Viruses of the genus Nucleopolyhedrovirus are considered desirable in integrated pest management (IPM) programmes because they:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → are species-specific and have no negative impacts on plants, mammals, birds, fish or non-target insects
Integrated pest management (IPM) tries to control pests while protecting useful insects and the environment. Viruses of the genus Nucleopolyhedrovirus (a group of baculoviruses) suit this well. They are species-specific and narrow in spectrum: they attack only the target insect. So beneficial insects that are being conserved, and sensitive areas, are not harmed.
Option (1) are species-specific and have no negative impacts on plants, mammals, birds, fish or non-target insects — Correct. These viruses have no negative impacts on plants, mammals, birds, fish or even non-target insects. This is why they are desirable in an IPM programme.
Option (2) act as broad-spectrum insecticides against most insect pests of a crop — Incorrect. A broad-spectrum insecticide kills many kinds of insects, including useful ones. These viruses are the opposite: narrow-spectrum and species-specific.
Option (3) fix atmospheric nitrogen and so reduce the need for chemical fertilisers — Incorrect. Fixing atmospheric nitrogen is the work of biofertilisers such as Rhizobium, Azotobacter and cyanobacteria. A virus that attacks insects does not fix nitrogen.
Option (4) attack and kill the fungal pathogens that cause diseases in crop plants — Incorrect. Killing fungal plant pathogens is the role of the free-living fungus Trichoderma. Baculoviruses attack insects and other arthropods, not fungi.
NCERT Extract:
Microbes as Biocontrol Agents – “… The majority of baculoviruses used as biological control agents are in the genus Nucleopolyhedrovirus. These viruses are excellent candidates for species-specific, narrow spectrum insecticidal applications. They have been shown to have no negative impacts on plants, mammals, birds, fish or even on non-target insects. This is especially desirable when beneficial insects are being conserved to aid in an overall integrated pest management (IPM) programme, or when an ecologically sensitive area is being treated.”