Bio-Chemical Pesticides
Bio-chemical pesticides are materials derived from naturally occurring substances in the environment (plant, bacteria, or minerals): roots, leaves, seeds or flowers that have insecticidal and fungicidal properties. While these materials are for the most part safer to the user and the environment than chemical-based materials, they are still broad spectrum in nature (i.e., they may kill non-target organisms). The main advantage of their use is they are short-lived in the environment, being broken down into harmless by-products by UV rays from sunlight. The toxic residues from these materials last only 2 – 3 hours to several weeks depending on the material and crop being protected. Biochemical pesticides have the following qualities:
- naturally-occurring substances or structurally-similar and functionally identical to a naturally-occurring substance;
- a history of exposure to humans and the environment demonstrating minimal toxicity, or in the case of synthetically-derived biochemical pesticides, is equivalent to a naturally-occurring substance that has such a history; and
- a non-toxic mode of action to the target pest(s).
Bio-chemical pesticides include, but are not limited to: natural plant and insect regulators; naturally-occurring repellents and attractants; insect pheromones and kairomones; and enzymes.
Spinosad(Saccharoployspora spinosa)
This pesticide resulted from observations of a Caribbean soil sample found to be active on mosquito larvae. The microorganism, Saccharopolyspora spinosa, was isolated from the soil sample, and the insecticidal property of the spinosyns was identified. Most of the insecticidal activity is due to a mixture of spinosyns A and D, commonly referred to as spinosad. Insects that are exposed to spinosad exhibit classic symptoms of neurotoxicity: lack of coordination, prostration, tremors, and other involuntary muscle contractions leading to paralysis and death. Although the mode of action of spinosad is not fully understood, it appears to affect neuroreceptor function through a novel mechanism. Spinosad presents a favorable environmental profile. It does not leach, bio-accumulate, volatilize, or persist in the environment. Spinosad will degrade photochemically when exposed to light after application. Because spinosad strongly adsorbs to most soils, it does not leach through soil to groundwater. Spinosad demonstrates low mammalian and avian toxicity. No long-term health problems were noted in mammals, and a low potential for acute toxicity exists due to low oral, dermal, and inhalation toxicity. This is advantageous, because low mammalian toxicity imparts reduced risk to those who handle, mix, and apply the product. Although spinosad is moderately toxic to fish, this toxicity represents a reduced risk to fish when compared with many synthetic insecticides currently in use. Spinosad has proven effective in controlling many chewing insect pests in cotton, trees, fruits, vegetables, turf, and ornamentals. High selec