Potencial inseticida de extratos aquosos de Quassia amara L. no controle de Plutella xylostella L. 1758

Abstract

Insect management using phytoinsecticides has shown promise as an alternative control method, due to its source of bioactive compounds with adverse effects on insects. Furthermore, researchers seek to find substances in these plants that promote sustainable development in the agricultural sector and that present low toxicity to non-target individuals. Therefore, the objective of this work was to evaluate the insecticidal effect of the aqueous plant extract from Quassia amara L. (Simaroubaceae) in different concentrations on the control of the microlepidopteran Plutella xylostella (Linnaeus, 1758) (Lepidoptera: Plutellidae), verifying its effect on generations future and at different stages of the insect. For this, cabbage leaf discs measuring 8 cm in diameter were immersed in 50 ml of aqueous extract (5 and 10%) and distilled water (control). The discs were placed on filter paper at room temperature to remove excess moisture, and subsequently transferred to Petri dishes. Three recently oviposited P. xylostella eggs (0-24h) were inserted into each Petri dish. The biological cycle and the effect of extracts on the immature and adult phase were evaluated, with the following biological parameters being evaluated: duration and survival of eggs, pupal weight, longevity of female and male, duration and viability of larval and pupae, sex ratio, number of eggs per pair, egg viability and morphological deformations. The 5% extract affected the biological characteristics of P. xylostella to a lesser extent, such as deformities and dryness throughout the body, and also presented a higher mortality rate of 3rd instar larvae. While the 10% extract demonstrated greater influence on the 1st and 2nd stage larval phase, reducing the duration of the phase, presenting dryness and deformities in the surviving larvae, a result observed in the F1 generation of this extract. Larvae that had contact with 10% extract began their pupal stage earlier, but with a low survival rate and lower pupal weight compared to the 5% pupal weight.