If the cost of rearing moths is calculated at $5, 000 per million, the total cost for 

 moths for brood 1 would be $500, 000. It is assumed that the same number of moths 

 would be required for brood 2. 



Assuming that the theoretical effects are achieved during the first year, the number 

 of moths required for the second year could be reduced by one-half and still achieve 

 complete domination of the population. A mortality of 75 percent is assumed for the 

 population entering hibernation during the first winter after the program is initiated. 



The calculated trend of the hornworm population subjected to the 2-year program 

 as outlined, is shown in model 10. Theoretical elimination of the population would be 

 achieved by the end of the second season. 



Model 10. — Estimated trend of the hornworm population east of the Mississippi River 



when subjected to sterile-moth releases in a 2-year program. An increase 

 rate of five fold for each brood is assumed for a normal population . 

 Sterile insects are assumed to be fully competitive. Following a rigid 

 cultural program in the fall, the initial spring population is assumed to be 

 8 moths per acre on 1, 250, 000 acres of tobacco and tomatoes, making a 

 total of 10, 000, 000 moths in the total population at the start 





Natural moth 



Sterile moth 



Ratio of sterile 



Number of moths 



Broods 



population 



population 



to fertile moths 



reproducing 



First year 











1 



10,000,000 



100,000,000 



10:1 



909,090 



2 



4,545,450 



100,000,000 



22:1 



197,454 



Second year 











1 



246,818-^ 



50,000,000 



202:1 



1,215 



2 



6,075 



50,000,000 



8,230:1 







_!/ A mortality of 75 percent owing to hazards during hibernation was assumed. 

 Theoretically, a moth population of 987, 270 would have resulted from the 197,454 

 reproducing moths in the second brood in the absence of winter hazards. 



It is not possible to make an accurate estimate of the cost for a program of the 

 type projected. However, the cost for producing a total of 300, 000, 000 moths would 

 probably amount to about $1, 500, 000. If all other costs for such a program were 

 equivalent to the cost for rearing moths, the overall costs would be $3, 000, 000 to 

 achieve complete domination and elimination of the original established population. 



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