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Thursday, October 4, 2012

Fighting colony collapse disorder

By now, everyone has heard of the catastrophic losses to honeybee populations due to a phenomenon known as ‘colony collapse disorder’. While environmental factors such as pollution and pesticides have been implicated, one of the leading causes is probably infection by a parasitic mite named Varroa destructor.

A Varroa destructor attached to the back of a honeybee
By Waugsberg, 6/3/2007.

Luckily, bees have evolved some mechanisms for mitigating V. destructor infestations. One such method is called hygienic behavior (HB). In essence, it involves uncorking infected larvae from their sealed brood cells and chucking the sick babies out of the hive. However, not all bees or colonies of bees display the same degree of HB. If apiarists could breed for greater hygiene activity, they might be able to protect their bees from colony collapse.

The first step in creating a resistant bee colony is to find a genetic correlation with HB. To that end, University of British Columbia entomologists led by Robert Parker examined protein expression in bees from a variety of hives. They particularly looked at proteins produced within the antennae of nurse bees. After all, it’s the nurse bees that handle the larvae, and they presumably use their antennae to distinguish between the sick and healthy larvae. The researchers also determined the protein composition within the exoskeletons of larvae, the first line of attack for mites.

The entomologists did find specific proteins that correlated with high levels of HB, most notably factors that stimulate antimicrobial activity and clotting. As more data is collected, beekeepers might be able to use the information to stave off local extinctions in their hives.

Robert Parker, Marta Guarna, Andony Melathopoulos, Kyung-Mee Moon, Rick White, Elizabeth Huxter, Stephen Pernal, & Leonard Foster (2012). Correlation of proteome-wide changes with social immunity behaviors provides insight into resistance to the parasitic mite, Varroa destructor, in the honey bee (Apis mellifera) Genome Biology DOI: 10.1186/gb-2012-13-9-r81