Pest and their management in medicinal plants

PEST AND PEST MANAGEMENT IN MEDICINAL PLANTS
Pest is an undesired animal or plant which causes loss of cultivated plants. The different types of pests
infecting medicinal plants are as follows.
Types of pests
1) WEEDS
2) INSECTS
3) FUNGI/ VIRUSES
4) NON INSECT PESTS
a) Fungi and viruses
Examples: Ascochyta atropae causes necrosis of leaf. Cercospora atropae produces leaf spot disease.
b) Insects
Insects such as flea beetles, flies, moths, cutworms, grasshoppers, spiders, termites, etc, also produce
significant loss of cultivated plants.
c) Weeds
A weed is an undesired plant, it can produce losses more than any other pests or diseases. They cause
depletion and shortage of nutrients, water, light, and space to the cultivated plants. They also increase
the cost of labour and equipment and reduce the quality of cultivated plants.
Examples of weeds are Parthenium, Ragweed, Medican tea, Varnish tree, etc.
d) Non insect pests
They are further sub classified as follows.
 Vertebrates: Animals like monkeys, rats, rabbits, squirrels, birds, pigs etc.
 Invertebrates: Animals like crabs, snails, mites, nematodes, etc.
METHODS OF PEST CONTROL
Different techniques are followed to achieve pest control effectively. These methods are discussed as
follows.
1) Agricultural method
2) Biological method
3) Mechanical method
4) Chemical method
Mechanical method
It includes simple techniques like hand picking, pruming burning, using of pest traps, collection and
destruction of eggs, larvae and insects. Construction of concrete warehouses to protect from rodents
and animals. Rats and mouse traps are also used.
Agricultural method
It includes various methods such as crop rotation, inter cropping, integrated weed management
methods, solarisation etc. Production of pest and insect resistant plants through genetic engineering
technique is another approach.
Biological method
This method involves combating pests with other living organisms such as employment of cats to
combat rats and squirrels, employment of birds to combat insects. Some chemical substances
produced by female insects such as sex attractants, which can be used to lure male insects and prevent
reproduction.
Chemical control
Pests are controlled using chemical pesticides which include insecticides, fungicides, herbicides,
rodenticides. However these chemical substances are highly toxic to human beings. Improper use of
these chemical pesticides may lead to toxic effects on humanand animals. Examples:
o Rodenticides: Arsenic trioxide
o Insecticides: Malathion, Parathion, Methoxychlor.
o Miticides: Tetradifon, Chlorobenzolate
o Fungicides: Chlorophenols, Quaternary ammonium compounds, etc.
o Herbicides: 24 dichloro phenoxy acetic acid, Calcium arsenate, etc.
BIOPESTICIDES/BIOINSECTICIDES FOR PEST MANAGEMENT
These are pesticides obtained from natural sources like microorganisms, plants, animals, insects and
certain minerals. They offer enormous advantages over chemical pesticides which are as follows.
Advantages of bio pesticides over chemical pesticides
 They are non-toxic to plants as well as humans.
 They are biodegradable and do not leave any toxic residues.
 They are less expensive and can be grown along with the cultivated medicinal plants. >They
are eco friendly and do not affect soil fertility.
 They are safe to handle and use.
TYPES OF BIOPESTICIDES
They can be categorized depending on their source as follows.
 BIOCHEMICAL
 MICROBIAL
 PLANT PESTICIDES
Microbial pesticides:
They consist of microorganisms, microbial pesticides can control different kinds of pest:and are
relatively specific for its target pests. It is reported that some fungi are used to control weeds and
insects.
Biochemical pesticides
These are naturally occurring chemical substances which are obtained from insects and animals which
have the ability to control the pests by non toxic mechanisms. These include substances like insect sex
pheromones.
Plant pesticides
Various plants are reported to possess pesticidal and insecticidal properties. They can be grown along
with cultivated plants to combat insects and can be used in powdered form or the constituents can be
extracted from them and used to spray on the crops.
Example: Neem, Tobacco, Pyrethrum, Sabadilla, Derris, Ryania.