Characterization and selection of Bacillus thuringiensis isolates effective against Sitophilus oryzae

Abstract

The entomopathogenic bacterium Bacillus thuringiensis is a control agent with toxic and environmental characteristics that allows the control of pest insects according to the Integrate Pest Management (IPM) precepts. In order to find new strains, potentially toxic to Sitophilus oryzae L. 1763 (Coleoptera: Curculinidae), 1.073 strains of B. thuringiensis from parts of Brazil were used. Genetic material was extracted with InstaGene Matrix kit, used for the amplification of sequences in Polymerase chain reaction (PCR), and viewed in 1.5% agarose gel. The gene cry35Ba class was represented by 60 B. thuringiensis isolates (5.6%), which were then subjected to bioassays with S. oryzae larvae. Among the isolates studied, four caused more than 50% mortality in pathogenicity tests, and the isolates 544 and 622 were the most virulent, as determined by CL 50 estimates. The four toxic isolates had spherical, bi-pyramidal and cuboid crystals, and a 44-kDa protein was found in sodium dodecyl sulphate -polyacrylamide gel electrophoresis (SDS-PAGE), which coded for the product of cry35Ba genes. These data demonstrate the potential of B. thuringiensis for the management of S. oryzae larvae.

Isolation, identification and evaluation of mosquito entomopathogenic Bacillus species and related genera from randomly selected sites in Kenya

“…This low occurrence rate of mosquitocidal strains in soil was comparable with other reported results (Lukenge et al, 2017;Pereira et al, 2013) and this shows that mosquitocidal strains are rare to find as compared to other toxic strains against members of orders coleoptera and lepidoptera (Silva et al, 2012;Silva et al, 2010).…”

An entomopathogenic bacterium strain,Bacillus thuringiensis, as a biological control agent against the red palm weevil,Rhynchophorus ferrugineus(Coleoptera: Curculionidae)

“…Consolo et al reported that B. thuringiensis obtained from haemolymph of Cyclocephala signaticollis larvae was capable of causing 100% mortality 4 d after hemocoel injection and had an LC 50 of 3.3 × 10 5 cells mL −1 . Silva et al , demonstrating the potential of four screened B. thuringiensis strains, Bt ‐544, Bt ‐573, Bt ‐622 and Bt ‐629, for managing Sitophilus oryzae larvae, stated that the strains could reach or exceed 50% mortality, with an LC 50 of 4.7 × 10 3 spores mL −1 , 3.55 × 10 3 spores mL −1 , 9.14 × 10 3 spores mL −1 and 7.03 × 10 3 spores mL −1 , respectively . In a model organism, Tribolium castaneum , the LC 50 of different B. thuringiensis strains varied from 0.903 g g −1 to 1.413 g g −1 within 5 d of infection .…”

A Study on A LocalBacillus thuringiensis SP7 To Control Mosquito Larvae of Aedes aegypti

“…SP7 isolate has spherical crystal protein form, SP15 from observation shows spherical crystal protein form. Other observation showed crystal proteins of spherical shape 15,16,17 . …”