In the mid-1980s, the number one destructive pest of the western honey bee (Apis mellifera
), the parasitic mite Varroa destructor
, was introduced to the United States and has since spread to almost all honey bee colonies in North America. Varroa was first detected on western honey bees back in the 1950s after shifting from its original host, A. cerana. It now is present in most areas of the world where the western honey bee is present, as a result of natural migration, but most actively with assistance from humans who move bees for trade both legally and illegally (Navajas, 2010). It is now difficult to find a “varroa-free” western honey bee colony anywhere except for Australia and Newfoundland in Canada, and possibly a few other isolated island locations.
The Asian honey bee (Apis cerana
) co-evolved with Varroa and has specific behavioral characteristics, such as hygienic grooming, that help to minimize the effects of the mite. Other bee races, such as Africanized honey bees, also exhibit behavior patterns that reduce the build-up of Varroa, including, they swarm more frequently, leaving behind high parasite infestations in the brood, and build up new healthy colonies in a new location. The western honey bee does not have such defense mechanisms and is therefore more vulnerable to this parasite.
There are many other pests which negatively affect honey bee health, including:
- The gut parasites Nosema apis and Nosema ceranae
- Unicellular fungal and bacterial pathogens that are mostly global in distribution
- More than 20 species of viruses
- The Small Hive Beetle (Aethina tumida) now found in the United States, Africa and Australia
- The Asian Hornet (Vespa velutina), a predator spreading in Europe