Short-Term and Long-Term Effects of Methamidophos on Brood Rearing in Honey Bee (Hymenoptera: Apidae) Colonies

Abstract

Within 7 d, small honey bee ( Apis mellifera L.) colonies that consumed low levels of methamidophos in sugar syrup lost more eggs and larvae than control colonies, without conspicuous loss of adult worker bees. Youngest brood and brood at the transition between developmental stages were most sensitive. Development of surviving brood was not slowed appreciably by colony consumption of methamidophos. Environmental variables affected the sensitivity of brood to the pesticide. Colonies observed over a 13-wk period recovered rapidly and completely from a single 2.0 mg/liter treatment, without residual effect on uncapped brood, capped brood, honey storage, or queen survival. Larvae were more sensitive than queens, and adult workers were least sensitive. Brood and queens were less sensitive in small colonies than in large colonies. Implications for the mechanisms of pesticide damage to brood rearing and for remedial actions by beekeepers are discussed. The techniques described are effective for short-term and long-term studies of pesticide consumption on brood rearing and queen survival.