Department of Ecosystem Science and Management, University of Wyoming, Laramie, WY 82071, USA
Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, OH 43210, USA.
J Exp Biol. 2020 Jun 11;223(Pt 11):jeb218271. doi: 10.1242/jeb.218271.
Diet may be a significant determinant of insect gut microbiome composition. However, the extent to which dietary shifts shape both the composition and relevant functions of insect gut microbiomes, and ultimately impact host energy balance (i.e. metabolic phenotype), is not well understood. We investigated the impacts of diet switching on females maintained on a dog food (DF) diet relative to those fed a comparatively sub-optimal cellulose-amended dog food (CADF) diet for 4 weeks. After this period, dietary shift resulted in a significantly higher average mass-specific standard metabolic rate (SMR) in CADF-fed females compared with DF-fed females. We also uncovered significant C-enrichment in DF-fed insect samples relative to CADF-fed insect samples and lowered bacterial essential amino acid (EAA) provisioning in CADF-fed samples. Differences in SMR and EAA provisioning were not accompanied by significant differences in overall microbiome composition between the two groups. However, cellulolytic and nitrogen-fixing bacterial families dominant in wild omnivorous cockroaches and wood-feeding termites were significantly enriched in CADF-fed females than in DF-fed females, at the end of the study. We propose that these changes in microbiome composition after dietary shifts are associated with changes in EAA provisioning and possibly SMR. Further studies are needed to comprehensively understand the relative importance of gut microbial functions among the complexity of factors known to underscore SMR responses in insects under varying dietary conditions.
饮食可能是昆虫肠道微生物组组成的重要决定因素。然而，饮食变化在多大程度上塑造了昆虫肠道微生物组的组成和相关功能，并最终影响宿主的能量平衡（即代谢表型），目前还不太清楚。我们研究了饮食转换对以狗粮（DF）为食的雌性昆虫与以相对较差的纤维素改良狗粮（CADF）为食的雌性昆虫的影响，持续时间为 4 周。经过这段时间，与以 DF 为食的雌性昆虫相比，以 CADF 为食的雌性昆虫的平均比质量标准代谢率（SMR）显著升高。我们还发现，与以 CADF 为食的昆虫样本相比，以 DF 为食的昆虫样本中的 C 含量显著增加，并且以 CADF 为食的样本中的细菌必需氨基酸（EAA）供应减少。SMR 和 EAA 供应的差异并没有伴随着两组之间微生物组总体组成的显著差异。然而，在研究结束时，在以 CADF 为食的雌性昆虫中，纤维素分解菌和固氮菌科的丰度显著高于以 DF 为食的雌性昆虫，这些菌科在野生杂食性蟑螂和木质素食性白蚁中占主导地位。我们提出，这些饮食变化后微生物组组成的变化与 EAA 供应的变化有关，可能与 SMR 有关。需要进一步的研究来全面了解在不同饮食条件下，昆虫 SMR 反应中已知的各种因素的复杂性下，肠道微生物功能的相对重要性。
