As a bystander observing the debate on how, if, or when, to treat Nosema cerana infection in the commercial apiary environment, where significant losses are being experienced at different times and in different regions of Europe, Canada and USA, I must confess to a degree of confusion in trying to understand whats going on.
Some of the most recent Bee-L postings have somewhat crystallised the situation in my mind.
Allen presented a very interesting post, describing industry-wide coordinated simultaneous management of varroa and nosema treatments combined with improved supplementary protein nutrition as a possible explanation for the current lower level of overwintering losses experienced overall in Canada this season
As I understand it, the same lower level of overwintering losses may have occurred in northern states of USA, without the same deliberately coordinated management changes described by Allen, although I have no doubt individual beekeepers will have been applying similar management strategies. Perhaps weather has been a key factor...I'm sure our Chilean geographer friend (the one with all that spare time on his hands) will have a view on that, and could shed some light!
Higes 4 stages of development of the Nosema ceranae catastrophe could also explain this observation....stage 2, increased brood rearing over winter followed by stage 3... hives rebounding in the following season.
Randy it appears, is currently experiencing this situation....hives coming out of almonds so strong that they are at swarming strength and he is preoccupied splitting to avoid losing them into the trees. Meanwhile they have phenomenally high spore loads....10 to 15 million per bee! (Was that the figure?), but certainly well into the generally agreed critically dangerous level.
As I understand it, if Higes, and Bob Harrison are correct, he will lose them late this season or over winter at the end of this season, whatever treatment regime he employs, because the problem is too far advanced. If Juanse is correct, he can save them if he treats intensively now, and again in the autumn using Fumagillin at high dose.
I think all agree that Nosema ceranae is a very serious problem, probably at least as serious as varroa, and therefore requiring the same degree of monitoring and management. The question is therefore, does the current rebound in populations in Canada and USA represent an indicator of "solution found" OR "worst is yet to come"?
For Randy's bees, I guess time will tell within the next 12 months.
Have I lost the plot completely?
Comments anyone?
Regards
PeterD
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