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88 | IV. Categories of animal associations
on all the trees of the forest, i.e. the whole biotope, and Agrotis segetum
(segetis) is corrumpent on beets, lucerne and grains, as is the case for elaterid
beetle larvae. The species Opatrum sabulosum meanders through all the
arvideserta, and we find it in the most diverse oecuses, whilst Operophthera
brumata is at home on all kinds of fruit trees of the agrilignosa. The populations
following these corrumpents through the various coeti will also be present
throughout the biotope, as will the episites that find their prey in a multitude
of populations, as well as to the intercalary elements that find their food in
different trophic chains. The food chains emerging from such corrumpents,
therefore, need a rather extensive space. More precisely, the presocium
emerges from the unification of these food chains: if these populations are
projected onto an ample energy source, we notice that a community exists
over a larger space, that is above catenae and catenaria, which, with their
mixed populations represent an association that can only be recognised at
this scale, the presocium.
The presocium is composed of populations that cannot fit any catenarium,
because they are active over a much bigger area. These animals can enter a
series of catenae without being affected themselves in return, and their trophic
chains are also independent of each other. Thus, the presocium is an even
looser assemblage than a catenarium; representing a category whose members
are not tightly interdependent, where there are several independent catenaria,
loosely linked by a few obstants with a need for intermediary hosts, and by
a few intercalary elements.
Therefore, a presocium includes those populations that use several (or all)
energy sources of a biotope or of several oecuses. Any one of these populations
will absorb the energy made available by plants in several oecuses, or preys
on populations belonging to several catenaria. All the populations that use
more than one catenarium concurrently belong to the presocium; we can
demonstrate this using an example.
In the arvideserta, the semaphoront groups living in the catenae
Ceutorrhynchitena maculae-albae, Timaspiditena papaveris and Stenocaritena
fuliginosi only occupy the oecus represented by the poppy, and together form
one catenarium. The catenae Subcoccinellaetena vigintiquatuor-punctatae,
Phytodectaetena formicatae, Hyperaetena variabilis form a catenarium in the
lucerne oecus. Oscinellaetena frit, Chloropiditena pumilionis and Cephitena
pygmaei are members of the catenarium on wheat fields. It is indisputable
that the above catenaria belong to separate oecuses, and the obstant populations
linked to the individual catenae, are only present in those. (A catena extends
until the populations joining the trophic chain are clearly distinguishable
elements; their entirety is the catenarium.)
However, the Agrotiditena segetum can be active in the whole arvideserta,
spanning all three oecuses because, as a corrumpent, it is polyphagous, can
appear in several oecuses, and attracts an obstant coetus as well. Despite
this, the above named catenaria can exist; all that has materialised is that