Atividade inseticida da folha e da torta da semente de nim Azadirachta indica A. Juss. (Meliaceae) no controle de Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae) em milho Zea mays L. (Poaceae)

Abstract

The Spodoptera frugiperda fall armyworm is considered the main pest of the maize culture. The alternative control of this pest by means of Azadirachta indica A Juss. (Meliaceae) has been sufficiently promising; however, few works describe the use of neem residues in its control. This work was divided into a literature review and two experimental chapters. The first had as objective to evaluate the toxicity of aqueous leaf extracts and neem seed pie in worm of S. frugiperda fed with laboratory treated maize leaves. As for the second, the objective was to evaluate the leaf and pie of the neem seed effect, in three ways of application in greenhouse. In chapter I, the determination of the CL50 was done with analysis of Probit at two season of evaluation, besides a factorial 2x2+1 scheme to evaluate the biometric insect data and regressions to mortality. In chapter II, the variance analysis was carried out, the measurements being compared by the Tukey and Kruskal-Wallis test at 5% of significance. The estimated values of the CL50 for the aqueous extracts neem with leaf and pie were of 0.38% (m/v) and 0.31% (m/v), respectively. In relation to the length of the worm, width of the head and weight of the insect, there was significant interaction between the season and the treatments tested. There was significant difference between the tested aqueous extracts, to the 5 and to the 10 day after the first application. The pie treatment in the leaf-liquid way was what obtained the lowest note of damages with 2.08 in the note scale, but did not differ from the treatment with pie in the soil way. In the analysis of the leaf area, after the consumption of +3 leaf, there was observed a significant difference between the treatments with pie in liquid way 93.86 cm2 and the control 66.46 cm2. In laboratory, S. frugiperda worms were more susceptible to the aqueous leaf extract than to the aqueous pie extract of neem in relation to the mortality. There was difference between the season of evaluation in relation to the length of the worm, width of the head and weight. In greenhouse, the aqueous extract based on the pie was the most efficient in the control of worm of S. frugiperda. The leaf way in form of powder was the least efficient.