The cochineal insect has been used in checking the wild growth of:

Given below are two statements.
Statement $I$: Baculoviruses are pathogens that attack nematodes.
Statement $II$: Baculoviruses are used as biological control agents in ecologically sensitive areas as they are species-specific in their action.
In the light of the above statements, choose the correct answer from the options given below.

What is the ecological principle behind the biological control method of managing pest insects?

. . . . . . fish eat mosquito eggs.

Assertion $A$: The use of biocontrol agents prepared by microorganisms has become necessary as an alternative to chemical pesticides.
Reason $R$: The use of biological control agents helps maintain the balance of the ecosystem.
Which option is correct for Assertion $A$ and Reason $R$?

Natural insecticide obtained from neem is