Microbes or microorganisms are tiny single-celled creatures. They are small enough not to be seen by our naked eyes. Some microbes are useful in human welfare while others are harmful and toxic and make us ill. Let’s take a glance at the role of microbes as biocontrol agents.
The natural method of eliminating and controlling the insects, pests and another disease-causing agent using their natural, biological enemies is called biocontrol or biological control. The agents which are employed in biocontrol are called biocontrol agents. Microbes are one among them.
Biocontrol works on the principle of predation and parasitism. It is much reliable and healthier than killing insects and pest using insecticides and pesticides. Thus, they prevent pollution of soil and health issues related to insecticide poisoning, etc. Biocontrol agents are an integral part of organic farming. In organic farming, farmers believe in mutualism. In other words, organic farmers keep a balance of useful and harmful agents within the system. The chemicals used for eradicating pest and parasite might not be always successful and also harm useful agents too. Instead, farmers used biocontrol agents which predate on the insects and pests that cause the disease to crops. This approach of pest management needs a vivid knowledge about the life cycle, feeding habits of different life forms.
Microbes as Biocontrol Agents
Ladybird and dragonflies are two common insects which are employed to eradicate aphids and mosquitoes respectively. Other than insects, microbes are also used as biocontrol agents. These microbes may include bacteria, fungi, viruses, and protozoans. Microbes as biocontrol agents act in three ways, either they cause the disease to the pest or compete or kill them.
Biotechnology has extended widely and it has developed many biocontrol agents. For example, Bacillus thuringiensis which is often referred to as Bt is a microbial biocontrol agent. Spraying the solution made of spores of Bt on plants will kill the butterfly caterpillars. The spores ingested release the toxins in the guts of the larvae and get them killed. Biotechnology has developed disease-resistant and pest-resistant plants by injecting B. thuringiensis toxin genes into plants, e.g. Bt cotton. Fungus-like Trichoderma and baculoviruses of genus Nucleopolyhedrovirus are some other microbial biocontrol agents. These agents are specific in nature; this along with the cost limits their use.
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