Jarongsak Pumnuan, Veeranee Thongsri, Pongsak Krittayapornpong, and Sumonrut Jintanasirinurux

pp. 1037 - 1045

Abstract

The effectiveness in terms of insecticidal, repellency and antifeedant properties of ethanol, methanol
and hexane extracts of Gloriosa superba Linn., Acacia catechu Willd and Archidendron jiringa Nielsen on the
3^rd instar larvae of diamondback moth, Plutella xylostella Linn. was investigated. The leaf dipping method
with various concentrations (0.0 (5% acetone in water), 0.2, 0.4, 0.6, 0.8 and 1.0% extracts as well as 0.1% cypermethrin (positive control)) was used. Percentages of mortality, repellant and leaf damage were evaluated
at 24, 48 and 72 hours. The results showed that the methanol extracts of those three plant species were much
more effective in controlling diamondback moth than the ethanol and hexane extracts. Methanol and
ethanol extracts of G. superba, at a concentration of 1.0%, could completely control the diamondback moth
within 48 hours. The LC₅₀ values at 24 hours of those extracts were 0.35 and 0.52% (w/v), respectively. All
plant extracts as well as cypermethrin had no repellent property; less than 20% repellency was obtained.
The antifeedant test found that ethanol and methanol extracts of G. superba at a concentration of 1.0%
showed less than 10% leaf damage, whereas A. jiringa and A. catechu showed 10-20% and 20-50% leaf
damage within 24 hours, respectively. The hexane extracts gave low antifeedant results and were not significantly different than the control. Extracts of A. jiringa had greater growth inhibition properties than the
extracts of A. catechu. Particularly, methanol extracts of those two plants at a concentration of 0.6% caused
10 and 30% adult emergences of P. xylostella, respectively.