The autumn of bumblebees
All the bees born in spring and early summer are female, born from the queen’s eggs and the male’s stored sperm packet. They are all sisters who are 75% related to each other. We are up to late summer now, and things are going to get a little tense in the nest.
As late summer arrives the queen will begin to lay new queens and males. These males are not produced from the sperm packet but instead they are clones of the queen and not related to the sisters the same way, they are only related to the sisters by 50%. The males will only have the queen’s genes.
With all these workers in the nest being female, they could have gone out look for a mate— if they were allowed to. The queen however suppresses their mating instincts by releasing a pheromone. When she begins to lay the males, she will stop releasing the suppressing pheromone and the female workers will not be happy.
Why should they have to look after the males when they are not related in the same way? Due to the shift in pheromones the female workers may turn on the queen and, in some cases, they will kill her.
But some will continue to look after the larvae, which is fortunate for the new queens who still need time to grow and hatch, strong enough for their maiden flight and for mating with the new males. Once the new queens have mated, they will build their food reserves up for the winter ahead. The old queens who still control their nests will soon die off leaving only the new queens for the year ahead.
Tune in for the last of the Bumblebee series that will explain a bit more about the genetics and fun facts.