oa Biopesticide research and development: for safer agriculture, food and environment

In the frame of the protection of the environment that is continuously polluted by the massive use of chemical pesticides, we carried out a joint R&D project, on the development of biological pesticides using local bacterial strains isolated from Qatar and Tunisia. Microbial bioinsecticides were shown to be an efficient tool to control plant pests as well as human disease vectors. The Bacillus thuringiensis elta-endotoxins are the most valuable bioinsecticides currently used in commercial agriculture, forest management and mosquito control. This Gram-positive, spore-forming bacterium produces parasporal crystals composed of insecticidal elta-endotoxins. They exhibit a high specificity of insecticidal toxicity towards lepidopteran, coleopteran and dipteran insect species.

From both Qatar and Tunisia, hundreds of strains of B. thuringiensis were isolated and studied and their bioinsecticides coding genes cry were cloned and characterized. Among the Tunisian strains, we evidenced the abundance of the kurstaki subspecies active on the lepidopteran olive tree pathogenic insect P. oleae, whereas from the Qatari soil samples, we found large heterogeneity among the isolated strains. Moreover Bti strains, used for the control of disease vector mosquitoes, were more abundant in the Qatari Bt strain collection than in the Tunisian one. On the other hand, very particular Qatari B. thuringiensis strains synthesizing particular crystals and harbouring different plasmid profiles and probably synthesizing novel insecticides were evidenced.

Besides the genetic and molecular investigations, the development of a fermentation process for B. thuringiensis bioinsecticides production was also carried out and allowed us to do the scale-up of the production of bioinsecticides in a 430 litre fermenter. Important quantities of biological and environmentally safe insecticides were produced and applied successfully in the field.