Tobacco and nicotine explored as a pesticide

Tobacco, used on a small scale as a natural organic pesticide for hundreds of years, is getting new scientific attention as a potential mass-produced alternative to traditional commercial pesticides. That is the focus of a study by University of Western Ontario Faculty of Engineering researcher Dr Cedric Briens, and the topic of a report he recently published in the American Chemical Society’s bi-weekly journal Industrial & Engineering Chemistry Research.

Dr Briens and colleagues note that concerns about the health risks of tobacco have reduced demand and hurt tobacco farmers in some parts of the world. Scientists are looking for new uses for tobacco. One potential use is as a natural pesticide, due to tobacco’s content of toxic nicotine. For centuries, gardeners have used home-made mixtures of tobacco and water as a natural pesticide to kill insect pests. A “green” pesticide industry based on tobacco could provide additional income for farmers, and as well as a new eco-friendly pest-control agent, the scientists say.

They describe a promising way to convert tobacco leaves into pesticides with pyrolysis. That process involves heating tobacco leaves to about 900ºF in a vacuum, to produce an unrefined substance called bio-oil. The scientists tested tobacco bio-oil against a wide variety of insect pests, including 11 different fungi, four bacteria, and the Colorado potato beetle, a major agricultural pest that is increasingly resistant to current insecticides. The oil killed all of the beetles and blocked the growth of two types of bacteria and one fungus. Even after removal of the nicotine, the oil remained a very effective pesticide. The ability of the oil to block some but not all of the microorganisms suggests that tobacco bio-oil may have additional value as a more selective pesticide than those currently in use, the report indicates.