Bacillus thuringiensis strains isolated from Qatari soil, synthesizing δ-endotoxins highly active against the disease vector insect Aedes aegypti Bora Bora

Abstract

Bacillus thuringiensis (Bt) is a Gram-positive soil bacterium that has been recognized as an effective bioinsecticide active against plant, animal and human pathogenic and disease vector insects. During its sporulation phase, Bt produces crystals consisting of δ-endotoxins, which upon ingestion kill specifically insect larvae. Bt subsp. israelensis (Bti) is very active against dipteran insects. Bti based bioinsecticides are considered as a sustainable solution to control the Dipteran insects responsible of plant, animal and human diseases. In this study, Bti strains isolated from Qatar soil were analyzed for their insecticidal activities against the dipteran insect Aedes aegypti Bora Bora (Culicidae, Diptera) and for their δ-endotoxins yields per cell. Among the local Bti strains, four exceptional strains producing spherical crystals, were found to be more insecticidal than the reference strain Bti H14. When tested for their δ-endotoxin yield, the Bti QBT217 strain, producing typical spherical crystals and having the best insecticidal activity, was recognized as the best candidate strain for potential bioinsecticide production and biological control of dipteran insects, particularly the disease vector insect A. aegypti.

New native Bacillus thuringiensis strains induce high insecticidal action against Culex pipiens pallens larvae and adults

“…Preparation of spore-crystal mixture from local B. thuringiensis isolates exhibited larvicidal activity. Several preparations of spore-crystal mixture from B. thuringiensis strains with good mosquitocidal activity have been isolated from various parts of the world [ 19 , 62 , 71 , 72 ]. Among the preparation of spore-crystal mixture from B. thuringiensis isolates with significantly enhanced larvicidal activity identified in this study, the preparation with isolate A4 was the most toxic with bioactivity against C. pipiens pallens larvae (LC 50 : 1.4 ± 0.5 µg/ml and LC 95 : 15.3 ± 4.4 µg/ml; 5.1 × 10 7 CFU/µg per mg powder).…”

Evaluation of Roholtiella sp. Extract on Bell Pepper (Capsicum annuum L.) Yield and Quality in a Hydroponic Greenhouse System

“…However, their potential adverse effects on the environment coupled with a decrease in their efficiency after excessive and continuous applications have necessitated the need to restrict or drastically limit the use of chemical fertilizers and inorganic nutrients to come up with better, sustainable, and eco-friendly alternatives. Thus, organic fertilizers and eco-friendly practices for crop production and management, including fertigation and pest control, are the best options (Nair et al, 2020 ; Shah et al, 2021 ). The blue-green algae (BGA), i.e., cyanobacteria, form essential constituents of the soil microflora that increase soil nutrient composition and productivity either directly or indirectly (Vaishampayan et al, 2001 ; Mishra and Pabbi, 2004 ; Shariatmadari et al, 2015 ).…”

Larval survey of the dengue-endemic area in Samarinda: guide to determine risk containers

“…Currently, a vaccine advanced with an attenuated stay virus, the chimeric yellow fever 17Dtetravalent dengue vaccine (CYD-TDV), has been certified for scientific use in numerous countries, and plenty of vaccine applicants are nonetheless below studies and development [7]. Consequently, the disease control is more focused on the vector by reducing the density of mosquito populations around settlement areas through several ways: reduction or protection of potential breeding habitats [8], the use of natural predators such as larvae, fish, and copepods [9], or entomopathogenic bacteria (Bacillus thuringiensis) [10], and chemical control with insecticides for larvae and adult mosquitoes [11]. Sidodadi and Dadimulya villages are included in the working area of the Segiri Public Health Center, Samarinda Ulu District, Samarinda City.…”