What do bionematicides control?

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 $R$?

Which one of the following is $NOT$ a bioherbicide of bacterial origin?

What is the definition/explanation of the term 'Nematophagous'?

Pyrethrin is extracted from

Which was the first commercially developed insecticide?