16 TECHNICAL BULLETIN 149, IT. S. DEPT. OF AGEICULTTTBE 

 SECONDARILY INFECTED BEES 



The accurate determination of the effects of an inoculation upon 

 adult bees demands frequent observations and records. If exami- 

 nation is delayed beyond two days after death, secondary organisms 

 may materially affect the symptoms and obscure the pathogenic 

 organism. Examination during the last stages of disease before 

 death, or immediately after death, furnishes .the most conclusive 

 evidence of the pathogenic relations of an organism. The presence 

 of vegetating microorganisms in bees at this time is proof of their 

 growth and multiplication within living bees. As apparently normal 

 adult bees harbor large numbers of certain bacteria and yeasts 

 within the alimentary canal, particularly within the ventriculus and 

 the small and large intestines, their presence is of little pathogenic 

 significance. 



On the other hand, much weight may be given to the presence of 

 vegetating organisms of filamentous fungi within the alimentary 

 canal of living bees. The presence of vegetating organisms of any 

 sort within the blood or tissues is evidence of their pathogenic growth, 

 since the tissues and blood of healthy bees are always sterile. Under 

 favorable conditions, however, they may be invaded after death by 

 organisms present within the alimentary canal. 



What has been said concerning diseases of adult bees is true to a 

 lesser extent for diseases of their brood. Normally brood harbors 

 fewer bacteria than do the adult bees. During the first two or 

 three days of the life of the larvae, when their food consists only 

 of pap, which is believed to be a glandular secretion, it is often diffi- 

 cult to demonstrate the presence of microorganisms within the diges- 

 tive tract either microscopically or by culture. When such young 

 larvae die of other causes than bacterial disease the remains fre- 

 quently dry down without being attacked by putrefactive bacteria 

 or fungi. Microorganisms are found within the alimentary canal 

 of older larvae and pupae, after pollen and honey are mixed with the 

 food, but they are fewer in number than within the worker bees of 

 the field force. Secondary invaders rarely appear after the death 

 of infected brood with the possible exception of those dying from 

 European foulbrood. The causative organism of American foul- 

 brood can be recognized in old brood, remains, whereas the absence 

 of putrefactive organisms is the rule with sacbrood. 



During these experiments examinations were made at frequent 

 intervals after the inoculations were made. Adult bees were watched 

 more closely than brood in order to observe the symptoms of disease 

 before they were modified by secondary invaders. Kecords were 

 kept of microscopical and macroscopical examinations and were 

 compared with similar records of bees used as cheeks upon the 

 experiments. 



RESULTS OP INOCULATIONS AND SYMPTOMS OF THE DISEASES 



PRODUCED 



SYMPTOMS PRODUCED BY THE ASPERGILLI 



The inoculation of bees with a number of species of Aspergillus 

 resulted in the rapid appearance of mycosis and the death of the bees. 

 With some of the more virulent species all of the bees inocjilated and 



