Veterinary medicine

A veterinarian targets the bee parasite

Organic acids could be the answer in the fight against the parasite Varroa destructor, an acarian that decimates bee populations. According to a study by Dr Pascal Dubreuil, a professor in the Faculty of Veterinary Medicine at University of Montréal, treating the hives with formic acid and oxalic acid has yielded some encouraging results. Bee-keepers could obtain authorization to use oxalic acid in the 2004 season if the federal government (ARLA) approves its use.

The parasite has caused widespread damage to hives since 2002, as 43% of bee-keepers report death rates in excess of 50%. 2003 was no better, many colonies failing to survive the winter. “Mortality this high has serious consequences for bee-keepers, but it also causes a drop in pollination,” notes the researcher. The success of many crops—strawberries, blueberries, cranberries, apples, cucumbers, pumpkins, etc.—depends on good pollination. Studies have demonstrated that the more hives are placed in the blueberry farms, the higher the blueberry production, and the upper limit on growth is still unknown. In a blueberry-producing region like the Saguenay-Lac-Saint-Jean area, this is important news. Professor Dubreuil’s research is funded by the Québec Ministry of Agriculture, Fisheries and Food.

So what is this alarming parasite? Native to Asia, Varroa destructor spread around the world in a just few years through sales of queens, some of which were infected. The parasite has been in Québec for a dozen years. “Varroa destructor reproduces at the same time as the bees and lives on their backs,” explains the veterinarian, whose parents were beekeepers. The bees can tolerate the presence of the acarian, but beyond a certain level the hive is endangered.

Currently, beekeepers are keeping the parasite in check with acaricides like Apistans or Coumaphos. These chemicals must be used with care, because they can leave residues in the honey. Moreover, over the years Varroa destructor has developed a resistance to Apistan. In the fall of 2002, Apistan proved ineffective in several apiaries.