Saturday, June 02, 2012

Beekeeping - Mite Control

Upon opening up our hive in April we noticed varroa mites on the bottom board and even saw a few clinging to the thoraxes of a few ladies. Unfortunately, most hives in the United States suffer from some level of mite infestation but a heavy load can several cripple or kill a colony. Populations of mites tend to increase over time, meaning that older hives can often have large numbers of blood-sucking vermin. 

Bad news. 
Here is a bit from wiki

Varroa destructor is an external parasitic mite that attacks honey bees Apis cerana and Apis mellifera. The disease caused by the mites is called varroatosis.Varroa destructor can only replicate in a honey bee colony. It attaches at the body of the bee and weakens the bee by sucking hemolymph. In this process RNA viruses such as the deformed wing virus (DWV) spread to bees. A significant mite infestation will lead to the death of a honey bee colony, usually in the late autumn through early spring. The Varroa mite is the parasite with the most pronounced economic impact on the beekeeping industry. It may be a contributing factor to colony collapse disorder (CCD), as research shows it is the main factor for collapsed colonies in OntarioCanada.[1]

There are a few ways to fight mite infestation but aside from throwing large amounts of insecticides at them, the other methods that are available to beekeepers are often aimed at simply controlling the mite populations, rather than eliminating them completely. 

For example, we use a screened bottom board on our hive, in the hopes that mites that fall off their host bee will slip through the hive bottom and end up on the earth, where we fervently hope they'll be consumed by ants or some other carnivorous bug. 

Other beekeepers will insert a short frame into their deep supers as honeybees are likely to use the empty space to raise drone (male) brood. For reasons I don't quite understand, mites prefer to lay their eggs alongside drone larvae (rather than female workers). 
Since drones in a hive with a strong, healthy queen are seen as expendable, beekeepers will periodically remove the short frame and stick it in the freezer, killing both drone larvae and mites. As I said, it's a way to control (not eliminate) mite populations. 

Another option that is thought to have some impact is a periodic dusting of sugar. Evidently sugar granules are approximately the size of a mite's foot pad. A foot covered in slippery sugar makes it difficult to hang on to one's host and mites tumble down onto the bottom board.

Sugar is harmless to the bees - in fact - it'll even serve as a small snack for the bee ladies. Experts differ on what type of sugar is best for mite control. Some suggest that regular cane sugar, ground with a coffee grinder into a super-fine size, is superior, however, powdered sugar is also widely employed to fight the wee little buggers.

 People also hypothesize that the application of the sugar causes the bees to spend more time cleaning themselves, which can often knock the mites off and onto the ground.

We can attest to this last bit: our girls immediately settled down to begin a grooming regimen.

I don't have any pictures of the mites. Next time we open up the hives, I'm going to try and snag a bee that has one. They are smaller than the head of a pin and are typically situated on the bee's broad thorax (right behind the head, between the wings).
 Both mom and I have remarked on numerous occasions that each colony has a distinct personality. Our first year we had a hive that was generally ornery and nasty. You could tell how pissed off they were by the level of their humming. Loud=not good.
This hive is the polar opposite. They are sweet and gentle and oh so very calm. That may change, depending on a few factors (honey levels, queen problems, etc) but right now they remain a pleasure to work with.

We'll keep you posted on the success of our sugar dusting operation.