Extratos aquosos de Simarouba versicolor A. St. Hill. (Simaroubaceae) afetam a biologia de Spodoptera frugiperda J.E. Smith, 1797 (Lepidoptera: Noctuidae)

Abstract

Spodoptera frugiperda (J.E Smith, 1797) (Lepidoptera: Noctuidae) popularly known as the corn borer caterpillar, is the main pest of corn culture, causing losses in grain yield that can reach up to 25% of economic damage. The species stands out not only for the damage it causes, but also for its high degree of resistance to synthetic insecticides. Currently, chemical control is the main method of controlling S. frugiperda, however, cases of resistant populations to the main chemical groups have already been registered in the country, making the introduction of alternative methods of pest control necessary. Thus, the objective of the work was to evaluate the insecticidal potential of Simarouba versicolor A. St Hill (Simaroubacea) in caterpillars of Spodoptera frugiperda.For the preparation of aqueous extracts of S. versicolor (EASv), the weight/volume ratio was used. Thus, 3g, 1.5g, 0.3g of S. versicolor leaf powder were weighed in analytical scales and placed separately in Becker's containing 30 ml of stylized water each, thus obtaining a final concentration of 10%, 5% and 1% respectively. After 24 hours, the extracts were filtered with filter paper so that they could be used. Next, artificial diet cubes and corn leaves were dipped into the aqueous extract of S. versicolor and fed to S frugiperda caterpillars. The diet cubes and corn leaves containing the aqueous extract of S. versicolor were changed daily until complete larval development or death of the caterpillars. Pupae at 24 hours of age were weighed on analytical scales, sexed and transferred to 50 ml plastic cups with lids. After emergence, couples of the same age were formed per treatment and confined in cages made with plastic jars lined with sulfite paper to serve as substrate for oviposition. Four treatments were used, with 10 replicates and 5 sub-samples each. In the experiment with artificial diet, the aqueous extract of S. versicolor was efficient in controlling S. frugiperda, causing total mortality of the caterpillars at 5% and 10% concentrations, and affecting the development of larval, pupal and adult stages at 1% concentration. In the experiment using corn leaves, the aqueous extract of S. versicolor affected the larval stage of S. frugiperda causing 100% mortality in all concentrations used. It was concluded that aqueous extract of Simarouba versicolor at concentrations of 1%, 5% and 10% were efficient in controlling the larval stage of Spodotera frugiperda, causing 100% mortality. Moreover, among the concentrations tested, the 1% concentration stands out in the experiment using corn leaves, since it has the same percentage of mortality as the 5% and 10% extract, but in a smaller dose, allowing economy of material during the preparation of the dose.