Caterpillars lack a resident gut microbiome
Caterpillars lack a resident gut microbiome
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DOI：
10.1073/pnas.1707186114
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发表时间：
2017-09-05
影响因子：
11.1
通讯作者：
Fierer, Noah
中科院分区：
文献类型：
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作者：
Hammer, Tobin J.;Janzen, Daniel H.;Fierer, Noah
许多动物都栖息着微生物共生体，这些共生体影响宿主的发育、生理、生态相互作用和进化多样化。然而，尽管这些昆虫种类繁多，是许多生态系统中的主要农业害虫和优势食草动物，但缺乏确凿的证据证明鳞翅目幼虫（毛毛虫）中常驻微生物组的存在和功能重要性。利用 16S rRNA 基因测序和定量 PCR，我们对美国和哥斯达黎加野生食叶毛虫的肠道微生物组进行了表征，这些毛毛虫代表 15 个科的 124 个物种。与使用相同方法检测的其他昆虫和脊椎动物相比，我们在毛毛虫肠道中检测到的微生物密度异常低，并且个体之间存在差异。此外，与叶子相关的微生物的丰度和组成也反映在食用相同植物的毛毛虫的粪便中。因此，与食物一起摄入的微生物存在于毛毛虫肠道中（尽管可能已死亡或处于休眠状态），但宿主特异性的常驻共生体基本上不存在。为了测试瞬时微生物是否仍然有助于摄食和发育，我们对现场收集的模型物种 Manduca sexta 毛毛虫进行了实验。抗生素对肠道细菌活性的抑制不会显着影响毛毛虫的体重增加、发育或存活。高 pH 值、简单的肠道结构和快速的运输时间是毛毛虫消化生理学的典型特征，可能会阻止微生物定植。此外，宿主编码的消化和解毒机制可能使毛虫食草不需要微生物。毛毛虫说明了独立于共生体的潜在生态和进化益处，这种生活方式可能在动物中普遍存在。
Many animals are inhabited by microbial symbionts that influence their hosts' development, physiology, ecological interactions, and evolutionary diversification. However, firm evidence for the existence and functional importance of resident microbiomes in larval Lepidoptera (caterpillars) is lacking, despite the fact that these insects are enormously diverse, major agricultural pests, and dominant herbivores in many ecosystems. Using 16S rRNA gene sequencing and quantitative PCR, we characterized the gut microbiomes of wild leaf-feeding caterpillars in the United States and Costa Rica, representing 124 species from 15 families. Compared with other insects and vertebrates assayed using the same methods, the microbes that we detected in caterpillar guts were unusually low-density and variable among individuals. Furthermore, the abundance and composition of leaf-associated microbes were reflected in the feces of caterpillars consuming the same plants. Thus, microbes ingested with food are present (although possibly dead or dormant) in the caterpillar gut, but host-specific, resident symbionts are largely absent. To test whether transient microbes might still contribute to feeding and development, we conducted an experiment on field-collected caterpillars of the model species Manduca sexta. Antibiotic suppression of gut bacterial activity did not significantly affect caterpillar weight gain, development, or survival. The high pH, simple gut structure, and fast transit times that typify caterpillar digestive physiology may prevent microbial colonization. Moreover, host-encoded digestive and detoxification mechanisms likely render microbes unnecessary for caterpillar herbivory. Caterpillars illustrate the potential ecological and evolutionary benefits of independence from symbionts, a lifestyle that may be widespread among animals.