Homeowners often use more pesticide (per unit area) than agricultural producers and should consider minimizing or eliminating pesticide use wherever possible. Avoid spraying when the crop or other plants in the field or nearby (including weeds) are in bloom. Do not spray when winds favor drifting, and use ground applications instead of air where possible. Apply insecticides in the late evening, night, or very early morning when fewer bees will be foraging, and when spray drift and volatilization due to extreme heat are at a minimum. Use chemicals with reduced risk to bees whenever possible (see Tables below). Dust may be unavoidable in some cases, such as during the planting of treated corn and soybean seeds – small amounts of these chemicals mixed and forced into dust plumes by planters is very highly toxic to bees. If insecticides must be used, several steps may be taken by the grower to reduce the hazard to bees.
Ensure that there is a pest problem before applying any insecticide. Pesticides are often over-applied because applications are made prophylactically. Reducing the Hazard (Growers and Homeowners) Honey bees often prefer stagnant pools for drinking water. Contaminated water sources are also a culprit, as bees seem to favor ponds, wheel ruts and mud puddles for their drinking water. Uptake of contaminated soil water by both crop and non-crop plants is a new and important route for exposure as well – many types of pollen from crops and non-crops alike has been found to be contaminated with pesticides. The recent popularity of systemic insecticides, primary neonicotinoids, however, have led to new exposure routes. When bees are killed by pesticides it is often because the product drifted directly onto the bees or onto flowers that the bees are feeding on. Bees will sometimes forage in field crops when these are producing pollen, including field corn and soybeans. Planting of corn and soybean seed, typically treated with neonicotinoid insecticides, can lead to bee kills as well when bees fly through the dust that arises during planting with pneumatic planting equipment. Dandelion, wild mustard, white clover, yellow rocket, sweet clover, milkweed, goldenrod, and aster blossoms all attract bees and are often present in areas beside crop fields, ditches, or roadsides. Indiana is a heavily agricultural state, and bees may be attracted to a crop that is in bloom, or may be attracted into treated crop fields by the presence of blooming weeds even though the crop itself is not in bloom. In addition, bees may be exposed to pesticides en route to collect these resources, in dusts or liquids suspended in the air as they fly through it. All are potential sources of pesticide exposure. When Pesticide Poisoning May Occurīees consume pollen, nectar and water to survive. This is the main reason that working out a single “solution” to honey bee declines is an unrealistic expectation. Remember that bees won’t encounter any of these mortality factors in isolation usually two or more are present at any given time. In addition, pesticides are an ongoing concern and can kill bees outright or bees can receive sub-lethal doses that may reduce the colony population or cause the bees to succumb to diseases. Bees can also suffer from poor nutrition when few floral sources are available or when there is too much competition from other hives.
Moving bee hives long distances for pollination or to overwinter them in warmer climates can add stress, often resulting in up to 5% colony losses in a single move. Honey bees are also affected by diseases such as American foulbrood, European foulbrood and dysentery, caused by a microsporidian parasite.
Refer to “Mites of Honey Bees” for more information. Most bee researchers believe that Varroa mites and the viruses that they transmit to honey bees are the biggest single mortality factor for honey bees. Honey bees are our key pollinator and saddled with a range of challenges to colony health. Social insects, such as honey bees, can quickly spread harmful organisms through the colony.
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