Prevalence and seasonality of Nosema species in Quebec honey bees

Nosemosis is a disease of adult honey bees, Apis mellifera Linnaeus (Hymenoptera: Apidae), caused by two described species of Microsporidia: Nosema ceranae Fries and Nosema apis Zander. The epidemiology of N. apis is well understood; however, little is known about N. ceranae in Canadian apiaries. The following study aimed to determine the seasonal patterns of N. ceranae and N. apis in European honey bees in a Quebec, Canada, apiary. Honey bees from six hives were sampled from 2008 to 2010 and the amount of spores quantified by both microscopic spore counts and duplex quantitative polymerase chain reaction (qPCR). Results demonstrated that duplex qPCR was the most sensitive technique and was able to detect N. ceranae in samples confirmed negative for microscopic spore counts and conventional polymerase chain reaction (PCR) detection. Results show that N. ceranae is the more prevalent parasite and was present in 75% of collections as single or mixed infections in the sampled apiary. The prevalence of N. apis was lower representing 29.7% throughout the 3 years of the study, and by 2010 was present only as mixed infections. Seasonal patterns of N. apis were consistent with previously published data with peaks in spring and autumn months, while N. ceranae peak infections varied throughout the 3-year study.