Food Chain Contamination by Neonicotinoids—A Matter of Concern

Neonicotinoids, often abbreviated as neonics, represent a group of insecticides that possess neuro-active properties and share a chemical resemblance to nicotine. It acts by disrupting the cholinergic impulses of the insect nervous system. A large proportion of applied neonicotinoids remain as residues in soil or waterbodies, which may be because of their systemic nature, notable water solubility, and long half-lives. These insecticides can reach the food chain through multiple routes, including treated crops, adulterated seeds, contaminated soil and water, and surface runoff, as well as via exposed organisms. As the plants absorb the chemicals and/or the contaminated organisms are consumed, neonicotinoids disperse and accumulate throughout the food chain and environment, potentially impacting diverse organisms within the ecosystem, including human health. Numerous beneficial arthropods at the primary consumer level, like bees, bumblebees, wasps, hoverflies, etc., become contaminated by neonicotinoids from the farmland system. Soil-dwelling organisms like earthworms, molluscs, etc., as well as aquatic insects like Daphnia, chironomid larvae, mayfly and dragonfly nymphs, etc., can also be affected by these insecticides. From these primary consumers, neonicotinoids propagate to top consumers like reptiles, birds, and mammals. As a consequence, organisms of different trophic levels suffer from sub-lethal to lethal effects, leading to potential disruptions in the entire ecosystem’s stability. Addressing this issue requires regulatory authorities and farmers to embrace sustainable and eco-friendly alternatives, mitigating the impact of neonicotinoids on the delicate balance of the food chain and the environment. This chapter delves into how neonicotinoids contaminate and spread throughout the food chain, and their impact on ecosystems and biodiversity, and emphasizes regulatory measures to reduce contamination.