> The recent study by Rick Fell lab is excellent study from north west USA. 

Hi Medhat, 
Thanks for pitching in. I am sure you meant north east USA. Which is what I have been saying, there is regional variation.

> We have started tackling this issue in our research to define thresholds and treatment time that is good for our climate.

Again, this points to fine tuning the recommendations to specific regions. I would never second guess the experience of others in other regions, especially as radically different as the northern provinces, Spain, or California. 

On the other hand, one must be very careful when considering cause and effect here. High spore counts do not necessarily indicate a causal relationship, they may be symptomatic. 

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In this study, providing Nosema-infected bees with sterilized pollen, confirmed that pollen feeding increased the spore loads of honey bees by several times. These results indicate that spore loads may not be used alone as a direct indicator of the severity of N. ceranae infection in honey bees. In conclusion, the influence of pollen consumption on spore loads in honey bees should be considered when spore load is used as a criterion in studies or diagnosis. Spore load alone is not a reliable health indicator of Nosema-infected bees.

Spore Loads May Not be Used Alone as a Direct Indicator of the Severity of Nosema ceranae Infection in Honey Bees Apis mellifera J. Econ. Entomol. 107(6): 2037Ð2044 (2014)



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Fumagillin is the only antibiotic approved for control of nosema disease in honey bees and has been extensively used inUnited States apiculture for more than 50 years for control of Nosema apis. We showed that spore production by Nosema ceranae, an emerging microsporidian pathogen in honey bees, increased in response to declining fumagillin concentrations, up to 100% higher than that of infected bees that have not been exposed to fumagillin.

Huang W-F, Solter LF, Yau PM, Imai BS (2013) Nosema ceranae Escapes Fumagillin Control in Honey Bees. PLoS Pathog 9(3): 

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