Land mangers, urban farmers, and home gardeners are often faced with pest control decisions, including whether to use chemicals and if so, which ones to apply. Although pesticides are commonly used and considered a method of choice by many, they are harmful to bees and other insect pollinators.
Insecticides can kill directly as poisons enter a pollinator’s body by penetrating its integument (“skin”), or when it ingests poisoned nectar and/or pollen grains. Slow-acting poisons in pollen and nectar brought back to bee nests can ultimately kill the developing larvae. In other cases, pesticides do not kill the insect outright, but rather affect its ability to fly, navigate, or conduct other activities important to survival.
Herbicides used to kill weeds are also detrimental to pollinators, often removing flowering plants that native bees and other pollinators rely on. For example, dandelions, red and white clover, and plantain are all common lawn "weeds" that provide nectar and pollen for bees and other pollinators.
Least Toxic Approaches
To minimize impacts on pollinators, it’s important to avoid the use of chemical pesticides if possible. Instead, use one of two proven systems to control pests: organic growing or integrated pest management.
- Organic growers refrain from using synthetic pesticides and instead promote and enhance natural diversity and biological cycles to make a garden or farm as self-sufficient as possible.
- Integrated pest management employs many of the same practices as organic growing, but does not rule out synthetic pesticides as a last resort. A systematic process, IPM involves prevention, monitoring, and choosing the least toxic pest control when action is necessary.
Both IPM and organic growing include measures such as using lures and baits that help monitor pest populations and even attract them away from plants without the use of chemical pesticides. Selecting pest-resistant plants is another basic preventive practice.
Among the many other tools of a least-toxic approach to pest management is maintaining diverse habitat for beneficial insects such as lady beetles and assassin bugs, which prey directly on pests. Other beneficials are parasitoids, such as parasitic wasps, which develop in or on pest larvae, ultimately killing them to help keep populations in check. Recent studies indicate that daisy-like native flowers such as asters and coneflowers, along with culinary herbs such as dill and parsley that produce inverted parasol-shaped inflorescences, are best at attracting these beneficial insects. Many also provide nectar and pollen for pollinators. For more information on beneficial insects, see here. If chemical pesticides are necessary, they should be applied in the evening or at night when most pollinators are not actively foraging.