Neonicotinoids and Other Insect Nicotinic Receptor Competitive Modulators: Progress and Prospects

Area of Science:

• Agricultural Science
• Toxicology
• Entomology

Background:

• Neonicotinoids are widely used systemic insecticides for pest control in agriculture and veterinary medicine.
• Key commercial neonicotinoids include nitroimines (imidacloprid, clothianidin, thiamethoxam, dinotefuran) and nitromethylenes (nitenpyram, cycloxaprid), alongside cyanoimines (acetamiprid, thiacloprid).

Purpose of the Study:

• To review the chemical classes, mode of action, and toxicological profiles of neonicotinoids and related compounds.
• To highlight differential toxicity among neonicotinoid subclasses, particularly concerning pollinators.
• To discuss plant stress tolerance induction and metabolic fate.

Main Methods:

• Literature review of neonicotinoid chemistry, pharmacology, and toxicology.
• Comparison of neonicotinoid structures and their interaction with nicotinic acetylcholine receptors (nAChRs).
• Analysis of toxicity data across different species, with a focus on insects and mammals.

Main Results:

• Neonicotinoids act as nAChR agonists, exhibiting high potency against insect nAChRs and lower toxicity to mammalian nAChRs.
• Nitroimines and nitromethylenes show higher toxicity to honey bees compared to cyanoimines.
• Related compounds like sulfoxaflor, flupyradifurone, and triflumezopyrim also target nAChRs with varying mechanisms.
• Some neonicotinoids can induce plant stress tolerance, and they are generally metabolized with favorable toxicological profiles for non-pollinators.

Conclusions:

• Neonicotinoids represent a significant class of insecticides with a common mode of action but varying toxicity profiles.
• Differential sensitivity of pollinators, especially honey bees, to certain neonicotinoid subclasses necessitates careful consideration in pest management strategies.
• Understanding the nAChR interactions and metabolic pathways is crucial for assessing the environmental impact and safety of these widely used agrochemicals.