A SYNOPSIS O F THE PESTICIDE PROBLEM
123
Pesticides characteristically affect ecological relationships, and man and
his actions are an integral part of the whole - not only has he produced
the need for pesticides but he has invented them and controlled their
use according to experience of their action in the field: there is a reciprocal reaction. Pesticide control as well as pest control is an essential
“ecological factor”. Further, all the effects on relationships have to be
seen in relation to time since the initial effects produce others which
themselves interact. Eventually strong selective pressures cause genetic
changes. The evolution of the pest/pesticide relationship is shown
schematically in Fig. 5. The development of the human factor has
shown characteristics which are similar to certain ecological developments. In the first place, by growing crops in monocultures man has
created simplified situations in which some species present are likely
to become pests. To control them he has used powerful, largely nonspecific chemicals with density-independent effects. His actions have
led in some cases to resurgences of pests, the formation of new pests,
resistant strains in pests and varying degrees of damage to beneficial
species including himself. As a result man has reacted in different
ways :
1. He continues treatments which continue to give successful results
(e.g. control of weeds in cereal crops with selective herbicides).
2. He invents new pesticides to replace the old. This postpones pest
control problems rather than solves them. It produces a rapidly
changing pesticide situation which provides little time for species
to adapt.
3. He attempts to exclude pests altogether by growing crops in
enclosed places. This process of simplification is impossible in the
field.
and
4. He takes the more radical steps of doing ecological research
so as to harness naturally occurring beneficial factors, and to refine
chemical methods so that pesticides are less toxic and more
specific.
This last development results in a more complicated type of pest control
in which biological complexity is reintroduced into the system. The
pesticide problem is one of many in which short-term solutions are often
the enemies of long-term ones. But there are hopeful signs that the
human approach to pesticide use is evolving from a simple one with
diminishing long-term prospects to a complex one with good long-term
prospects. This should be reflected in increasing atability in the ecosystems affected by pesticides. In other words the whole pesticide
situation is, to some extent, self-regulatory.
123
Pesticides characteristically affect ecological relationships, and man and
his actions are an integral part of the whole - not only has he produced
the need for pesticides but he has invented them and controlled their
use according to experience of their action in the field: there is a reciprocal reaction. Pesticide control as well as pest control is an essential
“ecological factor”. Further, all the effects on relationships have to be
seen in relation to time since the initial effects produce others which
themselves interact. Eventually strong selective pressures cause genetic
changes. The evolution of the pest/pesticide relationship is shown
schematically in Fig. 5. The development of the human factor has
shown characteristics which are similar to certain ecological developments. In the first place, by growing crops in monocultures man has
created simplified situations in which some species present are likely
to become pests. To control them he has used powerful, largely nonspecific chemicals with density-independent effects. His actions have
led in some cases to resurgences of pests, the formation of new pests,
resistant strains in pests and varying degrees of damage to beneficial
species including himself. As a result man has reacted in different
ways :
1. He continues treatments which continue to give successful results
(e.g. control of weeds in cereal crops with selective herbicides).
2. He invents new pesticides to replace the old. This postpones pest
control problems rather than solves them. It produces a rapidly
changing pesticide situation which provides little time for species
to adapt.
3. He attempts to exclude pests altogether by growing crops in
enclosed places. This process of simplification is impossible in the
field.
and
4. He takes the more radical steps of doing ecological research
so as to harness naturally occurring beneficial factors, and to refine
chemical methods so that pesticides are less toxic and more
specific.
This last development results in a more complicated type of pest control
in which biological complexity is reintroduced into the system. The
pesticide problem is one of many in which short-term solutions are often
the enemies of long-term ones. But there are hopeful signs that the
human approach to pesticide use is evolving from a simple one with
diminishing long-term prospects to a complex one with good long-term
prospects. This should be reflected in increasing atability in the ecosystems affected by pesticides. In other words the whole pesticide
situation is, to some extent, self-regulatory.