Evaluation of some plant extracts against maize weevil, Sitophilus zeamais (Coleoptera: Curculionidae) under laboratory conditions

Abstract

Laboratory studies were conducted to evaluate the insecticidal potential of extracts of eight plants viz. lemon grass (Cymbopogon flexousus), turmeric (Curcuma longa), basil (Ocimum basilicum), harmal (Peganum harmala), heeng (Ferula assa-foetida), neem (Azadirachta indica), tumma (Citrullus colocynthis) and mint (Mentha arvensis) against maize weevil, Sitophilus zeamais using three concentrations (5, 10 and 15%) at three time intervals (2, 4 and 6 days) in the laboratory. The results revealed that maize weevil mortality was increased with the increase in concentration and time interval. Maximum mortality (86.67%) of the pest was observed with the use A. indica extract at 15% concentration after 6 days of application followed by C. colocynthis extract (81.66%), P. harmala (76.66%), C. longa (71.67%), O. basilicum (66.66%), F. assafoetida (61.66%), C. flexousus (58.33%) and M. arvensis (53.33%). The lowest mortality (22.78%) was observed against lowest concentration of C. flexousus. Overall results show that mortality of the insect increased with the increase in concentration and exposure time.