Abstract
Spodoptera frugiperda (SMITH, 1797) (Lepidoptera: Noctuidae) affects diverse crops of great economic interest, for instance, it can cause severe yield losses in maize, rice and sorghum. In this study, a selection and characterization of Bacillus thuringiensis (BERLINER, 1911) isolates with a high insecticidal activity against S. frugiperda was performed. Fifty-two crystal-forming B. thuringiensis isolates that were identified from 3384 Bacillus -like colonies were examined and screened by PCR for the presence cry genes ( cry 1, cry 1Aa, cry 1Ab, cry 1Ac, cry 1D, cry 2 and cry 2Ab). Four isolates that showed high toxicity towards S. frugiperda were shown to harbor cry 2 genes. The crystals were analyzed by electron microscopy and showed bipyramidal and cuboidal shapes. Furthermore, these four isolates had lethal concentration (LC 50 ) values of 44.5 ng/cm 2 (SUFT01), 74.0 ng/cm 2 (SUFT02), 89.0 ng/cm 2 (SUFT03) and 108 ng/cm 2 (SUFT 04) to neonate S. frugiperda larvae. An ultrastructural analysis of midgut cells from S. frugiperda incubated with the SUFT01 spore-crystal complex showed disruptions in cellular integrity and in the microvilli of the midgut columnar cells. The isolates characterized in this work are good candidates for the control of S. frugiperda , and could be used for the formulation of new bioinsecticides.
Highlights
The Lepidopteran insect Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae) affects diverse crops of great economic interest, for instance, it can cause severe yield losses in maize, rice and sorghum (Gallo et al, 2002)
The selection of new isolates of Bt that are toxic against S. frugiperda and could serve as a source of new cry genes, which could be introduced into economically important plant genomes that need protection against this important pest
The occurrence of Bt having higher levels of toxicity towards S. frugiperda was more prevalent in soil samples from the south-west region of Tocantins State (Araguaçu and Sandolândia), including four isolates that induced more than an 80% mortality in neonate S. frugiperda larvae
Summary
The Lepidopteran insect Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae) affects diverse crops of great economic interest, for instance, it can cause severe yield losses in maize, rice and sorghum (Gallo et al, 2002). Bacillus thuringiensis (BERLINER, 1911) (Bt) produces an array of Cry proteins with are potentially toxic to S. frugiperda (SANTOS et al, 2009; VALICENTE et al, 2010). The interest in this microorganism stems from its potential as an economical, effective, speciesspecific and environmentally safe pesticide (ARRIETA; ESPINOSA, 2006). The selection of new isolates of Bt that are toxic against S. frugiperda and could serve as a source of new cry genes, which could be introduced into economically important plant genomes that need protection against this important pest. New Bt isolates were characterizated and shown potential for further research that may lead to the development of new biopesticides
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
