Molecular characterization of Bacillus thuringiensis strains to control Spodoptera eridania (Cramer) (Lepidoptera: Noctuidae) population

Déborah Heloísa Bittencourt Machado,Bárbara França Negri,Kalynka Gabriela Do Livramento,Luciano Vilela Paiva,Fernando Hercos Valicente,Wesley Pires Flausino Máximo

doi:10.1590/1806-9665-rbent-2019-47

Abstract

Abstract The main objective of this study was to characterize the toxicity and genetic divergence of 18 Bacillus thuringiensis strains in the biological control of Spodoptera eridania. Bacterial suspensions were added to the S. eridania diet. Half of the selected B. thuringiensis strains caused high mortality seven days after infection. The genetic divergence of B. thuringiensis strains was assessed based on Enterobacterial Repetitive Intergenic Consensus (ERIC) and Repetitive Extragenic Palindromic (REP) sequences, and five phylogenetic groups were formed. Despite their genetic diversity B. thuringiensis strains did not show any correlation between the collection sites and toxicity to larvae. Some B. thuringiensis strains are highly toxic to S. eridania, thus highlighting the potential of their endotoxins as biopesticides.

Highlights

During the year 2017/18 the total grain yield in Brazil was estimated to be 229.53 million tons, and trends indicate further increase in the upcoming (CONAB, 2018)
All B. thuringiensis strains led S. eridania larvae to death, but mortality level induced in caterpillars was isolate-dependent
Electrophoresis profile of the Polymerase Chain Reaction (PCR) products amplified with Enterobacterial Repetitive Intergenic Consensus (ERIC) primers (Figure 2A) exhibited the presence of 6 to 10 fragments which ranged from 100 bp to 1,500 bp, while the Repetitive Extragenic Palindromic (REP) primers (Figure 2B) amplified 1 to 10 fragments per strain with sizes ranging between 50 and 2,000 bp

Summary

Introduction

During the year 2017/18 the total grain yield in Brazil was estimated to be 229.53 million tons, and trends indicate further increase in the upcoming (CONAB, 2018). Such expectation of agricultural growth may not be achieved due to the emergence of phytosanitary issues responsible for causing crop injuries in many agricultural regions. B. thuringiensis sub-species represent about 98% of formulated sprayable bacterial microbial pesticides (Lacey et al, 2015). It still represents only 2% of the global pesticide market (Bravo et al, 2011)

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Results

Conclusion