horizons have been broadened tremendously, 
and this has brought about a situation that is 
exciting and challenging to biological scientists 
engaged in the suppression of pest organisms, 
These accelerated changes have been par- 
ticularly impressive in the areas of research 
dealing with pest control by biological means. 
The enthusiasm and support for more work 
on the nonchemical aspects of pest control 
are unprecedented, and this has two major 
and immediate benefits: (1) It makes a better 
balanced research program and (2) it en- 
courages the development of integrated control 
techniques, 
The unmistakable trend is toward the de- 
velopment of broadly based control programs 
with a definite ecological orientation. Perhaps 
this was always inevitable. Certainly it is 
understandable, because pest control is 
basically achieved by simply creating an 
environment unsuitable for the survival or 
increase of the pest. The really significant 
thing now is that more and more attention is 
being given to the biotic aspects of this 
environment. As a result, there is anincreas- 
ing awareness of the tremendous potential of 
using biological phenomena in pestcontrol, 
There are numerous, convincing, and well- 
documented demonstrations of the suppression 
of arthropod pests by purposely introduced 
parasites and predators. This is the now 
familiar procedure that we recognize as bio- 
logical control. Its basic principles were 
extended to use phytophagous insects for the 
spectacular control of weeds in Australia, 
Hawaii, and California. Another logical exten- 
sion has been the widespread use of pathogens 
to reduce populations of insects and certain 
vertebrates through the technique known as 
microbial control. These examples of applied 
ecology have now become a familiar part of 
our pest-control concepts, and are easily 
caught in the scholastic net of acceptable 
definitions of biological control. 
Although not so easily included in the defi- 
nition of biological control, there are never- 
theless other outstanding advancements that 
utilize biological phenomena to control pest 
organisms and that are undeniably examples 
of pest control by biological means. Among 
these achievements are the use of resistant 
varieties of crop plants, the application of 
the phenomenon of antagonism as a plant 
disease-control tactic, and the fascinating 
"autocidal" innovations, particularly the dra- 
matic application of the male sterility prin- 
ciple. 
The contributions to this symposium give 
us an exciting view of the future of pest 
control by biological means. They also re- 
veal that this area of pest control, with its 
tremendous potential, has scarcely been ex- 
plored and should be fully exploited in the 
future. 
PROBLEMS ASSOCIATED WITH THE DEVELOPMENT AND USE 
OF PEST-CONTROL MEASURES 
Nyle C, Brady, Director, Science and Education, 
U.S. Department of Agriculture, Washington, D.C. 
One of the simpler views of life holds that 
problems really aren't as complicated as the 
experts make them out to be... and that 
difficulties can be resolved fairly quickly and 
easily if only the experts do what seems 
obvious to everyone else. 
How pleasant it would be if we could so 
lightly view the crushing responsibilities of 
the 20th century ...how reassuring to see 
the answers to its subtle and defiant problems 
so clearly and confidently stated. 
59 
But how much more difficult it is to 
have to face up to the unpleasant realities 
of providing meaningful and lasting answers-- 
whether in the field of international rela- 
tions, or automation, or pesticides. How much 
more trying to have to juggle a whole host 
of potentially lethal weapons, so to speak, 
while at the same time balancing on a 
tightrope and being urged to proceed in 
both directions at the same time--as is 
happening now in the field of pesticides. The 
