Molecular characterization and pathogenicity of isolates of Beauveria spp. to fall armyworm

Abstract

-The objective of this work was to evaluate the pathogenicity of 24 Beauveria isolates to Spodoptera frugiperda larvae, and characterize them molecularly through rDNA-ITS sequencing and RAPD markers. Sequencing of rDNA-ITS fragments of 570 bp allowed the identification of isolates as B. bassiana or B. brongniarti by sequence comparison to GenBank. Sixty seven polymorphic RAPD fragments were capable to differentiate 20 among 24 Beauveria isolates, grouping them according to the derived host insect and to pathogenicity against maize fall armyworm larvae. Three RAPD markers were highly associated to the pathogenicity against S. frugiperda, explaining up to 67% of the phenotypic variation. Besides identification and molecular characterization of Beauveria isolates, ITS sequence and RAPD markers proved to be very useful in selecting the isolates potentially effective against S. frugiperda larvae and in monitoring field release of these microorganisms in biocontrol programs.Index terms: Spodoptera frugiperda, entomopathogenic fungi, RAPD, rDNA-ITS. Caracterização molecular e virulência de isolados de Beauveria spp. contra a lagarta-do-cartuchoResumo -O objetivo deste trabalho foi avaliar a patogenicidade de 24 isolados de Beauveria contra larvas de Spodoptera frugiperda e caracterizá-los molecularmente, por meio do seqüenciamento da região ITS do rDNA e de marcadores RAPD. O seqüenciamento de fragmentos de 570 pares de bases, da região ITS do rDNA, possibilitou a identificação dos isolados como B. bassiana e B. brongniarti, pela comparação com seqüências depositadas no GenBank. Sessenta e sete fragmentos polimórficos de RAPD foram capazes de diferenciar 20 entre 24 isolados de Beauveria, e agrupá-los de acordo com o inseto hospedeiro e com a patogenicidade contra a lagarta-do-cartucho do milho. Os marcadores RAPD foram altamente associados à patogenicidade contra S. frugiperda e explicaram até 67% da variação fenotípica. Além da identificação e caracterização molecular de isolados de Beauveria, o seqüenciamento da região ITS, aliado aos marcadores RAPD, é útil na seleção de isolados potencialmente eficazes contra larvas de S. frugiperda e no monitoramento de liberações desses microrganismos em programas de biocontrole.Termos para indexação: Spodoptera frugiperda, fungo entomopatogênico, RAPD, rDNA-ITS.

Characterization and activity of entomopathogenic fungi isolates against “paraguay tea ampul” (Gyropsylla spegazziniana) (Lizer & Trelles) (Hemiptera: Psyllidae)

“…The proportion of monomorphic loci between the most virulent isolates was low (16.2%). Although some studies have reported a relationship between the molecular profile of isolates of entomopathogenic fungi and their initial host (CARNEIRO et al, 2008;OLIVEIRA et al, 2011) or geographical origin (FERNANDES et al, 2009), such a relationship was not found in the present study, either through analysis of the rDNA-ITS region or the groups generated via RAPD analysis, similar to the results of Becerra-Velásquez et al (2007) and Mendonça et al (2012).…”

In vitro assay on homeopathic solutions on Metarhizium anisopliae (Metsch) Sorok (Ascomycota: Clavicipitaceae)

“…Furthermore, the informational presence of S. frugiperda in homeopathic preparation may have been based on the homeopathy principles, a factor to stimulate the growth of fungus that is pathogenic to this insect (Carneiro et al, 2008).…”

Analysis of genetic diversity among different isolates of Beauveria bassiana by RAPD-PCR

“…The number of bands generated by each primer differed from 4 (OPA09) to 13 (OPA03 and OPQ01), with an average of 5.3 bands per primer. The size of the bands varied from 300 (OPZ19) to 3800 (OPA 13) base pairs (Carneiro et al, 2008).…”