Research looks at natural predators for bee threat

Destroying the destructor

Research looks at breeding and natural predators for bee survival

Auckland, New Zealand. 8 May 2009. Scientists are investigating ways to control the destructive varroa mite, a cause of major devastation to honey bees.

With funding from the National Beekeepers Association and the Sustainable Farming Fund, entomologists at Plant & Food Research are looking at ways to either control the varroa mite in bee colonies or breed bees resistant to varroa infestation.

Varroa destructor is a small parasitic mite which infests honey bees and can transfer fatal viral pathogens. Australia is the only Western country which remains varroa-free, with varroa first being detected in the North Island of New Zealand in 2000 and in the South Island in 2006.

Researchers are looking at breeding bees which display natural varroa resistance. They have identified a genetic trait, 'delayed suppression of mite reproduction' or SMRD, which produces varroa mites which cannot reproduce. By selectively breeding for the trait, using artificial insemination of queens, the team has produced a population with high numbers of varroa resistant bees.

“Through the isolation of our bee colonies, on the previously bee unpopulated Great Mercury Island, we can control how the bees breed,” says scientist Michelle Taylor. “We now seem to have a population which has high levels of genetic varroa resistance, which we will be able to use to increase the levels of natural resistance on the mainland and begin to control the varroa mite.”

Other Plant & Food Research scientists are looking at natural predators of the varroa mite as a means of control.

Chelifers, a type of pseudoscorpion, are small arachnids which naturally prey on mites and larvae. Entomologists are looking at whether it is possible to commercially rear chelifers, and how well they can control the varroa mite when introduced to bee hives.

Scientist Brad Howlett says native chelifers can survive in hives, are tolerated by honey bees and readily eat varroa mites. “However, we do not know how many mites they eat over a longer time period or how best to rear them to provide a reliable commercial source of supply. By building better understanding of these small arachnids, we may be able to introduce them to hives as a biological control for the varroa mite.”

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