Inbread Bumblebees Have Their Problems

July 26th, 2009

Bumblebee population decline may be in for even more bad news. With the decrease in the bee populations, it has been found that there is a high likelihood of increased bumblebee inbreeding. Researchers have provided the first proof that inbreeding reduces colony fitness under natural conditions by increasing the production of reproductively inefficient ‘diploid’ males.

Males of unfertilized eggs are normally haploid, which means they have one set of chromosomes. Females come from a father and a mother, and are diploid, which means they have 2 sets of chromosomes. With the inbreeding the possibility of freak diploid males increases.

Penelope Whitehorn (I think she sold me car insurance once), from the University of Stirling, UK, led a team of researchers who sought to investigate the effects of a generation of these diploid males on the fitness of bumblebee colonies. She said, “The study of genetic diversity and inbreeding in bumblebees is currently of particular importance as many species have been suffering from significant population declines. The intensification of agriculture and the associated loss of flower-rich meadows and other habitats on which bumblebees depend has led to isolation of groups of bees and a consequent loss of their genetic diversity, increasing their susceptibility to possible deleterious effects of inbreeding”.

This study demonstrates that diploid males are extremely detrimental for wild bumblebee colonies. Diploid males are produced at the expense of industrious females, but unlike these female workers, they do not contribute to colony growth and productivity. In fact, they do not function very well as males either, as they are much less fertile than normal males and any offspring they do produce are always unviable or infertile. The researchers conclude that diploid males may act as indicators of the genetic health of populations, and that their detection could be used as an informative tool in bee conservation.