Natural Pesticides (Biopesticides) and Uses in Pest Management- A Critical Review

This paper focuses on new types of biopesticides, examine the specificity to harmful pests, and the selectivity to beneficial animals. Many of the modern pesticides used today, persist in soil for years and compound the store of toxins in the soil, air and water. The toxic build-up of these chemicals has been shown to cause damage in animals, plants, human health and are not easily degradable in the environment. Study has shown that some plants contain components that are toxic to insects and pest called biopesticides or natural pesticides. Natural pesticides are pesticides made by organisms usually for their own defense, or are derived from a natural source such as plant, animal, bacteria, and certain mineral, use to control pest naturally with less effect or no effect. Examples of these natural pesticides are Rotenone (Derris sp.), carboxin, fluroacetate, nicotine, neem (Azadiracta indica), microbial pesticide Bacillus thuringiensis, and pyrethrins. Natural pesticides usually target specific sites in the insect such as nervous system, resulting in knock-down, lack of coordination, paralysis and death. Rotenone inhibits the transfer of electron from NADH to ubiquinone, it disrupts energy metabolism by inhibition of the electron transport system (ETS) and blockage of ATP synthesis in the mitochondria. Nicotine inhibits and compete with neurotransmitter by binding to acetylcholine receptors at the nerve synapses and causing uncontrolled nerve discharge. Fluoroacetate and carboxin inhibits the citric acid cycle by binding to aconitase and succinate dehydrogenase respectively. Pyrethrin exerts their toxic effect by disrupting the sodium and potassium ion exchange process, which interrupt the normal transmission of nerve impulses. Most botanical pesticides shows their effect through contact, respiratory, or stomach poisons to the target organism. Botanical pesticides are generally highly bio-degradable, and they become inactive within hours or a few days and can easily be broken down by stomach acids in mammals, so toxicity to humans and animals is very low to non-target organisms and are ecofriendly. Since they are also very effective, natural pesticides should be the first choice for pest management, which in turn reduces the bioavailability of metal and noxious effect in the environment. This review explains the major natural pesticides, mechanism, mode of action and origin.