Parasites and disease
The pinhead-sized varroa bee mite is probably bee enemy number one in New Zealand, and seems to be a major threat in many other areas of the world too. This parasite attacks both developing bee larvae and adult bees, causing deformities, weakness and vulnerability to viruses that ultimately kill the hive.
Since arriving in New Zealand in April 2000, varroa has spread throughout all managed hives in the North Island, over half in the South Island. At one point more than a third of all New Zealand beekeepers had given up in the wake of the disease, and the rest have been forced to use chemical treatments to keep their hives alive. Some are now concerned that the use of these chemicals to control the mite might, ironically, also be a contributing factor to the potential for colony collapse, as it increases the bees’ vulnerability to other diseases.
Dr Mark Goodwin, another scientist with Plant and Food Research, said: “Varroa is the largest threat but several new diseases have been identified in bees recently. These have jumped species as varroa did 60 years ago. The most notable is Nosema ceranae, a stomach parasite, and Israelite Acute Paralysis virus. This latter is the probably the cause of the colony collapse disorder seen in the USA.”