Efeito inseticida do óleo essencial de Mentha sp. sobre Thaumastocoris peregrinus Carpintero & Dellapé, 2006 (Hemiptera: Thaumastocoridade)

Abstract

Thaumastocoris peregrinus Carpintero & Dellapé, 2006 (Hemiptera: Thaumastocoridae) is a phytophagous insect, native to Australia. This insect feeds on eucalyptus leaves, causing damage to these plantations, which have considerable economic value for the forest sector. Thus, sustainable control methods have been studied, such as the use of botanical insecticides. Therefore, the objective of this work was to evaluate the insecticidal effect of Mentha sp. essential oil, at different concentrations, on T. peregrinus nymphs. The experiment was conducted from the creation of T. peregrinus, established in the Laboratory of Biological Control. For this, eucalyptus leaves were collected and selected, which were immersed in concentrations (0, 0.5%, 0.75% and 1) of Mentha essential oil. To compose the control, distilled water sterilized with Tween 80® (0.01%) was used. The petioles of the leaves containing the treatments were attached to an eppendorf with water and placed, together with 10 nymphs of the 5th instar of T. peregrinus, inside gerbox boxes, each box being considered a repetition. The bioassay was maintained in a rearing room (27 ± 2°C, RH 60 ± 10% and photoperiod of 12 h). The evaluations took place every 12 hours, for seven days until they totaled 168 hours of exposure. Mentha sp. essential oil, at 1%, affected the longevity of T. peregrinus nymphs, causing total mortality of 84% of this insect. This may occur due to the composition of Mentha sp., which is rich in carvone, menthol and menthone and probably caused damage to the nervous system of T. peregrinus nymphs. The essential oil of Mentha sp. it has potential for new tests, such as field tests, which may aim at the development of a commercial product.