Question

1.How does mode of transmission shape virulence?

2. What species of fungus is being developed as a biopesticide against malarial mosquitos, and why might it be more effective than chemical insecticides?

Answer 1

1)Mode of transmission is related to virulence by a trade-off mechanism which means that the factor governing this principle is the rate of the growth of the pathoge. The rate of growth of pathogen is directly related to the increase in the rate of transmission of the infection of the infection to the host. This further decreases the virulence response after an initial increase in virulence due to the death of the host organism in which infection was caused. It depends upon a number of factors like :

• the mode of transmission of the pathogen in the host.
• the ability of pathogen to grow and reproduce inside the body and organs of the host.
• the ability and amount of virulence present in the strain of the pathogen causing infection.
• the ability of the pathogen antigens to evade the immune system of the host and cause infection. This is called as immune subversion.
• the ability and strength of the immune cells of the host to destroy the foreign pathogens and fight against them.
• the amount of the release of the toxins released by the pathogen and the type of the signaling or the quorum sensing response in the host infected with the disease.
• The need and requirement of the host body for the development of the pathogen larvae with supply of nutrients and food.

2) The isolates of the fungal species like Beauveria bassiana have the potential to kill the mosquito species which are resistant to the chemical insecticides available in the market. The growth rate of mosquito and fungus strain depends upon the temperature in the environment. The temperatures were maintained at 32^oC and the experiments were conducted in rats infected with the strains of plasmodium before exposing them the fungal chemical to check the activity of this chemical derived from fungal spores.