irj 18, 1918. U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF ENTOMOLOGY CIRCULAR No. 169. L. O. HOWARD. Enlomolotiirt »nd Chief ol Burcu. SACBROOD, A DISEASE OF BEES, ny G. V. WHITE, M. I).. Ph. D., WMHIN^TON : GOVERNMENT PRINTING OFFICE ! lilt BUREAU OF ENTOMOLOGY. L. O. Howabd, Entomologist and Chief of Bureau. C. L. Maklatt, Entomologist and Acting Chief in Absence of Chief. R. S. Clifton, Executive Assistant. w. F. Tastet, Chief Clerk. F. H. Chittenden, in charge of truck crop and -stored product insect investigations. A. D. Hopkins, in charge of forest insect investigations. W. D. Hunter, in charge of southern field crop insect investigations. F. M. Webster, in'charge of cereal and forage insect investigations. A. L. Quaintance, in charge of deciduous fruit insect investigations. E. F. Phillips, in charge of bee culture. D. M. Rogers, in charge of preventing spread of moths, field work. Roll*. P. Currie, in charge of editorial work. Mabel Colcord, in charge of library. Investigations in Bee Culturj . E. F. Phillips, in charge. G. F. White, J. A. Nelson, experts. G. S. Demuth, A. H. McCray, N. E. McIndoo, apicultural assistants. D. B. Casteel, collaborator. Pearle H. Garrison, preparator. ii Circular No. 169. ImatA Jtnoarj 16, 1013. United Stales Department of Agriculture, BUREAU OF ENTOMOLOGY. L. O. HOWARD, Entomologist and Chief ol Bureau. SACBBOOD, A DISEASE OF BEES. r.\ G, I. White, .\i. i >.. rii. n. Expert m Bacteriotooy, l\ ll:ol>l < I l(i\. The purpose of this preliminary paper i- to disease briefly a dis- ease, which has been recognized by the bee keeper- for many years as dead brood, that i- different From foul brood. Sacbrood, therefore, is no new disease. Samples of it have been received from all the States except three, together with samples from Canada. This disease really has had no name. In recent years many bee keepers have by mistake spoken od it a- " pickled brood." The pickled brood a- William R. I low aid describes it. however, i- a \ei\ different disease. Before considering sacbrood it might lie well to explain briefly what is meant by pickled brood. l'l< SUED BBOOD. In 1S!)C> William R. Howard, of Texas, wrote a paper in which he describes a disease of bees that he call- " pickled brood." He de- clared in his paper that the disease was caused by a fungus to winch he gave the name Aspergillus pottirtf. In 1898 he wrote a 9econd paper in which he says that the fungus may attack not only the larvae and pupa? but adult bees a- well. M i.i— en in 1906 mentioned a disease of bees which he says is caused by a fungus Btated by him to he similar to Aspergillus ftavus ami easily isolated from the larva', pupae, and adult bees affected by the disease. These two men. then. Howard and Maa—en. have each written of a disease of bees which they believe to he caused by a fungus. By each it is claimed that the fungus can attack adult bees a- well a- the larva? and pupa'. Howard named the disease which he mentioned "pickled brood," and bfaassen referred to the disease which at- 1 This .-irrui.ir will be followed by ii bulletin ..f thi< bureau in which this d be treated more fully. 2 SACBROOD, A DISEASE OF BEES. tracted his attention as an " aspergillusmycosis in bees." The dis- eases, as described by Howard and Maassen. then, would be called fungous diseases. II' there are any such fungous diseases of bees in the United States they have not yet attracted the attention of the bee keepers. I base this conclusion upon the fact that during my study of bee disease- there has not yet been received from the bee keepers any sample that could be considered a fungous disease. If future investigations demonstrate that there exists a fungous disease like the one Howard has described, then the name " pickled brood " can be used to desig- nate it. When using the term "pickled brood" in the future the possible disease, condition described by Howard will be meant. A DISEASE OF THE BROOD WHICH IS NOT FOIL BROOD. There is a disease of the brood of bees that has attracted consid- erable attention among bee keepers that is neither American foul brood, European foul brood, pickled brood, chilled brood, nor starved brood. This disorder of the brood has for many years been recognized by bee keepers as being different from foul brood. Doo- little, of America, in 1881 wrote of a disease which he says is similar to and called foul brood but which is not foul brood. He writes that the larvae die here and there throughout the brood comb and that the disease may disappear entirely or it may reappear the next sea- son. Jones, of Canada, in 1883 wrote also of a disease which results in a dying of the brood, with appearances similar to foul brood; but he states that the disease is not foul brood. He says that the bees frequently remove the dead brood and that no further trouble ensues, Simmins, of England, in 1887 wrote of dead brood which he says is not foul brood, and describes the difference in appearance between the brood dead of the disease and brood dead of foul brood. He states, furthermore, that the condition is different from chilled brood and that Cheshire did not find any microscopic evidence of disease in larvae dead of the disease. An editorial in one of the bee. journals in 1892 is of particular interest at this point. The editor wrote that he had recently encountered dead brood which did not seem to be infectious and which lacked two decisive symptoms of the real foul brood, viz. the ropiness and the glue-pot odor. My own study of this dead brood, recognized by the bee keepers as being different from foul brood, was begun in 1902. Eight sam- ples labeled " pickled brood " were received from the bee inspectors of New York State during 1002 and 1003. These samples were ex- amined and were found to be practically free from microorganisms. The results of these examinations were published in January. 1004. Burri. of Switzerland, in 1000 reported the results of the examination of 25 samples of brood material thought by the bee keepers to be BROOD, \ DISEA8E OF B] I 3. diseased. He placed the results of his examinations under the follow- ing headings: "Sour brood," "stinking foul brood," "nonstinking foul brood," and "* < l»-:i « 1 brood free from bacteria." Pour <>f ili«' 25 sample- examined contained dead brood free from bacteria and unac- companied by other diseases. Kiirsteiner, of Switzerland, in L910, in classifying the results obtained from -:i 1 1 1 j »K •- examined by him, made the -nine classification as made by Burri. During the past six 826 samples of this disease have been received by the Bureau of Entomology and diagnosed in it- bacteriological laboratory. There is, therefore, n disorder attacking the brood <>f bees in which brood dies, but in which there has n<>t been demonstrated anj micro- organism to which tlic cause of the trouble could be attributed. For this disease the name of "sacbrood " is here suggested. rm \ \ mi BAI BBOOD. A- stated, my first examination of this dead brood was made in 1902, when samples were received < 1 i :• !_rii<>-«-. I by bee keepers as "pickled brood." The fad was easily determined at thai time that tin- disease could not lie considered n fungous disease and was there- fore not pickled brood. In the past m\ preference has been to refer to this condition only as the " -o-called pickled hrood." Since the <1 i~.:i- t - is not pickled hrood. it will produce less confusion and he more scientific if the term "pickled brood " he entirely omitted in the mime for the disease. Many larvae dead of this disease can he removed from the cell without rupturing their body w;ill. When thus removed they have the appearance of a -mall closed sac. This character suggested the name "sacbrood." The name has the virtue. therefore, of being both appropriate ami brief. l Hi: -1 MPTOM8 "i - v BBOOD. The strength of a colony in which sacbrood is present is frequently not noticeably diminished. When the brood i- badly infected, how- ever, the colony naturally becomes appreciably weakened thereby. The hrood die- after the t imc of capping. The dead larva' are there- fore almost always found extended lengthwise in the cell ami lying with the dorsal side against the lower wall. It is not unusual to find many larva- dead of this disease in uncapped cell-. Such brood, however, had been uncapped by the hee- after it died. In tin- disease the cappings are frequently punctured by the hee-. Occasionally a capping has a hole through it. indicating that the capping itself had never been completed. A larva dead of this disease loses it- normal color and assumes at first a slightly yellowish tint. " Brown" i- the most characteristic appearance assumed by the larva during it- decay. Various shade- are observed. The term "gray" might sometimes appropriately be \i~vA to designate it. The form of the larva <\t'.]'] 4 SACBROOD, A DISEASE OF BEES. of this disease changes much less than it does in foul brood. The body wall is not easily broken, as a rule. On this account often the entire larva can be removed from the cell intact. The content of this saolike larva is more or less watery. The head end is usually turned markedly upward. The dried larva or scale is easily removed from the lower side Avail. There is practically no odor to the brood combs. THE INFECTIOUS NATURE AND CAUSE OF SACBROOD. In the study of samples of this disease received directly from bee keepers no microorganisms have been found, either culturally or microscopically, to which the cause of the disease can be attributed. This fact, together with the fact that the disease often disappears without any great loss to the colony, would tend to indicate that the disease is not infectious. The experimental evidence which I have obtained proves, however, that the disease is infectious. EXPERIMENTAL WORK WITH SACBROOD. Evidence has been obtained by me that sacbrood can be trans- mitted from diseased to healthy brood. Three healthy colonies were inoculated each with diseased material from a different locality, and in each of these three experimental colonies the disease was pro- duced. These results indicated at once that sacbrood is an infec- tious disease. The microscopical and cultural study of the infected and dead brood in these experimental colonies, as in the case of the diseased brood in samples direct from the apiary, failed to show any organism to which the cause of the disease could be attributed. This led naturally to a study of the condition to determine whether or not the virus of the disease was so small that it had not been seen. To obtain evidence on this point material containing the virus was filtered, using an earthenware filter. The three colonies in which the disease had been produced experimentally furnished the disease material for the experiments. Larvae, sick and dead, of sacbrood were picked from the combs, crushed, and diluted with sterile water. This suspension was filtered by the use of the Berkefeld filter. From each of the three diseased colonies a separate filtrate was obtained, which was fed in sirup to healthy colonies. Six colonies were thus fed — two with each of the three separate filtrates. As a result of these inoculations sacbrood with typical symptoms of the disease was produced in all of the six colonies thus fed. One more experiment will be mentioned at this time. In this the diseased brood used was taken from one of the colonies in which the disease had been produced by feeding filtrate. Disease material from this colony was filtered as before and fed to two healthy colonies, BROOD, \ DISE \>i OF BEES. with the result thai sacbr i was produced in each. It might be mentioned here also that other experiments made indicate that the virus i-> killed by the application of a comparatively small amount of heat ■ l ii colonies, therefore, Bacbrood has been produced experiment ally by feeding t<> healthy colonies the virus of this di <;i~c. In B of the 11 colonies the disease was produced by virus that had passed through the Berkefeld filter. The disease, therefore, which bee keepers have for a long time recognized as being different from either American or European foul brood Im^ now been demonstrated to be :in infectious disease that is caused by a filterable \ini-. The conclusion to lx v drawn from thi> work, therefore, is that Bacbrood is an infectious disease of the brood <>f bees caused bj an infecting agent thnt is so small, or of such m nature, ihnt it will l>;i-^ through the pores of a Berkefeld filter. The three principal brood diseases, thru, are now :ill known to be infectious. These diseases are: American foul brood, caused by Hit, illns larvce; European foul .brood, caused by BaciUtu pluton; niitl sacbrood, caused by a filterable virus. Approved : James Wn a »n, S n inn/ of ■ Igrit ultun . Washington, I). ('.. December /" 1912. vnniTioNWL corn- ofthi | ibJ I a pro cured from t ho BupiuuNTXirD- m Of DOCUM mmenl Printing Office, Washington . D. C. .at 5 cents pa copy UNIVfcKSITY OF FLORIDA 3 1262 09216 5090