Over the past decade populations of honey bees and other pollinators have been in decline worldwide. This phenomenon, often referred to in media as Colony Collapse Disorder (CCD), is characterized by a rapid loss of a colony’s adult worker bee population, and has been associated with varroa mites, viruses, environmental stress, and pesticides. Reports of the ‘mysterious disappearance of bees’ abound in scholarly studies and the media, along with disclaimers that no causal effect has been proven.
An article entitled "Existing Scientific Evidence of the Effects of Neonicotinoid Pesticides on Bees", which appeared in an online European Parliament publication (EAA, 2012), describes a causal effect – bee poisoning by neonicotinoid pesticides.Mounting undeniable scientific evidence has surfaced from around the globe linking neonicotinoid pesticides to mass bee deaths.
In order to protect honey bees, various member states of the European Union have taken regulatory action on the use of specific neonicotinoids. The European Parliament report describes that "neonicotinoids block an intrinsic chemical pathway which transmits nerve impulses to the insect central nervous system" causing irreversible and cumulative damage to the central nervous system and death. Bees exposed to neonicotinoids exhibit convulsions, tremors, and uncoordinated movements typical of exposure to neurotoxins.
Neonicotinoids are systemic pesticides that are absorbed into plant tissues. The poisons are highly soluble in water and are applied to a variety of agricultural crops with sprays, seed coatings, soil drenchers and granules, injections into tree trunks, or as an additive to irrigation water. Neonicotinoids migrate through soil and the entire plant all the way to the flowers. This causes toxic, lethal, and chronic exposure to non-target species including earthworms, birds, fish, and pollinators (Mason, et al., 2012). Additional exposure routes also exist depending on the method of application. Neonicotinoids are able to remain in the plant tissues for months to several years.
Even low dose exposure to neonicotinoids can result in serious sub-lethal effects on insects. Residues in nectar and pollen often lead to long-term exposure for pollinators. There is no safe level of exposure, as even tiny amounts of insecticides can have long term negative effects. The European Parliament publication (EAA, 2012) reported sub-lethal effects include a wide range of behavioural disturbances in honey bees including: