Schinus terebinthifolia leaf extract is a larvicidal, pupicidal, and oviposition deterring agent against Plutella xylostella

Plutella xylostella is a major pest of brassicas worldwide, and the main strategy for controlling this pest is the use of insecticides. However, indiscriminate use of insecticides is associated with environmental problems and resistant insect populations. Therefore, natural compounds are required to control P. xylostella. In this work, we evaluated the insecticidal effects of Schinus terebinthifolia leaf extract and a lectin (SteLL) isolated from it on this insect. The extract did not affect egg hatching but caused larvae mortality (LC50: 144.9 and 117.4 mg/mL at 96 and 144 h, respectively). The survival log-rank test indicated a reduction trend in median survival times after the treatments. The percentage of individuals that died at the larval or pupal stage ranged between 32.5% and 90% in the treatment groups (20-150 mg/mL) and 12.5% in the control group (0.15M NaCl). Treatment of the larvae with the extract (100 mg/mL) reduced adult fertility; in addition, the eggs showed decreased viability. The females laid their eggs preferentially at oviposition sites treated with 0.15M NaCl (control) when compared with the sites treated with the extract at 20 and 50 mg/mL, with deterrent indexes of 68.02% and 88.02% recorded at 48 h, respectively. SteLL (0.2 mg/mL) was not toxic to the larvae; so, it is not responsible for the insecticidal effect of the extract. The leaf extract of S. terebinthifolia is a new insecticidal agent against P. xylostella, as it kills the immature insects and has a strong oviposition deterrent effect. (C) 2019 SAAB. Published by Elsevier B.V. All rights reserved.