Robbing

What is robbing?

 
Robbing is generally defined as foraging honey bees from one colony taking honey from another (Fig.28).

Since AFB can reduce the adult bee population of colonies to the point where they become susceptible to robbing, this is one of the natural mechanisms for the spread of AFB between colonies.

Figure 28: A colony being robbed out

 

The spread of AFB through robbing

Researchers were presented with a graphic example of the spread of AFB through robbing several years ago.

A truckload of 80 colonies was returned from kiwifruit pollination and put into a holding site. Twenty of the colonies were moved to another apiary within a couple of days. A further 20 were removed from the holding site to another apiary two weeks later. Of the 40 colonies that remained at the holding site, 88% had to be destroyed over the following three months because they had contracted AFB. However, none of the first 20 hives that were removed developed the disease, while 80% of the 20 colonies that were removed two weeks later had to be destroyed.

At some time between the moving of the first group of hives and the second group two weeks later, 85% of the colonies at the dumpsite contracted AFB. The only reasonable explanation was that a large number of the colonies left on the site had robbed an infected hive or a supply of infected honey. Unfortunately, the source of the infection was never found.

This example illustrates the dramatic AFB potential associated with robbing. There are also however, a number of anecdotal reports of diseased colonies being robbed out without the remainder of the colonies in the apiary becoming infected. Possible reasons for this lack of disease spread include spore levels in the other colonies never getting high enough to create an infection, or the robbing bees coming from a different apiary.

Bees robbing honey from diseased colonies can be an important mechanism of AFB spread.