by Viktor GLUPOV, Dr. Sc. (Biol.), head of the Institute of Animal Taxonomy and Ecology, Siberian Branch of the Russian Academy of Sciences, head of the Laboratory of Insect Pathology; Vadim KRYUKOV, Cand. Sc. (Biol.), Vyacheslav MARTEMYANOV, Cand. Sc. (Biol.), and Natalya YURLOVA, Cand. Sc. (Biol.), scientists of this laboratory Parasites are inseparable components of natural ecosystems essential to their functioning. They are playing the key role not only in the dynamics of host populations and communities, but also in the structure of alimentary chains; they are also making an important contribution to the biomass and energy. Their presence has been detected at various levels of hierarchy: from protozoans, viruses, bacteria, and fungi up to multicellular plants and animals. Understanding how this complex system works so as to act upon it is an important scientific problem. стр. 12 Trematodes make an important contribution to the biomass of water ecosystems. The cercaria biomass is comparable to the host Lymnaea stagnalis biomass (A). The biomass of the two prevalent trematode species (Echinoparyphium aconiatum and Plagiorchis elegans) is 50.8 and 58.3 percent of the host mollusk biomass, respectively (B). WHO ARE THEY? Many living organisms, often invisible, surround us. Even the human body is a comfortable home for parasitic "residents" seen only under a microscope. This coexistence is called symbiosis (literally--"living together"). Most often it is associated with interrelationships implying mutual profit (importantly, in biological literature it is called mutualism--a word derived from the adjective "mutual"). In reality it may be different, for the coexistence profit vectors can be of different direction. In some cases it can be cooperation, sometimes very close. For example, the human digestive system just cannot work without enteric flora microorganisms. On the other hand, unwanted guests can infest the human body ... Читать далее