@article {1548,
	title = {The role of the subelytral cavity in water loss in the flightless dung beetle, Circellium bacchus (Coleoptera : Scarabaeinae)},
	journal = {European Journal Of Entomology},
	volume = {99},
	number = {2},
	year = {2002},
	note = {digital copy},
	pages = {253-258},
	abstract = {Circellium bacchus is a flightless telecoprid (ball-rolling) dung beetle, endemic to the afrotropical region, where it is found in a few restricted populations in the eastern Cape of South Africa. Its apterous condition and large size (mass ranges from 6 to 12 g) are considered to be adaptations to a semi-arid habitat. This beetle is active in the sun for long periods, walking between widely scattered dung pats, thus is under selection pressure to reduce water loss. C bacchus has eight spiracles on each side of the body. The metathoracic spiracle and six abdominal spiracles open into the sub-elytral cavity, which is closed. The mesothoracic spiracle is the largest and most exposed, occurring ventrally in the membrane connecting the prothorax and mesothorax. When at rest a cyclic form of respiration, known as discontinuous gas exchange cycle, is used by C. bacchus, releasing a burst of carbon dioxide approximately once an hour when the spiracles open for about 33 minutes. Flow-through respirometry was used to measure water loss from the thorax (being the head, prothorax and mesothorax) and elytral case (containing the metathorax and abdomen) separately. The total water loss of C. bacchus could be divided up as 65\% cuticular water loss from the thorax, 35\% cuticular water loss from the elytral case, 4\% respiratory water loss from the thorax and no measurable respiratory water loss from the elytral case. 1.51 mug of water is lost for every mul of CO2 emitted during respiration in the thorax. Thus, the main avenue for both respiration and respiratory water loss is via the mesothoracic spiracles, suggesting that the primary function of the subelytral cavity is not to reduce respiratory water loss.},
	keywords = {Circellium bacchus, desert tenebrionid beetles, discontinuous gas exchange cycle, Discontinuous gas-exchange, dung beetle, insects, patterns, physiology, respiration, Scarabaeidae, subelytral cavity, terrestrial, trait information, ventilation, water loss},
	url = {<Go to ISI>://000177174200016 },
	author = {Duncan, F. D.}
}
@article {1549,
	title = {Discontinuous gas exchange in dung beetles: patterns and ecological implications},
	journal = {Oecologia},
	volume = {122},
	number = {4},
	year = {2000},
	note = {Times Cited: 11Cited Reference Count: 40Cited References:      BARTHOLOMEW GA, 1985, J COMP PHYSIOL B, V155, P155     BERNON G, 1981, THESIS U BOWLING GRE     CAMBEFORT Y, 1991, DUNG BEETLE ECOLOGY, P22     CAMBEFORT Y, 1991, DUNG BEETLE ECOLOGY, P36     CAMBEFORT Y, 1991, DUNG BEETLE ECOLOGY, P51     CHOWN SL, 1995, FUNCT ECOL, V9, P30     DAVIS ALV, 1995, ACTA OECOL, V16, P641     DAVIS ALV, 1996, AGR ECOSYST ENVIRON, V58, P157     DOUBE BM, 1990, B ENTOMOL RES, V80, P259     DOUBE BM, 1983, B ENTOMOL RES, V73, P357     DOUBE BM, 1991, DUNG BEETLE ECOLOGY, P133     DUNCAN FD, 1997, PHYSIOL ENTOMOL, V22, P310     DUNCAN FD, 1993, PHYSIOL ENTOMOL, V18, P372     FERREIRA MC, 1972, REV ENT MOCAM, V11, P5     HADLEY NF, 1994, PHYSIOL ZOOL, V67, P175     HEINRICH B, 1979, PHYSIOL ZOOL, V52, P489     HOLTER P, 1991, PEDOBIOLOGIA, V35, P281     KESTLER A, 1985, ENV PHYSL BIOCH INSE, P137     KLOK CJ, 1994, THESIS U PRETORIA     LIGHTON JRB, 1996, ANNU REV ENTOMOL, V41, P309     LIGHTON JRB, 1991, CONCISE ENCY BIOL BI, P201     LIGHTON JRB, 1993, J COMP PHYSIOL B, V163, P11     LIGHTON JRB, 1995, J EXP BIOL, V198, P521     LIGHTON JRB, 1995, J EXP BIOL, V198, P1613     LIGHTON JRB, 1992, J EXP BIOL, V173, P289     LIGHTON JRB, 1991, J EXP BIOL, V159, P249     LIGHTON JRB, 1990, J EXP BIOL, V151, P71     LIGHTON JRB, 1988, J EXP BIOL, V134, P363     LIGHTON JRB, 1988, J INSECT PHYSL, V34, P361     LIGHTON JRB, 1994, PHYSIOL ZOOL, V67, P142     LIGHTON JRB, 1985, PHYSIOL ZOOL, V58, P390     MILLER PL, 1981, LOCOMOTION ENERGETIC, P367     OSBERG D, 1988, THESIS U WITWATERSRA     OSBERG DC, 1992, J ENTOMOL SOC S AFR, V55, P85     OSBERG DC, 1993, TROP ZOOL, V6, P243     PASCHALIDIS KM, 1974, THESIS RHODES U GRAH     SCHMIDTNIELSEN K, 1980, ANIMAL PHYSL ADAPTAT     SLAMA K, 1988, WOODS HOLE OCEANOGR, V175, P289     TRIBE GD, 1976, THESIS U NATAL PIETE     ZAR JH, 1984, BIOSTATISTICAL ANALEnglishArticle303YGOECOLOGIA},
	month = {Mar},
	pages = {452-458},
	abstract = {This study correlates a distinctive pattern of external gas exchanger referred to as the discontinuous gas exchange cycle (DGC), observed in the laboratory, with habitat associations of five species of telecoprid dung beetles. The beetles were chosen from a variety of habitats that would be expected to present different amounts of water stress. All five species exhibited DGC. Sisyphus fasciculatus has been recorded only in woodland areas, and does not have strict spiracular control during its DGC. Anachalcos convexus and Scarabaeus rusticus are associated with open mesic habitats. Both species exhibit a distinct DGC, previously found in some other insect species, but intermediate within this study group. Sc. flavicornis and Circellium bacchus are typically found in arid regions, and have the most unusual form of DGC with spiracular fluttering during the burst phase. These results support the hypothesis that spiracular fluttering reduces respiratory water loss. From this study we conclude that the DGC is an ancestral adaptation. most probably as a result of anoxic environments in underground burrows, but that spiracular control is enhanced to reduce respiratory water lass in beetle species that live in arid habitats.},
	keywords = {ant, COLEOPTERA, discontinuous gas exchange cycle, formicidae, habitat association, hymenoptera, namib desert, respiration, Scarabaeidae, Scarabaeinae, south-africa, telecoprid, tenebrionid beetles, terrestrial insects, ventilatory patterns},
	url = {<Go to ISI>://000086455000002},
	author = {Duncan, F. D. and Byrne, M. J.}
}
@article {1550,
	title = {Respiratory airflow in a wingless dung beetle},
	journal = {The Journal of Experimental Biology},
	volume = {205},
	year = {2002},
	pages = {2489-2497},
	abstract = {The sealed subelytral cavity of many flightless beetle species is widely acknowledged to be an adaptation to water saving in arid-habitat species. However, this hypothesis relies on the acceptance of two largely untested assumptions: (i) that the movement of respiratory gases is unidirectional from anterior to posterior and (ii) that the coordinated action of the spiracles directs this flow. We tested these assumptions by simultaneously measuring CO2 and O2 exchange at the anterior mesothorax, independently of gas exchange in the posterior body, which included the subelytral cavity, of a large apterous beetle, Circellium bacchus. Flow-through respirometry revealed a marked discontinuous gas-exchange cycle (DGC) pattern from the anterior half of the body. Very little CO2was released from the posterior body, where the DGC was not apparent. Labelled air was shown to flow forwards from the posterior to the anterior body. Individual sampling from the mesothoracic spiracles revealed that the right mesothoracic spiracle, lying outside the elytral cavity, is the primary route for respiratory gas exchange in C. bacchusat rest. This discovery necessitates a reassessment of the currently assumed role of the subelytral cavity in water conservation and is, to our knowledge, the first demonstration of forward airflow associated with the unilateral use of a single thoracic spiracle for respiration in an insect. },
	keywords = {Circellium bacchus, discontinuous gas exchange cycle, dung beetle, respiration, Scarabaeidae, spiracle, subelytral cavity.},
	author = {Duncan, Frances D. and Byrne, Marcus J.}
}
