Saturday, December 1, 2012

What Happened to the Hive?

A beekeeper asks for my thoughts about the loss of a colony of bees. He explains, “I had a good sized colony, three boxes high, bottom and part of second were a mix of brood and honey, and top was all honey. Earlier in the summer I had another six inch super on top which was filled.” In late August, finding his hive empty, he explains, “There was no sound, in fact there was not one bee, and there was not one dead bee either. Every bee was gone.” However, on the day before, the hive showed much bee activity. Attempting to understand colony losses is curious and worthwhile.

The complete abandoning of a bee hive, called “absconding,” is not common in the temperate zone unless conditions make the hive completely undesirable. Colony Collapse Disorder has drawn much attention in recent years, but the conditions here don’t fit its definition. With CCD, there is a loss of older adult bees, but the hive is left with a queen, nurse bees, and brood. A very common cause of the loss of a colony of honey bees, however, is colony collapse due to Varroa mite infestation. This is particularly common in the time period of late summer, as in this late August case. Honey bee colonies grow rapidly in the spring to produce large populations of foragers to harvest nectar and pollen while flowers are in bloom. The queen slows her egg laying in the summer and the colony population gently declines. Parasitic Varroa mite populations follow a different pattern. Mites in a bee hive increase in number gradually throughout the year. By late summer bee numbers are declining while mites are increasing. As the Varroa mites bite bees, they spread bacterial, fungal, and viral infections throughout the colony, eventually killing it. Why was there plenty of hive activity the day before? Robber bees were removing honey stores. Today’s photo shows guard bees challenging incoming foragers. Guards are absent from dead hives.

No comments:

Post a Comment