Search results for "Bacillus thuringiensis"
showing 10 items of 211 documents
A Bacillus thuringiensis strain producing epizootics on Plodia interpunctella: A case study
2012
Abstract After several disease outbreaks in laboratory cultures of pyralid moths in Tabriz University, Iran, during 2004 and 2005, a new Bacillus thuringiensis aizawai strain EF495116 (BTA) was isolated from a dead Plodia interpunctella larva. A complete characterization of the strain was performed, including serological identification, protein and plasmid pattern determination, a PCR-based identification of virulence-related genes, nucleotide sequence analysis of the 16S rDNA and gyrB genes (in order to find out relationships between the species with other virulent Bacillus pathogens), and biological activity assays. These studies revealed that BTA produced a major parasporal protein band …
Susceptibility of ostrinia nubilalis to bacillus thuringiensis var. kurstaki
2003
Baseline susceptibility of European corn borer larvae, Ostrinia nubilalis (Hübner), to a commercial formulation of Bacillus thuringiensis var. kurstaki was determined for different strains in 7 geographic locations in the corn area of North Italy (Po Valley). For the bioassay 7 different doses, raised on a meredic diet, were used and the data was analysed with the Probit analysis. Differences in the susceptibility among the northern Italian populations of O. nubilalis were recorded, which can be attributed to natural variability. The ECB collected near Como and Torino was the most susceptible, respectively with LC50 of 0.23 and 0.57 mg/ml. The most tolerant ones were the larvae coming from …
Susceptibility to BT of wild lepidopteran species in Nature Reserve in Sicily
2010
A wide range of crop plants and trees have been transformed with genes derived from the soil bacterium Bacillus thuringiensis (Bt) to express insecticidal proteins (insect-resistant Bt plants). Whereas the adoption of Bt plants constitutes one of the most common uses of transgenic plants in agriculture, the environmental benefits and risks remain an issue. To preserve the natural reserve and their fauna UE proposed that in future the Member State specify a minimum separation distance of metres between fields of GM plants and nature reserves or to forbid cultivation of GM plant in particular area based on scientific data. Natural reserve in Sicily have many endemism and rare species so next …
An alternative set of test to bioassay for bioinsecticides
2010
The development of an assay to determine insecticidal properties for either biological and conventional plant protection products plays an important role on the early screening of potential pathogens or derived toxins candidates. The standard methods for the evaluation it has been by bioassay, especially determination of LD50 or LC 50 requiring the use of relatively large numbers of insects and toxin tests. There are several problems connected with these bioassays: availability of insects and in the right life stage, mass producing the candidate species, preparation, reproducibly and costs relative to intensive manpower. These aspects are really important especially when bio-insectides shou…
Bacillus thuringiensis treatment alters larval growth, hemocytes and modulation of Hsp70 in Rhynchophorus ferrugineus
2011
To study the pathogen-host relationship, we used the model of the entomopathogenic bacterium Bacillus thuringiensis (Bt) and Rhynchophorus ferrugineus, a quarantine pest that attacks the palm trees. In particular, we focused on the Bt stress-induced infections. We studied the effect of Bt on larval growth, on hemocytes and on the expression of the heat shock proteins (Hsp70). HSPs are rapidly synthesized in the cells after a stress exposition including pathogens. The Hsp70 was evaluated in the supernatant of the hemocyte lysate (HLS) obtained from larvae fed with Bt. This is the first time that the presence of Hsp70 has been recorded in R. ferrugineus. Bt has negative effects on larval grow…
Use of biorational insecticides for the control of Tuta absoluta (Meyrick) infestations on open field tomato
2012
Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), the tomato leaf miner, is one of the most devastating pests affecting tomato crops in Italy. Management of T. absoluta was assessed in open-field tests using three biorational insecticides, Azadirachtin, Bacillus thuringiensis var. kurstaki, and Beauveria bassiana, and a combination of three synthetic insecticides, Emamectin, Indoxacarb and Metaflumizone, as a control treatment. Our results showed that only the combination of Azadirachtin – B. thuringiensis was able to reduce the impact of tomato leaf miner on the fruit’s marketable production similarly to the control treatment. This finding suggests that biorational insecticides are a goo…
In vivo modulation of Bacillus thuringiensis (commercial form) on Holothuria tubulosa immune defense mechanisms
2010
In invertebrates, cellular and humoral components are evolved to maintain their homeostais and integrity. Both these components respond to different non-self such as microorganisms, vertebrate erythrocytes and foreign proteins. The aim of this research was to study the possible modulating effects of Bacillus thuringiensis (Bt) in a commercial and vegetative form on the immune response of the echinoderm, sea cucumber Holothuria tubulosa. Bt is one of the most used biopesticides worldwide, covering the 90% of the organic market. Sicily is a region vocated to biological control and agricultural area are often closed to the coastal area. Investigate the effect of biopesticides on other non targ…
Eco-physiological response of two marine bivalves to acute exposition to commercial Bt-based pesticide
2013
Microbial products based on the entomopathogenic bacterium Bacillus thuringiensis (Bt) are among the most common biopesticides used worldwide to suppress insect pests in forests, horticulture and agricultural crops. Some of the effects of commercial Bt have been recorded for terrestrial and freshwater non-target organisms but little research is available on marine fauna. Nevertheless, due to the contiguity of agro-ecosystems and coastal habitats, marine fauna may be highly influenced by this control method. We studied the effect of a commercial Bt product on the physiological and ecological responses and the energy budget of two of the most frequent marine intertidal bivalves in the Mediter…
Pathogenicity of intrathoracically administrated Bacillus thuringiensis spores in Blatta orientalis.
2006
Abstract The ability of Bacillus thuringiensis to produce septicaemia in Periplaneta americana and Blatta orientalis has been investigated. Spores and crystals from several wild-type strains as well as spores of a B. thuringiensis crystal-deficient mutant, were first orally administrated at high doses, and no significant mortality was recorded. Intrathoracic injection of spore suspensions in P. americana revealed that this species is not very susceptible to B. thuringiensis spores. B. orientalis , by contrast, was found to be very susceptible to B. thuringiensis , with a LD 50 of about 35,000 spores, that is similar to that reported on Lepidoptera challenged with parenterally injected B. th…
Tribolium castaneum immune defense genes are differentially expressed in response to Bacillus thuringiensis toxins sharing common receptor molecules …
2015
In Tribolium castaneum larvae we have demonstrated by RNA interference knockdown that the Bacillus thuringiensis Cry3Ba toxin receptors Cadherin-like and Sodium solute symporter proteins are also functional receptors of the less active Cry3Aa toxin. Differences in susceptibility to B. thuringiensis infection might not only rely on toxin-receptor interaction but also on host defense mechanisms. We compared the expression of the immune related genes encoding Apolipophorin-III and two antimicrobial peptides, Defensin3 and Defensin2 after B. thuringiensis challenge. All three genes were up-regulated following Cry3Ba spore-crystal intoxication whereas only Defensins gene expression was induced u…