The question is extremely confusing and needs rephrasing. The question relates to 'nanopesticide' and not metallic nanoparticles. I read: 'to prepare and detect the nano pesticide found in plant extracts' and I ask 'what nanopesticides and what plant extracts?'
By the way, silver nanoparticles are bactericides not pesticides. I read the question as requiring an easy route to a pesticide in nano form, not a metal in colloidal form (which is trivial). And thus I was thinking along the lines of hexane extraction of pyrethrum followed by emulsion encapsulation.