Carbaryl residues in bees, honey, and bee bread following exposure to carbaryl via the food supply

Abstract

Laboratory caged bees, as well as bee colonies under field conditions, were fed carbaryl-containing food solutions. A short 10-hour study reveals that the amount of the pesticide chemical residue found in bees compares quite closely with the amount consumed, even though the amount of carbaryl residue found is less than 3 per cent of the total amount of carbaryl consumed after the first 3 hours of feeding. The 10-hour study also shows that several hours can elapse before bees succumb to the pesticide chemical contaminant present in their food supply. In a long-term feeding study, bees were fed carbaryl-fortified solutions for 56 days after which time the bees were fed carbaryl-free solutions. Carbaryl residue found in honey appears to be quite stable and its level even increases with time; however, the primary cause for the increase is believed to be evaporation of the water from the honey stored in the colony. The carbaryl residue content of bee bread correlates well with the amount of residue found in the bees and it occurs in more concentrated levels than in honey throughout the 56-day period. The amount of carbaryl in bees decreases following the termination of the carbaryl fortification but detectable amounts of carbaryl residue are found at low levels, even up to 64 days later. The minimum detectable level of carbaryl residue in bee bread and honey was <0.001 ppm and <0.0005 ppm in bees.