104
N. W. MOORE
on a diet contaminated with DDT showed no ill effects until starved,
when they quickly died. The controls which had received no DDT
survived. It was highly probable, though not proved, that death occurred
as a result of the passage of DDT and/or its metabolites into the blood
stream. Since birds are known to use up their fat reserves on occasions
of special stress, for example in reproduction, on migration and when
starving, it is extremely likely that birds which contain appreciable
residues of pesticides in their fat are a t special risk. Ash and Sharpe
(1 964) have suggested that the extensive casualties observed during the
unusually cold spell of early 1963 were increased by pesticide poisoning.
Most wild bird eggs in Britain appear to contain residues of organochlorine insecticides (Taylor and Brady, 1964, Moore and Tatton, 1965
and unpublished). They are concentrated in the yolk. Female birds
may eliminate a significant proportion of their insecticide residues by
this means.
D. INTERACTION O F PESTICIDES
Frequently more than one pesticide is used on a crop, therefore many
animals are likely to ingest several chemicals simultaneously or consecutively. Analysis of bird tissues in Britain shows that most specimens
do in fact contain residues of two or more organochlorine insecticide
residues (Moore, 1965a).
The effects of multiple exposure may be purely additive. But in
recent years many instances have been discovered in which one organophosphorus insecticide can interact with another (Dubois, 1961). The
mechanism involves the inhibition by one insecticide of the metabolism
of the other. Street (1964) has demonstrated a DDT antagonism t o
dieldrin storage in the adipose tissue of rats. More work should be done
on the interaction of pesticides of different chemical families and between
pesticides and other contaminants.
No work appears to have been done on the effects of interaction of
pesticides on wild populations.
V. ECOLOGICAL EFFECTS O N SINGLE SPECIES
As shown above, each application of a pesticide results in a pesticideecosystem reaction however much it may be aimed a t one species.
Nevertheless, to understand the whole we need to understand the parts,
that is the effect or effects of a pesticide on individual species, and for
many practical purposes information on the effects on one species is all
that is required. There is now a very extensive literature on the effects
of pesticides on single sQecies. Many papers on very narrowly defined
problems raise questions of fundamental interest. The aim of this
A. INTRODUCTION
N. W. MOORE
on a diet contaminated with DDT showed no ill effects until starved,
when they quickly died. The controls which had received no DDT
survived. It was highly probable, though not proved, that death occurred
as a result of the passage of DDT and/or its metabolites into the blood
stream. Since birds are known to use up their fat reserves on occasions
of special stress, for example in reproduction, on migration and when
starving, it is extremely likely that birds which contain appreciable
residues of pesticides in their fat are a t special risk. Ash and Sharpe
(1 964) have suggested that the extensive casualties observed during the
unusually cold spell of early 1963 were increased by pesticide poisoning.
Most wild bird eggs in Britain appear to contain residues of organochlorine insecticides (Taylor and Brady, 1964, Moore and Tatton, 1965
and unpublished). They are concentrated in the yolk. Female birds
may eliminate a significant proportion of their insecticide residues by
this means.
D. INTERACTION O F PESTICIDES
Frequently more than one pesticide is used on a crop, therefore many
animals are likely to ingest several chemicals simultaneously or consecutively. Analysis of bird tissues in Britain shows that most specimens
do in fact contain residues of two or more organochlorine insecticide
residues (Moore, 1965a).
The effects of multiple exposure may be purely additive. But in
recent years many instances have been discovered in which one organophosphorus insecticide can interact with another (Dubois, 1961). The
mechanism involves the inhibition by one insecticide of the metabolism
of the other. Street (1964) has demonstrated a DDT antagonism t o
dieldrin storage in the adipose tissue of rats. More work should be done
on the interaction of pesticides of different chemical families and between
pesticides and other contaminants.
No work appears to have been done on the effects of interaction of
pesticides on wild populations.
V. ECOLOGICAL EFFECTS O N SINGLE SPECIES
As shown above, each application of a pesticide results in a pesticideecosystem reaction however much it may be aimed a t one species.
Nevertheless, to understand the whole we need to understand the parts,
that is the effect or effects of a pesticide on individual species, and for
many practical purposes information on the effects on one species is all
that is required. There is now a very extensive literature on the effects
of pesticides on single sQecies. Many papers on very narrowly defined
problems raise questions of fundamental interest. The aim of this
A. INTRODUCTION