How is it How is it identified? treated? ceranae cannot be diagnosed sim- , the antimicrobial treatment ply by observing the hive. The commonly used against , What you need to often associated with N. apis is not seen has been found to be equally effective with N. ceranae. As well, N. ceranae infected against in laboratory know about foragers often die in the field, resulting in a studies. lack of dead in front of the hive. However, some field studies have found The most noticeable symptom of a N. cera- Fumagillin to be ineffective at control- nae infection is a lack of spring build-up, ling N. cereanae infections in the long- Nosema Ceranae and a subsequent decrease in pro- term. Though spore levels decrease duction. The presence of these symptoms immediately after treatment, within 2 - 3 does not provide a definitive diagnosis of N. months they return to levels as high, or ceranae, however, as the same symptoms higher than, those of untreated colonies could result from other causes. and no improvement in colony strength or productivity is observed. This discrep- Though distinguishing between N. apis and ancy likely results from the way Fumagil- N. ceranae requires expensive genetic or lin is applied in the field, and highlights molecular testing, it is possible to diagnose the need to explore more effective ways a nosema infection with a microscopic ex- to administer the treatment. amination of the contents of a ’s abdo- men. Detailed instructions for the perfor- Promising research is currently being mance of this test can be found in the Tech- conducted at the University of Guelph nology Transfer Program fact sheet entitled to discover novel treatments that meet "Nosema Assessment Protocol". A digital the need for effective Nosema ceranae version is available on the TTP web site on control. In the meantime, the best de- the "Fact Sheets & Publications" page. fense against Nosema ceranae infection is to reduce the spore load in the hive by Alternatively, samples can be sent for di- replacing 2 - 3 old brood frames per year agnosis to one of the Ontario with foundation or newly-drawn comb. Diagnostic Labs: Jim Anderson, Tanglewood Honey Bee Lab The best defense against Nosema RR 1, 35548 Highway 41, Eganville, ON K0J 1T0 (613) 628-2890 ceranae infection is to replace 2 - Brenda Perrin, Perrin’s Bee Lab 3 old brood frames per year RR 2, 284 Country Lane, Cameron, ON K0M 1G0 (705) 359-1505

Technology Transfer Program When is it How does it What is it? active? impact colonies?

Nosema is a fungal parasite, known as a Nosema ceranae has displayed very differ- When compared with low levels of Nosema microsporidian, that infects the midgut ent life cycles in different parts of the world. ceranae infection (fewer than 500,000 of adult honeybees and leads to their Here in Ontario N. ceranae infections have spores/bee), high levels (over 1,000,000 premature death. There are two known been observed to follow a regular pattern, spores/bee) are associated with a sig- species of nosema that can infect the both in terms of spore counts and spore vi- nificant decrease in colony strength and western honeybee: Nosema apis and ability (percentage of spores which are able productivity. A recent study of Ontario Nosema ceranae. to reproduce and spread the infection). colonies found that by mid-summer highly infected colonies had 20% fewer bees, The species Nosema apis has been Spring 25% less brood, and 40% less honey than known for over a century - its life cycle, xx spore counts rapidly increasing colonies with a low level of infection. symptoms and treatment are relatively xx high viability of spores well understood. xx many new bees being infected An economic analysis of Nosema ceranae Summer infections in Ontario found that high levels Nosema ceranae, on the other hand, of infection come at a cost the beekeeper was not found in western honeybees xx spore counts reach their peak xx low viability of spores of roughly $70 per colony in lost produc- until 2006. Since that time N. ceranae tivity. has been found all over the world, and xx infection rates begin to decline in many places, including Ontario, it Fall Fortunately, even highly infected colo- has replaced Nosema apis as the most xx most young bees not infected nies recover by fall, and there is no link prevalent species. A study of Ontario xx proportion of infected bees in the between Nosema ceranae infection and colonies in 2012 and 2013 found 84% of hive is reduced winter mortality in Ontario. colonies were infected with N. ceranae, Nosema ceranae infections are most damag- Like varroa levels, nosema levels can differ while only 7% were infected with N. ing in the spring and early summer when the apis. significantly from one year to the next. In spores are rapidly reproducing. For this rea- spring 2013 the average spore counts were In light of the sudden prevalence of son, treatments applied in the early spring 3X higher than in spring 2012, likely due to Nosema ceranae in Ontario colonies, it are most likely to be effective. differences in weather. is important for beekeepers to under- This infection pattern contrasts with that of stand how it differs from the more fa- Nosema apis, which peaks in late winter/early miliar Nosema apis in terms of life cycle, spring before the beekeeper even opens the colony impacts, and treatment. colony. Nosema ceranae infection signif- icantly reduces colony strength and productivity Nosema ceranae infects 84% Early spring is the best time to of Ontario colonies treat for Nosema ceranae