Abstract

Purpose

Combining gamma irradiation and nanotechnology has become one of the most promising new approaches for area-wide (AW) pest management in recent years. The laboratory trials were conducted to determine the combining effects of BT-AgNPs and gamma irradiation for controlling P. gossypiella. Radio-sensitivity of male pupae at different doses of gamma radiation and the effectiveness of biosynthesized silver nanoparticles using Bacillus thuringiensis on larval instar were assayed. Additionally, the ultrastructure changes on the alimentary canal of 4^th instar larvae were studied to evaluate the impact of the combined approach at a cellular level.

Materials and methods

Laboratory- rearing technique was used for rearing Pectinophora gossypiella. The irradiation process was achieved at Co⁶⁰ - Gamma Chamber (4000 A). Alanine dosimeters were used for measuring the average absorbed dose and dose mapping. Preparation of Silver nanoparticles (AgNPs) using Bacillus thuringiensis (Bt) and their characterization has been investigated. The treated 4^th instar larvae by gamma irradiation or ∕and BT-AgNPs were dissected under the stereo microscope. The alimentary canal was obtained anatomically and Transmission Electron Microscope) was used in examining the stained sections.

Results

Based on the nonhatching eggs produced by irradiated males’ pupae, the values of effective doses were calculated. The effective doses ranged from 16 to 291 Gy for the ED₂₅ - ED₇₅. The sterility index reached 74.1% when irradiated with males by 291 Gy crossed with nonirradiated females and the adult emergence decreased to be 35.3%. The insecticidal potential of Bt-AgNPs on the 2^nd and 4^th larval instars was dose-dependent and its LC₅₀ toxicity value was 0. 3 and 0. 4 mg/ml, respectively. The lethal concentration LC₅₀ of the 2^nd instar larvae increased the larval and pupal mortality to 55% and 44.4%, respectively, and reduced the adult emergence to be 55.6%. The combining effects of Bt-AgNPs with 291 Gy induced 100% pupae mortality and there was no adult emergence in F1 generation. Such effects also severed the ultrastructure deformity of the midgut of the 4^th instar larvae after the two-day post-treatment.

Conclusions

The combining effects are recommended as an effective IPM program to control P. gossypiella by releasing sterile males (derived from pupae irradiated with 291 Gy) crossing with the normal females in the field, and reducing the fertility of the population to 31.2%. Subsequently, the resulted larvae treated with LC₅₀ of Bt-AgNPs prevented the adult emergence and stopped the life cycle of P. gossypiella.

中文翻译：

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使用苏云金芽孢杆菌和伽马射线照射组合生物合成的银纳米颗粒来控制棉果果蝇（鳞翅目：Gelechiidae）的评估

 抽象的

 目的

近年来，伽马射线照射和纳米技术的结合已成为最有前途的大面积（AW）害虫治理新方法之一。进行实验室试验以确定BT -AgNP 和伽马射线照射对控制棉麻蝇的联合作用。测定了雄性蛹在不同剂量伽马辐射下的放射敏感性以及使用苏云金芽孢杆菌生物合成的银纳米颗粒对幼虫龄的有效性。此外，还研究了⁴龄幼虫消化道的超微结构变化，以评估组合方法在细胞水平上的影响。

 材料和方法

棉果皮菌的饲养采用实验室饲养技术。辐照过程是在 Co ⁶⁰ - 伽玛室 (4000 A) 中实现的。丙氨酸剂量计用于测量平均吸收剂量和剂量图。研究了使用苏云金芽孢杆菌( Bt)制备银纳米颗粒 (AgNP) 及其表征。将经γ射线照射或∕和BT -AgNPs处理的4^龄幼虫在体视显微镜下解剖。从解剖学上获得消化道并使用透射电子显微镜检查染色切片。

 结果

根据受辐射的雄性蛹产生的未孵化卵，计算有效剂量值。 ED ₂₅ - ED ₇₅的有效剂量范围为16 至291 Gy。经291 Gy辐照的雄性与未辐照的雌性杂交，不育指数达到74.1%，成虫羽化率下降至35.3%。 Bt -AgNPs对2^龄和4^龄幼虫的杀虫潜力呈剂量依赖性，其LC ₅₀毒性值分别为0. 3和0. 4 mg/ml。 2^龄幼虫的致死浓度LC ₅₀使幼虫和蛹死亡率分别增加至55%和44.4%，并使成虫羽化率降低至55.6%。 Bt -AgNPs 与 291 Gy 的联合作用诱导了 100% 的蛹死亡率，并且 F1 代中没有成虫羽化。这种作用还消除了治疗两天后4^龄幼虫中肠的超微结构畸形。

 结论

推荐将组合效应作为有效的 IPM 方案，通过释放不育雄性（来自接受 291 Gy 辐照的蛹）与田间正常雌性杂交，并将种群的生育力降低至 31.2%，来控制棉蝇。随后，用 LC ₅₀的Bt- AgNP 处理得到的幼虫阻止了成虫的羽化并终止了棉蝇的生命周期。