Selection of Metarhizium anisopliae (Metsch.) and Beauveria bassiana (Bals.) isolates to control Alabama argillacea (Huebner) caterpillars

Abstract

The cotton leafworm, Alabama argillacea (Huebner, 1818) (Lepidoptera: Noctuidae), is considered to be one of the key pests in herbaceous cotton (Gossypium hirsutum L. r. latifolium Hutch) cropping, with constant occurrence in all cotton-growing states of Brazil. In this study Metarhizium anisopliae and Beauveria bassiana isolates were screened and evaluated for pathogenicity against Alabama argillaceae. Initially, a screening of ten isolates of each fungus in a concentracion of 10(8) conidia mL-1, was carried out on 3rd instar larvae of A. argillacea. Further studies were conducted to determine the pathogenicity and virulence of six and seven isolates of M. anisopliae and B. bassiana, respectively, against 3rd instar larvae of A. argillacea and using the concentrations of 10(6), 10(7), 10(8), and 10(9) conidia mL-1. The experiments were carried out in Recife, PE, Brazil, at 27 ± 2ºC, RH 70 ± 5% and a photophase of 12 hours. Mortalities caused by M. anisopliae isolate at the different concentrations ranged from 4.5 to 91.2%, the highest mortality percentage being found for the isolate 1189 at 10(9) conidia mL-1. The isolate 645 of B. bassiana caused the highest mortality at the highest concentration, followed by isolates 634, 604, and IPA 198. The lowest lethal time for B. bassiana and M. anisopliae, was achieved by the isolates 483 (4.1 days) and 1189 (2.0 days), respectively. The isolates 1189, 1022 e 866 of M. anisopliae and 483, IPA198 and 604 of B. bassiana, at 10(8) e 10(9) conidia mL-1 are promissing for use the integrated control of A. argillacea larvae, but M. anisopliae seems more effective.

Susceptibility of Alabama argillacea and Chrysodeixis includens (Lepidoptera: Noctuidae) larvae to Beauveria bassiana associated with kaolin

“…The B. bassiana CG138 isolate was the most effective against A. argillacea first-instar larvae, followed by the ESALQ 634 and CG 82 and CG 70 and ESALQ 645 as the least effective ( Table 2). Mortality of A. argillacea first-instar larvae with the GC 138 isolate was higher than that found (81, 74 and 40%) for third instar larvae of this species, with conidial suspension of B. bassiana strains UFRPE 645 (10 9 conidia mL -1 ), UFRPE 604 (10 8 conidia mL -1 ) and UFRPE 634 (10 7 conidia mL -1 ), respectively (César Filho et al, 2002). These differences can be attributed to the inoculation and conidia concentration of this pathogen (Santoro et al, 2007), and to the larvae development stage (César Filho et al, 2002).…”

“…Mortality of A. argillacea first-instar larvae with the GC 138 isolate was higher than that found (81, 74 and 40%) for third instar larvae of this species, with conidial suspension of B. bassiana strains UFRPE 645 (10 9 conidia mL -1 ), UFRPE 604 (10 8 conidia mL -1 ) and UFRPE 634 (10 7 conidia mL -1 ), respectively (César Filho et al, 2002). These differences can be attributed to the inoculation and conidia concentration of this pathogen (Santoro et al, 2007), and to the larvae development stage (César Filho et al, 2002). Neonate larvae differ in scale, metabolism, digestive physiology, sensory modalities and intestinal microbiota from those of the late stages (Mason and Raffa, 2014;Despland, 2018).…”

“…The strains of the fungus B. bassiana, CG 70, CG 82 and CG 138, were obtained from the mycology collection of the Biological Control Laboratory of Embrapa Recursos Genéticos e Biotecnologia in Brasília, Federal District, Brazil, and the Bb 634 and Bb 645 strains from the ESALQ-USP mycology collection, Piracicaba, São Paulo, Brazil. These strains have been tested because they are highly virulent to lepidopteran larvae (César Filho et al, 2002) and are not commercially available. These strains were stored at 7 °C in disposable Petri dishes with PDA (potato-dextrose-agar) and antibiotic (chloramphenicol) (PDA + A) and Nujol oil until the beginning of the bioassays (Table 1).…”

“…The entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin is produced and used in Brazil to manage insect pests of many orders (César Filho et al, 2002;Sree and Varma, 2015). The wide genetic variability of this entomopathogen increases its importance in microbial insect control.…”

A Laboratory Study on the Efficacy of Metarhizium anisopliae (Metsch.) Sorokin and Beauveria bassiana (Bals.) Vuill Against Spodoptera exigua (Hb.) (Lepidoptera: Noctuidae)

“…Treating 2 nd instar larvae of S. exigua by M. anisopliae resulted in a relatively low pupal deformation percentage of 9.41and 4.17% respectively, while there were no deformities in case of the control group (table 3). Filho et al (2002) screened for the Pathogenicity of Metarhizium anisopliae and Beauveria bassiana isolates against Alabama argillaceae in Brazil at 27 ± 2 o C, RH 70 ± 5%. They found that mortalities caused by the M. anisopliae isolates at the different concentrations ranged from 4.5 to 91.2%.…”