Pest & Pest Management in Medicinal Plants


As per PCI Syllabus (T. Y. B. Pharm Unit-I)


Pest and pest management in medicinal plants


Pest is an undesired animal or plant which cause: loss of cultivated plants, The different types of pests infecting medicinal plants are as follows.

Types of pests

Fungi/Viruses
Insects
Weeds
Non Insect Pest.

a) Fungi and Virus




They also include various other microorganism which infect the growing medicinal plant and cause loss of quality as well as quantity.
Examples: Ascochyta atropae causes necrosis of leaf. Cercospora atropae produces leaf spot disease.

b) Insects


Insects such as flea beetle, flies, moth, cutworms, grass hoppers, spiders, termites, etc, also produces 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, space to the cultivated plants. They also increase the cost of labour and equipment and reduce the quality of cultivated plant.
Example 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

i.Mechanical
ii.Agricultural
iii.Biological
iv.Chemical

i. 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 ware houses to protect from rodents and animals. Rats and mouse traps
are also used.

ii. 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.

iii. Biological method 


This method involves combating of 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. 

iv. 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 human and animals.

Examples:
Rodenticides: Arsenic trioxide.
Insecticides: Malathion, Parathion, Methoxychlor.
Miticides: Tetradifon, Chlorobenzolate.etc.
Fungicides: Chlorophenols, Quaternary ammonium compounds, 
Herbicides: 2,4 dichloro phenoxy acetic acid, Calcium arsenate, 

Biopesticides/ bioinsecticides for pest management 


These are pesticides obtained from natural sources like microorganisms,
plants,animals,insects & certain minerals. Biopesticides/ Bioinsecticides include all
the plants or substances which are derived from such plants that have the ability
to kill or resist the various pests and protect the cultivating medicinal plant.

Advantages of bio pesticide over chemical pesticides 

q They are non toxic to plants as well as humans. 
q They are biodegradable & do not leave any toxic residues
q They are less expensive and can be grown along with the cultivated medicinal
plants. 
q They are eco friendly and do not affect soil fertility.
q They are safe to handle and use.


Types of biopesticide



Microbial
Biochemical
Plant pesticides

Microbial pesticides:


They consist of microorganisms, microbial pesticides can control different kinds of pests 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 mechanism. These include substances like insect sex pheromones.


Plant pesticides


Various plants are reported to poses 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.

Examples: Neem, Tobacco, Pyrethrum,Derris,  Ryania.