The importance of inspecting hives more frequently
Obviously the more frequently beehives are inspected, the greater is the probability that any AFB colonies will be discovered before the disease can be spread to other hives. There are a number of examples of beekeepers in New Zealand successfully dealing with AFB outbreaks simply by increasing the frequency of disease inspections in their hives.
How often to inspect
At a minimum, hives should be inspected at least once in the spring and once in the autumn, but good beekeeping practice also involves further periodic disease inspections throughout the spring build-up period. The first spring inspection should occur once the colony has begun to expand its brood nest. The last autumn inspection can take place even after most of the brood has disappeared from the hive.
Late autumn (April-May) inspections are very quick, but can also be very effective, since a high proportion of the remaining brood that has not emerged is likely to have some abnormality. Data from seven years of targeted inspections by government inspectors in the 1990s in New Zealand shows that the percentage of AFB hives found in the autumn is greater than in the spring.
Infection caught early reduces risk significantly
Failure to give beehives an adequate level of inspection is one of the surest ways to spread AFB within an apiary, and to other apiaries. If an infection is not caught at an early stage, the hive can become weakened in population to the point where it begins to be robbed by foraging bees from other hives. Robbing thus becomes the means of spreading the disease, but only because of inadequate levels of management on the part of the beekeeper.
On the other hand, if the hives are visited on a monthly basis throughout the main production period of the year (August through to April), and the visit includes brood nest inspections, there is very little chance that an AFB infection in a hive can develop to the point where it becomes a source of infective material to bees from other hives.
Every hive should be inspected at least once in the spring and again in the autumn for AFB.