BOTANICALS Several pesticides are derived directly from plant or plant products. These are called botanical insecticides or botanicals. Many botanicals are preferred by organic farmers as they are natural products. Extraction of botanicals from the plants is expensive. Hence the use of botanicals in commercial agriculture is impractical. Following are some of the botanicals used by man: Pyrethrum Pyrethrum is an insecticide extracted from the flower petals of Chrysanthemum sp. grown in Kenya and Ecuador. It is commonly contained in household aerosol sprays. It is used use on fruit trees, .ornamentals, vegetables and flowers. Nicotine Nicotine is an alkaloid obtained from the extracts of tobacco leaves. Nicotine sulphate is very toxic to insects and also to man. It is the most dangerous botanical preparation. It is mainly used in the gardens against sucking insects and mites. Rotenone Rotenone is extracted from the roots of the legumes, Derris sp grown in Malaysia and the East Indies. Rotenone is used as an insecticide and also as a fish poison. It is also used as a fish poison for reclaiming lakes and ponds. Ryania Ryania is a botanical extracted from the stem and roots of Ryania speciosa, a shrub grown in Trinidad. It is effective against insects like the European corn borer, Ostrinia nubilalis and many other insect pests. Neem Extract Neem (Azadirachta indica) is an indigenous tree. It has good medicinal and insecticidal properties. Leaves and leaf-extracts have been used to repel insect pests of crops and stored grains. The active principle of this tree is azadirachtin. Neem products are active against more than 300 insect species, a large number of nematodes and other plant pathogens It is also eco-friendly. Hence, neem is an eco- friendly and a versatile botanical pesticide. The oil cake is used as a manure-cum- pesticide. Powdered oil-cake applied to the soil is a good source of plant nutrients. Extracts from several other plants are also used as pest control agents. A few of them are: seed extract of Pongamia glabra , leaf extract of Ipomea carnea, Vrtex negundo (nochi), Andrographis paniculataetc. Garlic Extract as a Fungicide Garlic (Allium sativum) has medicinal and some insecticidal properties. Garlic extracts also have fungicidal properties. Plant Products to Protect Stored Grains from Insect Attack Pudina (Mentha piperata) leaf extracts can inhibit and destroy the rice brown leaf spot fungus present on the surface of seeds. Several plant products are used to protect stored grains from insect attack, it is environment friendly, non-toxic and also economic. Layers of neem and Pongamia leaves are spread inside the storage bins of grains. Crushed neem leaves and fruits were used to plaster the walls of mud bins. Biological Control of Pests and Weeds Pesticides Any substance used for controlling, preventing, destroying, disabling or repelling a pest is called as pesticide. Several chemical pesticides h.r been used by man to control pests., such pesticides has certain disadvantages. Disadvantages of Pesticides 1. Pesticides are expensive and dangerous to the handler, the environment and the consumers of plant products. 2. Pesticides make the pests more resistant to chemical pesticides. 3. Pesticides often cause one species to be replaced by another sometimes the second pest may be more virulent. 4. Chemical pesticides not only kill the pests but also their natural enemies in the fields. 5. Sometimes, the use of pesticides will kill the major pests and the natural enemies of certain minor pests. Biological Control of Pests – Biopesticides "Biopesticides" are naturally occurring substances (biochemical pesticides) that control pests, microorganisms that control pests (microbial pesticides), and pesticidal substances produced by plants Characteristics of an Ideal Biological Control Organism It should be able to survive for an extended period in the field either in an active or inactive form. It should contacts the pathogen either directly or indirectly by diffusion of chemicals. Multiplication of the control organism in the laboratory should be simple and inexpensive. It should be a simple, efficient and inexpensive process of packaging, distribution and application. It should be specific for the target organism. It should not be a health hazard in its preparation and handling. It should be environment friendly. t should be active under the appropriate environmental conditions. It should control the target pathogen efficiently and economically. Three major classes of Biopesticides Microbial or biological pesticides may consist of bacteria, fungi or viruses Plant-incorporated protectants, (PIPs) (i.e. GM crops). Biochemical pesticides are naturally occurring substances that control pests by nontoxic mechanisms. BACTERIAL BIOPESTICIDES Several bacteria which kill certain insects are used as biopesticides. Some of them are : 1. Bacillus thuringiensis, 2. B.popilliae, 3. B. lentimorbus, 4. B.sphaericus, 5. Pseudomonas sp. and 6. Agrobacterium radiobacter.