Toxicity of Neonicotinoids to Honey Bees and Detoxification Mechanism in Honey Bees

Abstract

Agrochemicals are widely used in the present day agricultural practices and many non-targeted species like honey bees are affected by these agrochemicals and getting declined in the nature.To prevent this, detoxification mechanism needs to be studied and implemented in future aspects to protect the honey bees.Honeybee is a member of the genus Apis, involved in the production and storage of honey, construction of perennial, colonial nests from wax. Species of Apis mellifera pollinate a large variety of plants. Of all the honey bee species, only A.mellifera has been used extensively for commercial pollination of crops and other plants. Bees suffer serious effects from toxic chemicals in their environments. These include various synthetic chemicals, such as insecticides and fertilizers, as well as a variety of naturally occurring chemicals from plants. Insecticides are considered the major factors for the current decline in bee populations. However, detoxification mechanisms in healthy, unstressed honey bees are poorly characterized. A substance called p-coumaric acid specifically up-regulates all classes of detoxification genes as well as select antimicrobial peptide genes. This up-regulation has functional significancein that adding p-coumaric acid to a diet of sucrose increases midgut metabolism of coumaphos, a widely used in-hive acaricide, by ∼60%. As a major component of pollen grains, p-coumaric acid is ubiquitous in the natural diet of honey bees and mayfunction as a nutraceutical regulating immune and detoxification processes. In less than 20 years, neonicotinoids have become the most widely used class of insecticides with a global market share of more than 25%. These chemicals mimic the acetylcholine neurotransmitter and are highly neurotoxic to insects. At field realistic doses, neonicotinoids cause a wide range of adverse sublethal effects in honeybee andbumble bee colonies which affects colony performance through impairment of foraging success, brood and larval development, memory and learning, damage to the central nervous system, susceptibility to diseases, hive hygiene etc. The worldwide production of neonicotinoids is still mounting. Therefore a transition to pollinator-friendly alternatives to neonicotinoids is urgently needed for the sake of the sustainability of pollinator ecosystem services.