> What is the threshold for a sugar shake for spring and fall? > Is this out dated? > http://www.beelab.umn.edu/prod/groups/cfans/@pub/@[log in to unmask] Thanks for the links. I think the thresholds are the same for the Minnesota sugar shake and for alcohol wash if they are done correctly. However there are huge caveats in using small samples, either in hive numbers or in replications, and interpreting the results is about as objective and sometimes as meaningful as readings obtained from tea leaves or chicken entrails. I've done a lot of alcohol washes and mite drops and have to say that any one reading may not have any direct relationship to another from the same hive or to the true situation in any one hive. Any one reading can easily be off by a factor of 10 in high infestations and or even infinity where a zero count is found. This unreliability is due to uneven distribution of varroa in hives and to the problem of sampling in the correct area of the hive. A Bee Culture writer I often disagree with said it simply recently and earned my respect. He said that to get an accurate reading, _the sample MUST be a sample of young nurse bees which are found directly on an area of brood that is about to be capped_. Any other sample will not compare to what most researchers are using for comparison. Interestingly, though, the Reuter and Spivak poster does not appear to specify where in the hive to find the bees to shake. It also suggests a threshold that makes me shudder: The Minnesota poster says "If your colony has over 10-12 mites/100 bees, you should consider treatment. On the other band, the Ontario table says 2 or 3 mites/100 depending on season. I am far more comfortable with that. I guess it all depends on where you live how lucky you feel. I have the greatest respect for both Marla and Gary, but where I live, in my opinion and the opinion of successful beekeepers I know, the Minnesota recommendation would, with great probability, lead to disaster in a large outfit -- especially if that was a spring count, and far less so if that count was found after all brood had hatched in fall. I would love to hear Medhat's comments on this since he brought Alberta losses down from unbearable levels to near-normal by advocating very low thresholds, similar to Ontario's. Most Alberta commercial beekeepers take Medhat's thresholds as an upper limit and if any hives in a yard show the threshold, they treat all hives in that yard at the next window of opportunity. We are lucky to have Apivar and it is highly effective if properly used. > I recently read that the threshold numbers have been changed to a lower > mite count. They do not include a sugar shake on the Varroa Mite Threshold > Levels table posted here. > http://www.omafra.gov.on.ca/english/food/inspection/bees/11-treatment-recomms.htm#Monitor%20Varroa I think it is safe to use the alcohol wash numbers with the sugar shake, but I would be sure first to verify for myself that several of my sugar shakes get the same results as alcohol wash by putting the sugar shake bees and the sugar shaken out through an alcohol wash using isopropyl alcohol (98%) available at pharmacies (not washer fluid) Sadly, no test is idiot-proof and there are many details to observe. Fore one thing, in an alcohol wash, make sure the alcohol is at room temp or higher or the mites may not release in the one-minute shake. Also the 300 bees recommended is slightly too many for the standard shaker jar screen and will filter some mites from running into the lower jar if the operator technique is not perfect. I prefer 250 or 200 bees. The lower number results in less mathematical certainty, but the lower number also gives higher accuracy for the sample since mites are not caught in the mass of dead bees. Anyhow, this is big topic. My advice is to be conservative and take measures any time you see varroa in any numbers. Once they get above a low threshold, they balloon in numbers and the effect on the hives is IMO geometrically -- not linearly -- related to the number of mites/bee. Levels of other pathogens tend to build after several years at threshold and then collapses can occur at below-threshold levels. *********************************************** The BEE-L mailing list is powered by L-Soft's renowned LISTSERV(R) list management software. For more information, go to: http://www.lsoft.com/LISTSERV-powered.html Guidelines for posting to BEE-L can be found at: http://honeybeeworld.com/bee-l/guidelines.htm