Issakul, K: Characterization of a botanical insecticide from

Botanical insecticides derived from plants may be an alternative to the use of chemical pesticides. In general, they may consider being beneficial, safe to human and the environment. However, some of botanical pesticides have adverse effects. In this study, nine species of Thai local plants were selected for their highest insecticidal activity. Mammeasiamensiswas selected for purification and chemical identification of the active compound. Surangin B was identified as the active compound which had a higher insecticidal activity on the larvae of diamond back moths than methomyl insecticide. Crude ethanolic extract of M. siamensiswas formulated as emulsifiable concentrate (EC). The quality control of the extract from each batch was carried out with HPTLC. In the field study with Chinese kale, the mammea insecticide was slightly less efficient in the insect control than the synthetic methomyl insecticide. However, it showed a better effect in controlling the population of diamondback moth larvae than the studied synthetic insecticide. Moreover, the environmental friendly effect was also demonstrated by giving a slightly higher number of beneficial insects (natural enemies) than the methomyl treated and the control groups. Nevertheless, the yield of Chinese kale sprayed with mammea insecticide was not significantly different from that of the control group. In the net green house no insect pest interference was observed and mammea insecticide had a tendency to increase the yield of Chinese kale. Most of the physical plant properties i.e. height, fresh weight, dry weight, number of leaf and leaf length of Chinese kale were slightly higher than those after methomyl treatment and the control, respectively. Furthermore, all the analyzed quality parameters i.e. chlorophyll and carotenoid contents, reducing sugars, total dietary fiber, total ascorbic acid, total antioxidative activity, ascorbate peroxidase activity and free amino acid contents were not significant