Thursday, February 9, 2012

Varroa Sensitive Hygiene

Varroa mite on queen bee
    The varroa mite is a small mite (approximately 1mm in diameter) native to Asia and the Asian honey bee (Apis Cerana) which has developed a resistance to the mite enabling it to cope with it's presence. 

The lifecycle of the honey bee and varro mite.
     Over the last 50 years the varroa has spread from country to country having become a major threat in the last decade to both the native and honeybee populations throughout the world.  This blood sucking parasite is a carrier of 18 identified diseases and is considered a major contributor to Colony Collapse Disorder.   

Worldwide spread of the Varroa mite

     Australia remains the only beekeeping nation free of the varroa destructor mite (Australia still Varroa free).  In Canada the island portion of Newfoundland remains varroa free.  
     There are many methods of treating your hives for mites such as pesticides (Apistan and Checkmite), freezing drone brood (Varroa Mite controls), formic or oxalic acid, mineral oil and sugar dusting. As with all pesticides, the pests adapt and new, stronger chemicals like the neonicotinoid pesticides (Insecticides and Bees) must be applied.  Traces of the chemicals remain and accumulate in the wax.  This weakens the bees immune system and makes them more susceptible to pathogens and pests. 
     I believe the future of dealing with varroa will be breeding for varroa sensitive hygienic (VSH) behavior.  Many including myself believe that the VSH behavior traits are passed both genetically and through observed learning.  In hives with VSH behavior bees, bee pupae infected with mites are detected and removed.  Other VSH behavior traits include: more effective self grooming; group grooming; guard bees removing mites from bees entering the hive (either killing the mites or chasing them from the hive) and bees using their mandibles to kill the mites. Decreased drone production (most mite reproduction takes place in drone brood) and a higher resistance to diseases (the diseases passed by the mites kill the bees not the mites themselves) are also desirable breeding traits.  For a more detailed description of these VSH traits check out the bible of beekeeping, ScientificBeekeeping

     In the picture above the bees are chewing on a mite infested bee larvae (VSH behavior).  It is important to remember that Asian honey bees (Apis cerana), African honey bees (Apis mellifera scutellata), Africanized honey bees (hybrid European and African) and a strain of Russian honey bees are effectively resistant (VSH behavior) to the varroa mite.  Glenn Apiaries sells VSH queens and has distributed them throughout the United States. 
     This video shows bees displaying some VSH traits such as aggressive grooming and biting. 

     This year  I will be checking my mite test boards (Checking for bee mites) for signs of the varroa being bitten (missing legs).  A screened bottom board is a must for any beekeeper with mites. In preparation for the arrival of our bee packages at the end of the month I will be building two screened bottom boards.  The screened bottom board allows removed mites to fall out of the hive and as a bonus increases much needed circulation.
     For further information on hygienic behaviour in honey bees go to the Hygienic Behaviour section of our Beekeepers' Library.

     Check out the The Honeybee Conservancy dedicated to raising the awareness of the importance of bees to planet earth.



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