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By Kwame Aidoo
QUEEN EXCLUDERS are normally used to restrict the movement of queen bees to brood boxes within frame hives. The benefits of using queen excluders to manage colonies have been widely debated. Many beekeepers think they add to the operational cost and in some cases break the wings of worker bees. Some observers have concluded that workers' movements during heavy nectar flows are impeded by queen excluders thus reducing honey accumulation.
It is known that worker bees never abandon a queen during the mass movement of a colony during swarming, migration or absconding. However within a nest worker bees are known to abandon a queen for young brood. Absconding and migration are evolutionary traits associated mainly with tropical races of honey bees. During severe dearth periods whole colonies sometimes abandon their nests, carrying with them all available stores of food. This migration behaviour is stimulated by severe drought coupled with the absence of nearby forage sources. An established colony may abscond after heavy disturbance as happens during nest robbing by animals and the occurrence of bush fires. Invasion of a nest by other enemies such as ants and wax moths also leads to absconding.
Migration and absconding may result in total loss of productive colonies and therefore serious problems for the beekeeper.
The queen excluded entrance
In my attempts to build up an apiary of 25 strong colonies for my research work I suffered much colony loss through absconding. These were usually wild colonies which I had captured and hived. Unlike captured swarms, they were gone after a few days even though conditions were made conducive for them to stay. I decided that if I could detain the queen of a colony but allow free movement of workers in and out of the hive, then I may succeed in retaining my new colonies. Subsequently all new colonies were put in hives fitted with strips of zinc queen excluder (figure 1). A clearance space of 4 cm was left between the actual hive entrance and the strip of queen excluder (figure 2). This covered the entire length of the hive entrance and created a good space for movement, thus avoiding congestion. Worker movements in and out of the hive were observed and there appeared to be no obstruction in the movement of bees even during heavy nectar flows.
Colonies fitted with excluded entrances were left to establish themselves with comb building and food accumulation going on steadily. The queen excluded strips were then removed.
The use of the excluded entrance looks promising in preventing new colonies from absconding Supplementary feeding is required to control migration.
The effect of an excluded entrance on colony development at the initial stages of establishment needs further investigation. The use of an excluded entrance to control swarming in managed colonies could also be investigated: does the timely fitting of an excluded entrance to a colony at the beginning of the swarming season check the behaviour?
[Bees for Development Journal #25]