Bacillus thuringiensis is a Gram-positive, rod-shaped, and spore-forming microbial entomopathogen. The silverleaf whitefly, Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae), is a worldwide important cryptic species causing serious economic damage to several vegetable crops including tomato. The aim of this study was to characterize and evaluate the bio-insecticidal effects of locally isolated Bacillus thuringiensis (Bt) against Galleria mellonella and Bemisia tabaci. Thirty-one isolates of Bt were obtained from 70 soil samples based on cultural characterization coupled with insecticidal crystal protein detection. All of the 31 bacterial isolates were pre-screened for their bio-insecticidal property against the greater wax moth, Galleria mellonella L. larvae. Only 20 (64.5%) isolates were virulent to G. mellonella with a percentage mortality that ranged from 2.50 to 95%. The groEL gene sequences of all 20 entomopathogenic indigenous isolates displayed 99–100% similarity with Bt isolates. Bioassay evaluation of 12 selected isolates against 3rd to 4th nymphal instars of B. tabaci with spore-crystal suspensions of 1 × 109 spores/ml caused 0 to 31.25%, 0 to 57%, and 0 to 82.5% percentage mortality within 48, 96, and 144 h accordingly. Among isolates of Bt, isolate AAUDS-16 had the highest virulence, followed by the isolate AAUES-69D with LC50 values of 9.67 × 106 spores/ml and 1.16 × 107 spores/ml, respectively. The virulent isolates were tested for their growth response to a different temperature range between 15 and 40 °C. All isolates showed a maximum growth rate around 30 °C. Bt isolates of AAUES-69D and AAUDS-16 displayed high insecticidal potential against B. tabaci nymphs and G. mellonella larvae, and showed a maximum growth rate in a wide range of temperature. High virulence and temperature-tolerant isolates should be important candidates for diverse insecticidal toxin studies.

中文翻译：

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苏云金芽孢杆菌埃塞俄比亚分离株对梅勒埃勒菌（鳞翅目：Pyralidae）和番茄粉虱，烟粉虱（Bemisia tabaci（Genn。）（半翅目：Aleyrodidae）的埃塞俄比亚分离株的分离，表征和生物杀虫效率。

苏云金芽孢杆菌是革兰氏阳性，杆状，形成孢子的微生物昆虫病原体。银叶粉虱，烟粉虱（Bemisia tabaci，Genemi。）（半翅目：Aleyrodidae），是世界范围内重要的隐性物种，对包括番茄在内的几种蔬菜作物造成了严重的经济损失。这项研究的目的是表征和评估当地分离的苏云金芽孢杆菌（Bt）对马勒菌和烟粉虱的生物杀虫作用。基于文化表征和杀虫晶体蛋白检测，从70个土壤样品中获得了31株Bt菌株。对所有31种细菌分离株均进行了针对大蜡蛾幼虫Galleria mellonella L.的生物杀虫特性的预筛选。只有20个（64.5％）分离株对G具有毒性。病菌死亡率为2.50％至95％。所有20种有致病性的土著分离株的groEL基因序列与Bt分离株表现出99-100％的相似性。对烟粉虱第三至第四龄幼虫的12株分离菌株的生物测定评估，其孢子晶体悬浮液为1×109孢子/ ml，在48、96内可导致0至31.25％，0至57％和0至82.5％的死亡率，并相应地144小时。在Bt分离株中，分离株AAUDS-16的毒力最高，其次是AAUES-69D分离株，LC50值分别为9.67×106孢子/ ml和1.16×107孢子/ ml。测试了毒性分离株在15至40°C的不同温度范围内的生长反应。所有分离株均显示出30°C附近的最大生长速率。AAUES-69D和AAUDS-16的Bt分离株显示出对烟粉虱，甜菜蛾幼虫的高杀虫潜力，并在很宽的温度范围内显示出最大的生长速率。高毒力和耐高温的分离株应该成为各种杀虫毒素研究的重要候选对象。