10 Oct., 1916.] Noserna Apis in Victoria. 629 



NOSEMA APIS m VICTORIA. 



By F. R. Beuhne, Government Apiculiurist. 



ISTosema apis, an animal parasite of the digestive tract of the honey 

 bee, and the cause of a disease fatal to bees in Europe, was first dis- 

 covered in Victorian bees in 1909. (Journal of Agriculture, January, 

 1910, p. 58.) Following, as it did, upon a heavy mortality of bees 

 which occurred in the Stawell district during the winter and spring 

 of 1909, the discovery of the Nosema parasite in Victoria caused some 

 alarm amongst beekeepers. 



The investigations made in Great Britain proved that the parasite 

 when introduced into healthy bees produced the disease kno'vvn there 

 as Isle of Wight Disease. A comprehensive report of the investiga- 

 tions was published by the British Board of Agriculture in May, 1912. 

 The authors of this report (p. 126) recommend the destruction of the 

 bees and combs of affected hives as the only effectual means of dealing 

 with this disease. 



As the Victorian investigations, which were made by Mr. W. Laid- 

 law, B.Sc, Government Biologist, after the discovery of Nosema in 

 Victoria, proved that the parasite was present in almost every apiary, 

 that even wild bees in trees were affected, it appeared, therefore, hope- 

 less to attempt the eradication of the disease by destroying the infected 

 bees and combs. 



Bees from eighty-eight widely-separated apiaries were examined and 

 the presence of the Nosema parasite proved in all but two, one of 

 which was the departmental apiary at the Burnley School of Horticul- 

 ture. In several instances the bees which showed Xosema infection 

 came from apiaries in which no mortality or dwindling ever occurred, 

 and it appeared, therefore, doubtful whether the presence of the para- 

 site in the bees is in itself necessarily fatal, or that it greatly interferes 

 with the productiveness of the hives excepting under certain conditions 

 due to climatic influences. 



In view of the wide distribution of ISTosema in Australia, the fact 

 that losses occur only after drought seasons, and that no fresh out- 

 breaks of the disease followed the restocking with bees of defunct hives, 

 it would appear that under normal climatic conditions this parasite is, 

 in Australia, merely a casual inhabitant of the alimentary canal of 

 the bee. In fact, under ordinary conditions the disease is endemic, 

 and becomes epidemic only when the vitality of the bees is impaired 

 by the malnutrition during the bee's larval development, which is 

 caused by a dearth or the inferior quality of the nitrogenous food 

 which bees obtain solely from the pollen of the flowers of plants. 



The comparative harmlessness of ISTosema apis in Australia during 

 normal seasons suggested that the introduction of queen bees from 

 infected stocks in one locality to colonies free from the parasite located 

 in anotlier district would not necessarily produce infection, and that 

 affected dwindling colonies would probably recover in new and favor- 

 able surroundings. 



With a view of arriving at some definite conclusion on this point, 

 some tentative experiments were undertaken during the season 1913-14. 



