In the context of the environment, neonicotinoids refer to a class of synthetic insecticides chemically related to nicotine. They have been widely used in agriculture since the 1990s to control a variety of pests, especially sap-feeding insects like aphids and root-feeding grubs. Neonicotinoids act on the central nervous system of insects, leading to paralysis and death, and are considered to be more targeted than older classes of insecticides, with a lower toxicity to mammals.

General Description

Neonicotinoids are systemic chemicals, meaning they can be absorbed by a plant and distributed throughout its tissues, making all parts of the plant potentially toxic to pests. This systemic action allows for a variety of application methods, including seed coating, soil drenches, and foliar sprays. However, the widespread use of neonicotinoids has raised environmental concerns, particularly regarding their impact on non-target species, including pollinators like bees and butterflies, aquatic invertebrates, and birds.

Application Areas

• Agriculture: Used to protect crops from pests, neonicotinoids are applied to seeds, soil, or plants directly.
• Horticulture and Forestry: Utilized in the protection of trees and ornamental plants from damaging insects.
• Veterinary Medicine: Some neonicotinoids are used in products to control fleas and ticks in domestic animals.

Known Examples

Common neonicotinoids include imidacloprid, clothianidin, and thiamethoxam. These chemicals have been found in a variety of environments, including water bodies, due to runoff from agricultural fields, and have been detected in nectar and pollen, posing risks to pollinators.

Treatment and Risks

Neonicotinoids have been linked to adverse environmental effects, notably:

• Bee Colony Collapse Disorder: Several studies have associated neonicotinoid exposure with the decline in bee populations, affecting their navigation, foraging behavior, and immune systems.
• Impact on Aquatic Ecosystems: Neonicotinoids can accumulate in waterways, potentially harming aquatic insects and the species that rely on them for food.
• Bird Population Declines: Reductions in bird populations have been linked to a decrease in insect availability due to neonicotinoid use.

Due to these concerns, some countries and regions have restricted or banned the use of certain neonicotinoids. The European Union, for example, has banned the outdoor use of imidacloprid, clothianidin, and thiamethoxam.

Summary

Neonicotinoids are a widely used class of insecticides known for their systemic action and effectiveness against a range of pests. However, their environmental impact, particularly on non-target species like pollinators and aquatic invertebrates, has led to increased scrutiny and regulatory action. The debate over their use underscores the challenge of balancing the needs of modern agriculture with the preservation of environmental health and biodiversity.

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