Occurrence, characterization and insecticidal activity ofBacillus thuringiensisstrains isolated from argan fields in Morocco

Abstract

Soils collected from five locations in the argan forest (an endemic plant) in Morocco were used to form the first collection of Bacillus thuringiensis (Bt) strains from this area (58 strains). Here we found that the argan forest is a major source of Bt, as 90.62% of the samples contained Bt strains. These strains produced mainly spherical or irregular crystals that in some cases remained adhered to the spore after cell lysis. There was no strain producing bipyramidal crystals, suggesting the absence of strains bearing crv1 genes. This was confirmed by PCR analysis using eight primer pairs that can potentially detect 13 different groups of cry and cyt genes. Strains containing cry7/8 were the most abundant (25.53%), followed by strains harbouring cry9A (14.89%), cry11 (8.51%) and cry4 (4.25%). The mixtures of spores and crystals as well as culture supernatants were assayed for toxicity towards Ceratitis capitata (Medfly), showing up to 30% mortality. Our findings suggest that the argan region is a suitable target for future and wider screening programmes looking for strains bearing toxins or combinations of them to develop more efficient Bt-based formulates.

Assessment of the Antimicrobial Activity and the Entomocidal Potential of Bacillus thuringiensis Isolates from Algeria

“…For example, the expression of cry4 , cry10 , or cry11 genes give rise to spherical shape crystals, and their respective proteins are known to be active against Diptera [73,74,75,76]. Crystals with a bipyramidal shape result from the accumulation of Cry1 or Cry9 proteins, which are active mainly against Lepidoptera [24,77,78].…”

Screening and identification of a Bacillus thuringiensis strain S1/4 with large and efficient insecticidal activities

“…For decades, the isolation and the characterization of B. thuringiensis strains has been carried out in order to discover broader host range strains and insecticidal proteins with greater insecticidal activities . During this study, several B. thuringiensis isolates were characterized according to the vip and cry gene contents as well as the evaluation of the supernatant and the crystalline inclusion toxicities to consider their development for the optimization of biological control programs.…”

Insecticidal activity of a Moroccan strain ofStreptomyces phaeochromogenesLD-37 on larvae, pupae and adults of the Mediterranean fruit fly,Ceratitis capitata(Diptera: Tephritidae)

“…Larvae were reared in clear plastic containers (20 × 14 × 7 cm 3 ) on a diet composed of wheat bran, sucrose, brewer's yeast, Nipagin, Nipasol, benzoic acid and water at a volumetric ratio of (25:7:3:1:1:1:62). A mixture of sucrose and Brewer's yeast (4:1) was used as adult food (Aboussaid et al ., 2011).…”