Examples of Biopesticides

Animals or plants used wilfully to destroy pests are called Biopesticides. For common knowledge, we can divide them into bioherbicides and bioinsecticide.

Bioherbicides

Pesticides destroying herbs are called bioherbicides. One example is insect Cactoblastis cactorum, which eats only cactus of Opuntia variety. The first bioherbicides, developed in 1981 was a mycoherbicide based on the fungus Phytophthora palmivora. It controls the growth of milk weed vines in citrus orchards.

Bioinsecticide

Bioinsecticides are animals (including insects) that kill other insects. For example, the praying mantis eats aphids. Similarly, Gambusia fish is used to feed on larvae of mosquitoes.

Examples of Biopesticides

• Daisy plants (Chrysanthemum cinerariaefolium) were first used centuries ago as a lice remedy in the Middle East, and this led to the discovery of pyrethrum insecticides. The seeds contain a natural insecticide called pyrethrin, a generic name for six related active compounds. It is one of the safer insecticides for several reasons: it decomposes rapidly in sunlight; it has few known effects on mammals; and insects do not develop resistance to it, the safer insecticides for several reasons: it decomposes rapidly in sunlight; it has few known effects on mammals; and insects do not develop resistance to it. It is used on foodstuffs, in head lice shampoos, and in many indoor insect sprays. Lakhs of tonnes of mosquito coils made from pyrethrum are sold each year. Scientists have synthesized similar compounds called pyrethroids, but the chemical synthesis produces all geometric isomers of the compounds, many of which are ineffective and are difficult to separate from the active forms. The plant material contains only the active isomers.
• In South America, the natives use an extract of a forest vine to stun fish; this led to the discovery of rotenone, a biodegradable insecticide.
• The bacterium Bacillus thuringiensis produces toxic proteins that kill certain insects but are apparently harmless to humans. These are being produced and marketed as biopesticides.
• The Neem tree, in India, has been found to be a source of the insecticide azadirachtin, as well as fungicides, spermicide, and agents potentially valuable in birth control such as materials that prevent implantation or cause abortion. The tree has been used in traditional agriculture, medicine and cosmetics for centuries.