STUDY OF THE COMPOSITION OF MOLECULES IN GALL-FORMERS OF TWO INSECT ORDERS AND THEIR FODDER PLANTS USING RAMAN SPECTROSCOPY
M. I. Nikelshparg 1, E. I. Nikelshparg 2, V. V. Anikin 3, D. N. Bratashov 3
1Gymnasium No. 3, Saratov, Russia;
2Lomonosov Moscow State University, Moscow, Russia;
3Saratov State National Research University named after N.G. Chernyshevsky, Saratov, Russia;
Abstract
Studying the molecular composition of gall-forming insects trophically associated with certain types of fodder plants, is challenging, since it is at the junction of two sciences - botany and zoology. Each kingdom (plants and animals) has its own instrumental methods of study, so it is difficult to achieve uniformity of statistical data. One of the universal methods in this case is the Raman spectroscopy (RS). In addition to the possibility of using it on various biological objects, this method has another significant advantage - non-invasiveness. This is especially important for the study of biological molecules in developing living insects that go through several completely different stages during ontogenesis. One of the most difficult molecules to study is the carotenoid pigment. It is believed that phytophagous insects obtain carotenoids from plants through food intake. The aim of our work was to determine the composition of carotenoids in various orders of gall-forming insects and their fodder plants using RS.
The study involved two orders of insects, significantly different from each other: the Hymenoptera and beetles (Coleoptera). Both representatives were gall-formers. The order of Hymenoptera was represented by the gall-wasp Aulacidea hieracii l., 1758 (Hymenoptera: Cynipidae), developing on a weed plant, the hawkweed (Hieracium x robustum). The order of beetles was presented by a weevil Smicronyx smreczynskii F. Solari, 1952 (Coleoptera: Curculionidae), which forms galls on a dodder Cuscuta campestris. The dodder, in contrast to the hawkweed, is an obligate parasite, almost incapable of photosynthesis. The plant receives all its nutrients by absorbing them from other host plants.
For the experiment, the authors collected galls and stems on the hawkweed, in May-July 2019-2021, on the dodder - in May-July 2021 in the Volzhsky district of the city of Saratov. We used an inVia Renishaw (UK) Raman microspectrometer with a 532 nm laser, x5 objective, numerical aperture 0.75, signal accumulation time of 60 seconds at a power of no more than 0.3 mW, and a laser spot size of 5.4 μm. Living gall-forming larvae were removed from the galls onto a glass slide and the Raman spectra were immediately recorded. Spectra from galls and stems of the plants were recorded at the same time. After the studies, the slide with the larvae was put into a Petri dish and left for growing (continuation of development).
As a result, we found that the Raman spectra of the larvae of both orders of insects and both plant species contain typical peaks of carotenoids. However, we discovered that the carotenoid composition of the two orders of insects does not coincide with the composition of the carotenoids of the host plants. This fact gives reason to assume that these gall-forming insects have their own synthesis of carotenoids. Healthy adults emerged from irradiated larvae of both orders. Thus, we confirmed the safety and non-invasiveness of the Raman method for these animals.
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Matvey I. Nikelshparg
Gymnasium No. 3
Россия
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