Search results for "bacillus thuringiensis"
showing 10 items of 211 documents
Potential effects of transgenic cotton on soil ecosystem processes in Vietnam.
2008
Potential of the Bacillus thuringiensis Toxin Reservoir for the Control of Lobesia botrana (Lepidoptera: Tortricidae), a Major Pest of Grape Plants▿
2006
ABSTRACT The potential of Bacillus thuringiensis Cry proteins to control the grape pest Lobesia botrana was explored by testing first-instar larvae with Cry proteins belonging to the Cry1, Cry2, and Cry9 groups selected for their documented activities against Lepidoptera. Cry9Ca, a toxin from B. thuringiensis , was the protein most toxic to L. botrana larvae, followed in decreasing order by Cry2Ab, Cry1Ab, Cry2Aa, and Cry1Ia7, with 50% lethal concentration values of 0.09, 0.1, 1.4, 3.2, and 8.5 μg/ml of diet, respectively. In contrast, Cry1Fa and Cry1JA were not active at the assayed concentration (100 μg/ml). In vitro binding and competition experiments showed that none of the toxins teste…
Toxicity of several d-endotoxins of Bacillus thuringiensis against Helicoverpa armigera (Lepidoptera: Noctuidae) from Spain
2005
Abstract Toxicity and larval growth inhibition of 11 insecticidal proteins of Bacillus thuringiensis were evaluated against neonate larvae of Helicoverpa armigera, a major pest of important crops in Spain and other countries, by a whole-diet contamination method. The most active toxins were Cry1Ac4 and Cry2Aa1, with LC50 values of 3.5 and 6.3 μg/ml, respectively. At the concentrations tested, Cry1Ac4, Cry2Aa1, Cry9Ca, Cry1Fa1, Cry1Ab3, Cry2Ab2, Cry1Da, and Cry1Ja1, produced a significant growth inhibition, whereas Cry1Aa3, Cry1Ca2, and Cry1Ea had no effect.
Effet insecticide de Bacillus thuringiensis kurstaki et d’une toxine bactérienne, le Spinosad, à l’égard des blattes domestiques adultes (Blattella g…
2012
Les blattes sont très étudiées en raison de leur impact sur la santé humaine et animale, sur les cultures et l’habitat. Blattella germanica est une blatte domestique prédominante qui représente un vecteur potentiel des maladies. En raison de sa nuisance elle a fait l’objet de plusieurs études, en vue d’une lutte efficace. Ces dernières années, une nouvelle approche toxicologique est apparue, elle consiste à développer de nouveaux insecticides issus essentiellement des molécules biologiques telles que les plantes et les microorganismes comme les champignons et les bactéries. Dans cette étude on s’est intéressé aux effets induits par le Bacillus thuringiensiskurstaki sur les adultes de B. ger…
Increase in midgut microbiota load induces an apparent immune priming and increases tolerance to Bacillus thuringiensis
2010
Summary The insect immune system is comprised of both humoral and cellular components that are mobilized in response to parasitic or pathogenic infections. Activation of the immune response implies a consid- erable expenditure of energy and that is why insects rely on inducible pathways that are activated after coming into contact with the pathogenic agent. Known as immune priming, insects can prolong the activation of the immune response and transmit their immune status to the next generation. Starting from a laboratory colony of the lepidopteran Spodoptera exigua and using the lytic zone assay as a measure of the immune status, we selected for a sub-colony with high levels of immune activ…
Study of the aminopeptidase N gene family in the lepidopterans Ostrinia nubilalis (Hübner) and Bombyx mori (L.): Sequences, mapping and expression
2010
Aminopeptidases N (APNs) are a class of ectoenzymes present in lepidopteran larvae midguts, involved in the Bacillus thuringiensis (Bt) toxins mode of action. In the present work, seven aminopeptidases have been cloned from the midgut of Ostrinia nubilalis, the major Lepidopteran corn pest in the temperate climates. Six sequences were identified as APNs because of the presence of the HEXXH(X)18E and GAMEN motifs, as well as the signal peptide and the GPI-anchor sequences. The remaining sequence did not contain the two cellular targeting signals, indicating it belonged to the puromycin-sensitive aminopeptidase (PSA) family. An in silico analysis allowed us to find orthologous sequences in Bo…
Effect of Cry Toxins on Xylotrechus arvicola (Coleoptera: Cerambycidae) Larvae
2022
Simple Summary Xylotrechus arvicola is a destructive pest in vineyards (Vitis vinifera) in the main wine-producing areas of the Iberian Peninsula. X. arvicola larvae bore into the grapevine wood-making galleries, thus damaging the plant both directly and indirectly. The susceptibility of X. arvicola larvae to five coleopteran toxic Cry proteins was evaluated under laboratory conditions in order to deepen the knowledge of the effect of these proteins on this insect throughout its biological development. The Cry proteins tested could be applied to control X. arvicola larvae since they were able to kill them and cause serious alterations in the larvae during the remaining months of development…
Cadherin fragments of Lepidopteran and Coleopteran species do not enhance toxicity of Cry1Ca and Vip3Aa proteins to Spodoptera exigua (Hübner) (Lepid…
2020
Bacillus thuringiensis Berliner 1915 (Bt) is an entomopathogenic bacterium used to control insect pest worldwide. During its life cycle, Bt produces different insecticidal proteins, among which Veg...
Insecticidal Activity of Strains of Bacillus thuringiensis on Larvae and Adults of Bactrocera oleae Gmelin (Dipt. Tephritidae)
1999
The olive fly, Bactrocera oleae, is the key pest on olives in the Mediterranean area. The pest can destroy, in some cases, up to 70% of the olive production. Its control relies mainly on chemical treatments, sometimes applied by aircraft over vast areas, with their subsequent ecological and toxicological side effects. Bacillus thuringiensis is a spore-forming soil bacterium which produces a protein crystal toxic to some insects, including the orders of Lepidoptera, Diptera, and Coleoptera and other invertebrates. The aim of this study was to search for isolates toxic to B. oleae. Several hundred B. thuringiensis isolates were obtained from olive groves and olive presses in different areas o…
Ecological Mysteries: is <i>Bacillus thuringiensis</i> a Real Insect Pathogen?
2012
Bacillus thuringiensis ( Bt ) can kill insects and multiply in their bodies, but it can also grow in semi-synthetic media; is found in environments were insects are absent; and has been reported to require midgut-associated bacteria for toxicity. We propose here a novel life cycle for Bt combining insect-based and insect-independent life cycles.