First 'zap the crap', now 'Fry the fly': REIMS for insect identification

Iris Wagner, Natalie I. Koch, Joscelyn Sarsby, Nicola White, Tom A. R. Price, Sam Jones, Jane L. Hurst, Robert J. Beynon, (2020) The application of rapid evaporative ionisation mass spectrometry (REIMS) in the analysis of Drosophila species – a potential new tool in entomology Open Biology (in press)

There is increasing emphasis on the use of new analytical approaches in subject analysis and classification, particularly in respect of minimal sample preparation. Here, we demonstrate that Rapid Evaporative Ionisation Mass Spectrometry (REIMS), a method that captures metabolite mass spectra after rapid combustive degradation of an intact biological specimen, generates informative mass spectra from several arthropods, and more specifically, is capable of discerning differences between species and sex of several adult Drosophila species. A model including five Drosophila species, built using pattern recognition, achieves high correct classification rates (over 90%) using test data sets, and is able to resolve closely related species. The ease of discrimination of male and female specimens also demonstrates that sex specific differences reside in the REIMS metabolite patterns, whether analysed across all five species or specifically for D. melanogaster. Further, the same approach can correctly discriminate and assign Drosophila species at the larval stage, where these are morphologically highly similar or identical. REIMS offers a novel approach to insect typing and analysis, requiring a few seconds of data acquisition per sample and has considerable potential as a new tool for the field biologist.