Effects of Mangosteen’s Peels and Rambutan’s Seeds on Toxicity, Esterase and Glutathione-S-transferase in Rice Weevil (Sitophilus oryzae L.)

Abstract

Peel of Mangosteen (Garcina mangostana L.) and seed of rambutan (Nephilium lappaceum L.) were attracted by Soxhlet’s extraction using ethanol as a solvent. Both extracts were trialed with adult rice weevils (Sitophilus oryzae L.) by the impregnated filter paper method for the peel of mangosteen extracts, weevils showed LC50 at 24 hours at 4.91 ± 1.19%w/v. Seed of rambutan extracts showed LC50 at 6.81 ± 1.04%w/v.The addition of synergists, PB, TPP and DEM in the extracts reduced overall LC50 showing SR of ca. 1.3-1.6 folds. The in vitro enzyme studies in lived rice weevil after be tested in both extract at 12 hours showed  mangosteen’s peel extracts inhibited esterase and glutathione-S-transferase (GST) activities ca. 1.6 time. Rambutan’s seed extracts reduced esterase and GST activities ca. 1.33- 1.63 fold. The addition of synergists decreased activities of these enzymes more than 50% showing of CF ca. 1.19-12.17. This result suggested that synergists in the extracts could increase efficiency for the control of rice weevils.