Colony Collapse Disorder (CCD) is the most serious, abruptly die-off of European honey bee colonies across the world. The main symptom of CCD is simply no or a low number of adult honey bees present but with a live queen and no dead honey bees in the hive. Often there is still honey in the hive, and live brood is present. It is also characterized by delayed robbing and slower than normal invasion by common pests such as wax moth (Galleria mellonella) and small hive beetles (Aethina tumida). Now, in many countries CCD creates a very serious problem for beekeepers and threaten the pollination industry. CCD is economically significant because many agricultural crops worldwide are pollinated by bees. Beekeepers observed CCD in USA in 2006, then in Canada, Australia, Belgium, France, the Netherlands, Greece, Italy, Portugal and Spain. The reports have also come in from Switzerland, Germany, Finland and Poland.It is unlikely that a single factor is the cause of CCD; it is more likely that there is a complex of different components. The search for factors that are involved in CCD is focusing on few areas and the cause or causes of the syndrome are not yet fully understood. Many authorities attribute the problem to immunosuppression and biotic factors such as Varroa destructor mites, Nosema apis and Nosema ceranae and Israel acute paralysis virus (IABPV). Other proposed causes include environmental change-related stresses, malnutrition and pesticides, mainly neonicotinoids, migratory beekeeping. More speculative possibilities have included both cell phone radiation and genetically modified crops. Stress, in general, compromises the immune system of bees and may disrupt their social system, and individual immune response, making colonies more susceptible to diseases. The only pathogen found in almost all samples from honey bee colonies with CCD, but not in non-CCD colonies, was the Israeli acute paralysis virus (IABPV) that can be transmitted by the Varroa destructor mite. It was found in 96.1 percent of the CCD-bee samples. Some researchers have attributed the syndrome to the practice of feeding high fructose corn syrup to supplement winter stores. Affliction with Varroa mites also tends to weaken the immune system of the bees. However not all dying colonies are parasitized by these mites. Some genetically modified crops produce the natural insecticide Bt toxin, which was hypothesised to affect bees. No experiments have found evidence of any negative effect whatsoever on honey bee populations. The continuous movement and re-settlement render bee colonies less resistant to disorders. It was also suggested that climate change can make bee hives more vulnerable to CCD, and that the closerange electromagnetic field may reduce the ability of bees to return to their hive. Therefore, it seems that CCD may be due to a combination of many factors and that no single factor is the cause.
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