A good deal of my bees died during winter 2009-2010. They did survive this winter (smaller colonies), except in one yard, where again 50% died. As I could diagnose, by the *behaviour during summer*, it was caused by Nosema Ceranae. I changed my Varroa treatments, that was the only change in management. Treatments were done at the same time of the year (end of july). Since then I am very interested in publications which may lead to a better understanding. Sceptical remarks from people that were lucky enough and obvious did not suffer from Nosema c. so far, are of rather (un)academic nature and are noncommittal to me. For the moment I am visiting Niguaraca. I understood that also the Afrobees have Nosema c., but it seems that this does not affect the bees, Geert Van Eizenga My latest finding about Nosema ceranae are the following: ACCORDING BY THE WORLD ANIMAL HEALTH ORGANIZATION VARROA AND NOSEMA CERANAE ARE THE MAJOR PROBLEMS OF EUROPEAN BEES (January 2011) The ad hoc group in charge of OIE diseases of honey bees has proposed to revise the global distribution and Nosema health status, in light of the spread of Nosema ceranae. The group also proposed that pending the outcome of the review and view the relative risk associated with N. ceranae correction of the chapter on this and be reinserted in the Code. The group also discussed the health situation of the hives in the world. Looking to Europe, the group noted that the problem of beekeepers years is the varroa mite. The treatment is often applied too late or incorrectly, resulting in mortality of the entire colony of bees, mainly in autumn and winter. In spring, however, the most common cause of loss of colonies is Nosema. Nosema apis has been replaced almost entirely by Nosema ceranae, imported from Asia. Breeding disease resistant honeybees - Fries and Lindström, 2010 He (Fries) states, p.7 A range of different pathogens are described from adult honeybees. However, none *except* the nosema parasites appear to have the capacity to strongly impact colony vitality. p.8 Reports from Spain suggest that N. ceranae is much more virulent than N. apis, killing infected colonies within a year if not controlled. However, it appears that this level of virulence may not appear in many other areas. Quotations from: Manual Breeding disease resistant honeybees, which is part of the Specific Targeted Research Project BEE SHOP (Contract no. PL 022568) financed by the European Commission 6th Framework Programme. Ingemar Fries in California. Dr. Ingemar Fries, of Sweden, gave an overview of what we know and don’t know about Nosema ceranae at the January Mega-Meeting in Galveston, TX. California. Where he stated: Caged bee experiments show little difference in virulence. With inoculations containing mixed spores, N. ceranae produces spores in about four days, while N. apis takes about six. Maximum numbers of spores are pretty similar. …… In the bees, N. ceranae could develop over a wider temperature range than could N. apis. There are still questions about strain differences and whether or not pesticides and virus pressures will impact nosema development, he said. Interesting (in California) were the findings of Brenna Traver, Virginia Polytechnic Institute. She found: Using PCR (analyzes for nosema DNA), they found peak levels of infections in workers and drones from March through June. Levels were highest in hive drones in June, but highest in flying drones in July. In a small number of instances, PCR suggested that pupae can become infected before emerging from their cells. Grace Mulholland, also from Virginia Tech, examined bees for nosema infections using spore counts and PCR. She found that spore counts miss about 50 percent of low-level infections. In three different 100 individual bee samples, she found 82, 18, and 44 percent of the bees infected by PCR. By spore count, those same bees were 60, 8, and 4 percent infected, respectively. Can this be a reason why we tend not to get nosema treatments applied in a timely fashion, using spore count criteria? Could this be the reason that colonies in Spain collapse completely by the time that spores can be found in the brood nest workers? -- Green Bee Consultancy Drs.Geert Van Eizenga Marnelaan 41 9727 DS Groningen/Holland Tel.+31 505278909 Mob. +31616424299 *********************************************** 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