For people who prefer to use natural means to control insect pests, botanical insecticides/pesticides can be used instead of synthetic products. However, it is important to note that natural formulations break down more readily in soil. They are not stored in organic tissue, so their effects do not last as long as synthetic products.
The list of these natural alternatives, some of which have limited availability and variable success, include insecticidal soaps, repellent sprays, beneficial insects (like ladybugs). Among the better known natural alternatives are botanical pesticides, which possess little toxicity for warm-blooded animals, but they should nonetheless be handled with care.
Botanical pesticides are derived from plant material. They include:
Pyrethrins – the most popular and among the safest of botanical insecticides; derived from pyrethrum, a powder made from the pyrethrum daisy. Pyrethrins are often used as ingredients in insecticidal soaps, sprays, and other products. Many insects are highly susceptible to and quickly killed by pyrethrins, which degrade rapidly upon exposure to light and moisture. They are effective in low concentrations and are nontoxic to most mammals.
Rotenone – one of the oldest and most toxic of botanical insecticides; a powder derived from the roots of the plant genus Lonchocarpus from South America. Rotenone was long used as a fish poison before being used against insects such as cabbageworms, aphids, and thrips. Rotenone can take several days to kill. It is often combined with pyrethrins and is moderately toxic to most mammals.
Ryania – powder from the roots and stems of the South American shrub Ryania speciosa. Ryania breaks down more slowly than other botanical insecticides; it is effective against many insect pests while harmless to many beneficial insects and relatively nontoxic to mammals.
Sabadilla – not widely available; derived by grinding seeds of the sabadilla plant. Effective against leaf-feeding caterpillars, stink bugs, squash bugs, harlequin bugs, thrips. Sabadilla dust can be somewhat toxic to mammals. A mask should be worn when applying it because it can irritate the respiratory tract and cause violent sneezing.
Neem – the newest botanical insecticide; derived from seeds of the neem tree. Neem has a long history of use in products like toothpaste in countries like India. Unlike the other insecticides mentioned above, neem appears to have a hormonal effect on leaf-chewing beetles and caterpillars, disrupting their growth process. Neem is not toxic for humans; it is approved for use on any edible or ornamental plant.