Natural insecticides are those which are obtained from microorganisms and plants. The first natural insecticide used by man is azadirachtin obtained from Azadirachta in die a. Rotenone is another natural insecticide which is obtained from the roots of Derris and Lonchocarpers. It is harmless to warm blooded animals.
Chemical that is added to food and beverages is knowns as food preservative. It helps in preventing decay of food from the attack of microbes.
Food preservatives are of two types:
Natural preservatives: are the preservatives which are derived from natural sources. For examples: oregano and raspberry extract, vinegar, alcohol, salt, sugar and castor oil, etc.
Artificial preservatives: chemicals that delay or stop the growth of bacteria in foods, spoilage, and discoloration. For example- Benzoates, sulphates, Propionates, Nitrates, and Sorbates. These artificial preservatives can either be added to the food or sprayed on it.
It should be remembered to you that artificial preservatives are beneficial to us as they not only help to preserve the food but also enhance its palatability along with protecting the food against oxygen reactive species.