According to Russian researchers, dragon flies play a major role in transfer of nutrients, essential for terrestrial dwellers, from water to the shore.

Polyunsaturated omega-3 fatty acids are a symbol of healthy eating. Research, conducted within last 10 years, revealed many useful properties of these chemical substances. Omega-3 fatty acids tone up an organism, fight unhealthy oxidants, quench inflammations and modulate immune response. These essential substances assist heart beating, normalize the amount of cholesterol in blood, and help brain and eyes function better. However, human organism is unable to synthesize these essential components of metabolism himself. We can only get these acids with food – fish oil and some plants.

Omega-3 fatty acids contain unsaturated fatty acids with a carbon-carbon double bond starting after the third carbon atom from the end of the carbon chain. Essential for living organisms acids include eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are synthesized in marine fish, like salmon and herring, as well as some marine and freshwater microalgae. Polyunsaturated omega-3 fatty acids are essential not only for humans, but also for many animals.

Russian researchers followed EPA and DHA on their way from lake microalgae to dragon flies, and then to birds. Many insects, like caddis flies, mosquitoes and dayflies, spend their larval stage of life in water, where they feed on algae, and after transformation into an adult, they get eaten by animals or birds. Almost nothing was known about same aspect of dragon flies’ life, but the question is very interesting, since these insects inhabit vast expanses of shallow water reservoirs – lakes, ponds and puddles. Dragon flies are favourite food for those birds, which do not eat smaller insects, like mosquitoes.

Within a 20-year period scientists counted dragon flies at a field site in Siberia. Nine species of these insects were included into experiments: yellow-winged darter (Sympetrum flaveolum), vagrant darter (S. vulgatum), common blue damselfly (Enallagma cyathigerum), four-spotted chaser (Libellula quadrimaculata), ruby whiteface (Leucorrhinia rubicunda), red-eyed damselfly (Erythromma najas), Siberian winter damsel (Sympecma paedisca), emerald damselfly (Lestes dryas), and Baltic hawker (Aeshna serrata).

Calculations showed that during the season one square kilometer gave life to 2600 dragon flies. Average content of eicosapentaenoic acid and docosahexaenoic acid in insect bodies was 7.98 milligram for 1 gram of dry weight. These data allowed researchers to conclude that within one year dragon flies transported about 6.9 kilograms of essential fatty acids from water ecosystems to terrestrial ones. These figures are comparable with amphibian insects of other species, thus significant role of dragon flies in transport of essential nutrients, like fatty acids, should not be underestimated. No food additives with polyunsaturated omega-3 fatty acids from dragon flies exist to date. Anna Kizilova

Source: Russian Science and Technology.