The researchers reckon that the reason why so many honey bees are dying is down to a combination of factors that are found only, so far, in America. The Israeli acute paralysis virus may have had such a devastating effect there because of the presence of a parasite called the varroa mite. This parasite weakens the immune systems of bees, making the consequences of an infection more likely to be fatal. Tellingly, bees in Australia have not been infected by the parasite.
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