<i>Bacillus thuringiensis</i>isolates from soil and diseased insects in Egyptian cotton fields and their activity against lepidopterous insects

Sakr

Archives Of Phytopathology And Plant Protection

et al. 2012

This study aims to search for indigenous Bacillus thuringiensis (Bt) strains from the soils of different locations representing 11 Egyptian governorates. A total of 2671 colonies from 93 soil samples were examined. The total number of Bt positive soil samples was 40/93 i.e. 43.01%. The results indicate that the percentage of the occurrence of Bt in these samples was 3.818%. The Egyptian soil showed to be rich in Bt. The evaluation of the potential activity of 40 positive soil isolates against Spodoptera littoralis and Helicoverpa (¼Heliothis) armigera was carried out. Subsequently, LC 50 and LC 90 values and the potency of the Bt isolates were determined when applied against the target insects with reference to three standard preparations.

Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 87%

See 1 more Smart Citation

Bacillus thuringiensisisolates from Egyptian soils and their potential activity against lepidopterous insects

Sakr

Archives Of Phytopathology And Plant Protection

et al. 2012

Journal of Plant Protection Research

“…Due to indiscriminate and intensive use of insecticides in controlling this pest, the resistance of T. absoluta to these insecticides has frequently been reported (Salazar and Araya 1997;Siqueira et al 2000;Salazar and Araya 2001;Mahmoud et al 2015). Among various bio-rationale insecticides, B. thuringiensis, Beauveria bassiana, spinosad and azadirachtin are popularly used for controlling many insect pests (Merdan et al 2010;Salama et al 2012;AbdelRazek et al 2014;Abd El-Ghany et al 2015). This study evaluated the efficacy of different bio-rationale control agents, natural and chemical, for controlling this serious pest alone or even in IPM programs.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of some microbial agents, natural and chemical compounds for controlling tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

El-Ghany

Abdel-Razek

Ebadah

et al. 2016

Solanaceous plants have a great economic impact in Egypt. These groups of plants include potatoes, tomatoes and eggplants. The new invasive pest of tomatoes, Tuta absoluta (Meyrick) causes the greatest crop losses which can range from 60 to 100%.After its detection in Egypt during the last half of 2009, it spread quickly to all provinces in the country. We aiming to propose a sustainable control program for this devastating pest. In this research we tested three groups of control agents. The first was microbial and natural, the second -plant extracts and the third -chemical insecticides. Our results showed that the impact of T. absoluta can be greatly reduced by the use of sustainable control measures represented by different insecticide groups. Bioassay experiments showed that this devastating pest can be controlled with some compounds that give high mortality rates. Of these compounds, spinosad and Beauveria bassiana, microbial control agents, followed by azadirachtin, gave the best results in controlling T. absoluta. Of the chemical insecticides, lambda-cyhalotrin was the most effective, followed by lufenuron and profenofos. In conclusion we encourage farmers to use microbial and natural control measures in combating the tomato leafminer, T. absoluta, in Integrated Pest Mangement (IPM) programs.

Journal of Genetic Engineering and Biotechnology

“…[1], [2], [3], [4], [5], [6], [7], [8], [9]. [8], [10] studied the distribution of Bt in the soils of 22 governorates in Egypt searching for new indigenous isolates with potential activity against some lepidopterous insects.…”

Section: Introductionmentioning

confidence: 99%

Diversity of Bacillus thuringiensis isolates from Egyptian soils as shown by molecular characterization

Salama¹,

El-Ghany²,

Sakr³

2015

Different techniques were adopted for molecular characterization of several indigenous strains of Bacillus thuringiensis (Bt) previously isolated from Egyptian soil samples. These isolates show different toxicity levels against neonate larvae of both insect species; Spodoptera littoralis (Biosduval); and Helicoverpa armigera (Hübner). The parasporal crystals among the most potent isolates contained polypeptides of about 127 and 130 kDa. PCR screening for genes encoding different Cry genes was performed. The Cry 1 gene is the most abundant in these isolates (83.33%) among tested Cry-type genes, followed by Cry 1 gene subfamilies (Cry 1B and Cry 1C) with percentage of 38.88% and 77.77%, respectively. The tested isolates showed the presence of Cry 2A(a,b) gene, but not all of these isolates were positive for Cry 2 gene (55.55%). Only 27.77% and 16.66% of the tested isolates harbor Cry 4 and Cry 3 genes, respectively. All strains were negative in PCR assays for the Vip 3Aa1 gene. Moreover, DNA fingerprinting using RAPD-PCR was performed to detect the genetic similarities and dissimilarities among the different isolates and standard strains. Assessment of Bt diversity based on the combined analysis of their protein and RAPD-PCR banding patterns was performed. This study demonstrates that Bt strains isolated from Egyptian soil samples can be distinguished and identified on the basis of the distribution of Cry-type genes and RAPD fingerprints.