Biocid action of Piper tuberculatum Jacq. against Diatraea saccharalis (Lepidóptera, Pyralidae)

Abstract

The biocid action of DCM:MeOH (2:1), EtOH and aqueous extracts of leaves, stems and mature spikes (with fruits and seeds) of field plants and DCM:MeOH (2:1) extract of in vitro plants of Piper tuberculatum on III larval stage of Diatraea saccharalis was evaluated. The method was by inoculating the previously eluted extract with distillate water as topic applications on the larval mesothorax. Only DCM:MeOH and EtOH extracts of mature spikes and DCM:MeOH extract of in vitro plants showed significant levels of larval mortality. The corresponding highest toxic effect was (a) for mature spikes respect to in vitro plants and (b) EtOH extract respect to DCM:MeOH extract, according to the results showed for the lethal concentration to 50% (LC50) and 90% (LC90), in 72 hours of exposure. Thus, in the case of mature spikes was: LC50 0,11 mg/mL with EtOH and 0,16 mg/mL with DCM:MeOH) and LC90 (0,35 mg/mL with EtOH and 0,55 mg/mL with DCM:MeOH); and, in the case of in vitro plants, only with DCM:MeOH extract, was: LC50 0,39 mg/mL and LC90 2,62 mg/mL. The results of probit values-mortality lines showed the same tendency.