Insecticidal Activity of Some Medicinal Plants

Recent trend for the control of pests has been towards the use of substances of plant origin. Present investigation was carried out to determine the toxicity, residual effects and reduction in fertility of the plants viz. the Indian Oleander, Nerium indicum; apple of Sodom, Calotropis procera and Karonda, Carissa carandass methanolic leaves extract against adult of the red flour beetle, Tribolium castaneum and graham bean weevil, Callosobruchus analis as compared with the Coopex which is synthetic pyrethroid. The LD50 of N. indicum extract was found to be 9.43 l/cm2 and for Coopex it was 11.0 l/cm2. The residual effect after 4 days of treatment caused 54% mortality in the case of N. indicum extract and 40% for Coopex. However, after 7 days the mortality was 2% in the case of N. indicum extract and 10% in the case of Coopex. The trend of reduction in fertility was the same in both N. indicum leaves extract and Coopex, i.e., it was increased gradually from lower to higher doses. Nerium indicum leaves extract reduced fertility significantly compared with Coopex. It was also noted that extract of Car. carandass was more toxic as compared to other extract and Coopex against C. analis.