DESTRUCTION OF GERMS OF BEE DISEASES BY HEATING. 



Table II. — A summary of the experiments made to determine approximately the minimum 

 amount of heating necessary to render sacbrood material noninfectious. 



Dates of inocu- 

 lation. 



Temperature. 



Time of 

 heating. 



Results of inoculation. 





"C. 



Minutes. 





July 27,1912 



95 to 100 



2 



No disease produced. 



Aug. 8, 1912 



95 to 100 



2 



Do. 



Aug. 29,1912 



75 to 80 



10 



Do. 



Sept. 5,1912 



65 to 70 



20 



Do. 



Sept. 3,1912 



55 to 60 



20 



Do. 



Aug. 26,1913 



80 



15 



Do. 



Do. 



75 



15 



Do. 



Do. 



70 



15 



Do. 



Do. 



65 



15 



Do. 



Do. 



65 



15 



Do. 



Sept. 2,1913 



65 



15 



Do. 



Sept. 3,1913 



60 



20 



Do. 



Sept. 9,1913 



60 



15 



Do. 



Sept. 10, 1913 



60 



15 



Do, 



Sept. 17, 1913 



60 



10 



Do, 



Sept. 10, 1913 



58 



10 



Do. 



Sept. 17, 1913 



58 



10 



Do. 



Sept. 18, 1913 



57 



10 



Sacbrood produced. 



Sept. 9,1913 



55 



20 



Do. 



Sept. 10, 1913 



55 



10 



Do. 



Sept. 17, 1913 



55 



10 



Do. 



Aug 6, 1913 



50 



30 



Do 



From Table II it will be observed that when larvse dead of sacbrood 

 were heated 10 minutes at a temperature of 57° C. (134.6° F.) or less 

 and then fed to a healthy colony, sacbrood was produced ; if, on the 

 other hand, the dead larvse used in making the feeding were heated 

 to 58° C. (136.4° F.) or higher, the disease was not produced. The 

 conclusion to be drawn from these experiments is that the minimum 

 temperature, when maintained for 10 minutes, at which the infecting 

 agent causing sacbrood is destroyed lies somewhere between 55° C. 

 (131° F.) and 60° C. (140° F.), being near 58° C. (136.4° F.). 



DISEASES OF ADULT BEES, 



Very little is known about the diseases of adult bees. Many names 

 have been used for the purpose of designating them, but the number 

 of such diseases is probably small. There is only one adult disease 

 that can be diagnosed at present by laboratory methods. This one is 

 the Nosema disease. 



NOSEMA DISEASE. 



Fifty-seven years ago Dr. Donhoff made a more or less brief study 

 of a disease of adult bees in Germany. He observed that the stomach 

 was the organ that was primarily affected. By feeding to healthy 

 colonies in sirup the crushed stomachs from affected bees Donhoff 

 demonstrated that the disease could be transmitted to healthy colo- 

 nies. It was therefore infectious. 



The work by Donhoff had been practically forgotten, apparently, 

 when Zander, 1 of Erlangen, Germany, five years ago observed the 



1 Zander, E., Aug., 1909. Tierische Parasiten als Krankheitserreger bei der Biene. Munchener Bienen- 

 zeitung. 



