26 



BULLETIlSr 810, U. S. DEPARTMENT OF AGRICULTURE. 



EFFECT OF DRUGS ON EUROPEAN FOULBROOD 



Preliminary experiments have been made to obtain data relative 

 to the effect of drugs on Bacillus pluton. In conducting the experi- 

 ments a suspension of the stomach contents of larvse sick or recently 

 dead of European f oulbrood is made in an aqueous solution of the drug. 

 This is added to diluted honey and healthy brood is fed this sus- 

 pension. In some instances the direct and in others the indirect 

 method was followed. In Table XV are summarized the experiments 

 which were performed: 



Table XV. — The effect of drugs on European foulbrood 



Date of experiment.' 



Drugs. 



Strength. 



Results of inoculation. 



July 11. 

 May 31. 

 June 7- - 

 July 11. 

 June 21. 



Do. 

 May 31. 

 July 11. 

 June 7- - 

 July 11. 



Do. 

 May 31. 

 June 7- . 

 July 11. 

 May 31. 

 June 7-. 

 July 11. 

 May 31. 

 June 7.. 



Betanaphthol 



do - 



do 



Carbolic acid 



do 



do 



Oil of eucalyptus. 



do 



Formic acid 



do 



Salicylic acid 



do 



do 



Salol 



do 



do 



Quinifli 



do 



.....do 



1:2000 

 1:1000 

 2:1000 

 1:2000 

 1:1000 

 2:1000 

 4:1000 

 4:1000 

 1:1000 

 3:1000 

 1:2000 

 1:1000 

 2:1000 

 1:2000 

 1:1000 

 2:1000 

 2:1000 

 4:1000 

 10:1000 



European foulbrood produced. 



It will be observed from Table XV that European foulbrood was 

 produced in all cases in which larvse were fed a suspension of 

 Bacillus pluton in sirup medicated with betanaphthol, carbolic acid, 

 eucalyptus, formic acid, salicylic acid, salol, and quinin (bisulphate 

 of quinin) , respectively, in the proportions noted. 



The strongest solutions of the drugs used in the experiments are 

 in most instances ap.proximately the maximum proportion of the 

 chemical in honey that will be taken by the bees. These prelimi- 

 nary results indicate that drugs should not be depended upon, for 

 the present at least, in the treatment of European foulbrood, and 

 emphasize the fact that beekeepers should make sure that the value 

 of a drug has been demonstrated fully before it is used. 



TRANSMISSION OF EUROPEAN FOULBROOD 



While there is yet much to be learned concerning the transmission 

 of European foulbrood, the data at hand relative to this important 

 phase in the study of the disease justify certain statements in regard 

 to it. The disease can be produced experimentally by feeding a 

 healthy colony the crushed larvae sick or dead of the disease, sug- 

 gesting that infection takes place by way of the alimentary tract. 



