Sun Xiao, Small Gaston E, Zhou Xuan, Wang Donger, Li Hongwang, Liu Chunjiang
School of Agriculture and Biology and Research Centre for Low-Carbon Agriculture, Shanghai Jiao Tong University, Dongchuan Rd. 800, Shanghai 200240, China College of Agro-grassland Science, Nanjing Agricultural University, 1 Weigang Rd., Nanjing, 210095, China.
Department of Biology, University of St. Thomas, Saint Paul, MN 55105.
J Insect Sci. 2015 Apr 5;15(1). doi: 10.1093/jisesa/iev004. Print 2015.
Body size can be an important factor controlling consumer stoichiometry. In holometabolous insects, body size is typically associated with nutrient storage. Consumer stoichiometry is known to vary within species across a range of body sizes; however, the contribution of nutrient storage to this variation is not well understood. We used the fifth-instar larvae of the oak weevil (Coleoptera: Curculio davidi Fairmaire), which is characterized by a high capacity for nutrient storage, to investigate the effect of shifts in nutrient storage with body mass on variations in larva stoichiometry. Our results showed that weevil larvae with larger body mass had a lower carbon (C) content, reflecting decreases in the sequestration rate of C-rich lipids. Larger larvae had elevated concentrations of nitrogen (N), sulfur (S), and protein. The similar patterns of variation in elemental composition and macromolecule storage with body weight indicate that the shift in nutrient storage is the main factor causing the variation in larval stoichiometry with body weight. This finding was further supported by the low variation in residual larval biomass C, N, and S concentrations after lipid extraction. These results help decipher the physiological mechanism of stoichiometric regulation in growing organisms.
体型可能是控制消费者化学计量的一个重要因素。在全变态昆虫中，体型通常与营养储存相关。已知消费者化学计量在同一物种内会因体型范围不同而有所变化；然而，营养储存在这种变化中所起的作用尚未得到充分理解。我们利用橡实象甲（鞘翅目：大卫象甲）的五龄幼虫，其具有较高的营养储存能力，来研究营养储存随体重的变化对幼虫化学计量变化的影响。我们的结果表明，体重较大的象甲幼虫碳（C）含量较低，这反映了富含碳的脂质储存率的下降。较大的幼虫氮（N）、硫（S）和蛋白质浓度升高。元素组成和大分子储存随体重的相似变化模式表明，营养储存的变化是导致幼虫化学计量随体重变化的主要因素。脂质提取后幼虫剩余生物量中碳、氮和硫浓度的低变化进一步支持了这一发现。这些结果有助于解读生长生物中化学计量调节的生理机制。
