Enhancement of Food Production — BIOLOGY STD 12 Science — Question

(1) Biocontrol agents are the organisms like (bacteria, fungi, viruses and protozoans) act which are employed for controlling pathogens, pests and weeds.

(2) They cause the disease to the pest or compete or kill them.

(3) The use of biocontrol measures greatly reduces use of toxic chemicals and pesticides that are harmful to human beings and also pollute our environment.

(4) Biocontrol agents and their hosts.

• Bacteria (Bacillus thuringiensis, B. papilliae and B. lentimorbus Hosts : Caterpillars, cabbage worms, adult beetles
• Fungi (Beauveria bassiana, Entomophothora, pallidaroseum, Zoophthora radicans) Host : Aphid crocci, A. unguicilata, mealy bugs, mites, white flies, etc.
• Protozoans (Nosema locustae) Host: Grasshoppers, caterpillars, crickets
• Viruses (Nucleopolyhedro virus-NPV, Granulovirus-GV) Host : Caterpillars, Gypsy moth, ants and beetles.

(5) Some examples:

• Bacillus thuringiensis (Bt) is a microbiai pesticide used to get rid of butterfly, caterpillars.
• Trichoderma fungus is an effective biocontrol agent against soil borne fungal plant pathogens which infect roots and rhizomes.
• Phytophthora palmiuora is a mycoherbicide that controls milk weed in orchards.
• Pseudomonas spp. is a bacterial herbicide that attacks several weeds.
• Tyrea moth controls the weed Senecio jacobeac.