Elleuch J. auteur aut IRD Zghal R. Z. auteur aut IRD Lacroix Marie-Noëlle auteur aut IRD Chandre Fabrice auteur aut IRD Tounsi S. auteur aut IRD Jaoua S. auteur aut IRD text journalArticle eng text/pdf born digital access Biopesticides based on Bacillus thuringiensis israelensis are the most used and most successful around the world. This bacterium is characterized by a dynamic genome able to win or lose genetic materials which leads to a decrease in its effectiveness. The detection of such phenomena is of great importance to monitor the stability of B. thuringiensis strains in industrial production processes of biopesticides. New local B. thuringiensis israelensis isolates were investigated. They present variable levels of delta-endotoxins production and insecticidal activities against Aedes aegypti larvae. Searching on the origin of this variability, molecular and biochemical analyses were performed. The obtained results describe two main reasons of the decrease of B. thuringiensis israelensis insecticidal activity. The first reason was the deletion of cry4Aa and cry10Aa genes from the 128-kb pBtoxis plasmid as evidenced in three strains (BLB124, BLB199 and BLB506) among five. The second was the early degradation of Cry toxins by proteases in larvae midgut mainly due to some amino acids substitutions evidenced in Cry4Ba and Cryl1Aa delta-endotoxins detected in BLB356. Before biological treatment based on B. thuringiensis israelensis, the studies of microflore in each ecosystem have a great importance to succeed pest management programs. specialized Bacillus thuringiensis israelensis Aedes aegypti cry genes content Proteolysis 052 084 176 48-54 2015 0944-5013 https://www.documentation.ird.fr/hor/fdi:010064777 10.1016/j.micres.2015.04.007 0944-5013 [F B010064777] https://www.documentation.ird.fr/hor/fdi:010064777 https://www.documentation.ird.fr/intranet/publi/2015/07/010064777.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2015-07-29 2017-08-23 fdi:010064777 fre