Bee Health – Current Bee Decline | Syngenta

Bee Decline

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According to a USDA 2012 report, today’s colony strength is about 2.5 million. Honey bee colonies have been dying at a rate of about 30 percent per year over the past few winters. In the U.S., this phenomenon was coined “Colony Collapse Disorder” (CCD).

Colony Collapse Disorder (CCD)

CCD is characterized by the disappearance of adult honey bees but a live queen and brood are still in the hive. No dead bees are found in or around the hive and food stores are left untouched by robbing bees or other pests.

Bee health risk factors

Many experts agree that bee health is likely caused by several different factors including CCD, especially when acting together. These include the following:

  • Pests and diseases, in particular the Varroa mites and the viruses they carry, and the gut parasite Nosema ceranae
  • Poor nutrition in some areas due to a lack of quantity, availability and quality of nectar and pollen in areas with limited biodiversity
  • Lack of knowledge of professional and hygienic hive management
  • Genetic uniformity of the majority of honey bees, leading to weakened resistance to pests and diseases
  • Stress caused by commercial transportation over long distances to pollinate particular seasonal crops
  • Unusual weather.
  • Misused pesticides.

The scientific consensus from ongoing work suggests that while there is no single factor, the Varroa mite is the main factor involved in bee colony decline in certain parts of the world. For more causes and descriptions of bee stressors, visit Causes of Bee Stresses.

Varroa Mite

The Varroa mite is the most detrimental honey bee parasite in the world today. Varroa mites can be found in nearly all domesticated honey bee colonies, except in Australia. Varroa feed on brood and adult bees and move quickly from one bee to another. In the process, they inadvertently “inject” viruses into the bees on which they feed. Infected bees have lower weight, decreased immune response and decreased learning ability. Without treatment, the mites will destroy a colony of bees within 18 months. Beekeepers have learned to live with the mite by using available chemical treatments. But the mites have started to become resistant to the chemical treatments, making them difficult to eliminate.

Neonicotinoids

While experts do not cite neonicotinoids — a class of insecticide seed treatments proven to be extremely valuable to farmers — as a contributing factor to the disappearance of bees, the media has cited neonicotinoids as a main cause of bee population decline.

Due to the targeted application and uptake into the plant tissue, the use of neonicotinoid seed treatments reduces the number of pesticide applications and amount of pesticide used. Seed treatment application methods target the pesticide, limiting exposure and minimizing risks to beneficial insects including bees.

The evidence overwhelmingly suggests there is no direct correlation between neonicotinoid use and poor bee health. Our research has found no impact to bee colonies exposed to neonicotinoid-treated crops, even when exposed for several years1. These studies included exposure of bees to nectar, pollen and guttation water from treated crops, and dust during drilling. This has also been verified by independent monitoring programs that have demonstrated the safe use of these products.

1 Pilling et al. 2014. A four-year field program investigating long-term effects of repeated exposure of honey bee colonies to flowering crops treated with thiamethoxam. PLOS One. 8 (10 ) e77193
http://www.thecre.com/oira_pd/wp-content/uploads/2013/11/PLOS-One-Syngenta.pdf