Rotenoid

Rotenoids are a class of naturally occurring organic compounds produced by various plant species, primarily in the family Fabaceae (legumes). Chemically, they are isoflavonoids, closely related to isoflavones. Rotenoids are notable for their insecticidal properties, making some of them useful as botanical insecticides.

Characteristics and Properties

Rotenoids are complex molecules characterized by a fused ring system, typically consisting of five interconnected rings. They are generally colorless or pale yellow crystalline solids. The insecticidal activity of rotenoids stems from their ability to interfere with mitochondrial electron transport in insects and other invertebrates, specifically by inhibiting NADH dehydrogenase. This disrupts cellular respiration, leading to paralysis and death.

Sources

Rotenoids are found in the roots, stems, and leaves of various plant species. The most well-known source is Derris elliptica, a climbing plant native to Southeast Asia, whose roots have been traditionally used as a fish poison and insecticide. Other significant sources include species from the genera Lonchocarpus and Tephrosia.

Uses

Historically, rotenoid-containing plant extracts have been used for centuries as insecticides and piscicides (fish poisons) by indigenous populations. In modern agriculture, rotenone, a specific rotenoid, has been employed as a broad-spectrum insecticide to control various pests on crops, in gardens, and in animal husbandry. However, its use is declining due to environmental concerns and the availability of alternative insecticides.

Environmental Considerations

While derived from natural sources, rotenoids are not without environmental impact. Rotenone, in particular, is toxic to fish and other aquatic organisms. It can also affect beneficial insects and, to a lesser extent, mammals. Rotenoids degrade relatively quickly in sunlight and water, but their toxicity to aquatic life necessitates careful application and consideration of potential environmental consequences.

Regulation

The use of rotenoid-containing insecticides is subject to regulation in many countries. Regulations often specify permissible application rates, target pests, and restrictions on use near bodies of water. These regulations are intended to minimize the environmental risks associated with rotenoid use.