ABSTRACT
Use of synthetic insecticides for controlling insect pest creates several problems such as their persistent toxicity in food grains, the subsequent development of resistance in insect populations, effects the non-target organisms and other adverse environmental impacts. Many plant species produce substances that protect them by killing or repelling the insects that feed on them. Botanicals are naturally occurring chemicals (insect toxins) extracted or derived from plants or minerals used as natural insecticides. Thus, sound management of insect pest by other natural insecticides has more interest and is eco-friendly to nature with less reduced negative effects on the environment. However, in very early time of insect control, tobacco extract was used as a plant spray in parts of Europe and tobacco product nicotine was discovered in France to kill aphids. Botanical insecticides have different chemical structures and modes of action. Based on the physiological activity, there are six groups of botanical insecticides, namely; repellents, feeding deterrents/antifeedants, toxicants, natural grain protectants, chemosterilants/reproduction inhibitors and insect growth, and development inhibitors. These natural pesticides have many advantages over synthetic ones and may be more cost-effective as a whole, considering the environmental cost of chemical alternatives.142
