Varroa mites, chemicals and lack of nutrition cause bee decline, USDA says

Similar to other animals, bees require a balanced diet of sugar, protein, vitamins and minerals, and water. | File photo

The USDA recently reported that between April 2015 and April 2016, beekeepers in the U.S. lost 44 percent of their bee colonies.

Jay Evans, who runs the USDA’s bee lab in Beltsville, Maryland, has been looking into the causes behind the massive decline in bees in recent years. He said in a radio interview that the leading cause of honeybee deaths can be attributed to parasites, poor nutrition and the chemicals bees are exposed to.

“There are three major stresses on bees: one is biological – different parasites and pathogens, including the varroa mites, and these have been harder and harder to control,” Evans said. “And we know they are transmitting viruses. They’re actually having a huge impact on bees.”

Varroa mites are parasites that suck blood from adult bees and developing brood, which weakens infected honeybees and shortens their life by causing varroosis. Developing brood may have deformities such as missing legs or wings.

Drifting workers and drones spread the mites from colony to colony. The key to successfully controlling the spread of the parasite is early detection of low levels of varroa mite infestation. However, detecting well developed infestations is easier than detecting those just beginning.

Infestation usually occurs in the late fall through early spring, and because a major mite infestation can lead to the death of an entire bee colony, the deaths may be mistaken to be winter-related.

Similar to other animals, bees require a balanced diet of sugar, protein, vitamins and minerals, and water. The lack of nutrition also plays a crucial role in the death of bees, Evans explained.

“So if they’re placed in an area without forage, they simply can’t collect enough food to build a colony up in the summer,” he said. “There’s also some degree of chemical stress, both chemicals that beekeepers have to use to treat disease and possibly chemicals in the environment that the bees are picking up.”

Because honeybees are crucial to agriculture – pollinating billions of dollars’ worth of crop, researches are continuing to search for solutions to reduce the large number of bee deaths each year and breed tougher bees.

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U.S. Department of Agriculture 1400 Independence Avenue Southwest Washington, DC 20250

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