Botanical insecticides are naturally-occurring chemicals that are extracted from plants and are designed to prevent damage to plant life from certain insects while being less harmful to helpful insects.
Organic gardeners often opt for botanical insecticides rather than synthetic materials. In fact, even after the introduction of often cheaper synthetic pesticides, botanical insecticides are growing in popularity over recent years, especially in light of adverse health effects associated with exposure to some synthetic products. The regulations in many legalized cannabis markets require cultivators to use benign pesticides, such as in California, where capsaicin, cinnamon oil, clove oil, garlic oil, the terpenoid geraniol, peppermint oil, rosemary oil, sesame oil, and thyme oil comprise some of the approved pesticides, many of which contain abundant terpenes. Limonene and linalool are also good insecticides.
Botanical insecticides often have low toxicity levels and the ability to act and degrade quickly. As such, they don’t have the same types of long-term negatives that synthetic materials have, making them environmentally-friendly. Since botanical insecticides break down quickly, however, they may need to be reapplied more often. It should be noted, however, that botanical insecticides can be toxic to mammals, honeybees, fish, etc., so any product of interest should be researched prior to use.
Other examples of not-so-benign botanical insecticides include:
Pyrethrum. This common insecticide is derived from the pyrethrum daisy, which can be used as a companion plant to deter pets like aphids and spider mites. It can be used to protect against flies, fleas, and mosquitoes as well, but is toxic to cats, fish, and honeybees. Pyrethrum is mildly toxic to humans with an oral LD50 of 1,200-1,500 mg/kg of body weight.
Ryania. Damage from moths and earworms can be mitigated with the application of ryania, which is made from the stems of Ryania speciosa. It is very toxic to dogs. The oral LD50 of ryania in humans is 750-1,200 mg/kg of body weight.
Rotenone. This botanical insecticide comes from the Lonchocarpus genus which is in the legume family, and is native to South America and protects against beetles and other critters that feed on leaves. It is toxic to fish, so it should not be used near natural bodies of water. It is mildly toxic to humans, but a study on rats pointed to its ability to induce Parkinsonian symptoms.  The oral LD50 of ryania in humans is 60-1,500 mg/kg of body weight, depending on the solvent used.
Sabadilla. Derived from a lily native to Central and South America, sabadilla protects vegetation from caterpillars and various bugs. It’s important to note that sabadilla can kill some beneficial insects, and is toxic to bees. The oral LD50 of sabadilla in humans is 4,000 mg/kg of body weight.
Neem Oil. Native to India and other tropical areas, neem oil repels insects and may even interfere with their feeding and growth cycle. Plants can absorb neem oil so that insects that start feeding on plants can be affected. The oral LD50 of neem oil in humans is 13,000 mg/kg of body weight.
Used and applied accordingly, botanical insecticides can provide cannabis growers with a low-toxicity option that is gentler on the environment.
Reference Caboni P, Sherer TB, Zhang N, et al. Rotenone, deguelin, their metabolites, and the rat model of Parkinson’s disease. Chem Res Toxicol. 2004;17(11):1540-1548. [journal impact factor = 3.739; times cited = 155]
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