Surfactants in Water Drown Honey Bees 123

Abstract

Apis mellifera L. drowned in water containing as little as 25 ppmv of Multi-Film X-77®, and higher concentrations (100 ppmv and above) caused very heavy losses. Yet X-77 and 6 other surfactants (Brij® 30, Brij® 92, dimethyl sulfoxide, Span® 20, Tween® 20, and XF-1-3655 (nonionic water soluble silicone-glycol copolymer)) were relatively nontoxic to the bees as stomach poisons. Drowning occurred when the X-77 water was supplied in plastic buckets, dirt ponds, and cement ditches. The bees preferred water without X-77 to water containing X-77 by more than a 10 to 1 margin when given a free choice on drip boards or in cement ponds. X-77 retained sufficient activity to drown bees in cement ponds for more than 60 days after it was added at 500 ppmv to the water. During hot weather in June, July, and August, 1971, caged colonies with X-77 added to their water supply quickly ceased rearing brood, and all unsealed larvae died and some of the colonies died. Yet colonies receiving the same treatment during cooler weather did not suffer any observable damage although there was a continuous and heavy loss of water carriers. Surfactants in small ponds, puddles, or irrigation ditches could cause bee losses. Given free choice, bees preferred water without X-77, but collected large quantities of water containing surfactant when confined to cages or when in apiaries with no other water source available.