Nosema apis Zander infection levels in honeybees of known age
A. A. M. El-Shemy And R. S. Pickard
The mean Nosema spore count/sampled worker bee was determined for flying bees (8.93 x 106), entrance bees (6.77 x 106) and central comb bees (0.31 x 106; n = 210). More than 80% of the counts were derived from the ventriculi and small intestines with the remainder deriving from the recta. It was concluded that assessments of Nosema infection level/colony should not be based on bees sampled from the broodnest. No spores were found in workers of less than 8 days old. Mean spore count/infected bee increased almost linearly from 9 days old to 24 days old (> 15 x 106). The highest spore count/bee was 45.20 x 106. Of bees over 22 days old, 70% carried Nosema spores. The expression of infection levels in terms of number of infected bees as a percentage of sampled bees, rather than actual spore counts, was found to be a simple but satisfactory method of assessment.