Common Insect Vectors in Bangladesh

>> Tuesday, May 10, 2011

Insect vectors are those insects which bear and transmit plant and diseases from one to another .Insects provide a system that can deliver pathogens directly to the bloodstream and are essential to the spread of some infections. From a pathogen’s perspective, moving from host to host is essential to survival; yet, the skin presents a barrier. Wounds, burns, and catheters provide opportunities for entry for some pathogens, but insect-borne bacteria have an advantage. Still, arthropod-transmitted microbes must be able to survive in the arthropod’s gut, proliferate, and then become positioned (such as in the insect’s salivary gland) for delivery to the animal host. Many dangerous diseases bear transmitted through the agency of insects. Insect borne diseases take a heavy tall of human life. About a million of people die and a few hundred million suffer from such diseases through out the world with in year. About four hundred million people live in areas where malaria is still highly endemic. It is estimated that at least 100 million causes occur annual resulting in death of 1 million.


Mosquitoes, sandflies, blackflies, housefly, tsetsefly, human flea, human louse etc., are transmitting pathogens and causing various diseases in man and are described below :

Water-related insect vector diseases

These consist of a number of insect-borne diseases where the insect(known as a vector) spends a significant portion of its life cycle breeding or biting around water. These diseases include malaria, filariasis, yellow fever, dengue, and onchocerciasis (river blindness.)Domestic water and sanitation projects are unlikely to influence such diseases, with the possible exception of filariasis.


Inset plays a very importance role in transnmission plant diseases ..

There are six difference ways by whice insect help in the spread and development of plant diseases:

1) Direct production of diseases without a help of pathogen .

2) Dissemination of the pathogen

3) Inoculation of the suscept with pathogen

4) Ingression of the pathogen into the suscept

5) Invasion of the suscept by the pathogen

6) Prevention of the pathogen

1 ) Direct production of diseases without a help of pathogen .

Some insects can cause diseases to plant. There some insects which have the capability to secrete phytotoxic chemicals and thus cause diseases to plants. These insects are called toxicogenic insects

In most of the cases Hemipteran insects are toxicogenic to plants .They have piercing sucking type mouthparts. During sucking they inject phytotoxic substances into the plant body . As a result normal physiological process of the plant are hampered and the plant or plant parts are died .These diseases are called non – pathogenic or physiological diseases

Examples: i ) potato leaf hoper (Empoasca fabae ) causing hoper burn of potato ii ) Cercopid ( Thomaspis saccharina ) causing frog hoper blight of sugarcane

2 ) Dissemination of the pathogen :

Transfer of pathogen from a diseased plant to another suscept plant is called dissemination.

Some inoculums of pathogen do not have any organ to disseminate. These are disseminated by some other ways like by wind, rain, insect and so on. Some insects help to disseminate diseases.

Example: i) Gummosis of sugarcane (Bacterial diseases) by flies.

ii) Tungro diseases of rice (Virus diseases) by grasshopper.

The disease first occurs in leaves and sticky substances are produced there, which contain bacterial cells. When flies eat these gummy substances they take the bacterial cells in there digestive system and transfer it by excreta.

3 ) Inoculation of the suscept with pathogen

Inoculation means transportation of inoculum to a particular part of the plant where injection may result.Insects play significant role in inoculation.

Example: i . Blosom blight is a bacterial disease, which infect floral parts. ii. . Honey bee during collection of necter from infected flower also collects inocula and then transfers them to non infected flowers . Thus it helps in inoculation of blossom blight .


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