Honeybee glands as possible infection reservoirs of Nosema ceranae and Nosema apis in naturally infected forager bees

Abstract

Aims: To determine whether Nosema ceranae and Nosema apis are present in different gland tissues of honeybee, Apis mellifera L. and to monitor spore presence and quantity in these glands in naturally infected hives from July 2009 to July 2010 in Quebec, Canada.

Methods and results: Nosema spp. were quantified using duplex quantitative real-time PCR in the thoracic salivary, hypopharyngeal, mandibular glands, and venom sac and glands of A. mellifera over a period of 8 months. Both Nosema species were present in all the glands as single or mixed species; however, N. apis was not present as single-species detections in the salivary glands (see Table 2). Nosema ceranae was more prevalent throughout the 8 months. Significant correlative relationships were established for N. ceranae and N. apis levels in the honeybee glands and those found within the intestines of forager honeybees. Overall, the seasonality of N. ceranae and N. apis in the different glands tightly followed the seasonal patterns in the honeybee guts.

Conclusions: Nosema ceranae and N. apis are not tissue specific, and honeybee glands have potential to become a useful indicator of the extent of disease in the colony and may represent a potential infection reservoir.

Significance and impact of the study: First report of spore load quantification of Nosema spp. in different honeybee glands.