Pesticides and Bees
Pollinating insects are important for fruit crops. Insecticide application during the bloom period should only be considered when an insect problem which threatens the crop is present. Some of the insecticides registered for fruit crops clearly indicate that they are not to be applied during the bloom period. Others do give recommendations for application during bloom but caution must be used to minimize bee poisoning.
All insecticides listed in the Guide (except Foray and Dipel) are poisonous to bees and other pollinating insects. There are a number of common sense steps that should be taken to avoid accidental poisoning of bee colonies:
- Do not apply any insecticides to flowering crops during the time of day when bees are active.
- If it is necessary to spray a crop where honey bees are foraging, do so early in the morning or late evening when bees are not active. There may be a greater risk of bee poisoning with morning applications.
- Emulsifiable (liquid) formulations usually have a shorter residual toxicity to bees than wettable powders.
- If bee colonies are near the field to be treated, contact the beekeeper at least 48 hours before insecticide application.
- Communication between growers, commercial pesticide applicators and beekeepers is still the most effective strategy for avoiding bee poisoning.
The following table indicates the maximum times required for the insecticides listed in the Guide to be degraded by weather to a low hazard level for bees. These times are to be used as general guidelines only, since most of these insecticides have not been tested for bee toxicity under western Canadian conditions, and environmental conditions will influence the rate at which pesticides degrade.
Fungicides are generally not considered to have toxic effects on bees however Captan has been reported to have toxic effects on honey bee larvae. Captan is not harmful to the adult bees but can be carried back to the honey bee colony and may then have toxic effects on the brood.
Field Hazard of Insecticides to Honey Bees
| Insecticide | Toxicity Rating | aResidue Hazard (Days) |
| Apollo SC | c |
c |
| Cygon | 1 |
7 |
| Cymbush | b |
b |
| Decis | 2 |
1 |
| Diazinon | 1 |
2 |
| Dibrom | 1 |
1.5 |
| Dipel, Foray | 3 |
_b |
| Endosulfan | 2 |
2 |
| Furadan 480F | 1 |
5 |
| Guthion | 1 |
5 |
| Kelthane | 3 |
none |
| Lagon | 1 |
7 |
| Lannate | 1 |
1.5 |
| Lorsban | 1 |
3.5 |
| Malathion | 2 |
2 |
| Metasystox-R | 2 |
0.5 |
| Morestan | 3 |
b |
| Orthene | 1 |
2.5 |
| Pirimor | 2 |
0.5 |
| Pyrinex | 1 |
3.5 |
| Ripcord | b |
b |
| Sevin | 1 |
7 |
| Sniper | 1 |
5 |
| Thiodan | 2 |
2 |
| Thionex | 2 |
b |
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