PEST CONTROL BY CHEMICAL, BIOLOGICAL, 
GENETIC, AND PHYSICAL MEANS 
A Symposium 
INTRODUCTION 
E, F, Knipling, Chairman, Section 0 (Agriculture), and Director, 
Entomology Research Division, Agricultural Research 
Service, U.S, Department of Agriculture, Beltsville, Md. 
Pest control is necessary to provide the food, 
fiber, and other agricultural items required by 
the expanding world population. It is also 
essential to control the many arthropod vectors 
that transmit devastating diseases to man, such 
as malaria, typhus, and plague. 
The role that pesticides can take inimprov- 
ing the welfare of mankind throughout the world 
has been clearly demonstrated during the past 
two decades--a period during which hundreds 
of new insecticides, herbicides, nematocides, 
fungicides, and other pesticides came into ex- 
tensive use. 
It would be difficult to appraise accurately 
the benefits to mankind that have already ac- 
crued as the result of the many new chemical 
weapons available for the control of pests. It 
would likewise be difficult to imagine the ad- 
verse impact on man's future welfare and 
economy if we couldnot rely onthe use of these 
valuable chemical agents or did not know of 
alternate ways to control pests. People tend to 
forget the past and accept new developments as 
a matter of fact. However, in dealing with pest 
problems, people must maintain constant vigi- 
lance to meet new situations and to maintain 
the advances that have been made. 
As valuable as pesticides have been, their 
increased use has resulted in some complex 
problems because of side effects they can pro- 
duce to many beneficial nontarget organisms 
in our environment. Most pesticides, especially 
those designed to destroy animal pests--in- 
vertebrates or vertebrates--can be expected 
to be hazardous to at least some other animal 
species if exposed to the pesticide. Past basic 
knowledge has permitted development of only 
a few chemicals sufficiently selective in basic 
action or sufficiently selective in manner of use 
to destroy the target pest without creating 
hazards to other animals in the same general 
environment, This does not mean that progress 
has not been made in selective use of pesti- 
cides, Such progress will be pointed out by the 
scientists who will discuss certain pesticides 
and methods of using them against both verte- 
brate and invertebrate pests, Although there 
has been progress, in most instances we donot 
yet have the materials and methods to achieve 
the degree of selectivity that we would like to 
have. 
From an overall viewpoint, a great deal can 
be said about our progress in employing pesti- 
cides without leaving high-level residues in 
our food supply. It is somewhat surprising, 
moreover, that the many highly toxic pesticides 
have been employed without creating more 
hazards to people that handle them in com- 
parison with the hazards of common drugs, 
household chemicals of many kinds, common 
industrial chemicals, and similar substances. 
At the same time, much can be said about the 
known and potential adverse impact of pesti- 
cides for the control of certain pests without 
exposing other organisms inthe same environ- 
ment to the spray or to the residues that may 
remain, Free-ranging organisms cannot be 
excluded from sprayed areas. All the pesticide 
applied in a given environment may not remain 
in that environment. 
