Stemona collinsae crude extracts on Plutella.xylostella Extraction of stemona roots (3 kg) by maceration in solvents that have different pole order from l ow to high yielded crude extracts as follows (w/w) : hexane, 0.35%; dichloromethane, 0.63% and methanol, 9.27%. Bioassays of the crude extracts 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 Jiyavorranant (2001) on the dichloromethane extract of
stemona tuberose Lour. against Plutella xylostella.
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