Botanical Insecticides
Botanical insecticides, sometimes referred to as "botanicals", are naturally occurring insecticides derived from plants. But like conventional synthetic insecticides, they have advantages and disadvantages and should be judged accordingly. Each product should be evaluated in terms of its toxicity, effectiveness, environmental impacts, and costs. Some of the advantages of botanicals include rapid degradation, rapid action, low toxicity to non-target organisms, selectivity, and low toxicity to plants. Some of the disadvantages are rapid degradation where it doesn’t last long enough to control the pest, high toxicity of certain botanicals, lack of efficacy and toxicity data, high cost and limited availability. Some examples of botanicals, Pyrethrum is the powdered, dried flower heads of the pyrethrum daisy. The term pyrethrins refers to the six related insecticidal compounds that occur naturally in pyrethrum dust. Pyrethrins affect the nervous systems of insects and are extremely fast-acting. Most products containing pyrethrins also contain the synergist PBO to make them much more effective. It is interesting that many synthetic insecticides used today mimic pyrethrins and are called "pyrethroids". Rotenone is extracted from the roots of tropical legumes such as Lonchocarpus from South America and Derris from Asia. Rotenone is a powerful inhibitor of respiration in nerve and muscle cells. It is effective against many insects, particularly leaf-feeding beetles and caterpillars. It is interesting to note that rotenone is extremely toxic to fish and is used in fish management programs. Nicotene is an alkaloid derived from tobacco and other Nicotiana species. It is an extremely fast-acting nerve toxin that is primarily used in greenhouses and gardens as a fumigant and contact poison to control aphids, thrips and mites. Nicotene is highly toxic and must be handled with care. Neem products are derived from the neem tree. The active ingredient, azadirachtin, is both a feeding deterrent and a growth regulator effective against a variety of insect pests. Remember, even when using botanicals, that it is very important to read and follow all the directions on the label.