If we can safely assume that the attainment of a population level averaging two 

 boll weevils per acre (one male and one female) is within the range of practicability 

 with current control methods, the total boll weevil population for final elimination would 

 be of the order of 20 million boll weevils (10 million males and 10 million females). 

 Then, if we assume that an initial ratio of 100 or even 200 reasonably competitive 

 sterile males to 1 fertile male would be required to assure a further downward trend in 

 the population, we would have a highly promising system for final elimination of the 

 population. It is the writer's view that no insect species under field conditions could 

 continue to maintain its population level if subjected to such high ratios of reasonably 

 competitive, sterile insects. In order to achieve ratios of 200 sterile to 1 fertile boll 

 weevil during the first generation after treatment with insecticides, the production of 2 

 billion male boll weevils for use on 10 million acres would probably be required. 

 Additional releases at the original level for two more generations would require the 

 production of a total of 6 billion males or a total of 12 billion of both sexes . Theoreti- 

 cally, eradication should be achieved with a high safety margin. This many insects, on 

 casual analysis, may seem to be a staggering number, but in comparison with the costs 

 for a full-season, chemical-control program that would theoretically be necessary to 

 eliminate such a low population, the cost for producing 12 billion boll weevils should be 

 very low. 



Excellent progress, as the result of research by various laboratories of the 

 Entomology Research Division and State agricultural experiment stations, has been made 

 in developing ways to rear the insect in the laboratory. Research on mass-production 

 procedures is being carried out by R. T. Gast at the Boll Weevil Research Laboratory 

 at State College, Miss. Mass-rearing methods need to be perfected, but it is believed 

 that the insect could be mass-produced at a cost of $5, 000 per million males, and 

 possibly for less. If 6 billion males were needed for final elimination of a low-level 

 population, the cost of producing the sterile insects would be of the order of $30 million 

 for use on 10 million acres of cotton, which would amount to only $3 per acre. This 

 would be a nominal sum in relation to a cost of $20 or more per acre for 10 to 12 

 treatments with insecticides, but such insecticide treatments alone, theoretically, 

 would not be as effective as sterile males for eliminating a population, even after it had 

 been previously reduced as low as two boll weevils per acre. 



The above appears to be a reasonably accurate estimate of the number of insects 

 that would have to be dealt with following an intensive insecticide-control regime, both 

 in the fall and spring. The low-population level that seems to be attainable should fall 

 well within the range that could be managed by the sterility technique, if reasonably 

 competitive males can be produced. 



Ways of sterilizing the boll weevil without serious adverse effects on competitive- 

 ness of the males have not yet been achieved, as mentioned earlier in this publication, 

 but investigations are continuing at the Boll Weevil Research Laboratory. In spite of 

 the adverse effects on mating competitiveness resulting from current methods of pro- 

 ducing sterility, D. A. Lindquist and associates of the Division's laboratory at College 

 Station, Tex. , and T. B. Davich and associates of the Boll Weevil Research Laboratory at 



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