Bioactivity of stem bark extracts of Simaroubaceae plants and leaf extract Tephrosia vogelii on the cabbage head caterpillar, Crocidolomia pavonana (F.) (Lepidoptera: Crambidae).

Abstract

This study was conducted to evaluate the bioactivity of methanol stem bark extracts of some Simaroubaceae plants and ethyl acetate leaf extract of Tephrosia vogelii, either separately or in mixtures against-second instar larvae Crocidolomia pavonana, and phytotoxicity of the extracts on chinese cabbage. Bioassays with each active extract and their mixtures were done at six concentration levels with five replications, by a leaf dip feeding method. T. vogelii extract was 7.8 and 8.8 times more active than Quassia amara and Q. indica extracts, respectively, at LC50 level against C. pavonana larvae. T. vogelii extract at 0.25% inhibited feeding by C. pavonana larvae as high as 99.3% and caused 100% larval mortality. The mixture of T. vogelii and Q. amara extract was 3.6 and 3.8 times more toxic than T. vogelii and Q. indica mixture and had synergistic joint action both at LC50 and LC95 level. The treatments with all active extracts delayed the development of C. pavonana larvae from second to forth instar by 1.2-5.0 days compared with control. T. vogelii and Q. amara extracts and their mixture were not phytotoxic to chinese cabbage, and thus, they are potential to be used for controlling C. pavonana.