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construction that have further reduced natural habitat, drainage schemes that have
reclaimed marsh and estuarial lands for farming or factory development, and the
applications of enormous quantities of pesticides, herbicides and fertilisers that damage
indiscriminately both harmful and beneficial insects, making it necessary to develop
further experience and technology to overcome some of the effects of what has been
destroyed.
The sterility often remaining after drainage schemes, river channeling, urban sprawl,
factory development, and various farming changes have been implemented, reduce both
animal and plant populations, in some cases to a level where the ability to survive as a
species is lost because species viability has gone for ever.
As the species causing disasters to other life forms, we do not know for certain, exactly
what effects we are causing. We may very well wipe out a species which at some future
date might be required because of its ability to provide a drag, or fulfil some other
function, about which we have as yet no knowledge. Insect species are increasingly
recognised and used in the control of pest species, as with the beetle that eats the mealy
bug parasite of the greenhouse, ladybird beetles that predate on aphids, and the moth
whose caterpillars eat and thus control the spread of prickly pear cactus in Australia.
Some insect somewhere may be the control of the fly that spreads trypanosomiasis in
domestic cattle in Africa, or perhaps a bacterium may be found to control Anopheles, the
malaria carrying mosquito. If we cany on with no regard for other species, we may not
be able to replace the potential benefit we have lost.
All life forms are to some degree inter-related, our domestic stocks and strains derive
from wild species, and to maintain hybrid vigour, it is necessaiy to be able to mate back
to the original wild stock at some time. The chain of life passes from vegetation living on
soil minerals and organisms, via various herbivorous animals to carnivorous animals
(some of which will prey on others). At any stage death may intervene, when scavengers,
bacteria and fungi will begin the process of re-cycling the nutrient materials.
It may be a sobering thought that flies and beetles of various species often take an active
and important part in the pollination of plants, as do some species of bats and birds and
oppossums.
Interruption of the web of life often brings unforeseen results, as an example is the human
introduction of the myxomatosis virus into the rabbit population. With little to keep them
in check, the coarser plant growths began to suppress many of the grassland species, an
example is the reduction of wild Thyme, which brought reductions in ant colonies and the
eventual extinction of the Large Blue butterfly. We have a hazy notion of parts of the
web of life - perhaps we always will do - it is therefore rash to enter on practices which
have not been thoroughly investigated. Which bacteria/invertebrates/plants/animals do
we eliminate and which do we cultivate?
In May 1973 the Rare Breeds Survival Trust was set up by some concerned people
including some breeders of livestock, who realised that once the genes forming a specific
breed had been lost, they had gone for all time. It has been shown conclusively that it is
necessaiy to back-cross, that is to mate back from time to time to the original gene pool.
It is also impossible to say what qualities may be required in a future generation of stock.
It would be foolish in the extreme to lose the original gene base.
The monitoring and study of wildlife can indicate the state of our environment, the health
Essex Field Club Newsletter No. 20, February 1997