Nicotine

Nicotine is a potent alkaloid extracted from the tobacco plant (Nicotiana tabacum) that serves as a traditional contact and stomach insecticide. In the history of agricultural science, it has been recognized for its rapid knockdown effect on a wide range of soft-bodied insects, primarily through its neurotoxic properties affecting the central nervous system of target pests.

The mechanism of action of nicotine involves the stimulation of nicotinic acetylcholine receptors (nAChRs) in the nervous system of insects. By mimicking the neurotransmitter acetylcholine, nicotine causes persistent excitation of the nerves, leading to paralysis and death. This mode of action is particularly effective against pests that have developed resistance to certain classes of modern synthetic insecticides.

It is primarily utilized on a variety of horticultural and vegetable crops to manage infestations of aphids, thrips, leafhoppers, and various species of mites. While its use has decreased with the advent of neonicotinoids and other safer synthetic alternatives, nicotine-based formulations or tobacco dust preparations remain a reference point for organic and traditional integrated pest management (IPM) strategies.

Application of nicotine-based products requires precise timing and dosage. The substance is highly volatile and sensitive to photodecomposition, meaning that field applications are most effective when conducted during cooler, low-light conditions. Agronomists must ensure thorough coverage of the canopy, as the substance acts primarily through contact with the insect's cuticle or spiracles.

Safety is the most critical aspect when handling nicotine, as it is toxic to mammals through skin absorption, ingestion, or inhalation. Proper Personal Protective Equipment (PPE), including chemical-resistant gloves, respirators, and eye protection, is mandatory. Furthermore, stringent pre-harvest intervals (PHI) must be strictly observed to ensure the safety of the final agricultural produce for human consumption.