Bioatividade de extrato etanólico de espécies de Rubiaceae sobre Plutella xylostella L., 1958 (Lepidoptera: Plutellidae)

Abstract

The management of insects by means of plant extracts has shown to be very promising as an alternative method of control since they are great sources of bioactive compounds with adverse effects on insects. The experiments were carried out to find those that favor the development of the agricultural system with low toxicity to non-target individuals. Therefore, the purpose of this study was to evaluate the effects of ethanolic extracts of Alibertia edulis (Rich.) A. Rich., Alibertia intermedia (Mart.) and Alibertia sessilis (Vell.) K. Schum on the biological cycle of Plutella xylostella and the effect of extracts on the next generation. For this, kale leaf discs with 9 cm diameter were immersed in ethanolic extracts (1 and 3%) and distilled water (control). The discs were placed on filter paper at room temperature to remove excess moisture and were subsequently transferred to Petri dishes. A freshly hatched P. xylostella caterpillar was inserted into each Petri dish. The biological cycle was evaluated, and the caterpillars tested were used to evaluate the effect of the extracts on the next generation. The biological characteristics evaluated were: duration and survival of the larval and pupal phases, pupal weight, male and female longevity in days, sexual ratio, fecundity, egg survival and morphological deformations. The ethanolic extracts of A. edulis reduced the pupal weight, the egg survival in the parental generation, the larval survival and the pupae whereas the ethanolic extracts of A. intermedia had a greater influence on the parental generation, reducing the duration of the larval phase, the pupae weight and the egg survival. The extracts of A. sessilis affected less the biological characteristics of P. xylostella, reducing the pupae weight in the two generations studied. The results of this work were evaluated in relation to the insecticidal activities of Alibertia species on P. xylostella. The ethanolic extract of A. intermedia and A. edulis should be the focus for more detailed studies and evaluations.