The role of the subelytral cavity in water loss in the flightless dung beetle, Circellium bacchus (Coleoptera: Scarabaeinae)
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...
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| Format: | Article |
| Language: | English |
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Institute of Entomology, Biology Centre, Czech Academy of Science
2002-06-01
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| Series: | European Journal of Entomology |
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| Online Access: | https://www.eje.cz/artkey/eje-200202-0014_The_role_of_the_subelytral_cavity_in_water_loss_in_the_flightless_dung_beetle_Circellium_bacchus_Coleoptera.php |
| _version_ | 1818326714876428288 |
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| author | Frances D. DUNCAN |
| author_facet | Frances D. DUNCAN |
| author_sort | Frances D. DUNCAN |
| collection | DOAJ |
| description | 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 subelytral 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 µg of water is lost for every µl 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. |
| first_indexed | 2024-12-13T12:04:46Z |
| format | Article |
| id | doaj.art-4490ff745df14ead80aee9f14193a7a7 |
| institution | Directory Open Access Journal |
| issn | 1210-5759 1802-8829 |
| language | English |
| last_indexed | 2024-12-13T12:04:46Z |
| publishDate | 2002-06-01 |
| publisher | Institute of Entomology, Biology Centre, Czech Academy of Science |
| record_format | Article |
| series | European Journal of Entomology |
| spelling | doaj.art-4490ff745df14ead80aee9f14193a7a72022-12-21T23:46:59ZengInstitute of Entomology, Biology Centre, Czech Academy of ScienceEuropean Journal of Entomology1210-57591802-88292002-06-0199225325810.14411/eje.2002.034eje-200202-0014The role of the subelytral cavity in water loss in the flightless dung beetle, Circellium bacchus (Coleoptera: Scarabaeinae)Frances D. DUNCAN0School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown 2193, South Africa; e-mail: duncanfd@physiology.wits.ac.zaCircellium 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 subelytral 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 µg of water is lost for every µl 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.https://www.eje.cz/artkey/eje-200202-0014_The_role_of_the_subelytral_cavity_in_water_loss_in_the_flightless_dung_beetle_Circellium_bacchus_Coleoptera.phpsubelytral cavitywater lossdiscontinuous gas exchange cyclerespirationscarabaeidaecircellium bacchus |
| spellingShingle | Frances D. DUNCAN The role of the subelytral cavity in water loss in the flightless dung beetle, Circellium bacchus (Coleoptera: Scarabaeinae) European Journal of Entomology subelytral cavity water loss discontinuous gas exchange cycle respiration scarabaeidae circellium bacchus |
| title | The role of the subelytral cavity in water loss in the flightless dung beetle, Circellium bacchus (Coleoptera: Scarabaeinae) |
| title_full | The role of the subelytral cavity in water loss in the flightless dung beetle, Circellium bacchus (Coleoptera: Scarabaeinae) |
| title_fullStr | The role of the subelytral cavity in water loss in the flightless dung beetle, Circellium bacchus (Coleoptera: Scarabaeinae) |
| title_full_unstemmed | The role of the subelytral cavity in water loss in the flightless dung beetle, Circellium bacchus (Coleoptera: Scarabaeinae) |
| title_short | The role of the subelytral cavity in water loss in the flightless dung beetle, Circellium bacchus (Coleoptera: Scarabaeinae) |
| title_sort | role of the subelytral cavity in water loss in the flightless dung beetle circellium bacchus coleoptera scarabaeinae |
| topic | subelytral cavity water loss discontinuous gas exchange cycle respiration scarabaeidae circellium bacchus |
| url | https://www.eje.cz/artkey/eje-200202-0014_The_role_of_the_subelytral_cavity_in_water_loss_in_the_flightless_dung_beetle_Circellium_bacchus_Coleoptera.php |
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