Non-invasive lipid measurement in living insects using NMR microscopy

Abstract

SUMMARYNuclear magnetic resonance (NMR) microscopy allows us to image and quantify the distribution of NMR-active nuclei in living specimens. Using high-field NMR microscopy at a magnetic field strength of 14.1T and strong gradients up to 3Tm -1 , we show that separation of fat and water nuclear resonances in living insects can be achieved. In contrast to destructive conventional photometric and mass measurements, we demonstrate exemplarily in the European spruce bark beetle that NMR can be efficiently used to quantify absolute fat and water content in living insects. Additionally, anatomic images with a spatial in-plane resolution up to 10m and with high soft tissue contrast were acquired. We demonstrate that fat distribution and fat consumption of living insects can be obtained by magnetic resonance imaging (MRI). This enables future research to address questions where single individuals have to be measured several times, which is not possible with conventional destructive methods. Supplementary material available online at

Factors influencing dispersal by flight in bark beetles (Coleoptera: Curculionidae: Scolytinae): from genes to landscapes

“…Lipids are required for host colonization behaviours in Ips pini (Gast et al 1993;Wallin and Raffa 2000), but there is mixed evidence to support a correlation between lipid content and flight capacity in Ips studied to date. The relative lipid content of I. sexdentatus and I. typographus is not correlated with flight duration (Jactel 1993;Zolubas and Byers 1995;Schilling et al 2012). Ips sexdentatus beetles that fly, however, have significantly higher lipid content than non-flyers.…”

“…Proline is generated in the fat body from fatty acids and is transported to muscles via the protein-alanine shuttle system (Candy et al 1997). In I. typographus, proline content decreases rapidly with flight (Schilling et al 2012). After only 10 min of flight, proline levels decline by 66% compared with levels in unflown beetles, which suggests that proline is an important energy source for flight initiation in this species (Schilling et al 2012).…”

“…In addition, there is a positive correlation between lipid content and longdistance flight in I. sexdentatus (Jactel 1993). In I. typographus, lipids are consumed during long-distance flight; however, lipid metabolism is disproportionately low (Schilling et al 2012), suggesting that other energy sources may be used in addition to lipids to power flight in Ips species. Re-emergence from the reproductive host for a second flight period is related to lipid content in I. typographus (Zolubas and Byers 1995).…”

How and When Do Insects Rely on Endogenous Protein and Lipid Resources during Lethal Bouts of Starvation? A New Application for 13C-Breath testing

“…This limitation is confounded with the fact that VCO 2 can usually be measured in insects with greater accuracy than VO 2 [ 31 ]. Other non-invasive approaches like NMR microscopy can be used to quantify changes in the fat and water content in small insects over time and therefore may be used to estimate lipid oxidation [ 32 ]; but the method is not suitable for tracking changes in protein use or for making measurements in large numbers of individuals. Quantitative magnetic resonance (QMR) has been shown to be suitable for accurate measures of lean mass in large insects [ 33 ], but it is not suitable for quantifying the lipid content in their bodies.…”

Survivability and post‐diapause fitness in a scolytid beetle as a function of overwintering developmental stage and the implications for population dynamics

“…Therefore, beetles were cut between head, thorax and abdomen, and acylglycerols were extracted from the dissected beetles in chloroform. Lipids were measured colorimetrically as acylester equivalents, as described in Schilling et al ().…”