Key to bee collapse: Not enough sex partners?

Honeybees might be disappearing in droves in parts of the world because the queen bees aren’t having sex with enough males.

That’s the theory being investigated by researchers at the University of Leeds. Scientists there speculate bee colonies made up of offspring from many male partners might be more genetically diverse and, therefore, better able to resist outbreaks of disease.

“By making sure queens mate with enough genetically variable males, we may be able to boost resistance levels and so protect our honeybee populations from disease attacks like the ones we have seen hitting the US,” said Bill Hughes from the university’s Faculty of Biological Sciences.

“Given the choice, queen honeybees will typically mate with up to 12 different male partners in a matter of minutes and some with over 20,” Hughes said. “The record is the giant Asian honeybee whose queens normally mate with well over 40 males — and in one case was found to have mated with over a hundred.”

In declining honeybee populations, it’s possible that the number and variety of potential mates for a queen is becoming too low to maintain genetic diversity, which tends to also mean greater disease resistantance.

The Leeds scientists will be examining the question of genetic resistance by studying honeybee reactions to a common fungus parasite called Chalkbrood, under carefully controlled laboratory conditions.

The fungus, already found in the majority of UK hives, infects and “eats” larvae, giving them a chalky appearance. Individual larvae die but the parasite rarely kills the whole colony.

The loss of whole honeybee colonies in parts of the world has focused science’s attention on trying to find a solution. In 2008, for example, US average losses of honeybee colonies was 35 per cent, with some beekeepers losing 90 per cent of their colonies. A virus might have been a contributing factor; however, the same virus has been found in other countries yet does not seem to cause the same problems.

Hughes and his team think infections by hidden parasites in genetically susceptible bees may be combining with other factors to produce a lethal “perfect storm” which overwhelms their defences.

Honeybee survival is vital to the protection of food supplies because they pollinate up to a third of the food grown in the UK.