Effect of fumagillin treatment on Nosema infection, survival and populations of overwintering honeybee colonies

Winter survival of 194 honeybee (Apis mellifera) colonies was not affected adversely by nosema disease. Numbers of Nosema spores per bee after medication in the fall and in the spring decreased logarithmically with an increase in the amount of fumagillin fed in the range 200-800 mg (r = -0.381 and -0.323 for fall and spring respectively; P<0·01). Average numbers of spores in millions per bee for the surviving colonies in the spring were 10.15 ± 1.47, 4.93 ± 0.81, 2.76 ± 0.59 and 3.20 ± 1.59; and for the dead colonies 16.02 ± 2.65, 6.48 ± 2.65, 7.32 ± 7.32 and 0, with fall feedings of 200, 400, 600 and 800 mg fumagillin per colony, respectively.