THE DEVELOPMENT OF AMERICAN FOULBROOD IN 
RELATION TO THE METABOLISM OF ITS CAUSATIVE 
ORGANISM 
By A. P. Sturtevant, 2 
Agricultural Assistant , Bee Culture Investigations, Bureau of Entomology , United 
States Department of Agriculture 
INTRODUCTION 
American foulbrood is one of the two serious diseases affecting the brood of 
the honeybee. The specific cause of this disease is a pathogenic, spore-forming 
microorganism, known as Bacillus larvae. The occurrence of this organism in 
uniformly pure culture, accompanied by the gross effects of its activity, as mani¬ 
fested by the characteristic appearance and age of the diseased and dead larvae, 
differentiates American foulbrood from the other serious brood disease of bees, 
European foulbrood. The latter disease is caused by an entirely different non¬ 
spore-forming organism, Bacillus pluton , which causes a different manifestation 
of gross symptoms, complicated by the action of various secondary invaders. 
Certain limited facts concerning the characteristics of the various types of 
bacteria concerned in causing or associated with these brood diseases have been 
studied, from which various practical applications have been derived. As has 
been stated by Phillips (89)*, “Bacteriological studies of bee diseases have been 
useful to practical beekeepers in explaining the reasons for success or failure 
with various treatments attempted. These studies have been especially impor¬ 
tant, however, because through them methods of laboratory diagnosis of the 
different diseases have been worked out.” 
Advancement in knowledge concerning the etiological and biochemical rela¬ 
tionships of the brood diseases, particularly concerning differences in charac¬ 
teristics as related to gross symptoms, has been limited, however, because of the 
peculiar growth requirements of the causative organisms. There are funda¬ 
mental differences between American foulbrood and European foulbrood, par¬ 
ticularly as to characteristics of development, which, although recognized, have 
not been adequately explained by the incomplete data so far obtained on the 
metabolism of the causative organisms. 
The present investigation was undertaken to obtain further data concerning 
the growth requirements of Bacillus larvae , the cause of American foulbrood, by 
which to explain these differences in the symptoms and development of the two 
diseases. Through improved methods of cultivation, a study has been made of 
factors concerned in the metabolism of Bacillus larvae correlated with certain 
hitherto unrecognized biochemical factors associated with the metabolism of the 
normal honeybee laj*va. The results obtained add materially to the knowledge 
of the biology of the brood diseases. 
Acknowledgments are due to Dr. E. R. Whitmore, professor of bacteriology and preventive medicine 
of the George Washington University, for much valuable advice and many suggestions, and to Dr. E. F. 
Phillips, apiculturist, Bureau of Entomology, United^States Department of Agriculture, under whose 
direct supervision this work was done. Presented in part satisfaction of the requirements for the degree 
of doctor of philosophy at the George Washington University, April 21, 1923, This work was completed 
April 10, 1923. 
* Reference is made by number (italic) to “Literature cited,” p. 165-168. 
Journal of Agricultural Research, 
Washington, D. C. 
(129) 
Vol. XXVIII, No. 2 
Apr. 12, 1924 
Key No. K-128 
