The African Migratory Locust, Locusta migratoria migratorioides (Reiche & Fairmaire, 1849) (Orthoptera: Acrididae), is a major threat to agricultural crops and food security on a worldwide scale; hence, maintaining control over it is crucial. Photorhabdus luminescens bacteria can accomplish the efficient biocontrol agent criteria. As a result, the aim of this study was to assess the efficacy of the P. luminescens (EGAP3) strain and its cell-free filtrate against L. migratoria migratorioides, as well as to investigate changes in the activity of carbohydrates hydrolyzing enzymes, amylase, invertase, and trehalase in whole-body homogenates of the 5th nymphal instar under laboratory conditions and to investigate the histopathological changes in the midgut of the locust. The virulence of entomopathogenic bacteria was determined at different densities of 4 × 107, 4 × 106, 4 × 105, and 4 × 104 colony-forming units (CFU)/ml at different exposure times as well as different concentrations of its cell-free filtrate, undiluted cell-free filtrate (100, 50, 25, and 12.5%). The results indicated that higher-density cell suspension up to 4 × 107 cells.ml−1 and undiluted cell-free filtrate (100%) were the most effective insecticidal fluids, reaching up to 76.7 and 80%, respectively, after 7 days. The estimated LC50 value was 2.7 × 106 cells.ml−1 for bacteria, and the estimated LC50 value for cell-free filtrate was the 2nd dilution (50%). The data clarified the toxicological and histopathological effects and carbohydrate hydrolyzing enzyme activities of the host insect L. migratoria migratorioides, following bacteria and cell-free filtrate infection; that provides an overview of the efficiency of bacteria and their cell-free filtrate on the host. In conclusion, P. luminescens (EGAP3) and its toxins can be an optimal option for bio-controlling of L. migratoria migratorioides.

中文翻译：

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昆虫病原细菌 Photorhabdus luminescens 作为对抗非洲迁徙蝗虫 Locusta migratoria migratorioides (Reiche & Fairmaire, 1849) 的天敌（直翅目：蝗科）

非洲迁徙蝗虫 Locusta migratoria migratorioides (Reiche & Fairmaire, 1849)（直翅目：蝗科）是全球范围内对农作物和粮食安全的主要威胁；因此，保持对它的控制至关重要。Photorhabdus luminescens 细菌可以达到有效的生物防治剂标准。因此，本研究的目的是评估 P. luminescens (EGAP3) 菌株及其无细胞滤液对 L. migratoria migratorioides 的功效，以及研究碳水化合物水解酶、淀粉酶活性的变化、蔗糖酶和海藻糖酶在实验室条件下对 5 龄若虫全身匀浆进行研究，并研究蝗虫中肠的组织病理学变化。昆虫病原菌的毒力在不同的暴露时间和不同浓度的无细胞培养基中分别测定 4 × 107、4 × 106、4 × 105 和 4 × 104 菌落形成单位 (CFU)/ml。滤液，未稀释的无细胞滤液（100、50、25 和 12.5%）。结果表明，高达 4 × 107 个细胞.ml-1 的高密度细胞悬浮液和未稀释的无细胞滤液 (100%) 是最有效的杀虫液，7 天后分别达到 76.7% 和 80%。细菌的估计 LC50 值为 2.7 × 106 个细胞.ml-1，无细胞滤液的估计 LC50 值为第二次稀释 (50%)。数据阐明了寄主昆虫 L. migratoria migratorioides 的毒理学和组织病理学效应以及碳水化合物水解酶活性，细菌和无细胞滤液感染后；这提供了细菌及其无细胞滤液对宿主的效率的概述。综上所述，P. luminescens (EGAP3) 及其毒素可作为 L. migratoria migratorioides 生物防治的最佳选择。