March 21, 1918J 



NATURE 



47 



BEE DISEASE. 



IN the article which appeared in Nature of 

 August 23, 1917 (vol. xcix., p. 507), upon the 

 above subject, it was pointed out that, as popu- 

 larlv used at all events, the expression " Isle of 

 Wig-ht disease " connotes not so much a disease 

 a group of diseases, due to different organisms. 

 lie cause of this misuse .of the term is the in- 

 iibUity of the honey-bee to express otherwise than 

 by certain simple means the changes wrought on 

 its system by the introduction of various parasites 

 or poisons. The symptoms which are noticed by 

 lay observers, when bees are suffering from any 

 severe attack, are hastily assumed to be charac- 

 teristic of "Isle of Wight disease," and the 

 appearance of such symptoms in another colony is 

 •considered sufficient evidence that the same disease 

 \ present. 



As a result of this misconception thousands of 

 vases have been diagnosed as " Isle of Wight 

 disease" merely because "crawling" or dysen- 

 tery has been observed, while the dwindling of 

 the colony or the death of the entire stock has 

 often been accepted as conclusive proof without 

 any trouble being taken to ascertain whether some 

 other influence has been at work. If the honey- 

 bee were a dangerous pest, the extirpation of 

 which was desired by man for economic reasons, 

 this unwarranted assumption might be of compara- 

 tively little importance, but in the case of a highly 

 valuable insect, one of the very few which are of 

 direct service to man, and which it is to his in- 

 terest to keep alive, the error of thought leads 

 > serious consequences. It appears to have led 

 ime scientific workers to the conclusion that 

 ,osema apis is not the cause of any bee disease, 

 just as it has led unscientific observers to the belief 

 I hat "Isle of W'ight disease" must be the cause 

 I every case of extensive mortality in their 

 ;)iaries, when no other obvious explanation is 

 lorthcoming. From every point of view, there- 

 fore, it is desirable that it should be universally 

 '■ecognised that bees are liable to many diseases, 

 though their macroscropic symptoms are almost, 

 not entirely, identical, and that the only satis- 

 ;tory definition of "Isle of Wight disease" is 

 le "disease caused by Nosema apis." Bee- 

 ;pers should also realise that the presence of 

 is parasite can be determined, in our present 

 ite of knowledge, only by the examination of 

 affected organs of a bee under a microscope 

 high power. As it has been objected to this 

 Inition that certain bees of great resistant 

 ver may harbour Nosema apis in their intes- 

 »es without apparent ill-effects on their system, 

 further definition is needed, and either it must 

 admitted that every bee in which the parasite 

 ^ found is scientifically " diseased, " or a distinction 

 lust be drawn between actual and potential 

 disease, since it is believed that, in certain cir- 

 ^"^iimstances, even resistant parasite-carriers may 

 iddenly, and without ascertainable cause, sicken 

 Mid succumb to an attack. 

 The importance of this definition of " Isle of 

 NO 2525, VOL. lOl] 



Wight disease" becomes clear when its bearing 

 on scientific research into the treatment of bee 

 diseases is considered. During the last six or 

 seven years several remedies or preventives have 

 been tried, and reports on the results of the ex- 

 periments published in the journals devoted to 

 l>ee culture. First it was a coal-tar preparation, 

 then a compound of several well-known and 

 powerful antiseptics, then peroxide of hydrogen, 

 and at the present time "Flavine " is being widely 

 recommended. Each of these remedies has had its 

 vogue for a time, and the columns of the technical 

 Press have been filled with enthusiastic testimonials 

 from bee-keepers who have tried them with ap- 

 parent success, only to be followed at a later date 

 by letters from other bee-keepers who have com- 

 pletely failed to get any good results from their 

 use. It is not suggested that any of these testi- 

 monials were other than genuine, but in view of 

 what has been stated above it is at least regret- 

 table that in no case that can be traced has the 

 experimenter taken the trouble to ascertain by 

 microscopical examination whether Nosema apis 

 was present in the intestines of any of his bees, 

 or, in other words, whether his colonies were 

 really affected with "Isle of Wight disease" at 

 all. The result of such treatment may be satis- 

 factory to the owner of the bees, but it can have 

 no bearing on its value in other equally undeter- 

 mined cases of sickness. 



The neglect to ascertain beforehand whether 

 the causal organism of "Isle of Wight disease" 

 is actually present when the experiment is begun 

 must also invalidate the results in another way. 

 So long as the parasite is present even in a more 

 or less quiescent state, the affected bee is liable 

 to an attack of "actual disease," and complete 

 success cannot be claimed for any treatment unless 

 it can be shown that after a considerable lapse of 

 time the treated bees are free not only from the 

 symptoms of sickness, but also from the parasites 

 which may cause a fresh attack. In many cases 

 statements as to the efficacy of this or that drug 

 have been made within a few days, and even a 

 few hours, of its application, though it is well 

 known to all who have had any experience of bee 

 diseases that bees respond very readily to a 

 stimulus, and may under its influence reassume 

 the appearance of perfect health for a time. The 

 recovery, however, seldom lasts for long, and the 

 influence of the stimulus declines progressively. 

 Results should not, therefore, be published until 

 after a delay of several weeks, during which time 

 the bees should be carefully examined, and as the 

 susceptibility of bees to "Isle of Wight disease" 

 is greatest in the winter it would be better always 

 to postpone judgment in every case until the 

 spring, when the activity of the bees affords pre- 

 sumptive evidence of a cure. Nothing, however, 

 but a careful microscopical examination of several 

 specimens of the treated bees is sufficient to justify 

 the confident statement that a cure has been 

 effected. 



Further investigation into " Isle of Wight dis- 

 ease " is urgently needed, but it should proceed 



