51. Action of Bacillus thuringiensis (Bacillales: Bacillaceae) in the midgut of the sugarcane borer Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae).
- Author
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Daquila BV, Scudeler EL, Dossi FCA, Moreira DR, Pamphile JA, and Conte H
- Subjects
- Animals, Bacterial Proteins pharmacology, Digestive System growth & development, Endotoxins pharmacology, Hemolysin Proteins pharmacology, Larva drug effects, Larva growth & development, Moths growth & development, Pest Control, Biological methods, Saccharum growth & development, Bacillus thuringiensis, Biological Control Agents pharmacology, Digestive System drug effects, Moths drug effects, Saccharum microbiology
- Abstract
The relevance of Bacillus thuringiensis in pest control strategies have been increasing in recent decades. This entomopathogenic microorganism is considered safe, and its action is highly selective to target organisms. Its toxic effect is attributed to the toxins synthesized during sporulation. The nature of the produced toxins depends on the bacterial variety. Some varieties of B. thuringiensis can synthesize from one to eight distinct toxins, which have specific effects on different orders of susceptible insects. The sugarcane borer, Diatraea saccharalis, is a holometabolous lepidopteran that causes severe damage to sugar cane cultures during its larval phase. Therefore, to evaluate B. thuringiensis serovar Aizawai GC-91 efficiency and its effects on the midgut of first instar D. saccharalis larvae, we reared the insects with contaminated artificial diet for 144 h. Larvae mortality during this period revealed that 5, 10, and 20 g/L concentrations were the most efficient, resulting in 100% mortality of treated larvae, with LC
50 and LC90 estimated at 0.307 and 1.330 g/L, respectively. Furthermore, histological and ultrastructural analyses revealed damage to midgut cells. Within the first 24 h of treatment, the midgut of infected insects presented peritrophic membrane degeneration, cytoplasmic vacuolization, and cellular hypertrophy; spherites and calcium granules were also observed. At 48 h of treatment, the digestive system had collapsed, with microvilli degeneration, basement membrane and muscular fiber bundles disruption, and cellular lysis. These results confirm the toxicity of the B. thuringiensis serovar Aizawai GC-91 on D. saccharalis larvae and its potential use as a biocontroller against this pest species., (Copyright © 2019 Elsevier Inc. All rights reserved.)- Published
- 2019
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