Natural Isolates ofBacillus thuringiensis:Worldwide Distribution, Characterization, and Activity against Insect Pests

The control of Acromyrmex leaf-cutting ants is necessary due to the severe damage they cause to diverse crops. A possibility was to control them using the bacterium Bacillus thuringiensis (Bt) that characteristically produces insecticidal crystal proteins (ICPs). The ICPs have been effective in controlling lepidopterans, dipterans, and coleopterans, but their action against hymenopterans is unknown. This paper describes an attempt to isolate Bt from ants of two Acromyrmex species, to evaluate its pathogenicity towards these ants, and to test isolates by PCR. Bacterial isolates of Bt obtained from A. crassispinus and A. lundi have been assayed against A. lundi in the laboratory. The bioassays were carried out in BOD at 25°C, with a 12-hour photoperiod, until the seventh day after treatment. The Bt isolates obtained were submitted to total DNA extraction and tested by PCR with primers specific to cry genes. The results showed Bt presence in 40% of the assessed samples. The data from the in vivo assays showed a mortality rate higher than 50% in the target population, with the Bt HA48 isolate causing 100% of corrected mortality. The PCR results of Bt isolates showed a magnification of DNA fragments relative to cry1 genes in 22% of the isolates, and cry9 in 67%. Cry2, cry3, cry7, and cry8 genes were not detected in the tested samples, and 22% had no magnified DNA fragments corresponding to the assessed cry genes. The results are promising not only regarding allele identification in new isolates, but also fort the assays aimed at determining the Bt HA48 LC 50 's, which can eventually be applied in controlling of Acromyrmex leaf-cutting ants.Key words: bioassay, leaf-cutting ants, Bacillus thuringiensis. RESUMO Patogenicidade de Bacillus thuringiensis isolados de duas espécies deAcromyrmex (Hymenoptera, Formicidae)O controle das formigas-cortadeiras do gênero Acromyrmex é necessário em razão dos severos danos que causam a diversas culturas. Uma alternativa é a utilização da bactéria Bacillus thuringiensis (Bt), caracterizada pela produção de proteínas inseticidas eficazes para lepidópteros, dípteros e coleópteros, mas cuja ação é ainda desconhecida para himenópteros. O presente trabalho teve por objetivo isolar Bt a partir de formigas de duas espécies de Acromyrmex, avaliar sua patogenicidade a formigas-cortadeiras e testar por PCR.

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“…A similar method was used by Bernhard et al (1997) in isolating Bt from natural samples collected on all continents.…”

Section: Resultsmentioning

confidence: 99%

Pathogenicity of Bacillus thuringiensis isolated from two species of Acromyrmex (Hymenoptera, Formicidae)

et al. 2003

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“…Regarding the crystal shape analogy and its specific toxicity to insect orders, Taylor et al (1992), Bernhard et al (1997), and Habib and Andrade (1998) observed that the crystal shape can provide information on the insecticidal activity of a strain. In this study, the toxic isolate Bt117-4 showed cuboidal crystals, which are known to contain proteins toxic to Lepidoptera (Dankocsik et al, 1990;Wu et al 1991;Monnerat et al, 2007;Silva-Werneck and Ellar, 2008).…”

Section: Discussionmentioning

confidence: 99%

Two new Brazilian isolates of Bacillus thuringiensis toxic to Anticarsia gemmatalis (Lepidoptera: Noctuidae)

Fiúza¹,

Schünemann

Pinto

et al. 2012

Braz. J. Biol.

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Bacillus thuringiensis is a bacterium used for biopesticides production and pest-resistant plants due to the synthesis of protein crystals by cry genes, which are effective in controlling several insect orders such as Lepidoptera. This work aimed at the evaluation and characterisation of two new B. thuringiensis isolates active against A. gemmatalis (Hübner 1818) larvae, which is the soybean major pest. The results showed that Bt117-4 isolate amplified fragments corresponding to cry2 and cry9 genes, and synthesised protein fragments equivalent to 130, 90 and 45 kDa. The Bt3146-4 isolate amplified DNA fragments corresponding to cry9 gene and synthesised protein fragments of 70, 58 and 38 kDa. Transmission electron microscopy revealed the presence of protein crystals in both isolates. CL50 with Cry purified proteins from Bt117-4 and Bt3146-4, corresponded to 0.195 and 0.191 µg larvae-1, respectively. The two B. thuringiensis isolates selected in this study were effective to control velvetbean caterpillar at laboratory conditions. Field tests should be carried on to develop new biopesticides formulation as well for cry genes resource for Anticarsia gemmatalis resistant transgenic plants.

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“…Worldwide, natural B. thuringiensis strains isolated from different habitats are established as B. thuringiensis culture collections (Martin and Travers, 1989;Ben-Dov et al, 1997;Bernhard et al, 1997;Bravo et al, 1998;Iriarte et al, 2000;Kim et al, 1998;Hongyu et al, 2000;Uribe et al, 2003). They are important for reflecting biodiversity through sampling sites and finding new strains with high toxicity against target insect species.…”

Section: Introductionmentioning

confidence: 99%

Identification and bioactivity of native strains of Bacillus thuringiensis from grain-related habitats in Turkey

Apaydin¹,

Çınar²,

Turanli³

et al. 2008

Biological Control

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A native collection of Bacillus thuringiensis (Bt) strains originated from grain-related habitats in Turkey was characterized according to serotype, cry1 gene content, and bioactivity against Ephestia kuehniella (Lepidoptera: Phycitidae) and Spodoptera littoralis (Lepidoptera: Noctuidae). Twenty-three different serotypes as well as 24 unknown serotypes were obtained from 56 positively agglutinated strains with previously characterized antisera. Most common serovars were sotto, kim, and tochigiensis with the percentages of 14, 14, and 13, respectively. Among the cry1 gene-positive 36 strains, cry1E (100%), cry1Aa (94%), cry1Ac (92%), and cry1D (83%) genes were the most abundant. Bioactivity tests with 56 Bt strains carrying cry1, cry2, and/or cry9 genes indicated that all of them resulted in growth retardation or inhibition of larvae of both E. kuehniella and S. littoralis; however, only one strain, 85PPb (serovar morrisoni), caused high mortality in both insects (84% and 100%, respectively). Different crystal morphology was observed for the strain 85PPb and the standard strain B. thuringiensis subsp. morrisoni. Finally, no correlation was found among serotype, cry gene content and biotoxicity of Bt strains in the collection.

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Natural Isolates ofBacillus thuringiensis:Worldwide Distribution, Characterization, and Activity against Insect Pests

Cited by 147 publications

References 20 publications

Pathogenicity of Bacillus thuringiensis isolated from two species of Acromyrmex (Hymenoptera, Formicidae)

Pathogenicity of Bacillus thuringiensis isolated from two species of Acromyrmex (Hymenoptera, Formicidae)

Two new Brazilian isolates of Bacillus thuringiensis toxic to Anticarsia gemmatalis (Lepidoptera: Noctuidae)

Identification and bioactivity of native strains of Bacillus thuringiensis from grain-related habitats in Turkey

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