Samman and Gatenby — Acarinc or Isle of Wight Bee Disease. 359 



their nutriment. According to John Rennic it is the feeding of the mites 

 tliat weakens the bee. 



Rennie's (1921) paper (jointly witli Wliite), in the Transactions of the Royal 

 Society of Edinljurgli, lias been sui3erseded by his late memoir (No. 6) published 

 by the North of Scotland College of Agriculture, and entitled "Acarinc Disease 

 Explained."' In the Transactions of the Royal Society of Edinburgh (as well 

 as in Rennie's joint papers) is one by Bruce White on the "Pathology of 

 Isle of Wight IDisease in Hive Bees." White mentions that female mites may 

 advance as far as the secondary tracheae before depositing eggs; in the later 

 stages of attack the mites may attain the small tracheae, the thoracic air-sacs, 

 and the vessels of the head. Regarding the tracheal system. White states that 

 the change in colour of the tube is accompanied by an increasing hardness 

 and brittleness of the parts, which become rigid. In the early stages of attack 

 there may show, here and there, a few fragments of brownish matter, the 

 faeces of the invading adults. Such granules increase in number, finally 

 forming bands upon the tracheal wall. They are brownish or yellowish in 

 colour, and when densely aggregated appear black. 



White also states that such foecal matter may become inhaled into the 

 smaller passages, forming emboli in the tracheoles. 



The muscular system may be visibly affected, the iibres showing atrophic 

 changes ; but the number of such showing these signs is small. This author 

 performed the ingenious experiment of blocking up the stigmata, or openings 

 leading to the tubes, in healthy bees, and found that, in some cases, states 

 resembling the symptoms of Isle of Wight disease were produced. White 

 undoubtedly, in this Way, has added very strong evidence to the view that 

 the acarid is the causative agent of the disease. 



Experiments on infection with Acarapis woodi have been made by Miss Elsie 

 J. Harvey, one of Rennie's assistants. Miss Harvey came to the conclusion 

 that bees wei-e not usually, if at all, infected before emergence from cells. 

 Clean bees placed in a queen cage could be infected if kept in a diseased 

 hive. Miss Harvey showed that experimental infection is not easy to effect, 

 but that the disease is spread by bodily contact between infective and non- 

 infected bees. 



Rennie, after Bruce White's and Miss Hai-vey's discovery of the causative 

 agent of the disease, attempted to classify the mite. He placed it in Canestrini "s 

 genus "Tarsonemus" and gave it the specific name of "woodi" after A. H. E. 

 Wood, a gentleman much interested in apiculture. Rennie's excursion into 

 the treacherous grounds of systematic acarology was not altogether successful, 

 for Hirst has removed this form from the genus Tarsonemus and placed it in 

 the genus Acarapis, which is clasely allied. 



Hirst states that there is no nymphal stage either in Acarapis or Tarsonemus, 

 this being entirely suppressed. This disease is spread by adult mites. 



The Cure or Prevention of Isle of Wight or Acarine Disease. 



We know that the causative organism of this disease is an acarid — the female 

 of which is tracheate, the male non-tracheate. The healthy bees are infected 

 by peripatetic females, which leave the thoracic tracheae of infected bees, and 

 wander into the tracheae of non-infected bees. The acarids live on the 

 haemocoel fluid of the bees. 



The problem is to kill the acarids either (a) in the tracheae, by feeding 

 the bees on some substance which might so affect the haemocoel fluid of the host, 

 as to make it toxic to the parasites; or {b) in the tracheae by some gas o;' 

 fumigaut which might poison the mites without killing the bees themselves; 



