Pathogenicity of indigenous soil isolate of Bacillus thuringiensis to Helicoverpa armigera Hubner 1809 (Lepidoptera: Noctuidae)

文献类型： 外文期刊

第一作者： Ma, Chun-Sen

作者： Ma, Chun-Sen;Majeed, Muhammad Zeeshan;Riaz, Muhammad Asam;Khan, Muneeba Arif;Ahmad, Salman;Riaz, Muhammad Asam

作者机构：

关键词： Bacillus thuringiensis; Microbial insecticides; Helicoverpa armigera; Toxicity evaluation

期刊名称：EGYPTIAN JOURNAL OF BIOLOGICAL PEST CONTROL （ 影响因子：1.995； 五年影响因子：1.115 ）

ISSN： 1110-1768

年卷期： 2018 年 28 卷

页码：

收录情况： SCI

摘要： This study evaluated the pathogenicity of indigenous soil isolate of Bacillus thuringiensis (Bt) strains, applied without and along with 1.0% MgCl2 salt, to Helicoverpa armigera Hubner (Lepidoptera: Noctuidae). Toxicity and effect of Bt isolate on larval development (weight) were assessed using in vitro bioassays. Six concentrations of the tested Bt with salt (i.e., 1.0 x 10(7), 0.5 x 10(5), 1.0 x 10(5), 1.5 x 10(5), and 2.0 x 10(5) cfu/ml), five without salt (i.e., 0.5 x 10(5), 1.0 x 10(5), 1.5 x 10(5), and 2.0 x 10(5) cfu/ml), and control were bioassayed against third-instar larvae of H. armigera under a complete randomized design (CRD), with four replications. Results revealed that both larval mortality and weight changes were significantly affected by time (F-5,F- 19 = 35.98; P < 0.001 and F-5,F- 19 = 11.01; P < 0.001, respectively) and treatments (F-5, (19) = 27.45; P < 0.001 and F-5,F- 19 = 25.07; P < 0.001). The highest larval mortality (91.1%) was exhibited by the highest concentration (1.0 x 10(7) cfu/ml), followed by 2.0 x 105 cfu/ml concentration, without salt (88.9%) and with salt (66.7%). Median lethal concentration (LC50) values of isolated Bt strain were 1.7 and 1.27 x 10(5) cfu/ml, without salt, and 1.80 and 1.13 x 10(5) cfu/ml, with salt, at 96 and 120 h, respectively. Regarding the impact of Bt isolate on larval development, treatment with the highest concentration (1.0 x 10(7) cfu/ml) had the most significant and negative impact on larval weight change (R-2 = 0.53), followed by 2.0 x 10(5) cfu/ml Bt concentration (R-2 = 0.40). There was no obvious synergistic or additive effect, but rather an inhibition was observed on the pathogenicity potential or larvicidal effect of Bt isolate.

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