| A Biometrical Study
of the Influence of Size of Brood Cell Upon the Size and Variability
of the Honeybee (Apis mellifera L.) by Roy A. Grout, 1931 |
| REVIEW OF LITERATURE - PART 1 Naturalists and observers have been interested in the size, shape and types of brood cells of a bee colony for many centuries. These studies date back at least to the fourth century B.C. to that ancient pioneer in the development of science, Aristotle. In a review of the literature of this subject we must also mention such outstanding naturalists as Swammerdam, Reamur, Maraldi and the mathematician, Koenig, who observed the marvelously consistent shape of the cells of the honey comb and studied the mathematics of its structure. According to Ruber (31), Schirach, who discovered that the worker bee was possessed of the same sex as the queen bee, stated that nothing but certain physical conditions, such as a special food and a more spacious lodging, was needed for the worker bee larvae to become real queens. Desiring the support of an eminent philosopher in his contentions, he corresponded with Bonnet, who in turn corresponded with Huber, who confirmed Schirach's results. It was the great naturalist, Huber (32), who, in 1791, at the suggestion of Bonnet, first attempted to investigate the effect of the size of cells upon the size of the honeybee. He removed from a hive all combs containing worker cells, leaving only drone combs. Moths invaded the hive, however, and ruined his first experiment. On his second attempt, he observed that the queen finally oviposted with reluctance in the drone comb, but that on the forth day the bees disappeared from their cells. Upon placing in the hive a frame containing sealed drone brood in small cells, he observed that the bees set about to remove the drone brood from the cells so that the queen might have a suitable place to ovipost. Ruber next attempted to rear worker bees in drone cells by grafting the worker bee larvae in the cells of a drone comb by removing the drone larvae and placing them with 1 day old worker larvae. This experiment was successful, but Ruber, upon examining the pupa in an advanced stage, did not recognize any difference in the size of the bees. He then repeated the experiment using drone larvae instead of worker larvae. This time he observed that the drones reared in the drone cells were larger than those reared in worker cells. Many observers since Huber have conducted similar experiments and have observed the phenomenon of worker brood reared in drone cells sealed with level cappings. Thus, Alley (1), in 1869, records placing a queen and three pounds of bees on drone combs with the result that worker bees were reared in level-capped drone cells. He does not state, however, whether he noticed any changes in the size of the emerging brood. Gundelach, according to Michailov (43), placed a swarm of bees in a glass-walled observation hive on drone comb and observed worker bees emerging from the large cells. Berlepsch (9), in 1876, conducted a similar experiment and confirmed the results of Gundelach. He also cited a similar result obtained by Bessel. Other investigations cited by Michailov (43) were made by Gunther, Klempin, Zarudski, Zesselski, Lehzen and Hanneman, and Buttel-Reepen. Pincot, according to Gillet-Croix (26), investigated the phenomenon at the biginning of the present century and Getaz (25) cites Drory of France and a similar case in Germany. None of the above observers, however, investigated the size of the bee by microscopical examination but depended entirely upon visual examination. Only Zarudski claimed that there was any increase in the size of worker bees due to their rearing in drone cells. The first microscopical examination of the chitinous parts of worker bees reared in drone cells was conducted in 1901 by Martynov (41), who measured 100 proboscides of bees from the apiary of the Moscow Institute. He determined that the average length of proboscis of worker bees emerging from normal worker cells was 6.06 mm., while the length of proboscis of those emerging from drone cells was 7.01 mm., showing an increase of 0.95 mm. A similar and more extensive investigation was undertaken by Michailov (43), in 1925, who chanced to find in one of his colonies a drone comb containing worker brood sealed with level cappings. Taking advantage of this opportunity, Michailov, who had previously stated that there was no great difference in the size of worker bees reared in drone cells, made a microscopical examination of 6 characteristics of 200 bees, 100 taken from the drone comb and an equal number from a normal brood comb, taken at approximately the same time. He determined by statistical methods that the bees reared in drone cells were significantly larger than their worker-cell sisters and drew the following conclusions in this respect: 1. That worker bees reared in drone cells weigh 11.36% more than worker bees reared in worker cells. 2. That the proboscis increases 4.83% in length due to the effect of the larger cells. 3. That the increase in the size of cell gives a corresponding increase in the size of the right fore wing, an increase in length of 2.69% and an increase in width of 2.06%. 4. That the increase of the size of the cell causes an increase in the sum of the widths of the third and fourth tergites of 4.37%. 5. There is no significant differences in the average number of hooks on the right hind wing between the two groups of bees. 6. That the bees reared in the drone cells are decidedly more variable than their worker-cell sisters except in the case of the number of hooks on the right hind wing where the variation is consistant in both groups and therefore unrelated to size of cell. A further pursuit of the literature relating to the effect of the size of the brood cell upon the size and variability of the honeybee leads into several more or less distinct controversies and studies which bear upon the subject from various angles. The first of these controversies concerns itself with an extensive discussion of the length of proboscis and its relation to honey storing ability with special reference to ability to forage upon and pollinate red clover (Trifolium pratense). The second controversy has to do with the effect of the age of the brood comb upon the size of the honeybee. Both of the above controversies have influenced and have operated to bring about a controversy concerning the use of artificial foundation with an enlarged cell base. The last controversy is concerned largely with the study of the variability of social insects due to the variability of the brood cells. Since the above four controversies occurred at approximately the same time, the writer feels that the best method of approach to a review of their literature is to discuss each subject separately. |