- A Highly Pathogenic Strain of Bacillus thuringiensis serovar kurstaki in Lepidopteran Pests
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Hatice Kati , Kazim Sezen , Remziye Nalcacioglu , Zihni Demirbag
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J. Microbiol. 2007;45(6):553-557.
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DOI: https://doi.org/2609 [pii]
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 Abstract
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In order to detect and identify the most toxic Bacillus thuringiensis strains against pests, we isolated a B. thuringiensis strain (Bn1) from Balaninus nucum (Coleoptera: Curculionidae), the most damaging hazelnut pest. Bn1 was characterized via morphological, biochemical, and molecular techniques. The isolate was serotyped, and the results showed that Bn1 was the B. thuringiensis serovar, kurstaki (H3abc). The scanning electron microscopy indicated that Bn1 has crystals with cubic and bipyramidal shapes. The Polymerase Chain Reactions (PCRs) revealed the presence of the cry1 and cry2 genes. The presence of Cry1 and Cry2 proteins in the Bn1 isolate was confirmed via SDS-PAGE, at approximately 130 kDa and 65 kDa, respectively. The bioassays conducted to determine the insecticidal activity of the Bn1 isolate were conducted with four distinct insects, using spore-crystal mixtures. We noted that Bn1 has higher toxicity as compared with the standard B. thuringiensis subsp. kurstaki (HD-1). The highest observed mortality was 90% against Malacosoma neustria and Lymantria dispar larvae. Our results show that the B. thuringiensis isolate (Bn1) may prove valuable as a significant microbial control agent against lepidopteran pests.
- The First Study on Bacterial Flora and Biological Control Agent of Anoplus roboris (Sufr., Coleoptera)
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Ismail Demir , Kazim Sezen , Zihni Demirbag
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J. Microbiol. 2002;40(2):104-108.
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Abstract
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The hazelnut leaf holer (Anoplus roboris Sufr., Coleoptera: Curculionidae) is a devastating pest of hazelnut and oak trees. It causes approximately 20-30% economic damage to hazelnut production per year in Turkey. In the present study, in order to find a more effective and safe biological control agent against A. roboris, we investigated the bacterial flora of the hazelnut leave holer, and tested them for insecticidal effects on it. According to morphological, physiological and biochemical tests, bacterial flora were identified as Bacillus circulans (Ar1), Bacillus polymyxa (Ar2), Enterobacter sp. (Ar3) and Bacillus sphaericus (Ar4). Insecticidal effects of bacterial isolates were performed on adult A. roboris. The highest insecticidal effect determined was 67% by B. sphaericus within eight days. The insecticidal effects of the other isolates (Ar1, Ar2 and Ar3) were determined as 33%, 47% and 47% within the same period, respectively.
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