Banca de QUALIFICAÇÃO: EDUARDO ALVES DE SOUZA

Susceptibility of Spodoptera spp. (Lepidoptera, Noctuidae) to the entomopathogenic action of endophytic strains of Bacillus in maize (Zea mays L.)

Biological control; Spodoptera Complex; endophytic bacillus

The Spodoptera complex is known to cause economic damage to agricultural crops such as maize. Spodoptera frugiperda and S. cosmioides are pests of economic importance that cause defoliation and damage to the reproductive structures of plants. Traditional control with chemical pesticides has been less effective due to increased pest resistance. An adopted alternative is the use of Bacillus, a bacterium that produces specific toxins for the target species, being a more efficient option for the control of these pests. In this perspective, the objective of this study will be to select and evaluate endophytic strains of Bacillus with entomopathogenic capacity on Spodoptera frugiperda and S. cosmioides in corn (Z. mays). 38 strains belonging to the Bacillus cereus group will be used, including the species Bacillus thuringiensis, previously characterized and taxonomically classified, from the Laboratory of Genetics and Biochemistry of Embrapa Agrobiologia. An insect rearing of the two species of Spodoptera will be set up to carry out the bioassays. The in vitro bioassay will aim to select the strains in relation to the in vitro mortality of these first instar caterpillars. In the bioassay in a greenhouse, Bacillus strains that provide mortality greater than 70% in laboratory experiments will be used, and will be later inoculated in corn seeds. At this stage, in addition to evaluating the ability of the strains to control the Spodoptera caterpillars and the damage caused by the latter to the plants, the power of the Bacillus strains to establish itself in the plant tissues of maize will be analyzed through the in-house hybridization method. in situ fluorescence with tyramide signal amplification (FISH-TSA) and quantify the bacterial load in plants through quantitative PCR (qPCR). It is expected that the project will contribute with relevant information on the control efficiency of different strains of endophytic Bacillus included within the group of Bacillus cereus on S. frugiperda and S. cosmioides. It is also intended to understand the plant-endophyte-insect interaction, which will be observed from the colonization of plants by endophytes, their survival and multiplication in plant tissues, as well as their effects on insects.