238 



Four out of the six strains with the highest pretreatment mite counts 

 were laying below the average production level at the end of the trial. 

 All six strains showed little or no change in mite populations during 

 the trial. Of the remaining six strains, four of which were laying 

 above the average, only one strain, strain 4, had a mite population 

 change of less than +2X. Only two strains, strains 2 and 3, produced 

 above the production mean and maintained mite populations ranking among 

 the six highest in the pre- and post-treatment counts. 



No matter what conclusions may be drawn from Table 77, it is inter- 

 esting to note that the treated counterparts of the strains in Table 77, 

 all with different pretreatment mite populations, had their populations 

 reduced to zero or close to it. Yet, only one strain had a significant 

 increase in production due to treatment. A longer trial including 

 initial development of mite populations is necessary to more completely 

 investigate the factors involved in this phenomenon. 



