Insecticidal activitiy of spiked pepper (Piper aduncum) extracts from riau on the cabbage head caterpillar (Crocidolomia pavonana)

Abstract

Spiked pepper (Piper aduncum) is a potential source of botanical insecticides. Its insecticidal activity has been widely reported, but the insecticidal activity of this plant collected from different locations has not been much studied, especially in Indonesia. The objectives of this research were (1) to evaluate the toxicity of P. aduncum leaf and fruit extracts from Riau to Crocidolomia pavonana larvae, (2) to evaluate the effect of the four most active P. aduncum extracts on feeding activity of C. pavonana larvae, (3) to evaluate the persistence and phytotoxicity of the four most active P. aduncum extracts, and (4) to examine qualitative property of the test P. aduncum extracts. P. aduncum leaves and fruits collected from ten different locations in Riau were extracted with ethyl acetate using maceration method. The toxicity test was conducted using a residual leaf feeding method. Mortality data was recorded and analyzed using probit analysis. The feeding inhibition activity test of the four most active extract was conducted using a choice method at concentrations of LC25 and LC50. The feeding inhibition data were subjected to analisys of variance followed by Duncan’s multiple range test at 5% level. The persistence of the four most active P. aduncum extracts was tested at LC95 and 2 x LC95 levels using direct spray method on broccoli plants. Mortality data were analyzed by analysis of variance followed by Duncan's multiple test at the 5% level. The symptom of phytotoxicity on broccoli leaves was observed. Qualitative examination of extract components was done using thin layer chromatography technique. Where P. aduncum fruit oil containing 76% dillapiole was included in the TLC test for comparison. The results showed that P. aduncum extracts collected from ten different locations had strong insecticidal activity and are potential to be used as sources of botanical insecticides. Among 20 extracts tested, four extracts had the highest activity, i.e. fruit extract from XIII Koto Kampar (LC95 0.209%), Pekanbaru (LC95 0.211%), Bangkinang Barat A (LC95 0.212%), and Cerenti (LC95 0.216%). The four most active extracts showed antifeedant effect at LC50 level. These four extracts lost their activity after being exposed to sunlight for 24 hours. Plant extracts tested did not cause phytotoxic effect on broccoli. Qualitative examination show the same separation pattern.