Genetic diversity of Brazilian Bacillus thuringiensis isolates with toxicity against Aedes aegypti (Diptera: Culicidae)

Fernandes, Geysla Da Costa; Costa, Dalton Kaynnan de Prado; Oliveira, Nayanne Santos; Sousa, Emanuelle Cristine Pereira de; Machado, Déborah Heloísa Bittencourt; Polanczyk, Ricardo Antônio; Siqueira, Herbert A.A.; Silva, Maria Cleoneide da

doi:10.1038/s41598-022-18559-0

Cited by 7 publications

(3 citation statements)

References 58 publications

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“…Other studies highlight the importance of the toxic activity of Cyt proteins on mosquito larvae that are vectors of human diseases like dengue, malaria and lymphatic filariasis, among others (Fernandes et al., 2021; Van Frankenhuyzen, 2017). Thus, identifying cyt genes in Bt strains is important to control some coleopteran and lepidopteran pests.…”

Section: Discussionmentioning

confidence: 99%

Bacillus thuringiensis strains to control Noctuidae pests

Nascimento,

de Carvalho,

Martins

et al. 2024

J Applied Entomology

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This study aimed to select and characterize Bacillus thuringiensis strains with toxic activity on Helicoverpa armigera, Spodoptera cosmioides and Spodoptera eridania. Fifty B. thuringiensis (Bt) strains were used in selective bioassays for high mortality on H. armigera, and the four most efficient strains were tested on S. cosmioides and S. eridania. Twelve Bt strains were characterized by PCR to detect some cry, cyt and vip genes. Bioassays were also performed to detect the production of β‐exotoxins. Strain 237 caused a mortality rate of 95.6% due to β‐exotoxins. Strains 1368, 1521, 1814 and 3299 showed toxic activity on S. eridania. However, no strain was effective on S. cosmioides. The presence of β‐exotoxin was detected only in strain 237. The molecular characterization of the strains using specific cry, cyt and vip primers showed a great genetic diversity among the 12 strains that showed some mortality on H. armigera and S. eridania. Our results showed that detecting β‐exotoxin in Bt strains is important as it is toxic to insects and vertebrates and persistent in the environment. Strains 1368, 1521, 1814 and 3299 did not show toxicity to H. armigera, while they were toxic to S. eridania and did not produce β‐exotoxin. These strains may be useful for new formulations of biopesticides as well as for cloning and expression of plants' genes.

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Section: Discussionmentioning

confidence: 99%

Bacillus thuringiensis strains to control Noctuidae pests

Nascimento,

de Carvalho,

Martins

et al. 2024

J Applied Entomology

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“…None of the B. thuringiensis isolates harbored all of the investigated cry and cyt genes, but this result is perhaps expected since none of the known B. thuringiensis species or subspecies presents all of the potential genes. However, some isolates may present high toxicity to susceptible insects even with a synthetic composition of cry - cyt genes [ 62 ]. The number of genes in a single isolate does not appear to be the factor determining the immediate death of the susceptible insect per se, but it may affect the toxic activity of bacteria when they encounter optimal conditions in the gut of the insect.…”

Section: Discussionmentioning

confidence: 99%

“…Preparation of spore-crystal mixture from local B. thuringiensis isolates exhibited larvicidal activity. Several preparations of spore-crystal mixture from B. thuringiensis strains with good mosquitocidal activity have been isolated from various parts of the world [ 19 , 62 , 71 , 72 ]. Among the preparation of spore-crystal mixture from B. thuringiensis isolates with significantly enhanced larvicidal activity identified in this study, the preparation with isolate A4 was the most toxic with bioactivity against C. pipiens pallens larvae (LC 50 : 1.4 ± 0.5 µg/ml and LC 95 : 15.3 ± 4.4 µg/ml; 5.1 × 10 7 CFU/µg per mg powder).…”

Section: Discussionmentioning

confidence: 99%

New native Bacillus thuringiensis strains induce high insecticidal action against Culex pipiens pallens larvae and adults

Ma¹,

Hu²,

Ding³

et al. 2023

BMC Microbiol

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Mosquitoes of many species are key disease vectors, killing millions of people each year. Bacillus thuringiensis-based insecticide formulations are largely recognized as among the most effective, ecologically safe, and long-lasting methods of managing insect pests. New B. thuringiensis strains with high mosquito control effectiveness were isolated, identified, genetically defined, and physiologically characterized. Eight B. thuringiensis strains were identified and shown to carry endotoxin-producing genes. Using a scanning electron microscope, results revealed typical crystal forms of various shapes in B. thuringiensis strains. Fourteen cry and cyt genes were found in the strains examined. Although the genome of the B. thuringiensis A4 strain had twelve cry and cyt genes, not all of them were expressed, and only a few protein profiles were observed. The larvicidal activity of the eight B. thuringiensis strains was found to be positive (LC50: 1.4–28.5 g/ml and LC95: 15.3-130.3 g/ml). Bioassays in a laboratory environment demonstrated that preparations containing B. thuringiensis spores and crystals were particularly active to mosquito larvae and adults. These new findings show that the novel preparation containing B. thuringiensis A4 spores and crystals mixture might be used to control larval and adult mosquitoes in a sustainable and ecologically friendly manner.

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