300 



GLEANINGS IN BEE CULTURE 



May, 1922 



moving about in the cells, which accounts 

 for the irregular positions of the dead larvae 

 in these cases. Large numbers of the vege- 

 tative rods and spores of Bacillus alvei are 

 found in larvae dying at this age. Under 

 these conditions the irregular positions, 

 shapes and colors of the dead larvae all vary 

 more or less from the characteristic features 

 of the dead coiled larvae in typical Euro- 

 pean foul brood (Fig. 1). They have a 

 dark-brown color and a granular, lumpy, 

 stringiness or old, dried rubber consistency. 

 These cause the confusion sometimes experi- 

 enced by beekeepers in differentiating be- 

 tween the diseases. 



Furthermore, there is a characteristic 

 odor associated with this condition which 

 is caused by the putrefactive activities of 

 Bacillus alvei. The odor is never found as- 

 sociated with any other condition or brood- 

 disease organism. It has been described as 

 similar to that of putrid, decaying meat. 

 It is markedly different from the typical 

 American foul brood and is much more dis- 

 agreeably persistent. The activity of Bac- 

 illus alvei also, without doubt, causes the 

 rather granular, lumpy, stringy consistency 

 sometimes encountered and mistaken for 

 the typical glue-like roping of American foul 

 brood. Tlie dried-down scale from this type 

 of dead larva in European foul brood is 

 easily removed from the cell walls (Fig. 1 n). 

 The brittle American foul brood scale ad- 

 heres tenaciously to the lower side wall in 

 practically all cases (Fig. 2). This latter 

 feature of American foul brood is a result 

 of the glue-like consistency of the decompo- 

 sition products from the action of Bacillus 

 larvae on the tissues of the larva. 



The occasional similarity between Euro- 

 pean foul brood and American foul brood 

 when Bacillus alvei'is abundant can be ex- 

 plained by the fact that the non-pathogenic 

 Bacillus alvei and the pathogenic Bacillus 

 larvae, the cause of American foul brood, 

 are "cousins." They belong to the same 

 general family of bacteria, and therefore 

 have somewhat similar characteristics of ac- 

 tion regarding putrefactive functions. The 

 two organisms are quite different, however, 

 in that Bacillus alvei has putrefactive func- 

 tions alone while Bacillus larvae combines 

 the power of primarily producing disease 

 with the ability to decompose the remains. 



The important fact in the above discus- 

 sion is, as will be seen later, that the pri- 

 mary activities of Bacillus plutou do not 

 prevent the growth of secondary invading 

 organisms which cause most of the varia- 

 tions and so-called abnormalities in the 

 symptoms of European foul brood. 



Uniform Symptoms in American Foul 

 Brood. 



It may be well to turn now to American 

 foul brood for comparison. Fortunately the 

 problem in this disease is much more sim- 

 ple. The symptoms in American foul brood 

 nearly always are found to be uniform in 

 character. Every diseased cell contains a 

 dead larva or scale, all having practically 



the same appearance as to consistency, color 

 and position in the cell. This is true even 

 under varied external conditions (Fig. 2). 



The reason for the uniformity of symp- 

 toms in this disease, in comparison with the 

 great variations sometimes found in Euro- 

 pean foul brood, is explained by the fact 

 that in American foul brood there is found 

 practically never another micro-organism 

 associated with the disease. This is Bacil- 

 lus larvae, the cause of the disease. This 

 pathogenic, spore-forming organism not 

 only kills the larA^a but carries out the de- 



Fig. 1. — European foul brood, 

 a, j, k, normal sealed cells; r, 

 normal coiled larva at age at 

 which a majority are attacked by 

 the disease; b, p, first indications 

 of disease, uneasy movements, a 

 light discoloration and promin- 

 ence of the tracheae, or turning in cell with back 

 out showing grayish yellow line of intestine; 

 f h, m, q, various stages of disease in coiled 

 larvae, moist, melting, cream-colored, to partly 

 dried cheesy, light-brown coffee color; c, charac- 

 teristic yellow. brown, coiled scale showing tra- 

 cheae; d, e, g, i, 1, o, irregularly coiled and par- 

 tially extended larvae, darker-brown, moist, cheesy 

 with sometimes a tendency to coarse, lumpy, string- 

 ing accompanied often by a strong, putrid, decay- 

 ing-meat odor; n, partially dried-down scale ir- 

 regularly extended on lower side wall or along the 

 side walls in a corkscrew-like position. These 

 are darker-gray brown, rarely adhere to the cell 

 walls to any extent, having the consistency of old 

 rotten rubber and always the putrid decaying-meat 

 odor. These are often found under perforated or 

 discolored cappings, not shown here. 



composition of the remains. Furthermore, 

 and this is an important factor in the rea- 

 soning, the products of growth and decom- 

 position apparently prevent the growth of 

 any other organisms. This condition causes 

 the vegetative rods soon to form the resist- 

 ant resting-stage spores. There are no sec- 

 ondary invaders in American foul brood, 

 and what few variations are seen are due to. 

 differences in the age of the larva at the 

 time of death. 



Reason for Delayed Death in American Foul 

 Brood. 

 li<irinu'< larrac gains entrance to tlie larva 

 generally in the spore stage, in the larval 

 food. This occurs at about the same stage 

 as in European foul brood, while the larva 

 is still coiled in the cell. Only rarely, how- 

 ever, do coiled larvae die. This is appar- 

 ently because it takes some time for the 

 resting-stage spores to germinate into the 



