Larvicidal activity of Piper tuberculatum on Spodoptera frugiperda (Lepidoptera: Noctuidae) under laboratory conditions

The larvicidal activity of the neotropical "matico" Piper tuberculatum was evaluated. The secondary compounds were extracted of leaves, stems and mature spikes with fruits and seeds from wild plants and in vitro plants of Piper tuberculatum. The acute toxicities to the fall armyworm, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae), of extracts of spikes with fruits and seeds and in vitro plants of P. tuberculatum were evaluated by means of contact bioassays. Only CH₂Cl₂:MeOH (2:1) and EtOH extracts of mature spikes and CH₂Cl₂:MeOH (2:1) extract from in vitro plants showed significant levels of larval mortality. The CH₂Cl₂:MeOH (2:1) and EtOH extracts of mature spikes caused 90% mortality when doses of 0.1850 mg/μL were applied to the S. frugiperda in 24 and 48 h of exposure, respectively. The CH₂Cl₂:MeOH (2:1) extract from in vitro plants caused 95% mortality when doses of 0.1850 mg/μL were too applied in 48 h of exposure. The mature spikes test best results were: LD₅₀ 0.001 mg/μL with EtOH and 0.007 mg/μL with CH₂Cl₂:MeOH (2:1) and LD₉₀ 0.027 mg/μL with EtOH and 0.103 mg/μL with CH₂Cl₂:MeOH (2:1); and, in the case of in vitro plants, only CH₂Cl₂:MeOH (2:1) extract was: LD₅₀ 0.003 mg/μL and LD₉₀ 0.060 mg/μL. The potential value of extracts derived from P. tuberculatum as efficient insecticides against S. frugiperda is discussed.