Biologia e comportamento de Spodoptera frugiperda (J.E. SMITH) (lepidoptera: noctuidae) e indução de resistência em milho tratado com microrganismos eficientes e silício

Abstract

The corn crop, of great importance in Brazil, is subject to the incidence of pests, mainly Spodoptera frugiperda, which affect all production systems. Thus, based on the benefits of effective microorganisms (EM) and silicon, the aim was to evaluate the effect of EM preparations and glass water, as tools for the control of the caterpillar in the culture of corn grown in soils from organic and conventional production management. For this, two research stages were carried out. In the first step, solid EM, liquid EM, glass water, solid EM + glass water and liquid EM + glass water were evaluated in soil from organic and conventional management, with corn cultivation. Aspects of the soil metabolic quotient (qCO2), mortality and cannibalism, and biological aspects of S. frugiperda fed with corn leaves that received the above treatments were evaluated. Based on the results obtained, a second experimental stage was carried out, where liquid EM, glass water and liquid EM + glass water were evaluated in soil from conventional management, with corn cultivation. Therefore, the parameters analyzed were: Si concentration in glass water, leaf Si concentration in the corn plant, qCO2 aspects, mortality and cannibalism, biology and food preference of S. frugiperda fed with corn leaves that received the treatments above, in addition to the analysis of resistance-inducing enzymes. In the first stage, the soil type practically did not influence the treatments on the biological and behavioral parameters of S. frugiperda, however the treatments reduced the qCO2 aspects in organic management soil, while they increased in conventional management soil, since the associated use of EM and glass water provided higher mortality and, in some cases, longer development time for S. frugiperda compared to the control. In the second stage, the glass water was not shown to be a source of silicon, the treatments did not alter aspects of qCO2 nor the behavioral aspects, mortality and cannibalism. In the biological and behavioral aspects of the caterpillar, there was an influence on the weight of pupae, there was an influence on food preference, and mortality rates equal or lower than the control, and resistance inducing enzymes, only changed the peroxidase index. The absence of efficient results for the control of the cartridge caterpillar may be correlated to the lack of availability of silicon by the glass water, when applied to the soil, associated with the fact that the EM did not show enough activity to improve the nutritional aspects of the cultivation, so that it does not present favorable conditions for the development of the pest species. therefore, further studies are needed to evaluate the efficiency of EM and glass water in controlling S. frugiperda in corn.