New method to control bee parasite

A way to control a parasitic mite that is responsible for the dwindling number of bee colonies worldwide has been discovered.

Varroa destructor has become harder to control since the 1980’s after developing resistance to several pesticides. Oxalic acid is used as a natural miticide to protect the bees and researchers looked into what method of application was the most effective.

Scientists from the University of Sussex state oxalic acid applied via sublimation in honey bee colonies, was a highly effective way of controlling V. destructor, without harming the bees.

International bee research association science director Norman Carreck, said: “The publication of this study is very timely, as an oxalic acid product has for the first time recently been approved in the UK, and beekeepers will want to see these results obtained under UK conditions.”

Trickling, spraying and sublimation (heating crystals to form a vapour) at three doses, was carried out on more than 100 honey bee colonies. Sublimation was found to cause the highest V. destructor mortality rates, with the least honey bee casualties at the lowest concentration of oxalic acid.

More than 95% of colonies treated in winter survived until spring with 98% mortality rate for the mites.

V destructor is also believed to be responsible for colony collapse disorder, where a large number of worker bees just fly off and leave behind the queen bee with a few immature bees to look after her.

RNA interference is another proposed method to ‘knock out’ genes in the mite to render them harmless. Another is developing strains of bees that can detect damaged pupae and remove from the bee hive before the infection spreads further.

The paper was published in the Journal of Apicultural Research.