S. Mahunka szerk.: Folia Entomologica Hungarica 45/2. (Budapest, 1984)

IN MEMÓRIÁM PROF.DR.GUSZTÁV SZELÉNYI On 18th February 1983 the Hungarian Entomological Society held a memorial session to the homage of Prof.Dr. Gusztáv SZELÉNYI who died on 22nd October 1982. The four speakers of the session (Gy. SÁRINGER, T. JERMY, B. NAGY and J.B. SZABÓ) dealt with Prof. SZELÉNYI' s biography and gave concise surveys on the scientific achievements which hallmark his creative work In three domains of biology: ecology, applied entomology and taxonomy. Prof. SZELÉNYI spent all 42 years of service as a research entomologist and later as the head of the Zoological Section in the Research Institute for Plant Protection, Budapest. Although only the smaller part of his publications deal especially with questions of ecology, his whole oeuvre Is so much governed by ecological thinking that he must be regarded first of all as an ecologist, particularly as a community ecologist. His approach to the study of animal communities was characterized by the strong emphasis of the function of different animal organisms In the communities, In his opinion synecology has to be based on autecology of animal populations because otherwise their function in the community cannot be revealed. Accordingly, he distinguished the following five groups of life-forms representing structural units (elements) of all communities: 1) Producing elements, i.e. autotrophic plants which, by photo- or chemosynthesis, provide the source of energy indispensable for all communities. 2) Corrupting elements, i.e. primary consuments: plant and animal organisms attacking living pi ants. 3) Resisting elements, i.e. organisms attacking living animals (parasites, predators, pathogens of animals). 4) Intercalary elements, I.e. organisms consuming dead organic matter. 5) Sustaining elements, i.e. organisms whose activity is vital for the existence of other organisms (pollinators, symbionts, etc.). Prof. SZELÉNYI defined the zoocenosis as follows: "A zoocenosis Is the whole of animal populations which, along a food chain, depend on a common source of energy (plant, plant community)." The following categories of animal communities (zoocenoses) exist: 1) Catena or host-community: It consists of a corrupting population and of resisting populations depending on the latter. 2) Catenarium or host-plant community: it is the sum of host-communities depending on the population of a plant species. 3) Presocium or biotop-community. Many Invertebrate animal populations do not depend on a single plant species but are oligo- or polyphagous. Also the intercalary and sustaining elements are mostly polyphagous. They all belong to this category. 4) Supersocion or acme-community is the highest category. It consists of the vertebrates of a natural biocenosis since they use many different sources of energy available In the biocenosis. Prof. SZELÉNYI emphasized the importance of keeping in mind HENNIG's notion, the semaphoront, when revealing the function of a certain animal population in a community because e.g.in holometabolous insects one semaphoront (larva) may represent a corrupting element while an other (adult) a sustaining one. The terms "blotop" and "biocenosis" have been defined by many authors quite differently.lt is, therefore, worth to cite Prof. SZELÉNYI'

s definitions reflecting his original thinking: "The biotop Is a part of the space which harbours the source of energy necessary for the formation and maintenance of a biocenosis". "The biocenosis is the association of plant and animal organisms around plant organisms which produce organic compounds, it consists of Interdependent structural elements and shows a physiognomically uniform appearance in a certain part of the biosphere". Prof. SZELÉNYI emphasized that in each plant community there are always several or even many animal communities most of which exist independently from each other. The biocenosis is the whole of largely independent organisms which can be ranged into the above mentioned structural elements. However, the latter represent only different tasks to be fulfilled in the biocenosis but the species can replace each other within a structural element without jeopardizing the completion of the task. Thus, contrary to several authors who regard the biocenoses as the wholes of strictly interdependent populations where the removal of even a single population would endanger the normal function of the whole biocenosis, Prof. SZELÉNYI supposes that the structure of the biocenoses is much less rigid: one population can easily replace the other in fulfilling the same function