Biopesticide is a pesticide which is $(a)$ not chemical in nature $(b)$ more specific in action against the pest $(c)$ safer for environment than chemical pesticides

A popularly known bio-pesticide is $Bt$ toxin, which is produced by a bacterium called Bacillus thuringiensis. $Bt$ toxin gene has been cloned from this bacterium and expressed in plants. $Bt$ toxin protein when ingested by the insect, gets converted to its active form due to the alkaline $\mathrm{pH}$ of the gut. The activated toxin binds to the surface of midgut epithelial cells and create pores that cause cell swelling and lysis and eventually kills the insect.