University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange
Masters Theses Graduate School
6-1971
Elevational Studies of Silphidae (Insecta: Coleoptera) in Southeast Tennessee
Barry Charles Lumpkin University of Tennessee, Knoxville
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Recommended Citation Lumpkin, Barry Charles, "Elevational Studies of Silphidae (Insecta: Coleoptera) in Southeast Tennessee. " Master's Thesis, University of Tennessee, 1971. https://trace.tennessee.edu/utk_gradthes/4237
This Thesis is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Masters Theses by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council:
I am submitting herewith a thesis written by Barry Charles Lumpkin entitled "Elevational Studies of Silphidae (Insecta: Coleoptera) in Southeast Tennessee." I have examined the final electronic copy of this thesis for form and content and recommend that it be accepted in partial fulfillment of the requirements for the degree of Master of Science, with a major in Wildlife and Fisheries Science.
Arthur C. Cole, Major Professor
We have read this thesis and recommend its acceptance:
J.N. Liles, R.R. Schmoller
Accepted for the Council: Carolyn R. Hodges
Vice Provost and Dean of the Graduate School
(Original signatures are on file with official studentecor r ds.) /,/
May 4, 1971
To the Graduate Council:
I am submitting herewith a thesis written by Barry Charles Lumpkin entitled 11Elevational Studies of Silphidae (Insecta: Coleoptera) in Southeast Tennessee." I recommend that it be accepted for nine quarter hours of credit in partial fulfillment of the requirements for the de gree of Master of Science, with a major in.Zoology.
We have read this thesis and recommend its acceptance:
Accepted for the Council:
Graduate Studies and Research ELEVATIONAL STUDIES OF SILPHIDAE (INSECTA: COLEOPrERA) IN SOUTHEAST TENNESSEE
A Thesis
Presented to
the Graduate Council of
The University of Tennessee
In Partial Fulfillment
of the Requirements for the Degree
Master of Science
by
Barry Charles Lumpkin
June 1971 ACKNOWLEDGEMENTS
The author wishes to express his sincere appreciation to his major professor, Dr. Arthur C. Cele, for his patient guidance and scholarly criticism in the preparation of this manuscript. Thanks are also given to the other members ef the author's advisory committee, Dr.
J. N. Liles and Dr. R. R. Schmoller, for their editorial advice and technical assistance.
Additional thanks is extended to the Great Smoky Mountains
National Park and staff for its valuable assistance in carrying out this project, and for the use of the park insect collection as an aid in identification. Also thanks to the Department of Zoology and Ento mology, The University of Tennessee, Knoxville, for providing a re search vehicle.
ii 97�663 ABSTRACT
During the period of June 17-December 2, 1970 baited pit-fall traps were used to collect 3467 specimens of Silphidae and related car rion frequenting Coleoptera at varying altitudes (800-6500 ft. ) in south east Tennessee. Ten species of Silphidae and representatives of five other families of beetles (Carabidae, Staphylinidae, Histeridae, Scara baeidae, and Trogidae) were consistently collected from the traps during the study period, The genus Nicrophorous appeared to occupy the higher elevations in the study area while the genus Silphidae occupied the lower elevations. !· marginatus and!· hydrophiloides appeared to have their elevational centers at higher altitudes than those found in the study area. The population peaks for!· vespilloides, !• orbicouis, li• tomentosus, and�. americana were reached in late summer. !· margin atus, !· pustulatus, !• surinamensis, �. noveboracensis, and�. inegualis appear to have reached their population peaks before this study began.
The Carabidae and Staphylinidae exhibited three centers of elevational distribution (800, 2000, and 5000 ft.). The Histeridae exhibited two elevational peaks (800 and 1000 ft.), while both the Scarabaeidae and Trogidae only exhibited one peak each (900 and 1000 ft.). The Histeridae,
Scarabaeidae, and Trogidae appear to reach their population peaks in late summer, while Carabidae and Staphylinidae appear to have reached their population peaks before this study began.
iii TABLE OF CONTENTS
CHAPTER PAGE
I. INTRODUCTION. .. . 1
II. PROCEDURE . 3
Location of Study Area. 3
Materials and Methods . 12
Microclimatic Conditions of the Study Area. . 16
III. RESUL_TS • 23
Identification. 23
Elevational Centers of Distribution of the Silphidae. . 26
Seasonal Succession of the Silphidae. . 26 Notes on Related Coleoptera . . . . 30 DI. DISCUSSION. 38 v. SUMMA.RY . . . 44 LITERATURE CITED. 46
VITA. 50
iv LIST OF TABLES
TABLE PAGE I. Altitude and County-State Locatien of Trap Sites •• . . . . 6 II. Means (Degrees F.) of Ground Temperatures for Indi- vidual Traps and Trap Sites June 17 Through December 2 •• 18
III. Means (Degrees F.) of Air Temperatures for Individual
Traps and Trap Sites June 17 Through December 2 ••• 21
rJ. Total Number of Coleoptera Cellected in Carrion Baited Traps June 17 Through December 2 ...... • . . . . 24 v. Total Number of Silphidae Collected in Carrion Baited Traps June 17 Thr0Ugh December 2 ...... • • � . . . 24 VI. Numbers of Specimens of Silphidae Collected from A and B Traps at Each Trap Site June 17 Through December 2 . - . • 27
VII. Centers of Elevational Distribution for the Silphidae. . • 0 29
VIII. Comparison of the Numbers of Silphidae Collected During
Three Time Periods 0 • 0 e e • • e • ...... 31 IX. Numbers of Specimens of Related Coleoptera Collected from
A and B Traps at Each Trap Site June 17 Through
December 2 •••••• i •••••• ...... 33 X. Comparison of the Numbers of Related Coleoptera Collected
During Three Time Periods., • • • • • Q • • • • • • • • • • 36
V LIST OF FIGURES
FIGURE PAGE 1. Map of Study Area Showing Numbered Trap Sites Represented by X Marks. Small Insert Map Shows Study Area in Rela- tion to Tennessee•• v •••••••••••• ...... 5 2. Average Drop in Mean Ground Temperature (Degrees F.) Per Trap Site as Elevation is Increased ••••• •• • . . . 20 3. Average Drop in Mean Air Temperature (Degrees F.) Per Trap Site as Elevation is Increased. • . . . . • . • . . . • . • 22 4. Elevational Data for N. vesJ2illoides (-) and S. americana (- ---) • . . . . . • • . . . • • • . . . . • . • • . . . . • 28 5. Elevational Data for!• orbicouis (-)and!• tomentosus
E- --�) • e • • e • e • • • 0 • 0 0 • • • t • • ...... 28 6. Elevational Data for !•margina tus (-) and !• J2UStulatus
t'-- � ...... 0 • ' ...... 28 7. Elevational Data for N. surinam.ensis (-)and!•hydro
philoides � ---) • • • • D f 8 e e O e • e • 0 0 e • e • • • 28 . ' 8. · Seasonal Population Trends of Silphidae for Study Period June 17 Through December 2, !i� vespilloides (----�, !• orbicouis E-· -·), !• tom.entosus (-··-�, !• marginatus
<--L !· pustu1atus (...... ), [9 americana �---L !· surinam.ensis (-•.-), and !• hydrophiloides (- - • �. • . . . 32
vi vii
FIGURE PAGE
9. Elevational Data for Carabidae (-), Staphylinidae E- - --L
and the Histeridae (• ••.•) • • ' • 0 • 0 • • • 0 • • . . . . . 34 10. Elevational Data for Scarabaeidae (--) and Trogidae �--� 34
11. Seasonal Population Trends of Related Coleoptera for Study
Period June 17 Through December 2, Carabidae (-),
Staphylinidae (----), Histeridae (• • • -�, Scarabaeidae E-·-. -, ,
and Trogidae (-.. -�• ...... • • • 41 37 12. Centers of Elevational Distribution for Silphidae••••••• 40 CHAPTER I
INTRODUCTION
The Silphidae (Coleoptera) have been universally recognized by researchers as carrion related insects, Many superstitions and false ideas have been passed down from generation to generation concerning these active little insects (Abbott, 1927a, Fabre, 1899) , Enormous amounts of information on these insects has appeared in scientific journals for quite some time. One of the earlier papers by C. U. Clark
(1895) noted the feeding habits of these beetles, Further literature review reveals that almost all of the research that has been, and is being done on the Silphidae concerns their food locating and feeding habits (Steele, 1927; Walsh, 1933; Cole, 1942; Shubeck, 1968). Al though this seems to be the more important aspect of the relationship of silphids to man, other ecological factors need to be carefully studied in order to better understand these insects.
One such factor is the elevational relationships of the Silphidae.
It is known that there are many changes in environmentai infiuences (weather, soii, vegetation, etc.) as elevation increases or decreases, Likewise, the insect types should change along with these environmentai influences. Research on summer foliage insects of the Smoky Mountains of Tennessee by R. H. Whittaker in 1952, showed definite distributional patterns with relation to elevation in many groups of insects. Although ranges of most of the insects studied during this project overlapped tre mendously, centers of species distribution seemed to appear at various 1 2 elevations. Walker (1957) studied arthropods associated with decaying materials in our habitats of Middle Tennessee, but altitude was not a factor studied. Walker used different types of bait, and found that the degree of difference in collections from var ious habitats was quite large. G. F. Bornemissza (1957) studied the arthropod succession of carrion in Western Australia. Five different stages of carcass decompo sition were recognized, and these were correlated with the animal com munities occupying them. In the summers of 1962 and 1963, Jerry A.
Payne of the Radiation Ecology Section at Oak Ridge, Tennessee, found that a definite ecological succession occurred among the fauna of car rion, Several species of Silphidae appeared in his collections, but as with other researchers his work was done in a limited area of elevational variance, the average elevation being 750 to 850 feet above sea level.
In this paper I am presenting data on ten species of Silphidae which are common to southeast Tennessee. By the incorporation, with certain modifications, of the successful collection techniques of car rion related insects used by the forementioned researchers and others, such as Milne (1944); Howden (1950); Reed (1958); and Shubeck (1968, 1969), I attempted to find elevational centers of distribution for these ten species of silphids. Also included in this paper is a brief taxo nomic description of the species of Silphidae which were collected, a short study of the seasonal succession of the Silphidae in the study area, and notes on five other families of carrion-related or frequented
Coleoptera which were collected during the study period. CHAPTER II
PROCEDURE
Location of Study Area
The Smoky Mountain National Park and surrounding area in south east Tennessee afforded an excellent opportunity for this type of study.
Various elevations up to 6500 feet above sea level with vegetational changes similar to those found from Tennessee to Maine are exhibited and easily accessible to the researcher. The mountains themselves are part of the Blue Ridge Province (Fenneman, 1938), the Great Smoky
Mountains being the most rugged and highest of the northern range, the
Unakas, of this province. The rocks of these mountains are meta sedimentary of the Cambrian or late Pre-Cambrian age {Kieth, 1902;
Shose, 1949; King, 1949), and are complexly folded without great differ ences in hardness, Parent materials of soils in the range areas are fairly uniform, except for the limestones occurring in some of the coves or valleys at low elevations. The Smokies have existed as moun-. tains for perhaps sixty million years, and supported forests since the early Tertiary (Cain et al. , 1937; Cain, 1943). Because of the age and maturity of the mountains, their vegetational cover is nearly continu ous. Most of the vegetation which has not been recently disturbed is climax-stable and mature for its site {Whittaker, 1952). The variety of vegetation in the Smoky Mountains is perhaps as great as that of any comparable area of mountains in the United States. The 3 4 central relation of the Southern Appalachians to the Eastern forests as historical refuges and centers of existing distributions was early recognized (Adams, 1902) and has been carefully developed by Braun
(1935a, 1938, 1941, 1947, 1950). The remainder of the study area was located in the Great Valley area southeast of Knoxville, Tennessee. This consists mainly of crop or pasture land with mixed mesophytic forests.
Trap site 1 was located on The University of Tennessee Cherokee
Farm, Knoxville, and trap site 10 was located at Clingman's Dome in the
Great Smoky Mountains National Park. Straight line distance from trap site 1 to trap site 10 was approximately 80 miles (Figure 1) . An in crease in elevation beginning with site 1 was set up in site selection
(Table I).
Descriptions of the individual trap sites are as follows (refer to Figure 1 as needed):
Trap site!. (800 feet above sea level)--locate� approximately
0. 5 miles south of the Knoxville city limits on The University of Tennessee Cherokee Farm. Approximately 0.5 miles east of U. S. 129 on
Cherokee Trail. Vegetation consists primarily of mixed mesophytic woodland. The trees were of medium density. Ground cover was rather sparse, shaded areas being primarily covered with Japanese Honeysuckle
(Lonicera japonica Thumb.), and open areas with Broom-sedge (Andropogon virginicus L. ) . Leaf litter layer was approximately 0.5 to 1 inch thick. --- � w-�•1 4' Mtn. \,, �r Se�{rvil!e � 'I>- \,,Sla te(Knobs @ • •"' • t·-;.: <;;--> o,...\ � .A, ) r G. .J"-----, ' • 11 \1,...... '-./-"V - ·c I .
I"""" ,.,./ � '-' " 1 Pium,n C.n
,T----L----;--·ENNES SEE 1 ! ,,,J� I NOR1·H •�AllOLINA Figure 1. Map of study area showing numbered trap sites repre I •".i-;1k CJ1 sented by X marks. Small insert map shows study area in I relation to Tennessee. ,..,______6
TABLE I
ALTITUDE AND COUNTY-STATE LOCATIONS OF TRAP SITES
Site Number Altitude Ceunty-Sta.te l 800' Knox, Tennessee
2 900' Blount, Tennessee
3 960' Blount, Tennessee
4 1000' Blount, Tennessee
5 2000' Sevier, Tennessee
6 3000' Sevier, Tennessee 1 7 4000 Sevier, Tennessee 8 5000' Sevier, Tennessee 9 6000' Swain, N. Carolina
10 6500' Swain, N. Carolina 7
Trap site� (900 feet above sea level)--55 degrees 50 minutes N latitude, 85 degrees 56 minutes W longitude. Located approximately 9 miles southeast of the Knoxville city limits on The University of Ten nessee Farm northwest of Rockford, Tennessee. Vegetation consists pri marily of 4 acres of mixed mesophytic woodland surrounded by open pas ture land. The site has a well-developed herb stratum and low shrub coverage. Leaf litter is approximately 1 to 2 inches thick, and the site is located on a gentle southeast facing slope.
Trap site� (960 feet above sea level)--55 degrees 44 minutes N latitude, 85 degrees 48 minutes 50 seconds W longitude. Located approx imately 0.4 miles northwest of Walland, Tennessee; 200 feet west of
Tennessee State Highway No. 75. Vegetation consists primarily of Oak
(Leucobalanus), Maple (Aceraceae), and Flowering Dogwood {Cornus florida L. ). The site has medium shrub density with 50 percent ground coverage by Kudzu Vine (Pueraria lobata). Leaf litter is 1 to 2 inches thick, and the site has a gentle southeast facing slope.
Trap site! (1000 feet above sea level)--55 degrees 41 minutes
N latitude, 83 degrees 42 minutes 30 seconds W longitude. Located approximately 0.2 miles north of the Great Smoky Mountains National
Park boundary; approximately 400 feet northeast of Tennessee State
Highway No. 75. The trap site is appr0ximately 2. 5 miles southeast of
Townsend, Tennessee. Vegetation consists primarily of young Oak
{Leucobalanus), Flowering Dogwood (Cornus florida L.), White Pine
(� strobus L. ), and Sugar Maple {� saccharum Marsh, ) • Open 8 areas of Broom-sedge (Andropogon virginicus L.) into young pine stand.
Site has a thick shrub cover and leaf litter approximately 1 to 3 inches
thick. Located on a gentle southwest facing slope. The Little River is located approximately 200 feet southwest of the trap site.
Trap site§. (2000 feet above sea level)--35 degrees 41 minutes
30 seconds N latitude, 83 degrees 34 minutes W longitude. Site located approximately 300 feet from Tennessee State Highway No. 73, and approx imately 0.6 miles east from Laurel Falls parking lot in the Great Smoky
Mountains National Park, Laurel Falls parking lot is approximately 3 miles west of the Sugarlands Visitor Center on Tennessee State Highway
No, 73. Vegetation consists mainly of Sweetgum (Liquidambar styraciflua
L.), Flowering Dogwood (Cornus florida L.), Red Maple (Acer rubrum,L.), and Black Locust (Robinia pseudoacacia L.). Kudzu Vine is present, but only in small quantities. Herb coverage is slight, canopy cover is
quite thick with a few open areas of sunlight occupied by Blackberry,
Broom-sedge (Andropogon virginicus L.), and Japanese Honeysuckle (Loni
� japonica Thumb.). Shrub cover is slight, with leaf litter approx
imately l to 2 inches thick. Site is located on a gentle northeast facing slope. Trap�� (3000 feet above sea level)--35 degrees 37 minutes 30 seconds N latitude, 83 degrees 34 minutes W longitude. Located
approximately 400 feet northeast of U. S. 441, 0.6 miles northwest of
the Chimneys Campground in the Great Smoky Mountains National Park.
Chimneys Campground is approximately 4.5 miles southeast of the Sugar
lands Visitors Center on U. S. 441. Site 6 represented a typical Cove 9
Forest of the Smoky Mountains area. The principle canopy trees are
Yellow Buckeye (Aesculus octandra Marsh.), Silverbells (Halesia monti
�), White Basswoods (Tilia heterophylla Vent.), Sugar Maples (Acer
saccharum Marsh.), and Eastern Hemlock (Tsuga canadensis Carr.). This
Cove Forest, of the mixed mesophytic grouping, resembles the ancient Arctotertiary forests, and their affinities have been indicated exten
sively by Braun (1941, 1947) and Cain (1943). The canopy is far above
the rich herb carpet, with little intervening undergrowth. The leaf
litter is 1 to 3 inches thick, and the site has a gentle southwest
facing slope. Large boulders are common throughout the site area, Trap site l (4000 feet above sea level)--35 degrees 37 minutes N latitude, 83 degrees 25 minutes W longitude. Located approximately
400 feet northeast of U. S. 441 across the west prong of the Little
Pigeon River (sometimes referred to as the Oconaluftee River), and
approximately 1,2 miles southeast of the Alum Bluff Cave parking lot.
The Alum Bluff Cave parking lot is approximately 8.25 miles southeast
of the Sugarlands Visitors Center on U. S. 441. This site is another Cove Forest of the mixed mesophytic grouping. Vegetation consists ma.inly of Yellow Buckeye (Aesculus octandra Marsh.), Sugar Maple (Acer saccharrum Marsh.), Eastern Hemlock (Tsuga canadensis Carr.), Yellow
Birches (Betula allegheniensis Britten), Beeches (Fagus grandifolia Ehrh), and a few other varieties. Woody undergrowth is well developed with shrubs and many small stems of Mountain Maple (Acer spicatum Lam.). Herbaceous cover is very compact, and leaf litter is 1 to 2 inches 10 thick. Approximately 200 feet southeast of the trap site is the Little
Pigeon River which has a width of approximately 50 feet. The site is located on a gentle southwest facing slope.
Trap�� (5000 feet above sea level)--35 degrees 36 minutes 30 seconds N latitude, 83 degrees 24 minutes 30 seconds W longitude.
Located approximately 200 feet north of U. S. 441 at Newfound Gap in the Great Smoky Mountains National Park. Newfound Gap is approximately ll.5 miles from the Sugarlands Visitors Center on the Tennessee and
North Carolina border. This trap site is part of an Eastern Hemlock forest, a stand heavily dominated by Hemlock (Tsuga canadensis Carr. ), with some Rhododendron (Rhododendron maximum L. ) undergrowth, and a very sparse herb stratum. Large Hemlock stems strongly dominate the canopy, with some deciduous trees such as Yellow and Sweet Birch (Betula lenta
L.), and Silverbell. Leaf litter, mainly of Hemlock, is 0. 5 to 1 inch thick. The site is located on a gentle northwest facing slope.
Trap�� (6000 feet above sea level)--35 degrees 33 minutes
30 seconds N latitude, 83 degrees 33 minutes 30 seconds N longitude. This site is located approximately 100 feet off the Clingman's Dome road 0.16 miles north of the Clingma.n' s Dome parking lot. The Clingman's Dome parking lot is approximately 4.5 miles southwest of Newfound Gap. Vegetation is of the Red Spruce-Fraser Fir forest, south slope type, with a much denser canopy than site 8, and very sparse undergrowth.
This site is located on a steep south slope at 6000 feet elevation.
Spruce-Fir forests are absent from the southwestern half of their range, their survival of the xerothermic period apparently having been dependent 11
on the peaks over 6000 feet in the northeast half of their range
(Whittaker, 1948). The proportion of Fir increases toward the higher
elevations, and the more mesic sites (Whittaker, 1952). This type of forest is often referred to as "Canadian," but because of its high
endemism (Cain et al. , 1937), may be considered a member of the Spruce
Fir forest system of North America. This system is comparable in dis
tinctiveness to the subalpine forest of western ranges (Oosting and
Billings, 1951). The site is almost bare of undergrowth, with total
coverage of the equivalent layers under 20 percent. Red Spruce (Picea
rubens Sarg. ), and Fraser Fir (Abies fraseri Poir.) are dominant with
some small Yellow Birch (Betula alleghaniensis Britton). Leaf litter is approximately 0.5 to 1 inch thick.
Trap site 10 (6500 feet above sea level)--35 degrees 33 minutes
10 seconds N latitude, 83 degrees 33 minutes 40 seconds W longitude.
This site is located approximately 100 feet northeast of the Clingman's
Dome trail; 0.75 miles from the Clingman's Dome parking lot. The Cling
man's Dome parking lot is approximately 4.5 miles southwest of Newfound
Gap. Vegetation is of the Red Spruce-Fraser Fir forest, south slope type, as found in trap site 9, but with fewer Yellow Birch present.
There is a thick ground cover of ferns and mosses, with areas open to sunlight being occupied mainly by Blackberry. The canopy cover of the
shaded areas is almost complete, Very few intermediate shrubs are to
be found. Hobblebush is also present under the dense canopy. Leaf
litter is quite thick, forming a matting 2 to 4 inches deep. The site
is located on a very gentle south slope. 12
Materials and Methods
The collections which are reported here were made between June 17 and December 2, 1970. Thirty pit-fall traps were set out at ten trap sites of increasing elevation. Each trap site had one pit-fall trap located where it received direct sunlight throughout the day (designated trap A). A second pit-fall trap (designated trap B) was located where it was shaded throughout the day, and a third (designated trap C) un baited was located centrally between the former two traps to act as a control. The idea to use one-gallon food cans was taken from a research study on carrion beetles which was done in the Hutchenson Memorial
Forest in New Jersey (Shubeck, 1968). The cans were buried with the open end flush with the surface of the soil. I modified Shubeck's trap by adding several drainage holes in the bottom of the can, and a sheet of hardware cloth over the open end which was wired down to the trap.
This pit-fall trap was very successful in preventing the loss of live insects; I have collected as many as 181 carrion beetles at one time in a single trap. In most of the previous studies (Walker, 1957; Shu beck, 1968, 1969) number 10 (gallon-size) tin food cans were used, but I found that gallon paint cans which had been thoroughly cleaned made the better trap. The small lip around the top of the can was very effective in detaining those beetles which did manage to crawl up the side of the can. The hardware cloth served several purposes. First, it prevented debris from falling into the trap, thus providing escape for the beetles; second, it kept larger animals (skunk, opposum, raccoon 13 and bear) from removing the bait; and third, it prevented the escape of the beetles by flying. Flying was the first escape mechanism exhibited by the Silphidae upon completion of a reproductive cycle on the bait. This cycle, in general, included feeding, mating, egg-laying, and possible care of the young silphid larvae. Several of the holes in the hardware cloth were enlarged to allow for entrance of the larger species of Silphidae.
The use of chemical preservatives was quickly ruled out because of the possible effect they might have on the attractive quality of the bait. Also, drainage holes were necessary in the bottom of the cans because the areas in which the traps were located exhibited high rain fall.
Early testing with adult white mice as bait proved unsuccessful.
Total decomposition was achieved very quickly, usually within one week.
The lack of sufficient odor for beetle attraction, as well as the quick decomposition of the mice which prevented successful ma.ting and egg laying of the Silphidae, forced the selection of a larger animal as bait. After further testing, adult Syrian hamsters (Cricetus cricetus Leske.) proved sufficient as my standard bait. Both sexes were used randomly throughout my traps. These animals were easy to obtain once I had established a breeding stock in the laboratory. Previous carrion researchers have used only sections of animals within their traps, for example, chicken legs (Shubeck, 1968), but I chose to use the whole ani mal. This seemed to be a more natural situation. The hamsters were 14 killed within eight hours of introducing them into the traps. Total decomposition of the carrion ran approximately two weeks, after which new bait was placed in the traps. The carrion went through six stages of decomposition and was noted as such during collections. The six stages were: fresh, fresh-bloated, bloated, decay, decay-dry, and dry.
The rate of bait decomposition was much slower in the higher elevations
(above 3000 ft. ).
Several incidents of trap destruction by black bears (Euarctos americanus Gray) occurred in the early phases of trap site selection.
When this occurred the traps were resited in areas less frequented by bears before the data used in the study were accumulated.
The fact that collections from the traps were to be made pri marily during the height of the tourist season in the Great Smoky Moun tains National Park caused early concern for fear of human disturbance of the trap sites. Selecting sites away from hiking trails, picnicking, and camping areas was of utmost importance. Human pleasure seekers were everywhere, so trap sites had to be placed in areas that were less attractive to them. As mentioned earlier, collection of beetles from the traps was started June 17 and continued until December 2. Fresh bait was placed in the traps every two weeks. Cellections were made once a week during the twenty-five week period. All traps were visited within a six hour period on the same day; this period lasted from 10:30 A. M. until 4:30
P. M. Forceps were the principal collecting device used. Insect forms 15 which could readily fly escaped. Although the Silphidae were my main collecting objective, I attempted to keep account of other forms of Coleoptera present in the traps as much as possible. These beetle families consisted ma.inly of Staphylinidae (rove beetles), Histeridae (hister beetles), Carabidae (ground beetles), Scarabaeidae (dung beetles), and Trogidae (skin beetles). Where possible, 100 percent collections were made of these forms. However, certain of the smaller beetles were sometimes so numerous that only a portion could be collected in the time available. Insects so small that they were not noticed were frequently collected along with the debris adhering to the larger forms. Upon my arrival at the individual traps, time was spent esti mating the kinds and abundance of the species present (on and around the carrion bait), and notes were taken on the general behavior of the carrion fauna. Notes were made as to the relationships displayed on an autecological, as well as a synecological basis. The carcass was dis turbed as little as possible while collecting the specimens. Opening of the trap was usually all that was necessary t0 cause the beetles to leave the bait, therefore any movement of the carcass was rarely neces sary. Beetles taken from each trap were placed in coded individual vials of 70 percent alcohol for later species identification in the laboratory. After completing the collection for a trap, the date, time, trap number, and total number of beetles collected from the trap were recorded. During the course of the study 870 collections were 16 made; 120 of these were made from May 5 to June 17 before the actual data recording began. This procedure was used in order to discover any collection problems which had not been foreseen earlier in setting up the project.
Air temperatures and ground temperatures, as well as general weather and habitat conditions, were ta.ken for each trap during each collection. The condition of the bait with reference to color (clear, dark, or black), odor (slight, moderate, or strong), consistency (firm, mushy, moist, or dry), and the presence or absence of maggots (dipteron larvaej none, few, or many) was also noted.
Removal of debris from the hardware cloth cover was also done at this time, as well as assuring that the lip of the trap was flush with the ground. A small spade was carried on each collecting trip to accomplish this because heavy rains often caused erosion of the soil around the trap, especially on the sites which were located on steep slopes.
Microclimatic Conditions 2f. � Study � The idea to use ground temperatures as a measurement of the microclima.tic conditions of the study area was ta.ken from a study done by Royal E. Shanks (195 6) on the altitudinal and microclima.tic relation ships of soil temperatures under natural vegetation in the Smoky Mountains area. Shanks reported that the soil temperature trends were similar to the air temperature trends as measured by the weather stations, and by 17 maximum-minimum thermometers; also that soil temperatures and air temper atures in contrasting adjacent habitats showed similar microclimatic differences.
The soil temperatures for the trap sites that are presented in this paper were taken from a Weston dial-type metallic thermometer with an 8-inch stem, of which the terminal 2 inches is supposed to be in serted into ·.the soil to be checked. The thermometer was inserted into the soil at each trap site to a depth of 7 inches so that the terminal
2 inches would center at a 6 inch depth. The reading generally re quired about one minute to become constant. The readings were usually made to within 0. 5 degrees F. Three such readings were taken at each trap and their average recorded. As shown by Shanks ( 1956) the temper ature measurement at each trap closely reflected the weekly temperatures for that trap. Shanks also stated that it is unlikely that the temper ature at 6 inch depth is often greatly influenced by the infiltration of warm or cold water, and that soil temperatures taken with a dial type metallic thermometer at 6 inch depth appear to provide a convenient and useful index of environmental differences ; "they are consistent enough that considerable confidence may be placed in a single series of comparative measurements. " The means for the collection period of the individual traps were computed and are listed in Table II. The averages for the combined ground temperatures of A (sun-exposed) and B (shaded) traps are also listed in Table II. These study period temperature means show an 18
TABLE II
MEANS (DEGREES F.) OF GROUND TEMPERATURES FOR INDIVIDUA:4 TRAPS AND TRAP SITES JUNE 17 THROUGH DECEMBER 2
Trap Mean Per Average Mean Number Trap Trap Site 1A 66.0 B 65. 7 65.80 C 63.4 2A 65.7 B 60.5 63.10 C 65.8 3A 63.4 B 62 .0 62.70 C 62. 5 4A 62.7 B 62.0 62.30 C 63.0 5A 61.6 B 59. 3 60.40 C 59.9 6A 57.6 B 56.6 57 .10 C 60. 1 7A 53.3 B 53.0 53.10 C 53. 0 8A 54.4 B 50.9 52 .60 C 51.5 9A 52 .0 B 51.1 51.50 C 51.8 lOA 49.2 B 47.6 48 .40 C 49.l
Mean Difference Per Trap Site 1.93 19 average of 1.93 degrees F. drop in ground temperature per trap site with an increase in elevation. This decrease is shown in Figure 2 which plots elevation and trap site against the average ground temper ature means of A and B traps from each trap site.
Air temperature one foot above the pit-fall trap entrance was also taken at the time of each collection, but the use of these data in the environmental relationships of this study is questionable. Air temperature means for the collection periods of this study were com puted in the same manner as those for the ground temperature means, and are listed in Table III. Air temperature means for the individual trap sites were also plotted in the same manner as the ground tempera ture means and are shown in Figure 3. The study period temperature means for the air temperature showed a 2. 57 degrees F. drop per trap site with an increase in elevation. From the preceding microclima.tic data it is apparent that the ground arthropods are subjected to decreases in temperature as eleva tion increases, and that those arthropods on the ground are subjected to extremes in temperatures much less than those arthropods found one foot or more above the ground. As will be seen later in this study, differences in temperature at varying elevations may play an important role in the populations of the various species of Silphidae at these elevations. 70
65 ,...., �. 60 Ill Q) Q) 55 Q) .._,,A Q 50 Q)
45
40
1 2 3 4 5 6 7 8 9 10 Trap Site
Figure 2. Av erage drop in mean ground temperature (degrees F.) per trap site as elevation is increased. N 0 21
TABLE III
MEANS (DEGREES F.) OF AIR TEMPERATURES FOR INDIVIDUAL- TRAPS AND TRAP SI'IBS JUNE 17 THROUGH DECEMBER 2
Trap Mean Per Average Mean Number Tra..P Trap Site 1A 67.6 B 65.4 66.50 C 64.8 2A 71.0 B 64.3 67.60 C 65. 7 3A 73.4 B 64.0 68.70 C 69.4 4A 72.0 B 67 .2 69.60 C 70.4 5A 68.4 B 62.7 66. 50 C 64. 5 6A 60. 8 B 59.6 60.20 C 59.9 7A 57 ,7 - B 60.7 59.20 C 55.9 8A 57.7 B 55.3 56.50 C 55.2 9A 54.0 B 54.2 54.10 C 48.8 lOA 48.4 B 57 .7 49, 50 C 50.7
Mean Difference Per Trap Site 2.57 70
65
':"lit 60 t/l Cl) f 55 Cl) -A i:: 50
45
40
l 2 3 4 5 6 7 8 9 10 Trap Site Figure 3. Average drop in mean air temperature (degrees F .• ) per trap site as elevation is increased.
N N CHAPTER III
RESULTS
Identification
The six families of Coleoptera which were earlier mentioned were consistently trapped in the carrion baited pit-fall traps. The Silphidae were identified to species, and the remaining families were identified to family only. Identification was made in the laboratory, using speci
mens from The University of Tennessee, Knoxville, insect collection and
The Great Smoky Mountains National Park insect collection as references.
Published keys on the Silphidae by Arnett (1944, 1963), Hatch (1927),
and Jurasz-Wasowska (1960) aided in further species identification.
Table IV lists the total number of specimens collected during the study
period according to family.
Ten species of Silphidae belonging to four genera were collected in the study area. These genera included the following: (1) five species of Nicrophorous, (2) three species of Silpha, (3) one species of Necrodes, and (4) one species of Necrophilus. Table V lists the total number of specimens of Silphidae which were collected during the study period.
The following are general descriptions of the ten species of southeast Tennessee Silphidae considered in this paper. They were taken
from Hatch (1927) and Arnett (1944).
Nicrophorous vespilloides Hbst. Pronotum margined in part; antennae capitate. Pronotun not orbicular, transverse or cordate with distinct sculpturing, and widely margined on the sides and
23 24
TABLE J.V TOTAL NUMBER OF COLEOPTERA COLLECTED IN CARRION BAITED TRAPS JUNE 17 THROUGH DECEMBER 2
Total Collected Total Collected A and B Traps C Traps Silphidae 1844 99 Carabidae 324 130 Staphylinidae 368 11 Histeridae 403 5 Scarabaeidae 218 13 Trogidae 48 4 Total 3205 262 Total Collected During Study Period 3467
TABLE V TOTAL NUMBER OF SILPHIDAE COLLECTED IN CARR ION BAITED TRAPS JUNE 17 THROUGH DECEMBER 2
Total Collected Total Collected Species A and B Traps C Traps Nicrophorous vespilloides 1122 83 N. orbicouis 169 6 N. tomentosus 229 1 N. marginatus 36 0 !• pustulatus 19 0 Silpha a.mericana 179 5 S. noveboracensis 1 1 �· ineg_ualis 2 0 Necrodes surinamensis 24 0 Necrophilus hyd.rophiloides 63 2 Total 1844 99 Total Collected During Study Period 1943 25 back. Pronotum sinuate at the sides, base nearly as wide as the apex, sides and base widely margined, not cordate. Me tasternal epimeron glaborous . Elytra with orange fasciae. Hind tibia straight. Three terminal segments of antennae black. Nicrophorous orbicouis Say. Pronotum margined in part; antennae capitate. Pronotum orbicular, at times feebly sinuate at sides; also widely margined. Size normal, usually under 25 mm. in length. Elytra with flying hairs ; fasciae not emargina.te. Posterior tibiae straight ; posterior fasciae with inner lobe small. Posterior trocha.nter normal, emarginate behind ; marginal ridge of elytra attaining level of apex of scutellwn, pronotwn rounded at sides. Nicrophorous tomentosus Web. Pronotum margined in part; antennae capitate. Pronotum transverse, sinuate at sides. Pronotum strongly cordate, posterior tibiae straight. Pronotum pubescent ; sutural extremity of posterior elytral fascia normally tirlobed, antennal club black. Nicrophorous marginatus Fab. Pronotum margined in pa.rt ; antennae capitate. Pronotwn transverse ; strongly sinuate at sides. Pronotwn strongly cordate, less widely margined; pronotum glaborous ; sutural extremity of posterior elytral fascia normally trilobed. Posterior tibiae strongly arcuate along both margins ; disc of pronotum less strongly punctate, margins narrow ; anterior lines of pronotwn not attaining mid-dorsal line . Abdominal hairs black. Antennal club orange . Nicrophorous pustulatus Hersch. Pronotum margined in part ; antennae capitate. Pronotum transverse ; feebly sinuate at sides ; not strongly cordate, widely margined; posterior tibiae straight. Three terminal segments of antennae usually orange ; sutural extremity of posterior elytral fascia normally trilobed; pronotum less quadrilateral. Me tasternal pubescence black with immaculate elytra. Me taepimeron glaborous. Elytral margin much longer ; hypomera faintly orange ; elytra with distinct raised longitudinal lines. Silpha ame ricana L. Prothoracic spiracles covered; pronotum not orbicular. Eyes not-prominent, form less elongate. Antennae in serted close to eye and distant from margin of front. Labrum narrowly ema.rgina.te. Body metallic below; elytral intervals retic ulate. Broadly oval ; pronotwn black with yellow margins. Silpha noveboracensis Frost. Prothoracic spiracles covered; pronotwn not orbicular. Eyes not prominent ; form less elongate . Labrum broadly emarginate ; antennae inserted close to eye and dis tant from margin of front. Elytra costate, not squarely truncate. 26
Pronotum not emarginate at base. Elytral punctation coarser ;, pron0tum black with reddish margins.
Silpba inesualis Fab. Pr0th0racic spiracles covered; pronotum not orbicular. Eyes not prominent; form less elongate. Labrum broadly ema.rginate; antennae inserted close to eye, and distant from margin of front, Elytra costate, not squarely truncate, Pronotum not emarginate at base. Elytral punctation .fine; _pro-.. notum unicolorous.
Necrodes surinamensis F. Prothoracic spiracles exposed ; pro notum orbicular; form elongate; usually with orange bar or row of spots across elytra towards apex; eyes prominent ; antennae inserted close to eyes, and distant from margin of front.
-Necrophilus hydrophiloides Mann. Disc of pronotum sparsely punctate; rows of punctures on elytra impressed; intervals similar . Apex of elytra arcuate to suture, not prolonged; winged; equally punctate throughout ; seventh interval not elevated at humerus ; abdominal tergites largely membranous ; length 9-11 mm.
Elevational Centers � Distribution of � Silphidae
The total number of species collections for each trap site (ele vation) is listed in Table. VI. These collections were then plotted to show the possible elevational centers of distribution for the ten species of Silphidae which were collected during this research (Figures 4, 5,
6, and 7) . The median for the total number of specimens 0f each species was then computed to show specifically at which elevation the probable center of distribution would be found. Table VII lists the probable center of elevational distribution with trap site.
Seasonal Succession of the Silphidae
The study period was divided into three successional time periods.
These periods are as follows: early summer (June 17 through July 29) , late summer (July 31 through September 30) , and fall (October l through 27
TABLE VI NUMBERS OF SPECIMENS OF SILPHIDAE COLLECTED FROM A AND B TRAPS AT EACH TRAP SITE JUNE 17 THROUGH DECEMBER 2
Species l 2 3 4 5 6 7 8 9 10 Nicrophorous vespilloides 1 5 16 486 293 201 18 102
N. orbicouis 3 31 86 46 2
N. tomentosus 4 21 50 133 21
N. marginatus 1 1 1 6 27
N. pustulatus 2 7 8 2
Silpha a.mericana 1 3 169 2 s. noveboracensis 1 s. inequalis 2 Necrodes surina.mensis 1 1 22
Necrophilus hydrophiloides 1 14 10 16 22 28 1,,1 I I 1 ' I \ I I rd rd a, a, ., +> +> I 0 0 I a, a, I 7 ::f0 ::f0 0 0 Ill 30 Ill H H I a, a, I � 20 j ' z l?.i ' 150 I," ,\ 30 J '. 100 I I 20 / I 50 . 10
1 · 2 ••3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 Trap Site Trap Site Figure 4. Elevationa.l data. for N. Figure 5. Elevational data for vespilloides (-) and -s. americana N. orbicouis (-) and N. f---) . to mentosus 0--�.
110 110 100 100 rd rd a, 90 a, 90 +> +> 0 0 a, 80 a, 80 7 ::f0 70 0 Ill Ill 60 J..i H Q) a, 50 § z I 40 30 20 •, , ,.,, ... ,, "''\ I,' 10- 1' ' ' I 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 . 7 8 9 10 Tr�p Site Trap Site
Figure 6. Elevationa.l data for N. Figure 7, Elevational data for ) ma(---rgina.tus1 (- and !• pustul.a.tus N. surinamensis (-) and . N. hydrophiloides �--�. 29
TABLE VII CENTERS OF ELEVATIONAL DISTRIBUTION FOR THE SILPHIDAE
Species Elevation Trap Site Nicrophorous vespilloides 3500' 6-7
N. orbicouis 2000' 5 N. tomentosus 3000' 6
N. ma.rginatus 6500' 10
N. pustulatus 1500' 4-5
Silpha americana 1000' 4 s. noveboracensis 1000 ' 4 s. inequalis 2000' 5 Necrodes surinamensis 2000' 5
Necro,Ehilus hidrophiloides 5000' 8 30
December 2). The total number of each species of Silphidae was com piled from the collection data and is found in Table VIII. These data were then plotted to show the changes in numbers of the ten species collected during the three periods (Figure 8). Silpha noveboracensis and �. inequalis are not presented in Figure 8 due to the low numbers which were collected during the study period.
Notes £!!. Related Coleoptera
Five families of Coleoptera were collected in the carrion baited traps in addition to the Silphidae. These families were: Carabidae, Staphylinidae, Histeridae, Scarabaeidae, and Trogidae. The total numb ers of collected specimens for each family are listed in Table IV, page 24. As demonstrated by the large numbers of specimens collected
from the control traps (C), it is clear that the Carabidae were not attracted to the carrion, but were wandering predators that had acci dentally fallen into the traps. The remaining four families of Cole- ·
optera were clearly attracted to the carrion baited traps as seen in
Table IV. Since species identification of these five families of beetles
was beyond the scope of this paper, an attempt was made to find eleva tion.al distributions according to family. The collection data for each
elevation (trap site) are listed in Table IX. These data were then plotted to show probable elevation.al centers of distribution as seen
in Figures 9 and 10. 31
TABLE VIII COMPARISON OF THE NUMBERS OF SILPHIDAE COLLECTED DURING THREE TIME PERIODS
Early Late Species Summer Summer Fall
Nicrophorous .vespilloides 155 758 220
N. orbicouis 67 103 l
N. tomentosus 36 178 6 N. marginatus 20 15 1 N. pustulatus 12 7 0
Silpha americana 74 104 1 s. noveboracensis 1 0 0 s. inequalis 2 0 0 Necrodes surinamensis 22 2 0 Necrophilus hydrophiloides 21 22 20 32
I ' I ' 340 I '. 320 I ' ' '\ 300 ' / I ' 280 ' I '\ 260 I ' 240 I '\ ' • +:> 220 I C) ' Q) I 200 I I 0 • C,) 180 • ,,/\ • � 160 / l I Q) , ' 140 . . ' • 120 •• • .,,. 100 .·· .,.. -; -: :... \ �-;-:-,• ., • • 80 ----:..�·_, , ,, _,,,,-. .,,,,. I \ 60 �. ., I �:,,.,. '• ·· . '� '\ 40 1 ·� ', ., . '\ 20 ,,
• f , , •• • ' - • ,, ,, • ,,, ,-: .• : ,.., ,, •• • ',"'. � ... : :..: : ' '\ r�==-= .. .!..! ,. �•• • ; Early :-�-�.��t· ·�·:2:�·�· -�-:;·Late·�-i-� ·�·i-�;;· �- -�-�,��!�Fall5· ·� Summer Summer
Figure 8. Seasonal population trends of Silphidae for study period June 17 through December 2, N. vespilloides (- - -•-1, N. orbicouis �-· -� , !· tomentosus f- ··-), N. ma.rgina.tus r--) , !.!• pustulatus (· ...u) , §.. americana f----), !• surinamensis (- ··�, and !• hydrophiloides (- -• "1• 33
'.£ABLE IX
NUMBERS OF SPECIMENS OF RELATED COLEOPTERA COLLECTED FROM A AND B TRAPS AT EACH TRAP SITE JUNE 17 THROUGH DECEMBER 2
Fa.mily 1 2 3 4 5 6 7 8 9 10 Carabidae 85 29 9 15 98 8 2 47 16 8
Staphylinidae 117 24 46 62 79 14 1 16 1 3
Histerida.e 81 24 13 249 22
Scarabaeidae 13 39 69 54 25 18 1 4
Trogidae l l 2 20 5 19 1 ..'• 34 220 I ....•: . 200 .. .. : 180 .: 'd 160 . . (I) ; . 140 . . t(I) : . r-l . . r-l 120 : 0 I :. 0 I 100 Cl] H Cl) 80 � 60 :z; 40 20
1 2 3 4 5 6 7 8 9 10 Trap Site
Figure 9. Elevational data for Carabidae {-) , Staphylinidae €---7, and the Histeridae � .....).
220 200 'd .180 Cl) t 160 ::t 140 0 120 Cl] � 100 � 80 :z; 60 40 20
Trap Site
Figure 10. Elevational data for Scarabaeidae (-) and Trogidae (- ---, . 35
The study period was divided into three successional time periods as was done with the Silphidae (see page 26) . The total number of each family of Coleoptera which were collected during the three successional periods is listed in Table X. These data were then plotted to show the changes in numbers of the five families, and are presented in Figure 11. 36
TABLE X COMPARISON OF THE NUMBERS OF RELATED COLEOPTERA COLLECTED DURING THREE TIME PERIODS
Early Late Family Summer Summer Fall Carabidae 155 144 25
Staphylinidae 184 117 67 Histerid.a.e 177 207 19
Scarabaeid.a.e 67 97 54
Trogid.a.e 20 21 8 37
255 240 225 , 210 •' . . . ·. 195 •••• • ,. •. 180 ' .. · · .. ', ' ,. . 165 ' . .. · . rd ·...... � . 150 .. . ,-f 135 .• ,-f .• 120 '• tll 105 • •• .,,,,,,...- . 90 -· -· ..,. '• ,.. ! 75 -· -· -· ·�� ' 60 ·:' ....:,,...... 45 30 -. ,, -.. - . ,,_ .. - .. --... -...... 15 , ...... _
Early Late Fall Summer Summer
Figure 11. Seasonal population trends of related Coleoptera for study period June 17 through December 2 Carab idae (-) , Staphylinidae (- --1, Histeridae � .....),( Sca.rabaeidae (- -·1, and Trogidae \o-.. -� • CHAPTER J:V
DISCUSSION
The ten species of Silphidae collected in the study area form a representative group of this family which are found in a large region of the United States, generally east of the Mississippi to the eastern seaboard, and north of Georgia and Alabama to Canada. Howden (1950) collected all but Nicrophorous orbicouis and !!• pustulatus in North
Carolina. Payne and Crossley (1966) collected the same species near Clemson, South Carolina. Between Walker (1957) and Reed (1958) all ten species were recorded for Tennessee. Jaques (1915) recorded all but
Silpha noveboracensis and !!• pustulatus at Cedar Point, Ohio. All but
�. inequalis were recorded for Minnesota by Hatch (1927) . From the wide spread abundance of the Silphidae in the eastern United States, it may be possible to correlate the results of this study with the members of this family in other areas of the eastern United States.
When considering the elevational centers for the ten species of
Silphidae, it is first noticed that this family is spread almost com pletely over the entire elevational scale of the study a.i·ea. Table VIII, page 31, shows that the genus Silpha is found mainly below 2000 feet, while the genus Nicrophorous ranges from 1500 feet to the highest elevation of 6500 feet. The remaining two genera, Necrodes and Nicro philus, are found at 2000 feet and 5000 feet respectively. Referring back to Figure 2, page 20, which shows the mean g1·ound temperatures for 38 39 the study area, we find lower temperatures at the higher elevations, which are 3000 feet and above in this study. With the lower tempera tures there is a much higher rainfall than at the lower elevations, as was demonstrated by Shanks in 1954. A correlation could be ma.de between the presence of the genus Nicrophorous and the climate at these higher elevations.
Each species of Silphidae reveals an increase in numbers up to its center of elevational distribution, and a decrease in numbers above this center. Figure 12 shows each species of Silphidae and the eleva tion at which its center of distribution is found. A large drop in collection numbers is found for each species at trap site 9. This may possibly be attributed to the location of the trap site. As the study period progressed, this site was subjected to above normal winds, and was the steepest of the slopes in the study.
Seven of the ten species of Silphidae appear to reach their peak numbers within the elevations found in the study except for ·!· ma.rgin atus, !· surinamensis, and N. hydrophiloides, as seen in Figures 4, 5, 6, and 7, page 28. N. marginatus, the highest in elevation of its genus, seems to begin increasing in numbers at the last three trap sites. N. surinamensis reached its peak at trap site 5 (2000 feet in elevation) , but was not collected at all above this elevation. !• hydrophiloides shows an increase in numbers, which staggers, beginning at trap site 5 and increasing to trap site 10. The centers of elevational distribution for both !• ma.rginatus and !• hydrophiloides could possibly be at ele vations higher than those considered in this study. Nicrophorous rnarginatus
______hydrophiloides
Nicrophorous vespilloides ------tomentosus
Silpha inequalis, Nicrophorous orbicouis, Necrodes surinamensis Nicrophorous pustulatus 1000 ' Silpha a.mericana, Silpha noveboracensis
Figure 12. Centers of elevational distribution for Silphidae.
tJ:>. 0 41 The seasonal succession for most of the Silphid.ae may be con
sidered predictable as seen in Figure 8, page 32. !!• vespilloides, !!• orbicouis, !!• tomentosus, and �. a.mericana reached their population
peaks in late summer, and decreased in the fall. !!• marginatus, N. pustulatus, !!• surinamensis, �- noveboracensis, and �- inegualis appear to have reached their population peaks before this study began. All five species decreased gradually in their numbers through late summer to fall. Only one species of the ten studied in this paper remained relatively constant in numbers throughout the study period. In Figure
8, !!• hydr ophiloides shows almost identical numbers being collected during early summer, late summer, and fall, those numbers being 21, 22, and 20 respectively. As mentioned on the previous page 26, the eleva tional center of distribution for this species may be found at an alti tude above those studied in this paper. Referring to individual collec tion notes it is found that as the study period progressed this species seemed to move from higher to lower elevations. During early summer this species was collected ma.inly at trap site 10 (6500 feet), but by the fall specimens were consistently being taken as low as trap site 6 (3000 feet). The movement of the center of elevational distribution for a species is obvious only with !!• hydrophiloides; the remaining species seemingly are centered in only one elevational area during this study. During the last week of the study period, snowfall in the higher elevations was quite heavy. This marked the end of the appearance of
Silphid.ae in the traps at all of the higher elevations. This snowfall 42 with the lower temperatures throughout the study area apparently caused a retreat of members of this family and other Coleoptera into the soil. A short warming trend several weeks later caused the reappearance of a few specimens of Silphidae in the traps which were collected on a trip through the study area. When attempting to plot the centers of, elevational distribution for the five additional families of Coleoptera problems arose which ma.de the idea quite difficult. Here species identification is neces sary, but was not attempted due to lack of time. Speculation may be made from looking at the graphs on page 34 as to the numbers of species collected, and the centers of distribution for these species. The Carabidae exhibited three such peaks possibly having three species ; these peaks were at 800 feet, 2000 feet, and 5000 feet. The possi bility also exists that more than one species maybe dominant at each of these elevations. The Staphylini This study only begins to answer questions about the Silphidae and related carrion beetles. Knowledge concerning the place of insects in decompositiQn of dead animal matter is limited, and dur ing this period in time when man is steadily. destroying his environment through overpopulation and pollution, it becomes ever increasingly important that we understand the roles of decomposers and related fauna.. The Silphidae are well known to be members of this all important decomposer group . Should this family disappear from the ecosystem by some acci dental fault of man, what would take over its position in this cycle? The ecological. role of elevational speciation within the Coleoptera, as well as all arthropods, may hold the answer to many important ques tions about the environmental relationships of animals, and their in direct, or maybe direct, . effect upon man. CHAPTER V SUMMARY The intent of this research is to present elevational relation ships of the family Silphidae in southeast Tennessee. Ten species of Silphidae were collected in the study area which contained ten trap sites ranging in elevations from 800 feet to 6500 feet. Centers of elevational distribution were found for all ten species of Silphidae as well as seasonal trends in population numbers. Although the eleva tional centers overlapped tremendously, each species appeared to center at a specific elevation. Similar distributions and seasonal population trends were found for five additional families of Coleoptera. The Silphidae appeared to divide into two main elevational groups. In general, the genus Nicrophorous appeared to occupy the higher eleva tions of the study area while the genus Silpha occupied the lower ele vations. N. marginatus and �. hydrophiloides appeared to have their elevational centers at higher altitudes than those found in the · study area. The population peaks for !!• vespilloides, !!• orbicouis, !!• tomentosus, and�. americana were reached in late summer. !!· margin atus, !!· pustulatus, �- surinamensis,�. noveboracensis, and�· in egualis appear to have reached their population peaks before this study began. The Carabidae and Staphylinidae exhibited three centers of ele vational distribution (800, 2000, and 5000 feet). The Histeridae exhibited two elevational peaks (800 and 1000 feet), while both the 44 45 Scarabaeidae and Trogidae only exhibited one peak each (900 and 1000 feet) . The Histeridae, Scarabaeidae, and Trogidae appear to reach their population peaks in late summer, while Carabidae and Staphylinidae appear to have reached their population peaks before this study began. LITERATURE CITED LITERATURE CITED Abbott, C. E. 1927a. Experimental data on the olfactory sense of Coleoptera, with special reference to the Necrophorini. Ann. Ento. Soc. Amer. 20:207-216. Adams, c. C. 1902. 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Soc. 77: l38-l5l. Steele, B. F. 1927 . Notes on the feeding habits of carrion beetles. J. N. Y. Ento. Soc. 35: 77-81. Walker, T. J. , Jr. 1957. Ecological studies of the arthropods associ ated with certain decaying materials in four habitats. Ecology 38: 262-276. Walsh, G. B. 1933. Studies in the British necrophagous Coleoptera. II. The attractive powers of various natural baits. Ent. Mon. Mag. 69 : 28-32. Whittaker, R. H. 1948. A vegetation analysis of the Great Smoky Mountains. Ph. D. thesis, Univ. of Illinois. 1952. A study of summer foliage insect communities in the Great Smoky Mountains. Eco. Monog. �: l-44. VITA Barry Charles Lumpkin, was born in Albany, Georgia, on December 1 1 1947. He was educated in the elementary and junior high school system in Albany, Georgia, and graduated from Albany High School, Albany, Georgia, in June 1965. The following September he entered North Georgia College, Dahlonega, Georgia, and received a Bachelor of Science 1egree in Biology in June 1969. In September 1969 he entered The University of Tennessee, holding a graduate assistantship in the Department of Zoology and Entomology. 50