Rotenone is a natural, vegetable-based insecticide commonly used in home gardens, for lice and tick control on pets, and for fish population control. As a garden pesticide, it is sold commercially under some of the following names: Curex Flea Duster, Derrin, Cenol Garden Dust, Chem-Mite, Cibe Extract, and Green Cross Warble Powder.
Origins of Rotenone
Classified as a botanical extract, rotenone is derived from several types of plants in the pea (Leguminosae) family specifically Derris elliptica (derris) from the Malay States and Dutch East Indies, and Lonchocarpus species (cube, timbo, barbasco) from South America. The roots also contain additional ingredients considered toxic to insects. Use of the pesticide originates among indigenous people in South America and Africa who used the roots to paralyze fish and bring them up to the surface, according to the Pesticide Action Network.
How Is Rotenone Used?
Rotenone causes paralysis and inhibits cellular oxygen uptake to kill insects and fish. Commercially, it can be used alone or with other insecticides like pyrethrum, which comes from the flowers of plants in the Pyrethrum genus, which is part of the carnation family. As an all-purpose insecticide, it kills bean beetles, cage worms, coddling moths larvae, plum sawfly, ticks, mites and fleas.
Chemical Composition and Delivery
In powder form, rotenone is applied with standard dusting applicators on vegetable plants and sometimes on farm livestock as a mite and tick preventative. Although regulated by the Environmental Protection Agency (EPA), it is also used to kill off invasive fish species from non-native habitats. Though toxic to humans and other mammals, it breaks down rapidly in the environment (a week or less), especially when exposed to direct sunlight. As a liquid, it's often mixed with liquid soap or castor oil to improve adhesion to plant leaves and stems.
Rotenone has relatively low toxicity to mammals in most forms, according to the Cornell University Extension Toxicology Network. The exception is when rotenone is concentrated in an emulsion--it is then highly toxic. As a dusting powder, fine powders are more toxic than coarse particles, and inhalation is more toxic than ingestion. Symptoms of rotenone exposure in mammals can include: conjunctivitis, dermatitis, sore throat, and congestion. Ingesting rotenone can cause symptoms ranging from mild irritation to vomiting. Inhalation can cause increased respiration followed by depression and convulsions. Online resource Living With Bugs advises against dusting dogs or cats with rotenone to control fleas and ticks as safer methods of control are now available.
Because it is highly toxic to cold-blooded invertebrates, it's an invaluable tool for the U.S. Fish and Wildlife Service. When invasive and sometimes predatory fish species are inadvertently introduced into certain habitats, they can compete for limited resources and upset delicate ecosystems. Fish managers rely on a wide variety of tools to manage and assess fish populations. Rotenone is one of those tools and has been used since 1934. Because it is fast acting and has a short degradation time, it's an ideal choice for eliminating invasive fish populations.