Essay --

Bees are vital to our ecosystem and human society. They provide economically valuable pollination service. Roughly 90% of the world’s plant species are pollinated by bees. Without pollination by animals, most flowering plants would not reproduce sexually and humans would lose food and other plant products. In particular, honeybees remain the most valuable pollinators of crop monocultures worldwide. However, in recent years there has been an observation of honeybee decline. Around 2006 many beekeepers around the world began to notice that their honeybees are disappearing. This was a mystery that caught scientists’ attention. They entitled this mystery: colony-collapse disorder (CCD) (Walsh 2013). This disturbing trend continues until now - honeybees are still dying progressively. One - third of U.S. honeybee colonies disappeared during the past winter. Beekeepers experienced tremendous losses that went above 42%. As a result, the colony loss is putting intense pressure on the industry and agriculture. Scientific investigations of CCD suggest that microbial pathogens are causally involved (Suryanarayanan 2013). Different scientific studies that have identified different sets of associated microbial pathogens have suggested that the discovered pathogens are secondary infections, with the primary cause yet to be found. Scientists have been suggesting many theories on bee decline. Agricultural pesticides were considered as the most obvious suspects and specifically popular chemicals known as Neonicotinoids. Other theories were focused on bee killing pests or a varroa destructor - a parasitic mite that has ravaged honeybee colonies since it was accidentally introduced in U.S. in the 1980s. (Walsh 2013). The imp... ...erdose of insecticides near the hives of the bees. Adolescent bees, living in hives contaminated by pesticide, have their body surfaces and fat tissues poisoned with these substances. Besides leading to bee deaths, insecticides used in agriculture for combat work also causes the problem of residues remaining from chemicals used as varroacides. Bromopropylate, coumaphos (perizin) and melathion are typical examples of varroacides, whose residues have been examined in bee products such as honey. These chemical are oil-soluble and volatile. The impact of parasites and viruses on bees The varroa mite or varroa distracter is currently the most serious parasitic mite on honeybees. This parasite is feeding on the hemolymph of immature and adult bees (Harbo and Harris, 2001) .It causes many biological effects like weight loss, malformation and short lifespan of honeybees.