Read the following paragraph and answer the given questions.
Bio-fertilisers are organisms that enrich the nutrient quality of the soil like cyanobacteria, while there are organisms that help to control plant diseases and pests. The very familiar beetle, the ladybird and dragonflies are useful to get rid of aphids and mosquitoes, respectively. An example of microbial biocontrol agents that can be introduced to control butterfly caterpillars is certain bacteria, which are available in sachets in the form of dry spores. These spores are mixed with water and sprayed onto vulnerable plants. Trichoderma species that are very common in the root ecosystem, are very effective biocontrol agents of several plant pathogens. Baculoviruses attack insects and other arthropods. Usage of these viruses is desirable when an ecological sensitive area is being treated.
Which one of the following is used to control caterpillars of butterflies?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Bacillus thuringiensis
Option (1) Meloidegyne incognitia — Incorrect. It is a nematode pest of tobacco roots, controlled by RNAi.
Option (2) Agrobacterium tumifaciens — Incorrect. It is a plant pathogen whose Ti plasmid is used as a vector to put genes into plants.
Option (3) Bacillus thuringiensis — Correct. Its dried spores, sprayed on plants, kill butterfly caterpillars that eat them; the toxin is released in the gut of the larvae.
Option (4) Haemophilus influenzae — Incorrect. It is a bacterium that causes pneumonia in humans.
Note: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.
NCERT Extract:
Microbes as Biocontrol Agents – …
