)
- Insect predators and parasites play a vital role in keeping insect pests at manageable levels. Incorrect use of chemicals may kill these biological control agents that could result in population explosion of the pest later in the season.
- Careless use of insecticides may also kill pollinating insects resulting in poor fruit set and lower crop yields at the end of the season.
- It is the growers interest to optimize the efficacy of the pesticide used, while minimizing the chemicals impact on non-target organisms and the environment.
|Bumble bee||Yellowjacket wasp||Honey Bee|
|Adult and larval ladybird beetle feeding on aphids||Parasitic wasp pupae that emerged as larvae from a Bruce spanworm larva||Adult green and brown lacewings|
Steps to Minimize Pesticide Impact
- Understand the biology and life cycle of the insect pest and determine the best time for insecticide application.
- Select the least toxic insecticide whenever possible.
- Determine the potential impact of the selected insecticide on beneficial insects, such as predators and pollinators.
- Never apply an insecticide without first confirming that the insect pest population is threatening the crop.
- Before application, always read the label and follow instructions.
- Pollinating insects are particularly vulnerable to poisoning as they visit field crops during the blooming season. When bees are killed, growers lose their investment in pollination rental fees, and lose crop yield because of incomplete pollination.
- Honeybee poisoning occurs when foraging bees collect contaminated nectar or pollen from sprayed blooming crops or contaminated water sources.
- Honeybees are the most important pollinators but wild pollinators may also be important. These include bumblebees, orchard mason bees (Osmia spp.), leafcutter bees, etc.
The following precautions will help reduce the risk of bee poisoning:
- Move honeybee colonies into the field after pre-bloom insecticides have been applied. Have the colonies removed as soon as pollination is completed.
- Do not spray insecticides on the crop when the blossoms are open, or where spray drifts may contaminate the open blossom. If insecticides must be applied in case of emergency, spray in the evening when bees are not foraging. Some products allow for early morning sprays but they always pose a greater risk to bees than evening sprays. Bees usually do not forage at temperatures under 13C.
- If insecticide spraying is necessary when bees are foraging, contact the beekeeper(s) first to protect the bees.
- Use insecticides that are relatively non-hazardous to bees whenever possible. Diazinon, Guthion, Parathion and Sevin are hazardous to bees when applied anytime during bloom on which bees are foraging. The hazard exists even if they are applied in the early morning or late evening.
- Malathion is hazardous to bees when applied in the early morning and throughout the day. The hazard may be avoided when applied during the evening.
- Use the least hazardous formulation: liquid formulations are less toxic than wettable powder formulations.
- Ground applications are generally less hazardous than aerial applications as there is usually less drift.
- Work closely with your beekeeper to maximize your crop pollination and minimize problems.