8 2
N. W. MOORE
from a wide range of scientific disciplines, notably from toxicology
and population dynamics.
4. All possible effects cannot be foreseen from toxicological and
autecological studies, therefore it is often desirable to carry out
experiments on whole systems: to compare sprayed areas with unsprayed controls. Nevertheless, experiments of this type can never
produce absolutely reliable predictions on effects on constituent
species, because ecosystems change and so alterations in the system
may result in alterations in the effects on constituent species.
From all these considerations it will be seen that while we can
accurately describe the pesticide we cannot accurately describe the
system it affects. Its impact is on ill-defined complex interactions and
on phenomena that are frequently continuous; therefore effects can
only be predicted in terms of probability.
Most ecological situations are multifactorial ; when discussing the
increase or decrease of a population we should expect several causes.
Relatively simple cause and effect relationships may be found but we
should not expect them.
A full study of the effects of a given pesticide on a given species
requires assessment of all available information about the following:
1. The properties of the pesticide.
2. The manner of application of the pesticide.
3. Information on the extent to which the species comes in contact
with the pesticide. This can be obtained from:
( a ) Details of application, see 2 above (e.g. amount of active
ingredient per unit area).
( b ) The behaviour of the species in the sprayed area.
4. Response of the species to the chemical (data on acute and chronic
toxicity).
5. Information on the principal factors which control the population
of the species in situations in which no pesticide is used.
6. Toxicological information on the eEects of the pesticide on other
species which are principal controlling factors of the species studied
(see 5 above).
Consideration of ihformation of these types will suggest an hypothesis
that the pesticide is likely to have a certain effect on the species (e.g.
cause a decrease). This can be tested to a limited extent by performing
a field experiment of the type mentioned above.
In no case known to the author has all the necessary information
been available in any assessment of pesticide effect. The main gaps in
information are in toxicology and population ecology. Frequently no
toxicological data exist for the species concerned, and the assumption
has to be made that it reacts in the same way as a related standard
N. W. MOORE
from a wide range of scientific disciplines, notably from toxicology
and population dynamics.
4. All possible effects cannot be foreseen from toxicological and
autecological studies, therefore it is often desirable to carry out
experiments on whole systems: to compare sprayed areas with unsprayed controls. Nevertheless, experiments of this type can never
produce absolutely reliable predictions on effects on constituent
species, because ecosystems change and so alterations in the system
may result in alterations in the effects on constituent species.
From all these considerations it will be seen that while we can
accurately describe the pesticide we cannot accurately describe the
system it affects. Its impact is on ill-defined complex interactions and
on phenomena that are frequently continuous; therefore effects can
only be predicted in terms of probability.
Most ecological situations are multifactorial ; when discussing the
increase or decrease of a population we should expect several causes.
Relatively simple cause and effect relationships may be found but we
should not expect them.
A full study of the effects of a given pesticide on a given species
requires assessment of all available information about the following:
1. The properties of the pesticide.
2. The manner of application of the pesticide.
3. Information on the extent to which the species comes in contact
with the pesticide. This can be obtained from:
( a ) Details of application, see 2 above (e.g. amount of active
ingredient per unit area).
( b ) The behaviour of the species in the sprayed area.
4. Response of the species to the chemical (data on acute and chronic
toxicity).
5. Information on the principal factors which control the population
of the species in situations in which no pesticide is used.
6. Toxicological information on the eEects of the pesticide on other
species which are principal controlling factors of the species studied
(see 5 above).
Consideration of ihformation of these types will suggest an hypothesis
that the pesticide is likely to have a certain effect on the species (e.g.
cause a decrease). This can be tested to a limited extent by performing
a field experiment of the type mentioned above.
In no case known to the author has all the necessary information
been available in any assessment of pesticide effect. The main gaps in
information are in toxicology and population ecology. Frequently no
toxicological data exist for the species concerned, and the assumption
has to be made that it reacts in the same way as a related standard