The Oregon State University Extension Service has has revised its publication, "How to Reduce Bee Poisonings from Pesticides," in light of recent bumble bee deaths.

The publication, available free for download, contains the latest research and regulations pertaining to pesticides and bees, according to a news release.

It is designed for growers, commercial beekeepers and pesticide applicators in Oregon, Washington, Idaho and California.

An expanded color-coded chart details active ingredients and trade names of more than 100 conventional and organic pesticides, including bee toxicity levels and precautions.

It also describes residual toxicity periods for several pesticides.

In addition, the publication describes how to investigate and report suspected bee poisonings.

In Oregon, more than 50,000 bumble bees were killed in Wilsonville in June after linden trees were sprayed to control aphids.

In response, the Oregon Department of Agriculture restricted 18 pesticides that contain the active ingredient dinotefuran for six months.

Oregon State University researchers are investigating the effects of neonicotinoids, including dinotefuran, on native bees.