Stable Isotope Analysis of Lipid Allocation to Reproduction in Sarcophaga crassipalpis

1. Stable Isotope Analysis of Lipid Allocation to Reproduction in Sarcophaga crassipalpis Diana Jordan, Frank J. Wessels, and Daniel A. Hahn Entomology and Nematology Department, University of Florida, Gainesville, FL 32611 Methods Results • C4 (high 13C) and C3 (low 13C) plants have different isotopic profiles that are reflected in the 13C of higher level animals. Lipid Fractionation TLC plate showing fractionated lipids in clutch 2 egg and somatic tissues. Notice the large quantity of nonpolar lipids in egg tissues. Nonpolar Introduction Discussion C3 Low 13C MT • Preliminary data suggest that females increasingly use income resources to provision polar and neutral lipids to eggs and somatic growth/maintenance. • This indicates that S. crassipalpis females are primarily income breeders. • Determining how nutrient allocation changes over time is important for understanding the mechanisms underlying the plasticity of reproductive resource allocation. • Resources for reproduction and somatic growth/maintenance can be derived from two nutrient pools: larval capital or adult income. • Insect eggs are equally composed of lipids and proteins. • Yet protein has been the focus of the majority of reproductive resource allocation studies. • Resources can be labeled using dietary components with variations in stable isotope levels of 13C and 15N. Polar Egg Soma C4 High 13C FL Lipid 13CAnalysis C3 plant distribution increases as latitude increases. • S. crassipalpis adults and larvae feed on carrion and adults require a sugar source. • Income and capital were labeled using a combination Montana liver (low 13C) or Florida liver (high 13C), and beet sugar (low 13C) or cane sugar (high  13C). Future Directions • Run the remaining lipid samples to allow for complete statistical analysis and confirmation of trends. • This will provide the basis for further tradeoff studies, allowing for a detailed breakdown of lipid and bulk tradeoffs associated with reproduction. FL Cane Sugar Fig. 1. Preliminary data following capital and income allocation to polar lipids. or Acknowledgements MT Beet Sugar FL or MT Liver Overall Goal • Females were sampled immediately following eclosion, after the first clutch of eggs was fully provisioned, and after the second clutch. • Tissue lipids were fractionated into polar (storage / triglycerides) and nonpolar (membrane) components. • I thank Dr. Jason Curtis from the stable isotope lab at UF for his expertise running samples and advice in sample preparation. This research was funded by NSF-IOS-641505 and the FL State Agricultural Experiment Station. • Determine the allocation of capital and income resources to somatic tissue and egg tissue. Specifically I followed the allocation of larval and adult nutrients to neutral and polar lipids within these tissues. Fig. 2. Preliminary data following capital and income allocation to neutral lipids.