Abstract
Insecticidal activity of leaf and seed extracts of Tephrosia vogelii J. D. Hooker (Leguminosae) and fruit extract of Piper cubeba L. (Piperaceae) on the cabbage head caterpillar, Crocidolomia pavonana (L.) (Lepidoptera: Crambidae). Ethyl acetate leaf and seed extracts of Tephrosia vogelii and a solid fraction of ethyl acetate fruit extract of Piper cubeba were evaluated for their insecticidal activity on second-instar larvae Crocidolomia pavonana by a leaf-residue feeding method in the laboratory. Leaf extracts of purple and white-flowered T. vogelii showed the same pattern of component separation on silica gel TLC plate (Rf between 0.21 and 0.94), and likewise the separation of components of seed extracts of purple and white-flowered T. vogelii (Rf between 0.31 and 0.96). All four kinds of T. vogelii extracts showed intense UV-absorbing nonpolar spots (Rf > 0.8). Based on LC50 ratio at day 4, leaf extract of purple-flowered T. vogelii (LC50 0.075%) was 4.30, 2.70, 2.21, and 1.64 times more toxic than fruit extract of P. cubeba, seed extract of white-flowered T. vogelii, seed extract of purple-flowered T. vogelii, and leaf extract of white-flowered T. vogelii, respectively. All T. vogelii extracts were more toxic to C. pavonana larvae than P. cubeba fruit extract. At LC95 level, a mixture of leaf extract of purple-flowered T. vogelii and fruit extract of P. cubeba (5:9, w/w) was more toxic to C. pavonana larvae than each extract tested separately. This extract mixture had synergistic joint action against C. pavonana larvae both at LC50 and LC95 level. Thus, leaf extract of purple-flowered T. vogelii and its mixture with P. cubeba fruit extract are promising to be used for controlling C. pavonana.