High resolution 1H NMR spectroscopic studies of the composition of the haemolymph of crowd- and solitary-reared nymphs of the desert locust, Schistocerca gregaria

High resolution 1H NMR spectroscopy provided a rapid and non-invasive means of establishing a multicomponent profile of the low molecular weight organic metabolites present in the haemolymph of crowd-reared and solitary-reared desert locusts. Assignments of the 1H NMR resonances detected in the one-dimensional (1D) spectra were supported by the comparison of chemical shifts with those of commonly found metabolites, the application of 2D NMR spectroscopy, and spiking of authentic standards into the sample. The haemolymph metabolite profile was found to comprise trehalose, a series of amino acids, organic acids, lipids, ethanol and the polyamine putrescine. In total, it was possible to detect simultaneously and potentially quantify over 20 endogenous compounds. An interesting difference between the phases was the higher putrescine concentrations present in solitary-reared nymphs, which may indicate a role of this compound in phase determination. In addition, differences in the concentrations of trehalose, lipids, acetate and ethanol were also observed between solitary-reared and gregarious-reared nymphs enabling the ready differentiation of the two phases based on the NMR spectra of the haemolymph.