Disease Spread in Honeybees
For years, news of the decline of honeybee populations has spread, arousing concern and confusion since the deterioration cannot be traced to any single cause. Many theories have been presented surrounding this phenomenon, including environmental changes, overuse of pesticides, and the rapid spread of disease among domesticated honeybees. Focusing just on the disease problem, it is easy to see why such a thing would be difficult to fix or control when considering how tightly knit networks influence the spread of such a pathogen.
The possibility of spreading disease (p) is raised by the lowered immunity in the honeybees that comes from the incomplete diets and stress that result from frequently moving hives to unfamiliar areas to pollinate just one type of plant (ex. Blueberry plants – this can be thought of as only eating a single food) as agricultural workers often try to ensure that the bees will gather nectar mainly from the plants they are trying to pollinate.
In addition, the closely knit society of honeybees means that every bee in the hive is not very many levels removed from any other given honeybee, further increasing the possibility that the disease will spread (L goes down and k is very high as each bee has many direct contacts inside the hive).
The disease is not only spread through the hive, however, as undomesticated species either carry or receive the disease through indirect contact with an infected hive (perhaps through the flowers they were feeding on), devastating them just as much, or even more so than the honeybee population. While social bees can (sometimes) eventually recover from such an outbreak (through the buildup of resistance and allowing survivors to rebuild), a solitary bee is simply dead and any offspring it may have produced will never exist.
It is difficult to decrease the p value in a commercial honeybee hive, as they are routinely stressed and often do not have a very diverse food source to build up health. Likewise, it is difficult to decrease the contact any bee has with other bees in the hive, as many of these diseases are spread at the flowers bees visit for food and pollination, and it is difficult for a social bee to survive outside the hive.