MODEL FOR RAPID FIELD EVALUATION OF THE TOXICITY OF PESTICIDES TO HONEYBEE COLONIES
Honeybee colonies were exposed to sprays of pirimicarb, ethiofencarb and fenitrothion under model field conditions. The hives were placed in an area without food sources, and then attracted to a feeder with sucrose solution up to 20 m from hives. The hives, flying bees and feeder, were sprayed with the test product as soon as the bees started flying to the feeder. At 18°C, pirimicarb, ethiofencarb and fenitrothion (each 25 g a.i. in 10 litres of water) killed 8'6, 6'5 and 41'1%, respectively, of the bees in the colonies. At 22-23°, ethiofencarb at 50 g a.i. in 10 litres of water was more toxic than pirimicarb at the same dosage. The effect of pesticides was evaluated by counting the dead bees in the hives and in the test area, and live colony populations were subjectively evaluated.