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40 | II. Biocoenosis and zoocoenosis § THE STRUCTURAL ELEMENTS OF THE ANIMAL ASSEMBLAGE The semaphoronts found in a plant association can be grouped into seven coenological groups, there are: 1.) Corrumpent elements that are tightly linked to living plants, feeding on them. 2.) Obstant elements, feeding on other living animals. 3.) Sustinent elements that play a role in plant fertilisation. 4.) Intercalary elements that live on animal or plant excreta (Balogh 1953). 5.) Hospitants that feed on honeydew or nectar. 6.) Temporal (pro tempore) elements that, for some reason, live in extended contact with a member of the association, yet have no trophic relation to them. 7.) Peregrinant elements that are transients, with no relationship to any member of the association or zoocoenosis; they are en route to somewhere else, and only temporarily resident within the zoocoenosis. The herbivorous semaphoronts in a zoocoenosis fill the role of corrumpent (detrimental) elements, because their activity can cost the life of a host plant (in the case of root feeders), or can result in an inability to produce seeds. Consequently, certain plant species can disappear from a plant association, together with all herbivores, parasites and episites that are linked to the plant species. As a result, the association is in a state of slow change, termed succession by plant sociologists. One cannot deny that, in some cases, succession can be caused by herbivores; unfortunately, there is a lack of rigorous studies on this topic’. Corrumpent elements can, however, have a transforming impact without causing succession; there are numerous examples in the field of plant protection. Lymantria dispar, defoliating an oak forest, will certainly influence all trophic chains starting from leaf miners; these chains cannot be formed in the absence of the initial food source for the leaf miners. Anthonomus pomorum, attacking apple trees during bud burst, can cause all flowers to perish in bud stage. On such trees, neither Cydia pomonella, nor Hoplocampa testudinea, or species of Rhynchites can colonise. We avoid calling this competition as, rationally, we cannot justify how competition could occur between Anthonomus, which is active in March, and Cydia, that will swarm in May? Similarly, can we find any kind of conflict in the phenomenon whereby mining insects will disappear from a zoocoenosis because, due to the activity of caterpillars, there are no leaves left for them? In our opinion, there is no justification for attaching the phenomenon of competition into these events. The underlying cause is no more than the system of interactions that make a zoocoenosis itself; intense demographic + From our own experience, we can cite an event of grave damage, seen at Tahitotfalu, on 18 April 1935, where 3.62 ha of the village green was so badly damaged by Rhizotrogus larvae that the infested areas were all reddish brown, covered by dried-out grasses, without a single live plant; they could be pulled easily from the ground, as their roots were completely chewed away.
