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136 |VIL. Zoocoenological characteristics
On apple trees, such a population is that of Diaspidiotus perniciosus,
Eriosoma lanigerum, or a tortricid with two-three generations per year. In a
wheat field, these include Agriotes spp., Agrotis segetum, or species of wheat
flies, etc.
The population with the highest degree of corrumpency is not necessarily
also the dominant one. In a square metre of wheat field, a few larvae of Agrotis
can have a higher degree of corrumpency than a dozen of Oscinella frit. To
what degree numerical dominance is unsuitable as a characteristic of the real
role of a population can be seen especially well when the corrumpent activity
is by the larval semaphoronts, and not the adults. In such cases, the degree
of corrumpency of the adult population is zero, and the degree of corrumpency
of the given species can only be assessed via the activity of the larval population
that follows the adult generation. This clearly indicates what sort of errors
we can make during the study of zoocoenoses, if the importance of a species
is evaluated based only on the collected adults.
In many cases, we cannot yet measure the transformative effect. To assess,
for example, the impact of a caterpillar population, we ought to know the
per capita foliage consumption. Once we know this, we can calculate the
expected transformative effect by a simple multiplication (as in Rudnev 1951),
that, from the point of view of the community, expresses the share of the
available plant energy source that was used by the studied population. This
is also an indirect measure of the degree of corrumpency, because the larger
the transformative effect, the lower the chance for new populations to fit into
the coenosis, meaning the greater the degree of corrumpency of the population
responsible for the transformative effect.
Under our current knowledge, however, we cannot calculate, precisely,
the degree of corrumpency, because we do not yet know the constancy of
the species composition of the various zoocoenoses. The flourishing of
producent elements in a zoocoenosis is a potential condition for the full
development of a (partially- or nearly-developed) zoocoenosis. Any
corrumpent exhausting the producent energy source will impair this
possibility, forming a mechanism that acts against the expansion of the
biocoenosis. This factor is the degree of corrumpency whose magnitude is
inversely proportional to the degree of threat to the vitality of the producents.
The manifestation of the degree of corrumpency results in the interaction
between populations that utilise the same energy source. This interaction,
through degree of corrumpency, is the proof that the catenarium, presocium
and supersocion are indeed zoocoenological categories.
Currently, we can distinguish three levels of corrumpency. If most of the
energy source remains in a condition that it is available to the corrumpent
populations that become apparent later, the degree of corrumpency is
regressive. This degree is regressive when the transformative effect is <50%
of the energy source. The degree of corrumpency becomes progressive when
this energy use becomes >50% and, as it exceeds the 50% level, greater food