Insecticidal and Anti-Feedant Activity of Clerodendrum Extracts on Growth and Development of Castor Spiny Caterpillar, Ariadne merione

The castor spiny caterpillar Ariadne merione (F.) is a major lepidopteran pest affecting castor (Ricinus communis) crops mainly by causing defoliation which in turn reduces the photosynthesis and yield. The conventional pest control methods have been based on chemical control which although has been effective, has its drawbacks of being hazardous to the environment and human health besides leading to resistance by the pests. The present work aims at investigating the possibility of using Clerodendrum inerme, a plant belonging to the Lamiaceae family, as an eco-friendly solution for pest management. Insecticidal and anti-feedant efficacy of C. inerme leaf extracts, which were prepared using solvents hexane, acetone, and petroleum ether, was tested against A. merione larvae using leaf dip bioassay under no-choice situation. The findings showed that the hexane extract had the highest insecticidal (73%) and anti-feedent (97%) action. The petroleum ether extract also showed moderate insecticidal (50%) and anti-feedant activity (48%) but not as potent as the acetone extract having insecticidal and anti-feedant action of 60 and 74 per cent respectively. The results imply that C. inerme extracts, especially the hexane extract, could be used as botanical insecticides in IPM programs as a natural replacement for chemical insecticides.