Symbiotic interactions between insects and bacteria have been associated with a vast variety of physiological, ecological and evolutionary consequences for the host. A wide range of bacterial communities have been found in association with the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), an important pest of cultivated fruit in most regions of the world. We evaluated the diversity of gut bacteria in B. dorsalis specimens from several populations in Kenya and investigated the roles of individual bacterial isolates in the development of axenic (germ-free) B. dorsalis fly lines and their responses to the entomopathogenic fungus, Metarhizium anisopliae. We sequenced 16S rRNA to evaluate microbiomes and coupled this with bacterial culturing. Bacterial isolates were mono-associated with axenic B. dorsalis embryos. The shortest embryonic development period was recorded in flies with an intact gut microbiome while the longest period was recorded in axenic fly lines. Similarly, larval development was shortest in flies with an intact gut microbiome, in addition to flies inoculated with Providencia alcalifaciens. Adult B. dorsalis flies emerging from embryos that had been mono-associated with a strain of Lactococcus lactis had decreased survival when challenged with a standard dosage of M. anisopliae ICIPE69 conidia. However, there were no differences in survival between the germ-free lines and flies with an intact microbiome. These findings will contribute to the selection of probiotics used in artificial diets for B. dorsalis rearing and the development of improved integrated pest management strategies based on entomopathogenic fungi.

中文翻译：

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接种肠道细菌对 Bactrocera dorsalis 发育及其对昆虫病原真菌绿僵菌易感性的影响

昆虫和细菌之间的共生相互作用与宿主的各种生理、生态和进化后果有关。已发现与东方果蝇 Bactrocera dorsalis (Hendel) (双翅目：实蝇科) 相关的多种细菌群落，这是世界大部分地区栽培水果的重要害虫。我们评估了来自肯尼亚几个种群的 B. dorsalis 标本中肠道细菌的多样性，并研究了单个细菌分离株在无菌（无细菌）B. dorsalis 飞线发育中的作用及其对昆虫病原真菌绿僵菌的反应. 我们对 16S rRNA 进行测序以评估微生物组并将其与细菌培养相结合。细菌分离株与无菌 B. dorsalis 胚胎单相关。在具有完整肠道微生物组的果蝇中记录的胚胎发育期最短，而在无菌果蝇系中记录的胚胎发育期最长。同样，除了接种了普罗维登斯氏菌的果蝇外，具有完整肠道微生物组的果蝇的幼虫发育最短。当用标准剂量的 M. anisopliae ICIPE69 分生孢子攻击时，从与乳酸乳球菌菌株单一相关的胚胎中出现的成年 B. dorsalis 苍蝇的存活率降低。然而，无菌品系和具有完整微生物组的果蝇之间的存活率没有差异。这些发现将有助于选择用于饲养 B. dorsalis 的人工饲料中的益生菌，以及基于昆虫病原真菌的改进的综合害虫管理策略的开发。