Stemona collinsae crude extracts on Plutella.xylostella
Extraction of stemona roots (3 kg) by maceration in solvents that have different pole order from low to high yielded crude extracts as follows (w/w) : hexane, 0.35%; dichloromethane, 0.63% and methanol, 9.27%. Bioassays of t he crude extract s by leaf dipping met hod at concentration 0.5 to 2.0% w/v revealed that there was a significant effect of concentration rate on mortality of P. xylostella (p < 0.05) at 24 h exposure with mortality tending to increase with increasing concentrations (Table 1). Among the crude extracts tested, the dichloromethane extract gave the highest mortality to P. xylostella followed by methanol and hexane extract. The extracts caused 91.11 ± 0.6%, 85.56 ± 0.6 and 70.00 ± 1.7% mortality at 2% concentration for dichloromethane, methanol and hexane, respectively (Table 1) with LC
values of 0.60, 0.71, and 1.15 % (Table 2). This result corresponds to the report of Pitiyont et al. (2008) and Tikum et al. (2008) where dichloromethane extract of the root of Stemona burkillii was the most effective against Spodoptera litura and Spodoptera exiqua. A similar result was reported by Jiyavorranant (2001) on the dichloromethane extract of
stemona tuberose Lour. against Plutella xylostella.
Stemona collinsae crude extracts on Plutella.xylostella Extraction of stemona roots (3 kg) by maceration in solvents that have different pole order from low to high yielded crude extracts as follows (w/w) : hexane, 0.35%; dichloromethane, 0.63% and methanol, 9.27%. Bioassays of t he crude extract s by leaf dipping met hod at concentration 0.5 to 2.0% w/v revealed that there was a significant effect of concentration rate on mortality of P. xylostella (p < 0.05) at 24 h exposure with mortality tending to increase with increasing concentrations (Table 1). Among the crude extracts tested, the dichloromethane extract gave the highest mortality to P. xylostella followed by methanol and hexane extract. The extracts caused 91.11 ± 0.6%, 85.56 ± 0.6 and 70.00 ± 1.7% mortality at 2% concentration for dichloromethane, methanol and hexane, respectively (Table 1) with LC values of 0.60, 0.71, and 1.15 % (Table 2). This result corresponds to the report of Pitiyont et al. (2008) and Tikum et al. (2008) where dichloromethane extract of the root of Stemona burkillii was the most effective against Spodoptera litura and Spodoptera exiqua. A similar result was reported by Jiyavorranant (2001) on the dichloromethane extract ofstemona tuberose Lour. against Plutella xylostella.
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