Campaniform sensilla have been described from the wings, mouthparts, legs, and other parts of the insect body. These small sense organs were known under several terms until Berlese ( 1909) applied the term  campaniformi  because of their dome, or bell-shaped character. Numerous functions have been suggested for these organs which seem to be stress receptors of some sort. Very few attempts have been made to utilize these sensilla as taxonomic characters

Glass, Arthur W.

Hamrum, Charles L.

Sisson, Vern

English

University of Minnesota, Morris (UMM): Digital Well

Journal of the Minnesota Academy of Science Volume 29 Number 1 Article 28 1961 Campaniform sensilla Patterns on the Wings of Drosophila Charles L. Hamrum Gustavus Adolphus College Arthur W. Glass Gustavus Adolphus College Vern Sisson Gustavus Adolphus College Follow this and additional works at: https://digitalcommons.morris.umn.edu/jmas  Part of the Zoology Commons Recommended Citation Hamrum, C. L., Glass, A. W., & Sisson, V. (1961). Campaniform sensilla Patterns on the Wings of Drosophila. Journal of the Minnesota Academy of Science, Vol. 29 No.1, 240-244. Retrieved from https://digitalcommons.morris.umn.edu/jmas/vol29/iss1/28 This Article is brought to you for free and open access by the Journals at University of Minnesota Morris Digital Well. It has been accepted for inclusion in Journal of the Minnesota Academy of Science by an authorized editor of University of Minnesota Morris Digital Well. For more information, please contact skulann@morris.umn.edu. ZOOLOGY CAMPANIFORM SENSILLA PATTERNS ON THE WINGS OF DROSOPHILA 1 CHARLES L. HAMRUM, ARTHUR W. GLASS and VERN S1ssoN Gustavus Adolphus College, St. Peter Campaniform sensilla have been described from the wings, mouth-parts, legs, and other parts of the insect body. These small sense or-gans were known under several terms until Berlese ( 1909) applied the term "campaniformi" because of their dome, or bell-shaped char-acter. Numerous functions have been suggested for these organs which seem to be stress receptors of some sort. Very few attempts have been made to utilize these sensilla as taxonomic characters. Eastham (1936) did attempt to construct a key based upon the numbers and distribution of gill sensilla for the separation of Caenis nymphs. His success was limited to breaking the genus into what he believed to be related sections. Vogel (1911), Mclndoo (1917), Baus (1937), and Melin (1941) all believed the number and position of the wing campaniform sensilla indicate relationship within the Lepidoptera. Hamrum (1957) surveyed the wing sensilla patterns of 65 families within the Diptera, and found these patterns differed sig-nificantly among the family groups. Within the latter study, it was noted that the white eye mutant of Drosophila melanogaster displayed a wing sensilla pattern markedly different from the wild type of this species. This study was undertaken to test the value of companiform sen-silla patterns as a guide in recognizing Drosophila populations. METHODS. One wing was broken from the thorax of each dried speci-men by applying an insect pin to the extreme proximal region of the wing. The usual pre-mounting treatment consisted of boiling the wing in 95% alcohol for one minute to remove the air from the veins. The wing was then cleared in xylene, and placed in Piccolyte on a glass slide and covered with a cover slip. All veins were searched with a com-pound microscope using 430 magnifications, and if sensilla were found, their numbers and points of occurrence were recorded. The wing veins were designated under the Comstock-Needham system. The proximal portions of the subcosta (Sc) and radius (R) were di-vided into areas for descriptive purposes in order better to locate the sensilla groups occurring on these veins. These sensilla groups are shown in Figure 2. 1 Supported by the Minnesota Dental Foundation, Inc. 240 PROCEEDINGS, VOLUME TWENTY-NINE, 1961 Figure 1. Wing of Drosophila melanogaster showing veins normally bearing campaniform sensilla. All flies used in rearing experiments were reared on standard Dro-sophila media. Experimental crosses were made with single pairs selected from isolated pupae. REARING EXPERIMENTS. This investigation started with a wing sen-silla survey of several mutant strains of Drosophila melanogaster. These results are shown in Table 1. It was quickly evident that the sensilla counts on the bases of R and Sc could not be used. These areas are too often damaged when the wing is removed from the specimen. As Table 1 indicates, nearly all strains show approximately the same sensilla population as the wild type D. melanogaster. How-ever, white eye (Turtox), curved wing, and bifid cut garnet all show more sensilla than normal on the first branch of the radius (Rl). This deviation from the wild type is shown in Figure 2. Emphasis has been placed upon the Rl area for it normally bears 3 sensilla in all species examined. Another variable area, shown in Table 1, is the stem of the radius (R). Hamrum ( 1957) found that the size of the wing in Sarcophaga influences the sensilla population in this area. TABLE 1. Number of campaniform sensilla on the wing veins of mutant strains of Drosophila melanogaster. Sc (subcosta), Sc-h (subcosta and humerus), R (radius). strain Sc Sc-h R Rl wild type (Turtox) 5 1 10-12 3 wild type 5 2 10-12 3 white eye (Turtox) 5-6 1-4 12-14 4-9 white eye (Calif.) 5 2-3 12-13 3 ebony body 5 1-2 10-12 3 II ple 5-6 1 10-12 3 curved wing 5 1-2 11-14 3-6 r9/yf 5 1-2 9-12 3 bifid 5 2 7-12 3-7 scute 5 1-2 8-11 3 shifted 2 5 1-2 7-9 3 net vein 5 1-2 11-13 3 plexus 5 1-2 12-14 3 R4+5 4 4 4-5 4 4 3-4 3-4 3-5 4 4 3 4 4 241 THE MINNESOTA ACADEMY OF SCIENCE D. melanogaster wild D. me lanogaster white eye Figure 2. Base of wing showing greatest campaniform sensilla concentration. This figure illustrates the basic differences in sensilla distribution between wild and white eye strains of D. melanogaster. The larger winged species had the greatest number of sensilla. This observation seems to be also true for Drosophila. Crosses were made using a white eye (Turtox) or curved wing parent with wild or ebony eyes. The progeny showed some variation in Rl sensilla from the wild type. Whenever a curved wing fly was mated with a white eye fly, nearly all Fl individuals examined had more Rl sensilla than either parent. In the F2 and F3 individuals, the Rl sensilla pattern varies from fewer sensilla than either parent to more sensilla than both parents. Another change in sensilla distri-bution was noted in these F2 and F3 hybrids. Five or six sensilla were frequently observed along the course of R4+5. Hamrum (1957) found that 4 R4+5 sensilla is virtually constant for the Drosophilidae and related families. The white eye X curved wing matings seem to indicate that a significant wing sensilla change may occur in a very 242 PROCEEDINGS, VOLUME TwENTY-NINE, 1961 few generations. These experiments further suggest that deviations in sensilla pattern may indicate a reproductively isolated population. A wing bristle abnormality was observed among some of the white eye X curved wing F2 and F3 individuals. These structures often ap-peared to be intermediate between a normal trichoid sensillum and a campaniform sensillum. In other instances they would appear as nor-mal bristles in an area normally occupied by campaniform organs. Lees (1941) described such "intermediate" structures on the veins of the "hairy" wing mutant of D. melanogaster. Lees found the "hairy" wing to have almost twice the normal campaniform sensilla population. The presence of intermediate structures on this wing with profuse trichoid and campaniform sensilla prompted Lees to suggest that the trichoid and campaniform sensilla are homologous structures; The derivation of the various types of insect sensilla from a single basic type has been suggested. Snodgrass (1935) hinted that cam-paniform sensilla may have lost the bristles with the sockets alone remaining. Lees stated that the "hairy" gene is in control of extra bristle production on the wings and thorax of Drosophila. However, our white eye-curved wing hybrids are no more hairy on these parts than the wild type. At this time we are not prepared to explain the presence of these intermediate sensilla or the "out of place" sensilla which appeared in our experimental stock. These experiments, how-ever, do seem to serve as support for Lees idea on homology of the campaniform organs. SENSILLA PATTERNS OF DROSOPHILA SPECIES. The survey of Droso-phila melanogaster wild type and mutants was made from commercial stocks. Therefore it was deemed wise to determine if the cultured wild type had the same wing sensilla pattern as natural breeding wild stock. Four populations of D. melanogaster were trapped at different points in southern Minnesota. One consistant variation between the wild and cultivated stocks appeared in the Sc-h region. The commer-cial stock (Turtox) has only a single sensillum in this region, whereas the wild trapped flies all have two sensilla. Patterson and Stone (1952) have compiled a tremendous amount of information on evolution in Drosophila. Several species groups are treated in detail in this useful work. As is well known, many of the sibling species are very difficult to differentiate. Even chromosome configurations may not serve to· separate some species. Two well known sibling species of the obscura group, D. pseudoobscura and D. persimilis, fit into this category. Several wings of both species were examined. The general sensilla distribution was found to be similar to the wild D. melanogaster except for an occasional extra sensillum on the R4 + 5 in some specimens of D. pseudobscura. Our material was taken from several localities in western U.S. which carries the impli-cation that in some populations the R4 + 5 sensilla pattern may change. This is only a preliminary observation since rearing experiments in-volving these species will be continued. At present we cannot distin-24;J THE MINNESOTA ACADEMY OF SCIENCE guish between all specimens of D. pseudoobscura and D. persimilis on the basis of wing sensilla patterns. Six South American species belonging to the mesophragmatica group were also examined. Brncic et al (1957) studied _this group and prepared a key to separate these species: D. altiplanica, D. vira-cochi, D. gaucha, D. pavani, D. orkui, and D. mesophragmatica. Dr. Brncic generously provided us with dried specimens of the meso-phragmatica species. The wing sensilla pattern of this group is very similar to the North American species studied except for a short row of six sensilla on Sc. Six sensilla on the Sc were encountered only in some D. melanogaster mutants. This observation certainly does not do violence to the belief that the mesophragmatica group is composed of related species. Although this study is somewhat fragmentary in its present scope, it seems to indicate that campaniform sensilla distribution may be a useful indicator for evaluating certain Drosophila populations. No claim is made that sensilla distribution alone indicates close or dis-tant relationship; however, the inclusion of a new character can hardly handicap any phylogenetic study. LITERATURE CITED BAUS, A. 1937. Die Reduktion der Fltigel and Fli.igelsinneskuppeln bei Lepidipteren. Ztschur. f. Morph. u. dkol. der Tiere. 32: 1-46. BERLESE, A. 1909. Gli insetti. Vol. 1. Milano, Societa Editrice-Libraris. BRNCIC, D. and S. K. SANTIBATILDEEZ. 1957. The mesophragmatica group of species of Drosophila. Evolution. 11 : 300-310. EASTHAM, L. E. S. 1936. The sensillae and related structures on the gills of nymphs of the genus Caenis (Ephemeroptera). Roy. Ent. Soc. London, Trans. 85:401-414. HAMRUM, C. L. 1957. Taxonomic significance of certain sensilla on the wings of Diptera. (Unpublished Ph.D. Dissertation). Iowa State University Library, Ames. LEES, A. D. 1941. Homology of the campaniform organs on the wing of Drosophila melanogaster. Nature (London). 150:375. MclNDOO, N. E. 1917. The olfactory organs of Lepidoptera. Journ. Morph. 29:33-54. MELIN, D. 1941. Contributions to the knowledge of the flight of in-sects-Especially of the function of the campanif orm organs and halteres. Uppsala Univ. Arsskrift. 1941, no. 4. PATTERSON, J. T. and W. S. STONE. 1952. Evolution in the Genus Drosophila. New York. The Macmillan Co. SNODGRASS, R. E. 1935. Principles of insect morphology. New York, McGraw-Hill Book Co. VoGEL, R. 1911. Ober die Innervierung der Schmetterlingsfli.igel und i.iber die Bau und die Verbreitung der Sinnesorgane ... Ztschr. wiss. Zoo!. 98:68-134. 244 

Campaniform sensilla Patterns on the Wings of Drosophila

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Campaniform sensilla Patterns on the Wings of Drosophila

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