necessary amount of control. Elimination of all individuals of the pest 
species in a field may not always be desirable. The insecticide application 
ideally could lower the pest population below the economic level, and at the 
same time leave a food supply for an adequate number of beneficial insects 
to reduce any upsurge in populations of the pest. 
Integrated control is one of our bestapproaches to safe, effective insect 
control. But development of the complex programs involvedin this approach 
depends on our acquiring a muchbetter knowledge than we have of the funda- 
mentals of the ecology of insect pests as interrelated to their parasites and 
predators, insecticide use and its effects, and related crop-production 
practices. 
One of the major obstacles to the development of properly integrated 
biological and chemical control procedures for some insects lies in the 
necessity of employing insecticides for the routine control of certain key 
insects for which natural enemies are a minor control factor. For example, 
in areas infested with the boll weevil it is difficult to consider integrated 
biological and chemical control for the.bollworm. Biological agents are not 
effective in controlling the boll weevil and insecticides are necessary for 
this insect. The use of insecticides for boll weevil control destroys the 
natural enemies of the bollworm, which often control this insect effectively 
in the absence of insecticides. As a result insecticides may be required to 
control the bollworm. 
The same situation exists with other major insect pests and major 
crops. Also, fluctuation in abundance of different kinds of insects from year 
to year may necessitate the use of an insecticide for a normally minor pest 
and thus complicate the development of a properly integrated biological- 
chemical control program for other insect pests. 
OTHER CONTROLS WITHOUT CONVENTIONAL INSECTICIDES 
Scientists have long tried to find effective natural controls for insect 
pests. Achievements of biological control could not keep pace with the 
expanding pest problem. Chemical insecticides were adopted. Yetthere have 
always been farsighted scientists and many progressive farmers who felt 
that a better alternative can and must be found. 
In recent years other alternate methods of insect control have been 
receiving increased research attention. A variety of biological principles 
are being applied. Some of these principles are population attrition through 
induced sexual sterility, the selective attraction, trapping, and destruction 
of certain species, and the development of crop varieties which will resist 
or tolerate specific insects. 
The Sterility Methods of Insect Control 
One of the encouraging developments inthe conquest of man over insects 
is the concept of sexually sterilizing insects by various techniques so they 
may help destroy their own kind by preventing reproduction. This is the 
newest of the insect control methods. There are two ways in which the 
sterility principle might be used to help control or eradicate insects. 
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