40 



BULLETIE" 780, U. S. DEPAETMENT OF AGRICULTURE. 



The experiments summarized in Table XX show from the results 

 recorded that Nos&ma a'pis, when suspended in honey and kept at 

 room temperature, shielded from the light, remained virulent for 

 from 66 to 124 days, that is, from 2 to 4 months. The wide varia- 

 tion noted here probably is due very largely to the variation in 

 temperature of the honey suspension. 



PERIOD IN DEAD BEES. 



Among the factors tending to destroy Nosema apis within the 

 remains of dead bees are drying, putrefaction, and probably fermen- 

 tation. The temperature also is to be expected to vary the period 

 of resistance. In conducting the experiments, therefore, incubator, 

 room, outdoor, and refrigerator temperatures were used. Infected 

 bees were killed and kept in these different environments. After 

 different intervals suspensions were made in sirup, the crushed 

 bodies of from 5 to 10 of the infected bees being used. Colonies 

 were inoculated with the suspensions. 



AT INCUBATOR TEMPERATURE. 



Table XXI summarizes the results obtained when inoculations 

 were made with suspensions of Nosema-infected material from bodies 

 of bees kept at incubator temperature. 



Table XXI. — Resistance of Nosema apis within dead bees at incubator temperature 



(37:5° C). 



Date of inoculation. 



Results of inoculation. 



Apr. 9, 1916. . 

 Apr. 12, 1916. 

 Apr. 14, 1916. 

 June 27, 1916 

 July 1,1916.. 

 May 17, 1916. 

 Aug. 4, 1915. 

 Oct. 8, 1914.. 

 Aug. 8, 1915. 

 Aug. 17, 1915 

 Oct. 19, 1915. 

 Aug. 23, 1915 

 Aug. 6, 1914. 

 Nov. 2, 1914. 



Nosema infection produced. 



Do. 



Do. 

 No infection produced. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



By the results recorded in the experiments summarized in Table 

 XXI, it was shown that Nosema apis in the bodies of dead bees 

 kept at incubator temperature ceased to be virulent in less than one 

 week. 



AT ROOM TEMPERATURE. 



In Table XXII are summarized the experiments in which dead 

 bees, kept at room temperature, furnished the Nosema-infected 

 material for the suspensions used in the inoculations. 



