| 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 In 1929, a Russian worker by the name of Savelyeff (62) made an extensive investigation of the effect of various methods of killing, treating and preserving the chitinized parts of the bee skeleton with special reference to the proboscis. In a comparison of two methods, namely boiling fixation plus preservation in 70% alcohol and direct preservation in alcohol without fixation, he arrives at the conclusion the the differences obtained in a composite measurement of the proboscis (submentum plus mentum plus ligula) are not great enough to be due to any reason other than error in measuring. While the mentum showed an increase over the boiling-fixation method plus preservation in 70% alcohol, the submentum showed a decrease, while the ligula showed no significant dufference in length. Thus, contrary to Gubin, Savelyeff showed that the combined measurement of the three parts showed no significant difference due to the treatment. He agreed with Gubin that the use of a coefficient or constant to correct the length of the proboscis is improbable due to the different behavior of the parts. He differs with Gubin, however, in his conclusion that the correlation among the parts of the proboscis is the same as one would find in an examination of untreated material. Alpatov (2), in 1930, reported the result of an investigation of proboscides preserved and measured in alcohol in comparison with proboscides boiled in a 5% solution of potassium hydroxide. He found that the treatment with potassium hydroxide solution shortened the total length of the proboscis by 2.6%. At the same time he investigated the tongue length of the Mingrel bees (Apis mellifera var. caucasica Gorb.) and showed that this race had the longest proboscis of any of the races of honeybees. In Germany, Gotze (29), in 1927, declared that the probability of error with the Russian technique was so great that it was impossible to obtain correct results. In consequence, he measured the second member of the labial palpi as an estimation of the length of the proboscis. He also made a scientific examination of the ability of the bees to acquire nectar from several varieties of clover. Following the precedent of Ewert, he did not measure the ovary since the nectar stands above it if nectar is present in sufficient quantity. He found that if the nectar rising in the corolla tube reached a depth of 7.25 to 7.5 mm., the bees of one of his colonies, number 47, could regularly acquire nectar, while the rest of his bees could not work red clover unless the nectar rose beyond this point or the bee had a proboscis longer than the mean of its colony. He concluded that, in general, even those stocks having the longest average length of proboscis do not meet the requirements of clover storing ability; that, with each increase in the length of the proboscis, the ability to acquire nectar from red clover increases markedly; and that certain existing varieties of red clover can theoretically be used by those bees having the longest known proboscides. He maintains that a modification of the length of proboscis due to climate factors has yet to be proven by experimental data, in spite of the fact that Russian workers have shown that the length of proboscis seems to decrease going from south to north. In regard to the question of how much better use the longer proboscis will prove to be, we must mention Merrill (42), who, in 1922, investigated the relation of length of proboscis, carrying capacity and colony strength to honey storing ability. He determined that a correlation between length of proboscis alone and storing ability could not be found, but that the length of the proboscis plus carrying capacity and colony strength was highly correlated with yield. He concluded that: (1) there is a distinct correlation between length of proboscis, carrying capacity and the amount of honey stored; (2) there is a distinct relation between the number of bees found in the colony in the spring and the size of the above named physical characters; (3) that while it is very strongly indicated that it would be advantageous to a bee to excel in all three of these physical characters, yet, if she is deficient in one character, the disadvantage may be overcome if she possesses one of the other characters to a marked degree. Hutson (33), in 1926, continued this study, working with small numbers of bees, and confirmed the above results showing that there was no marked agreement between length of proboscis and honey stored, but that there was a marked agreement between the number of bees in a colony and the yield. Higher yields from long-tongued races have been reported rather frequently. In this connection it is well to note that Merrill and Hutson investigated only modifications of one and the same race. Zander (73), in 1919, reported unusually high yields from Caucasian bees in Germany. The constitution of the honey was at the same time totally different, and Zander believed that this race prepared the honey in a different manner since the source must have been the same. Similarly, Tiadmann (67), in 1925, tells how Cirsium oleraceum had been used by the Krain bees while the native Hannover bees could not acquire nectar from this source. According to Gotze (29), other high yields have been reported by conscientious observers such as Tuschoff and Braun in 1927, but whether these yields were based upon length of proboscis or other properties is not known. Furthert contributions to the question concerning the acquisition of nectar from red clover have been presented at intervals over a period of years in this country by outstanding figures such as Folsom (24), Phillips (51), Dadant (17), Demuth (20), Dietz (21), Pammell (48), Robertson (58), Pellett (50), and Burrill (11). Robertson believed that the bees perforated the corolla in order to reach the nectar. Dadant confirmed this statement. Pellett believed that bees could reach the nectar in some of the flower tubes, especially in years of drouth. Pammell observed honeybees on red clover but he did not believe, after measuring the corolla tube, that the tube is shortened enough by drouth to enable the bee to reach the nectar in it. Burrill cited many ways in which the honeybee could acquire nectar from red clover by means of perforations of the corolla tube due to other insects, honeydew secreted by aphids on clover, and sap leaks. |