DESTRUCTION OF GERMS OF BEE DISEASES BY HEATING. 7 



For the purpose of determining approximately the minimum amount 

 of heating that is sufficient to destroy the germ Nosema apis the inoc- 

 ulation experiments summarized in Table III were made. 



Table III. — Summary of experiments in vfkich the germ, Nosema apis, was heated and 



fed to healthy colonies. 



Dates of inocu- 

 lation. 



Tempera- 

 ture used 

 in heating. 



Time of 

 heating. 



Results of inoculation. 





°C. 



Minutes. 





Oct. 29,1912 



95 to 100 



5 



No Nosema infection produced. 



Nov. 12, 1912 



95 to 100 



5 



Do. 



Oct. 29,1912 



80 



20 



Do. 



Nov. 9,1912 



80 



10 



Do. 



Nov. 11, 1912 



68 to 70 



10 



Do. 



Do 



68 to 70 



10 



Do. 



Nov. 12, 1912 



65 



20 



Do. 



Jan. 8, 1913 



65 



10 



Do. 



Nov. 11, 1912 



60 



10 



Do. 



Do 



60 



10 



Do. 



Nov. 20, 1912 



60 



10 



Do. 



Feb. 8, 1913 



58 



10 



Do. 



Oct. 4, 1913 



58 



10 



Do. 



Feb. 8, 1913 



57 to 58 



15 



Do. 



Oct. 15,1913 



57 



10 



Do. 



Do 



57 



10 



Do. 



Oct. 4, 1913 



56 



10 



Nosema infection produced. 



Oct. 15,1913 



56 



10 



Do. 



Jan. 8, 1913 



55 



20 



Do. 



Jan. 31,1913 



55 



10 



Do. 



It will be observed from Table III that when Nosema apis was 

 heated to 57° C. (134.6° F.) or higher for 10 minutes and fed to 

 healthy bees no infection took place, but when held at tempera- 

 tures below 57° C. (134.6° F.) for the same period of time the bees 

 became Nosema infected. It is shown, therefore, that the minimum 

 temperature that will destroy the germ Nosema apis in 10 minutes 

 lies somewhere between 55° C. (131° F.) and 60° C. (140° F.), being 

 quite near 57° C. ( 134.6° F.) . 



By way of parenthesis it might be well to say a word or two further 

 regarding Nosema disease. The studies of this disease disclose the 

 interesting fact that it is not a new one hi American apiaries. There 

 is no cause, therefore, for anticipating any additional losses to our 

 apiaries. Indeed, since the presence of the disease is known, hopes 

 may be entertained that methods will be determined for reducing the 

 losses due to it. Considerable work must yet be done, however, 

 before methods for its control can be recommended. 



Nosema disease is being studied in England, Germany, Switzer- 

 land, and Australia. During the last two years the writer has de- 

 voted considerable time to its study in America. The plan is to 

 continue the studies during the present year, after which it is hoped 

 a further discussion of this disease will be justified. 



