Investigation of differences in the IR spectra of earthworms as a possible way of their taxonomic identification

IR spectrometry is successfully used for the taxonomic identification of various groups of invertebrates: butterflies, flies, grasshoppers, mosquitoes, weevils, and termites. Therefore, the purpose of this study was to assess the fundamental possibility of taxonomic identification of earthworms based on the study of the functional-group composition of their bodies by the method of IR-Fourier spectroscopy. Seven species of earth-worms from five genera were the objects of the study: Aporrectodea caliginosa, Eisenia fetida, Eisenia nordenskioldi, Lumbricus rubellus, Rhiphaeodrilus diplotetrathecus, Octolasion lacteum, Eisenia ventripapillata. IR absorption spectra were registered on an FT-801 IR-Fourier spectrometer in the range of 500-4000 cm-1. The position, intensity, and area of the absorption bands were determined on all spectra. The maximum differences between individual species in intensity and position of protein and nucleic acid absorption bands were established. Using the principal component method, it was shown that the classification was based on the characteristics of the absorption bands of stretching and bending vibrations of methyl and methylene groups, as well as amide groups in the structure of worms. At the same time, the division of earthworms into subgroups with similar spectral characteristics could be explained by several reasons: their origin, kinship, and the influence of the environment. The data obtained during the study confirm the possibility of using IR spectrometry for the identification of earthworms.