Processing Samples for Varroa and Nosema

The video above was taken at the Butte County Cooperative Extension building in Oroville, CA. Rob and I moved to California a little over a month ago to work with 16 northern California honey bee breeders. Since arriving here we have had the chance to do some field work with a few of the beekeepers in the area. Some of them have moved their bees out of the valley and up into the mountains in Shasta and Siskiyou Counties. Last week we collected 150 samples from two beekeepers from 12 different apiaries and this week we spent most of our time processing those samples for Varroa and Nosema.

The video shows Technician Rob Snyder processing a single honey bee sample for the parasitic mite Varroa and the fungus Nosema. Varroa uses the honey bee as its host feeding on its blood much like a tick would do on a human. Nosema is a fungus that causes the disease nosemosis which gives the bees dysentery. Both Varroa and Nosema are serious threats to the honey bee. Varroa is a known vector for viruses and Nosema can weaken colonies to the point of collapse. Processing samples is not the most desired task on our list but getting results to beekeepers is which makes processing these samples a necessary evil for us and the program.

A honey bee sample used to test for Varroa and Nosema consists of three hundred to four hundred bees taken from the brood nest of a hive. The bees are placed in a plastic bag and kept frozen until they are ready to be processed at the lab. Each sample is rinsed in soapy water two times and then run through a series of sieves to separate the mites from the bees. This allows us to more easily count the mites. Next, 100 bees are counted out from the sample and placed aside for Nosema testing. If mites are found in the sample then the remainder of the bees from that sample must be counted in order to get a mite to bee ratio. That ratio gives us and the beekeeper an idea of how bad the infestation is. After mites and bees are counted, the bees set aside for the Nosema test are crushed, water is added to make a slurry, and a drop of that slurry is placed on special slide called a hemacytometer so that the Nosema spores can be counted. Depending on how many Varroa mites and Nosema spores we find, processing a single sample can take anywhere from 5 to 15 minutes.

Once all of the samples are processed for Varroa and Nosema the data is entered into a spreadsheet and a report is generated for the beekeeper.


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