How to Reduce Bee Poisoning from Pesticides

Pollinators are essential to Pacific Northwest agriculture Commercially managed honey bees pol-­ linate a variety of crops in the Pacific North-­ west, including tree fruits, berries, cucurbits, and crops grown for seed. This activity is economically significant. In 2004, the value of bee-­pollinated crops in the region was approxi-­ mately $1.7 billion (Burgett, 2004). Nation-­ ally, the value of bee-­pollinated crops in 2000 was approximately $14.6 billion (Morse and Calderone, 2000). While honey bees are our most economically important pollinators, other managed bees, such as the alfalfa leafcutting bee and the alkali bee, are important as well. Native wild bees, including numerous species of bumble bee and orchard mason bees, are also prolific pollinators. Substantial portions of the text are taken from the 1999 version of that publication. species of bees are native to the Pacific North-­ west. The full value of their pollination services is unknown. The sensitivity of native bees to pesticides generally has not been studied. Many states have rules intended to reduce the hazard of insecticide applications to bees. The state Departments of Agriculture (Pacific Northwest) or Department of Pesticide Regulation (California) are the most reliable sources of current rules applicable to bees and pesticides. See " Investigating a suspected bee poisoning " (page 2) for specific contact information. Insecticides that are highly toxic to bees and that have a residual hazard longer than 8 hours are responsible for most of the bee poisoning incidents reported in the Pacific Northwest. Insecticides primarily respon-­ sible for bee poisoning are in the following chemical families: • Organophosphates (such as acephate, azinphos-­methyl, chlorpyrifos, diazinon, dimethoate, malathion, methamidophos, and methyl parathion) • N-­methyl carbamates (such as carbaryl and carbofuran) • Neonicotinoids (such as clothianidin, imida-­ cloprid, and thiamethoxam) Many pyrethroid insecticides are also highly toxic to bees, but some pyrethroids (such as esfenvalerate and permethrin) are repellent to bees when used under arid conditions prevalent in eastern Oregon, eastern Washington, and Idaho. Repellency reduces the potential for bee poisoning from these insecticides under arid conditions, but they are likely to pose a hazard to bees when used in humid areas. Most bee poisoning incidents occur when insecticides are applied to bee-­pollinated crops during the bloom period. Other causes include: • Insecticides applied to blooming weeds in the cover crop during applications to tree fruit orchards • Insecticides that drift onto adjacent bloom-­ ing crops or weeds • Bee collection of …