Natural Pesticides
Natural Pesticides
Natural Pesticides
PESTICIDES
• A pesticide is a substance that disrupts or kills organisms t
hat we consider to be pests such as weeds, damaging insects
, or microbes that cause disease.
•
Any substance or mixture of substances, intended for prev
enting, destroying, or mitigating any pest, or intended for use
as a plant growth regulator, defoliant or desiccant.
• Pest-
it is any animal, plant or microorganism that trouble, injuries o
r cause destruction of crop.
• Methods of pest control
• - They have two types- natural and artificial pest control.
• Natural pest control- they are prepared in nature due to prey-
predator relationships.
Beneficial insects are those insects which prey on harmful inse
cts or their larvae.
• Artificial pest control-
these are man made methods to control pest
• In agricultural production the synthetic pesticides are used
Tobacco
Synonym : Tobacco
Biological source: Tobacco consist of dried leaves of Nicotiona
tabacum belonging to the family Solanaceae.
colour : green to slightly brown
Odour : characteristic
Taste : bitter and acrid
Mode of action.
In both insects and mammals, nicotine is an extremely fast
acting nerve toxin. It competes with acetylcholine, the major neuro
transmitter, by bonding to acetylcholine receptors at nerve syn
apses and causing uncontrolled nerve firing.
This disruption of normal nerve impulse activity results in rapi
d failure of those body systems that depend on nervous input for p
roper functioning. In insects, the action of nicotine is fairly sele
ctive, and only certain types of insects are affected.
Chemical constituents
Consists of pyridine , piperidine type of alkaloids among them
1-10% nicotine, nornicotine, anabasine
Uses Insecticidal
free base of nicotine is more toxic than sulphate,
Mostly effective against minute soft body insects like aphides,
white flies, fruit tree borers, termites, cabbage butterfly larvae
Nicotine preparations are safer, easier to handle, less toxic to w
arm blooded animal
Pyrethrum
Pyrethrum
Synonym; Insect flowers, pyrethrum flowers
Biological source :It consist of dried unexpanded flower-
heads of Chrysanthemum cinerariaefolium
belonging to the family Compositae,
consists of NLT 0.7 % pyrethrins.
Before drying flower heads are non toxic to insect
Mode of action.
Pyrethrins exert their toxic effects by disrupting the sodium
and potassium ion exchange process in insect nerve fibers a
nd interrupting the normal transmission of nerve impulses.
Pyrethrins insecticides are extremely fast acting and cause
an immediate “knockdown” paralysis in insects.
Despite their rapid toxic action, however, many insects are
able to metabolize (break down) pyrethrins quickly. After a
brief period of paralysis, these insects may recover rather th
an die.