Insecticidal and antifeedant effects of Junellia aspera (Verbenaceae) triterpenes and derivatives on Sitophilus oryzae (Coleoptera: Curculionidae)

Triterpenes from Junellia aspera (Gillies ex Hook) (Verbenaceae) and chemical derivatives were evaluated for their antifeedant and toxic effects against adults of Sitophilus oryzae (L.). Five triterpenoids were acutely toxic by ingestion. The compounds maslinic acid (II), daucosterol (III), and 3β-hydroxy-12α-bromine-(28→13)-oxide-oleanane (IX) showed the highest toxic effects, while oleanolic acid (I) and oleanonic acid (VII) showed less toxicity. Daucosterol also exhibited important feeding deterrence activity. No toxicity was observed when the assayed compounds were topically applied.