Yield, composition and toxicity of piperaceae volatiles to pest insects

ABSTRACT The objective of this study was to investigate the influence of leaf drying techniques (bench and oven at 35 and 45 °C) on the essential oil (EO) yield of Piper aduncum L., Piper anonifolium Kunth, Piper crassinervium Kunth and Piper hispidinervum C. DC., and to analyze the chemical profile of EOs and the insecticidal potential of these oils against Ascia monuste orseis (Godart), Atta sexdens L., Zabrotes subfasciatus (Boheman), Cryptolestes ferrugineus (Stephens) and Sitophilus zeamais Motschulsky. EO yield was evaluated using four replicates of 100g of dry leaves. The EOs were obtained by hydrodistillation and subjected to GC-MS analysis to assess the chemical composition. Concentrations of 2.60 and 157.25 nL/cm2 were used in the oil toxicity bioassays. EO yield was higher in the species P. aduncum and P. hispidinervum using leaves dried in oven at 45 °C, with average yields of 4.72±0.04% and 2.61±0.26%, respectively. The major constituents present in the EOs of P. hispidinervum and P. aduncum were Safrole (98.80%) and Apiole (90.00%). For P. anonifolium, the major constituents were α-Muurolene (23.11%), y-Muurolene (16.60%) and Cadina-1(10), while for P. crassinervium, they were Viridiflorol (27.70%) and Sabinene (15.50%). It was found that the EOs of P. aduncum, P. anonifolium, P. crassinervium and P. hispidinervum had a toxic effect on insects, except for P. anonifolium and P. crassinervium for S. zeamais. EO yield was higher in the species P. aduncum and P. hispidinervum, and these oils caused a higher mortality rate for the investigated insects. RESUMO O objetivo desta pesquisa foi investigar a influência de técnicas de secagem de folhas (bancada e em estufa a 35 e 45 °C) sobre o rendimento do óleo essencial (OE) de Piper aduncum L., Piper anonifolium Kunth, Piper crassinervium Kunth e Piper hispidinervum C. DC.; analisar o perfil químico dos OEs; e o potencial inseticida destes óleos para Ascia monuste orseis (Godart), Atta sexdens L., e para Zabrotes subfasciatus (Boheman), para o besouro Cryptolestes ferrugineus (Stephens) e para Sitophilus zeamais Motschulsky. Avaliou-se o rendimento do OE utilizando quatro repetições de 100g de folhas secas. Os OEs foram obtidos por hidrodestilação e submetidos à análise por CG-EM para a constatação da composição química. Utilizou-se as concentrações 2,60 e 157,25 nL/cm2 nos bioensaios de toxicidade dos óleos. O rendimento dos OEs foi maior nas espécies P. aduncum e P. hispidinervum utilizando folhas s