Abstract
Neem oil (HN) deterred feeding by Reticulitermes speratus in a no-choice bioassay. A methanol extract of HN (HN-01) was 4-fold more active than HN. Twelve other methanol extracts were subsequently evaluated, of which six were potent (PC95≤1.0%w/w), three moderate (PC95=1-3%w/w), and the remaining three inactive (PC95 beyond bioassay limits). Eleven main limonoids were purified from the active chromatographic fractions of HN-01, which accounted for 81.5% of its activity. No acute toxicity was found, although R. speratus given doses higher than estimated PC95 tended to die faster than unfed ones. This suggests a possible use of potent neem extractives for termite control.
