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Botanical Insecticides


Botanical insecticides are naturally-occurring insect toxins derived from plants. Like synthetic insecticides, they have advantages and disadvantages, and should be evaluated in terms of effectiveness, toxicity, cost and environmental impact. Advantages of most botanical insecticides include almost immediate action, low toxicity to plants and to non-target organisms, selectivity, and rapid action and degradation. Disadvantages may include too rapid degradation to be effective, high cost, limited availability, lack of scientific data, and possible high levels of toxicity. Because of their rapid degradation, botanical insecticides must be applied frequently and precisely. Some will harm beneficial insects, while others are harmful to fish and other wildlife. It is important to always follow label directions, and to wear protective clothing when using botanicals, or any insecticide.
Some examples of botanical insecticides:

Nicotene: derived from tobacco, and commonly sold as nicotene sulfate, nicotene is a fast-acting contact killer for soft-bodied insects, but will not kill most chewing insects. Used to control aphids, thrips and caterpillars.

Pyrethrin: a fast-acting contact poison derived from the pyrethrum daisy. It is very toxic to cold-blooded animals, and some humans are allergic to pyrethrins. It is effective on most insects; like aphids, leafhoppers, cabbage worms, ants, and ticks......... but it will not control mites. It breaks down quickly in sunlight, air and water.

Rotenone: derived from the roots of over 68 plant species, rotenone is toxic to fish, cold-blooded and some warm-blooded animals. Rotenone is effective against many insects, including caterpillars, beetles, aphids, spider mites and carpenter ants.

Ryania: a slow-acting stomach poison, which has a longer residual than most botanicals, and has a low toxicity to mammals. Ryania is used on Japanese beetles, squash bugs, corn earworms, silkworms, onion thrips and other insects.

Sabadilla: derived from the seeds of South American lillies, sabadilla is very toxic to honey bees, but the least toxic botanical to humans. It is a contact and stomach poison, used to control grasshoppers, moths, aphids, squash bugs, harlequin bugs, and others.

Neem: derived from the neem tree that grows in arid tropical regions, extracts have been reported to control over 200 types of insects, mites and nematodes. Neem has low toxicity to animals, and is most effective when insect and plants are damp. The neem solution is only effective for 8 hours after mixing.

Missouri Botanical Garden, 2001-2011