isolates have been isolated from the collected samples (Salehi Jouzani et al. 2008b).
Most of the Bt isolates were from the humid region of Iran, particularly the Caspian
zone, and fewer isolates were found in the dry and the semidry zones. The Bt
distribution based on the plant flora showed that the largest number of Bt isolates
was collected from cotton and sunflower fields. In 2010, samples were collected
from the forest, grassland, and agricultural field soils, stored products, and insect
cadavers in West Azerbaijan province. Out of 740 samples, 48 Bt strains were
isolated (Aramideh et al. 2010). These isolates were characterized based on the
morphology of crystal proteins, the biochemical types (aesculin utilization, lecithinase production and acid formation from salicin and sucrose), and the insecticidal
activity against Pieris brassica (Lep.: Pieridae) and Culex pipiens. This study
introduced the potent Iranian Bt strains for controlling P. brassica and C. pipiens.
In another screening, the natural occurrence of Bt strains in apple orchards was
investigated collecting 180 soil samples from apple orchards in West Azerbaijan
Province (Iran) (Senfi et al. 2012). Based on the sodium acetate selective method and
the observation of parasporal crystals in bacterial cells, 40 Bt isolates were isolated
and characterized. Investigations on the crystal morphology and insecticidal activity
of Bt strains against E. kuehniella and P. brassicae showed that the majority of Bt
strains produced bipyramidal crystals and a few had toxicity greater than
B. thuringiensis subsp. kurstaki (Senfi et al. 2012). The isolation of Bt from infected
larvae has resulted in the discovery of highly potent local Bt strains. A new
B. thuringiensis subsp. aizawai strain EF495116 isolated from an infected Plodia
interpunctella (Lep.: Pyralidae) larva was thoroughly characterized based on serological identification, protein pattern, PCR-based analysis, sequencing of 16S rDNA
and gyrB genes, and insecticidal activity against P. interpunctella and Plutella
xylostella (Shojaaddini et al. 2012). Bt strain EF495116 was the cause of several
epizootic outbreaks in the insect colonies, P. interpunctella and E. kuehniella, reared
at Tabriz University, Iran. Different cry genes and virulence factors, namely cry1Aa,
cry1Ab, cry1Ac, cry1Ad, cry1B, cry1C, cry1D, cry1E, cry1F, cry1I, cry2A, cry9,
cry39, cry40, plcR, chit, vip1, vip2, vip3, and inhA2 were traced in this Bt strain
using general and specific primers. P. interpunctella and P. xylostella were found to
be highly susceptible to Bt strain EF495116 in laboratory bioassays. This suggests
that this strain has great potential to be used as an active ingredient in a
bio-insecticide (Shojaaddini et al. 2012).
By focusing on a specific ecological niche, a total of 37 Bt strains were isolated
from dead and infected Helicoverpa armigera Hüber (Lep.: Noctuidae) larvae in the
cotton fields without a history of Bt application in Khorasan Razavi province, Iran
(Keshavarzi 2008; Khojand et al. 2013). A high infestation rate of H. armigera and
also considerable biodiversity of Bt strains in the cotton field were found (Khojand
et al. 2013). A total of 100 soil samples from seven provinces, Guilan, Tehran,
Isfahan, Yazd, Kerman, Fars, and Hormozgan, in Iran were collected and 60 Bt
strains were isolated from these samples (Moazamian et al. 2016). The Bt isolates
were characterized based on the crystal morphology of parasporal crystals, biochemical experiments, and SDS-PAGE analysis. The majority of Bt strains produced
10 Progress on the Bacterium Bacillus thuringiensis and Its. . .
409
Most of the Bt isolates were from the humid region of Iran, particularly the Caspian
zone, and fewer isolates were found in the dry and the semidry zones. The Bt
distribution based on the plant flora showed that the largest number of Bt isolates
was collected from cotton and sunflower fields. In 2010, samples were collected
from the forest, grassland, and agricultural field soils, stored products, and insect
cadavers in West Azerbaijan province. Out of 740 samples, 48 Bt strains were
isolated (Aramideh et al. 2010). These isolates were characterized based on the
morphology of crystal proteins, the biochemical types (aesculin utilization, lecithinase production and acid formation from salicin and sucrose), and the insecticidal
activity against Pieris brassica (Lep.: Pieridae) and Culex pipiens. This study
introduced the potent Iranian Bt strains for controlling P. brassica and C. pipiens.
In another screening, the natural occurrence of Bt strains in apple orchards was
investigated collecting 180 soil samples from apple orchards in West Azerbaijan
Province (Iran) (Senfi et al. 2012). Based on the sodium acetate selective method and
the observation of parasporal crystals in bacterial cells, 40 Bt isolates were isolated
and characterized. Investigations on the crystal morphology and insecticidal activity
of Bt strains against E. kuehniella and P. brassicae showed that the majority of Bt
strains produced bipyramidal crystals and a few had toxicity greater than
B. thuringiensis subsp. kurstaki (Senfi et al. 2012). The isolation of Bt from infected
larvae has resulted in the discovery of highly potent local Bt strains. A new
B. thuringiensis subsp. aizawai strain EF495116 isolated from an infected Plodia
interpunctella (Lep.: Pyralidae) larva was thoroughly characterized based on serological identification, protein pattern, PCR-based analysis, sequencing of 16S rDNA
and gyrB genes, and insecticidal activity against P. interpunctella and Plutella
xylostella (Shojaaddini et al. 2012). Bt strain EF495116 was the cause of several
epizootic outbreaks in the insect colonies, P. interpunctella and E. kuehniella, reared
at Tabriz University, Iran. Different cry genes and virulence factors, namely cry1Aa,
cry1Ab, cry1Ac, cry1Ad, cry1B, cry1C, cry1D, cry1E, cry1F, cry1I, cry2A, cry9,
cry39, cry40, plcR, chit, vip1, vip2, vip3, and inhA2 were traced in this Bt strain
using general and specific primers. P. interpunctella and P. xylostella were found to
be highly susceptible to Bt strain EF495116 in laboratory bioassays. This suggests
that this strain has great potential to be used as an active ingredient in a
bio-insecticide (Shojaaddini et al. 2012).
By focusing on a specific ecological niche, a total of 37 Bt strains were isolated
from dead and infected Helicoverpa armigera Hüber (Lep.: Noctuidae) larvae in the
cotton fields without a history of Bt application in Khorasan Razavi province, Iran
(Keshavarzi 2008; Khojand et al. 2013). A high infestation rate of H. armigera and
also considerable biodiversity of Bt strains in the cotton field were found (Khojand
et al. 2013). A total of 100 soil samples from seven provinces, Guilan, Tehran,
Isfahan, Yazd, Kerman, Fars, and Hormozgan, in Iran were collected and 60 Bt
strains were isolated from these samples (Moazamian et al. 2016). The Bt isolates
were characterized based on the crystal morphology of parasporal crystals, biochemical experiments, and SDS-PAGE analysis. The majority of Bt strains produced
10 Progress on the Bacterium Bacillus thuringiensis and Its. . .
409