Composition comprises at least one insecticide, a non-ionic and/or an ionic dispersing agent, and an aqueous polymer dispersion, where: the polymer dispersion is prepared by polymerization in presence of a hydrocolloid as graft base； and the aqueous polymer dispersion is a cationic polymer dispersion that contains an emulsifying agent containing a structural component of at least one (meth)acrylic acid ester and/or (meth)acrylamide that contains a tertiary amino group. An independent claim is included for extending the effectiveness of pesticides comprising adding a polymer dispersion to the agent before the application, where the polymer dispersion in a concentration of 0.025 wt.% in demineralization water, exhibits a wavelength of 535 nm and a light path of 1 cm of a extinction of less than 2. ACTIVITY : Antiparasitic； Pesticide. The pesticidal activity of a spray solution (FL2) (comprising Crackdown SC 10(RTM: Permethrin) (7.14 wt.%), polymer dispersion (produced by adding oxidatively degraded potato starch (124.5 g) in deionized water (985 g) and dissolving by warming, adding 1% solution of iron(II) sulfate solution (42.7 g) and 3% hydrogen peroxide solution (116 g) and stirring at 86[deg] C for 15 minutes. after 15 minutes, adding a dosing solution comprising a mixture (321 g) of styrene, n-butylacrylate and tert.-butylacrylate and 3%-hydrogenperoxide solution (93.7 g) for 90 minutes at 86[deg] C and stirring for another 15 minutes at 86[deg] C, adding tert.-butyl hydroperoxide (2 g) and cooling the solution at room temperature, adding 10% solution of EDTA (10 g) as tetrasodium salt and 10% sodium hydroxide solution (13 g) and filtering the solution to obtain fine particle dispersion with a solids content of 24 wt.%) (0.60 wt.%) and water (92.26 wt.%)), was tested against Culex quinquefasciatusalong with a spray solution (FL1) (comprising Crackdown SC 10(RTM: Permethrin) (7.14 wt.%) and water (92.26 wt.%)) as control. The results showed that after 24 hours, the
