Atividade inseticida de um produto mineral e sua interação com o fungo entomopatogênico Beauveria bassiana visando ao controle da lagarta-do-cartucho-do-milho (Spodoptera frugiperda) (J.E.Smith)

Abstract

The objective of this work was to evaluate the insecticidal activity of the mineral product Fert-P and Beauveria bassiana, isolated and in associations, against Spodoptera frugiperda caterpillars in laboratory and greenhouse. The concentrations of conidia of B.bassiana were 1×108 and 1×109 and for Fert-P the concentrations were 4 and 8% in the laboratory and 8 and 16% in greenhouse. In the laboratory, the product was evaluated in artificial diet or not combined with fungus, with four replicates of 20 caterpillars of 3rd instar each. In the greenhouse, the product was applied on V3 stage corn plants and the leaves were offered to the laboratory caterpillars, treated or not with B. bassiana. Mortality and biological parameters were evaluated. The treatments that presented the highest efficiency in the laboratory were Fert-P 8% and Fert-P 8% + fungus in all interaction treatments with 77.5 and 80.0% of mortality, respectively. The larvae treated with FertP8% and Fert-P 8% + Fungus 1×108 and Fert-P 8% + Fungus 1×109 showed weights of 7 th day and also pupal lower and higher mortality of pupae than the other treatments. The duration of the pupal phase and pupal mortality were not affected by any treatment. In the greenhouse, treatments with the highest efficiency in larval and pupal mortality were Fungus 1×109 and Fungus 1×109 + Fert-P 8%, with a mortality rate of 40 and 50%. The Fert-P 8 + Fungus 1×109 treatment significantly reduced the development time of the caterpillar compared to Fert-P 8% alone. There was no intervention interference on the weight of the pupae. When the caterpillars were fed corn leaves sprayed with the product Fert- P 8% and Fert-P 16%, no insecticidal effect was observed when evaluated alone, requiring their interaction with the entomopathogenic fungus for a better efficiency in mortality.