surrounding areas, it would no doubt be possible to maintain control year after year 

 with far fewer insects than is required initially to achieve virtual elimination of the 

 population . 



Thus, even though it may not be possible to eradicate an insect population, the 

 initial cost for bringing it under control by the use of sterile insects should not be the 

 only factor to consider. The cost of a continuing sterile- insect-release program, in 

 relation to the costs for the control methods now available, has to be considered. For 

 the codling moth, continuing releases of sterile insects would no doubt be required in 

 many areas to prevent reestablishment by migrant moths. 



Research by Canadian entomologists on the sterile- insect method for codling moth 

 control has been imderway for a number of years under the direction of M. D. Proverbs. 

 More recently, similar research was undertaken by B. A. Butts and M. A. Brunson of 

 the Entomology Research Division. Encouraging results have been obtained. It appears 

 that the chances are good for achieving success in the development of the sterile-insect 

 procedure as a more economical, as well as a more desirable, way to control this key 

 insect species than by the use of insecticides. 



Other major insect pests, besides those discussed in some detail, should be 

 favorable subjects for investigation. For many other insects, however, including some 

 of our major pests, the chances of developing a practical way to use sterile-insect 

 releases, do not seem favorable at the present time. If the pest has a wide host range, 

 is present in large areas, has a high total population even at the lowest level in the 

 seasonal cycle, can readily disperse into cultivated crops from an abundance of wild 

 hosts, and the total economic loss is relatively low, it would seem desirable to concen- 

 trate on other methods of control. 



Whether or not the sterile-insect-release method will have economic advantages 

 over other methods of control for some of our major pests of agriculture is a debatable 

 question. For example, the writer has considered the role that the sterile-insect-release 

 method might have for controlling or eliminating the European corn borer. Investigators 

 have developed good information on the population density of this insect. In view of the 

 vast acreages of corn, the relatively low average loss per acre, and the relatively high 

 overwintered populations, this insect is not, in the writer's opinion, among the major 

 pests that could be controlled by the sterile-insect-release method. However, if some 

 reasonably low-cost procedure could be developed to reduce the natural population to 

 levels of the order of 100 moths per acre, the sterile-insect-release method might then 

 become the best procedure to follow for maintaining complete control of the pest. 



Mating Behavior a Factor in the Use 

 of the Sterile-Insect-Release Method 



When the sterile-insect-release method for population control was first employed, 

 the general, but erroneous, concept was advanced that a monogamous mating habit by the 

 insect was necessary for success. This belief still persists in the minds of many, so it 



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