Honey bee colony collapse disorder

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

If you have been listening to the radio or reading papers the last few weeks, chances are that you have already heard about the alarming honey bee die-offs around the country. The phenomenon is officially named “colony collapse disorder” (CCD). This disorder has the media all excited because it is large in scale (25 states are affected), came in quick (colonies that were fine in August-September collapsed around October-November), and hit people hard (many beekeepers with hundreds to thousands of colonies are losing 50-90 percent of their hives). The worst of it all, we do not yet know what causes it.

The symptom seems to be that bees simply disappear. Initially, people called it the disappearing disease (or fall dwindle disease). A colony with 40,000 bees in the fall, apparently healthy with lots of honey and pollen, suddenly has no or few bees left. Very few dead bees are found inside the hive or near the entrance. Strangely, wax moths, small hive beetles, robbing bees and other pests are slow to move into such newly abandoned colonies – taking two to three weeks rather than moving immediately into defenseless colonies.

There are several possible causes for hive deaths, several of them natural. One is tracheal mites (Acarapis woodi), which first were found in North America in the early 1980s. Tracheal mites particularly impact the ability of bees to overwinter by living in and plugging up bee trachea (breathing tubes). Mite infestation weakens and kills bees, so there are no or few individuals left in heavily infested colonies in the spring. In addition to mites, a new bee disease, Nosema ceranae, was found in hives in Europe, killing up to 60 percent of bees in some apiaries. Recently this disease was found in the hives in the United States. Another concern is that a pesticide or combination of pesticides is weakening the immune system of honey bees or affect their learning and orientation. Other suggested causes of CCD include cell phone use.

Unfortunately, all these factors (mites, disease and pesticides) are unlikely to be the causes of CCD. Scientists from Montana State University, North Carolina State University, Penn State University and the USDA Bee Lab in Beltsville MD, are collecting and analyzing a large number of bee samples. Hopefully, we will have the answer soon.

Midwest beekeepers and crop growers will be impacted by this new disorder in several ways. First, Michigan and surrounding states officially have CCD, which means some beekeepers are directly losing hives. Another impact in Michigan will be higher pollination fees for fruit and vegetable crops (for example apples, cherries, blueberries, cucumbers, squash). In the past few years, growers paid $40-$50 a colony to pollinate their crops in Michigan, because pollination is the critical step to insure a good crop for these fruits. But due to bee shortages, the fee per colony might be slightly increased this year by $5-$15 more per colony. It could be worse - almond growers in California paid as much as $200 a colony for this year’s pollination job, compared to $125-$160 per colony in the spring of 2006.

Field crops producers do not have to worry about pollination fees because corn, soybean and small grain crops are not bee-pollinated. However, bees visit field crops, especially alfalfa and soybean fields, to work flowers. The majority of insecticides used to control weevil and potato leafhopper in alfalfa, and soybean aphid in soybean, are highly toxic to bees. Given the recent reduction in hives, anything you can do to protect bees is important for the food supply. Here are some bee-protection tips:

  • Cut alfalfa before 10 percent bloom (bees are attracted to fields in bloom).
  • Note honey warning labels on insecticides used on alfalfa.
  • Notify bee keepers in your area when you treat. They may be able to restrict bee movement.
  • Spray in the evening when bees are not foraging.

Dr. Huang’s work is funded in part by MSU‘s AgBioResearch.

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