Owing to their small size, morphology and release modification properties, nanopesticides are considered promising alternative strategies for enhancing biological activity and minimizing pesticide losses. In this study, we used a colloidal self-assembly method to develop a morphology-stable, regularly rod-shaped nanoselenium pesticide carrier (NSer), which was further modified with chitosan. After loading penthiopyrad (PEN), the biological activity of NSer@PEN and its impact on the physiological and biochemical processes of plants were further compared with those of spherical nanoselenium pesticides (NSes@PEN) and commercial materials (20 % PEN SC). The biological activities were quantified through the EC