8 



NATURE 



[March 2, 1916 



bees, the spores pass into the dig-estive stomach 

 of the bee before underg-oing any further change. 

 Under the influence of the digestive fluids of the 

 host, the spore coat or sporocyst softens, and from 

 a pore in it a thin, anchoring thread or polar fila- 

 ment is shot out, which attaches the spore tem- 

 porarily to the wall of the bee's gut. Once an- 

 chored, a minute amoeboid germ or amoebula — 

 also termed a planont, because of its power of 

 wandering — emerges from the spore. It creeps 

 about over the surface of the epithelial lining, and 

 finally penetrates in or between cells. There it 

 becomes rounded, loses its power of movement, 

 and grows passively for a time at the expense of 

 the protoplasm of its host. Next, it commences 

 to multiply, and is termed a meront. The nucleus. 

 di\ides into two, and protoplasm collects around 

 each part. The resulting daughter forms separate 

 usually as soon as they are produced, and each 

 repeats the division, a cluster of potential spores, 

 known as sporoblasts, being thus formed. Mul- 

 tiple fission may also occur. Each sporoblast soon 

 secretes a sporocyst and becomes a single spore. 

 Duringf the time that the sporocyst is hardening 

 and becoming opaque, five nuclei are produced 

 within. Two of the nuclei contiol the formation 

 of the coat, one regulates the action of the polar 

 filament, and the other two are the nuclei of the 

 amoebula. These nuclei are not easily seen all at 

 one time, for when their function is fulfilled, all 

 except the two nuclei of the amcebula disappear. 



The most destructive period of the life-history 

 of Nosema apis is the meront stag^e. By the 

 formation of the meront colonies, the dig-estive 

 cells of the bee are rendered useless and the 

 digestive fluids are not properlv secreted. The 

 cells normally are cast off and then burst in order 

 to liberate the digestive fluid. But when they are 

 diseased, food, such as pollen, merely serves as 

 an irritant, and the infected bee succumbs the 

 more easily. 



Infection of bees takes place by the ingestion 

 of spores. When a bee is parasitised, its abdomen 

 is often somewhat distended and the slightest 

 touch is sufficient to produce discharge of bowel 

 contents. The result is that honey, comb, and 

 other bees are spattered with excrement that may 

 contain the spores of Nosema apis. Cleansing 

 operations are immediately commenced by other 

 bees, which by their very cleanliness may con- 

 tract the disease that results in their death. The 

 queen, too, may be infected by her attendants, 

 while the larvae that are fed on infected food may 

 die from the effects of the parasite. Sometimes 

 the larvae may give rise to a race of young bees, 

 perhaps already infected, but usually with im- 

 paired vitality, and thus less capable of resisting 

 infection by way of their food or drink. Water at 

 which bees drink also can be infected with spores. 



Other bees may acquire a tolerance for the para- 

 site and be relatively unharmed thereby. Such 

 infected bees act as parasite carriers, and void 

 Nosema spores constantly in their faeces. Show- 

 ing no external symptoms, they may remain unde- 

 tected in a hive for some time and ultimately cause 



NO. 2418, VOL. 97] 



jll^reat destruction among their fellows. Infected 

 drones also serve to spread the disease by their 

 roving habits, several hives in succession being 

 \'isitecl and polluted by them. 



Humble bees, wasps, ants, and wax-moths that 

 invade hives can also act as disseminators of 

 spores. Human agency is a further aid. The 

 sending away of unhealthy stocks, union of weak 

 ones, and the use of old comb, foundation and 

 equipment from " dead " hives have all contributed 

 to the spread of disease. 



Preventive measures should be vigorously 

 adopted. All hives from which the bees have died 

 out should be closed immediately to prevent rob- 

 bing and thereby the further dissemination of 

 disease by the robbers. As soon as possible all 

 dead bees, quilts, frames, comb, and foundation 

 in the hives should be burned. If the honey pre- 

 sent is extracted from the comb it should be used 

 for cooking purposes only, and not be re-fed to 

 bees. Similarly, if the comb is melted for beeswax 

 the latter should be used for domestic purposes 

 only, and not for making foundation. The in- 

 terior and exterior of the hive should be scorched 

 or charred over with a painter's lamp in order 

 to destroy the spores of Nosema apis. The soil 

 around and under the hives should also be purified 

 by fire. This is easily done by sprinkling petrol or 

 paraffin on the soil and setting light to it. The 

 ground should be well limed. Care should be 

 taken to exclude wasps from hives. These pests 

 were very troublesome in the summer of 191 5, and 

 many weakened colonies, some being convales- 

 cent, were robbed out and succumbed in the battle 

 with wasps. 



Finally, with regard to curative measures, it is 

 known that there are certain drugs that will cure 

 the bees, but their application is inadvisable, since 

 they may poison the honey. Other drugs that are 

 not injurious are known. These are very effective 

 if rightly applied, and if the beekeepers will only 

 help by strict attention to the hygienic and sani- 

 tary methods necessary for the prevention of the 

 disease. Without a due regard to such elemen- 

 tary and essential, but often neglected, sanitary 

 procedures, treatment is useless. A further point 

 is that, as with human disease, there is a point 

 when the malady is too far developed to be capable 

 of cure. The disease needs to be treated in its very 

 early stage, when often in the owner's opinion the 

 colony is healthy. Microscopic examination is 

 necessary to detect the parasite, and such exam- 

 ination should be obtained. Treatment based on 

 observations of external symptoms only is not 

 satisfactory, as the range of expression on the 

 part of the bee is very limited, and is apt to be 

 misleading so far as differentiation of disease is 

 concerned. However, prevention is better than 

 cure, and there is little doubt that if concerted 

 action were taken for the quick destruction by fire 

 of all infected materials the losses among- bees 

 would be enormously reduced, to the great advan- 

 tag-e both of the beekeeper, of the general public, 

 and of the hospitals where honey is much appre- 

 ciated and used. F. 



