Morphogenetic Effect of Botanicals, Andrographis paniculata and Clerodendron inerme on Beet Army Worm, Spodoptera exigua

Studies were conducted to understand the morphogenetic effect of hexane, dichloromethane, ethyl acetate and methanol extracts of two plant species, Andrographis paniculata and Clerodendron inerme on beet army worm, Spodoptera exigua Hubner, an emerging pest on tobacco through incorporation into artificial diet. The hexane extract of C. inerme at 0.05 and 0.1% concentrations recorded the highest mortality of larvae (90.0%), followed by methanol (62.5) and dichloromethane (59.4) extracts at 0.1% concentration. The larval period of S. exigua was the longest (19.8 days) when reared on the diet incorporated with dichloromethane extract of C. inerme. The lowest adult emergence (57.6%) was recorded in case of diet incorporated with dichloromethane extract at 0.1% concentration. As evidenced by a pupation index of less than 0.3%, the dichloromethane extracts of this plant supported very low pupation and resulted in high larval mortality. Hexane extract of A. paniculata resulted in high larval mortality (56.8%) and did not allow any adult emergence at both the concentrations tested. The possibility of developing a potent bio-pesticide from the hexane extracts of both these plants is discussed.