WARNING TO APIARISTS.
A NEW DISEASE.
In certain Victorian apiaries a peculiar disease, fatal to bees, was discovered last October. Bees affected by the disease were brought under the notice of the Commonwealth alyst, Mr W. Percy Wilkinson. Experiments were conducted, and Mr Wilkinson reported as follows to the Minister, for' Customs:—
several of the dead bees showed that they contained large numbers of an organism which had probably been the cause of death. Inoculation experiments of healthy bees were carried out by Mr Willgerodt, and it was found that the disease was readily transmissible by feeding bees with inoculated food. The results of this investigation lead to the conclusion that the disease observed in Victorian bees is due to an organism known as Nosema apis, first described by Dr Bander, of Erlangen, Germany." Mr Wilkinson says it is evident the disease is widespread in Victoria, and in the circumstances apairists in this State, as well as those in other parts of the Commonwealth, will do well to exercise every care "in combatting the evil effects of a development that might easily ruin the industry. Attention is directed, therefore, to the following instructive paper on the subject, which has been compiled by Mr 11. Beuhne, president of the Victorian Apiarists' Association, and Mr 0. Willgerodt, an officer in the Commonwealth customs laboratory, Melbourne:—
At a meeting of apiarists held in Weisrenfels on 9th August last year JDr Zander, of Erlangen, drew attention to a peculiar disease, which in i recent years has created enormous' havoc amongst bees. The disease is a ! malignant type of dysentery, caused by the invasion of the digestive tracts or the bee by a unicellular animal parasite of oval shape, which multiplies with great rapidity, and invades the intestinal cells in such numbers that practically nothing of the structure of the intestinal wall can be recognised under the microscope. Dr Zander discovered the above organism during 1907 in the intestines of bees suttering from malignant dysentery, 2i J? elieves tha* it ■is a member of the JNosema family, belonging to the group of Microsporidise. The words malignant dysentery" are used here to distinguish this disease from a comparatively harmless malady called dysentery, well known to beekeepers, to which bees are sometimes subject during spring time. Several Nosema species are known occurring as parasites m different animals. One of the best known is Nosema bombycis, which invades the silk .worm, and produces a disease known as "pebrine." This disease is said to have caused the French silk worm industry losses amounting to more than £40,000,000 up to the year 1867. The discovery by Tasteur of a successful method of overcoming this disease has proved ot. inestimable value to the world's silk industry. No means are at present available to enable one to decide with certainty whether the Nosema found in the bee is identical with any ■classified species. The name "Nosema apis" has been given to it by its discoverer in concurrence with Professor Doflein (Munich), one of the best known investigators of this class of organism. ,
The different stages of development of Nosema apis are very simple, but it must be mentioned that this parasite , like the rest of the. group to which, it belongs, will only thrive in living tissue, and not outside the living body of the bee. After it has ■exhausted the intestinal cells of the bee, it becomes surrounded with a sk'n, which protects it from desiccation and enables it to remain a] lyei for a long time outside the body ot the bee. These resistant forms termed spores, are seen in large numbers^ either single or in groups, when the intestine contents of the 'bee which has succumbed to the disease are observed under the microscope. The cells of Nosema apis are of oval shape, strongly refractive, and measure one-twohundredth mm. in length and one-fivehundredth mm. in breadth. While the intestinal contents of healthy bees are reddish and transparent, they become turbid and milky when the Nosema infection is well advanced. This turbid and milky coloration of the intestinal'contents or the bees which have succumbed to the disease is van indication for diognosmg the disease, even without the help of a miscroscope. The infection is spread to other healthy bees by the excreta of diseased bees coming in contact with the food.
This parasite is stated by Dr Zander to be the worst enemy beekeeoers have to contend with, as many thousands of swarms are destroyed by it annually in Europe. The loss caused by it is much larger than that caused by foul brood.
From hives infected by Nosema apis bees may be seen to fall to the ground from the opening of the hive in lar^e numbers; they are unable to. rise from the ground again, and soon die According to the degree of infection, they die either gradually or suddenly in an epidemic manner; the ground before the hives may be frequently STu thl<£- ly oo™*^ with dying bees. • if ultimate fate of swarms thus infected is . complete destruction, as
the queen also becomes infected and perishes.
An epidemic which presented simi- ' lar symptoms to those above dcs- i cribed has recently caused tremendous losses amongst beekeepers on the Isle of Wight, and also in Brazil. In j the diseased bees on the Isle of Wight, j Dr Maiden discovered a baccilius' which he named pestiformis apis, but has so far not succeeded in proving that the bacillus is the cause of the j epidemic.
Dr Zander laid special stress upon; the following measures intended t<> counteract the spread of the disease j caused by Nosema apis:—l. Swarms which are only slightly infected may recover if the queen remains healthy and a good natural increase takes place. 2. The combs, contaminated \ by the excreta of the infected bees | are the main cause of the spread of the disease. It is recommended to transfer swarms infected with malig nant dysentery into clean hives and start them on artificial combs. Any brood combs are placed in such a manner that they can be easily removed after the brood has left them. When opportunity offers, a new queen is substituted, as the queens of these infected swarms frequently die in the following winter. As these hives usually swarm very late, it is best to prevent swarming. The infected hives must be thoroughly cleaned with a solution of carbonate of soda in hot water. The combs should be removed and the bees given every opportunity for building new combs.
The renewal of the combs forms the basis for successfully combatting all diseases of bees.
An organism resembling in all respects the above described Nosema apis has been found by one of us, acting under the direction of the Commonwealth Analyst, in bees from colonies affected by dwindling occurring at many bee farms in Victoria. Several cages of healthy live bees and bees suffering from the disease were examined in October last. The intestines of the healthy bees were found to contain no parasite; in every diseased bee the intestines presented a milky appearance, their contents showing enormous numbers of an organism similar to Nosema apis. Experiments carried out with the object of infecting healthy bees by. feeding them with honey which had been' mixed with $he intestinal contents of affected bees were completely, successful; nearly all the b\ees so inoculated were found dead after two to five days, while a few succumbed in less than 24 hours after inoculation. In all of the bees which died after inoculation, the specific organism was round to be present in large numbers. In many instances the major portion of the intestinal contents of these dead bees resembled a pure culture of the organism. Without the help of the microscope; the disease can be readily diagnosed by the peculiar and milky coloration of the intestinal contents.
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WARNING TO APIARISTS., Marlborough Express, Volume XLIV, Issue 13, 18 January 1910
WARNING TO APIARISTS. Marlborough Express, Volume XLIV, Issue 13, 18 January 1910
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