Synergistic action of mixed extracts of Br ucea javanica (Simaroubaceae), Piper aduncum (Piperaceae), and Tephrosia vogelii (Leguminosae) against cabbage head caterpillar, Crocidolomia pavonana

Abstract

Extracts seeds, fruits, and leaves of Brucea javanica, Piper aduncum, and Tephrosia vogelii were tested separately and also in mixture (3:2.5:1) in the laboratory for their insecticidal activity against the cabbage head caterpillar, Crocidolomia pavonana. B. javanica, P. aduncum, and T. vogelii plant materials were extracted with ethyl acetate-methanol (9:1), ethyl acetate, and ethyl acetate respectively by using maceration method. Insecticidal bioassays were done by a leaf-residue feeding method. Second-instar larvae C. pavonana were fed extracttreated broccoli leaves for 48 hrs and then were presented untreated leaves until the surviving larvae reached the fourth-instar stage. Larval mortality was assessed at 5 days after treatment, and the data analyzed by the probit method. The results showed that larval mortality started at first day treatment and increased at second day’s treatment. After changing with untreated leaves the mortality decreased significantly. Based on LC50 and LC95 values, T. vogelii leaf extract was more toxic (LC50= 0.06%, LC95= 0.12%) than P. aduncum fruit extract (LC50 = 0.24%, LC95=0.32%) and B. javanica seed extract (LC50=0.17%, LC95 =0.41%). Based on value of LC50 (0.03%) and LC95 (0.05%), the toxicity of a mixture of B. javanica, P. aduncum, and T. vogelii extract (3:2.5:1) against C. pavonana larvae was very toxic. Based on the combination index according to the independent joint action model, the extract mixture had a strongly synergistic joint action against C. pavonana larvae, at level LC50 and LC95, with a combination index of 0.225 and 0.190. The mixture extract worked better than each single extract against C. pavonana