The Dytiscidae – based on the Greek dytikos (δυτικός), "able to dive" – are the predaceous diving beetles, a family of water beetles. They occur in virtually any freshwater habitat around the world, but a few species live among leaf litter.[1] The adults of most are between 1 and 2.5 cm (0.4–1.0 in) long, though much variation is seen between species. The European Dytiscus latissimus and Brazilian Megadytes ducalis are the largest, reaching up to 4.5 cm (1.8 in) and 4.75 cm (1.9 in) respectively.[1][2] In contrast, the smallest is likely the Australian Limbodessus atypicali of subterranean waters, which only is about 0.9 mm (0.035 in) long.[1] Most are dark brown, blackish, or dark olive in color with golden highlights in some subfamilies. The larvae are commonly known as water tigers due to their voracious appetite.[3] They have short, but sharp mandibles and immediately upon biting, they deliver digestive enzymes into prey to suck their liquefied remains. The family includes more than 4,000 described species in numerous genera.[4]
Contents
1Habitat
2Larvae and development
3Edibility
4Diving beetle conservation
5Cultural significance
6Ethnobiology
7Parasites
8Systematics
9References
10External links
Habitat
Diving beetles are the most diverse beetles in the aquatic environment and can be found in almost every kind of freshwater habitat, from small rock pools to big lakes. Some dytiscid species are also found in brackish water.[5] Diving beetles live in water bodies in various landscapes, including agricultural and urban landscapes.[6][7][8] Some species, such as Agabus uliginosus[6] and Acilius canaliculatus,[8] are found to be relatively tolerant to recent urbanization. One of the most important limiting factors for diving beetle occurrence is the presence of fish, which predate on the beetles (mostly on larvae), compete for food, and change the structure of the habitat. Many diving beetles species prefer habitats with aquatic vegetation,[7][9] while some species, such as Oreodytes sanmarkii, occur in exposed areas of waters.[10]
Larvae and development
Larva of the European diving beetle Dytiscus marginalis
When still in larval form, the beetles vary in size from about 1 to 5 cm (0.5 to 2.0 in). The larval bodies are shaped like crescents, with the tail long and covered with thin hairs. Six legs protrude from along the thorax, which also sports the same thin hairs. The head is flat and square, with a pair of long, large pincers. When hunting, they cling to grasses or pieces of wood along the bottom, and hold perfectly still until prey passes by, then they lunge, trapping their prey between their front legs and biting down with their pincers. The larvae are also known to partially consume prey and discard the carcass if another potential prey swims nearby. Their usual prey includes tadpoles and glassworms, among other smaller water-dwelling creatures. As the larvae mature, they crawl from the water on the sturdy legs, and bury themselves in the mud for pupation. After about a week, or longer in some species, they emerge from the mud as adults. Adult diving beetles have been found to oviposit their eggs within frog spawn in highly ephemeral habitats, with their eggs hatching within 24 hours after the frogs and the larvae voraciously predating on the recently hatched tadpoles.
Edibility
Adult Dytiscidae, particularly of the genus Cybister, are edible. Remnants of C. explanatus were found in prehistoric human coprolites in a Nevada cave, likely sourced from the Humboldt Sink.[11] In Mexico, C. explanatus is eaten roasted and salted to accompany tacos. In Japan, C. japonicus has been used as food in certain regions such as Nagano prefecture. In the Guangdong Province of China , the latter species, as well as C. bengalensis, C. guerini, C. limbatus, C. sugillatus, C. tripunctatus, and probably also the well-known great diving beetle (D. marginalis) are bred for human consumption, though as they are cumbersome to raise due to their carnivorous habit and have a fairly bland (though apparently not offensive) taste and little meat, this is decreasing. Dytiscidae are reportedly also eaten in Taiwan, Thailand, and New Guinea.[12]
Dytiscidae sp.
Diving beetle conservation
The greatest threat to diving beetles is the degradation and disappearance of their habitats due to anthropogenic activities.[1] For example, urbanisation has led to the decreasing quantity and quality of dytiscid habitats,[8] which consequentially has increased the distance between habitats.[13] Thus, dytiscids may be exposed to high predation risks during dispersal.
Dytiscid adults are eaten by many birds, mammals, reptiles, and other vertebrate predators, despite their arsenal of chemical defenses.[14] But by far the most important predator of diving beetles are fish, which limit the occurrence of most diving beetle species to fishless ponds, or to margins of aquatic habitats. Although the larvae of a few dytiscid species may become apex predators in small ponds, their presence is also often incompatible with fish. Therefore, the main focus of water beetle conservation is the protection of natural, fish-less habitats.
In the European Union, two species of diving beetles are protected by the Berne Convention on the Conservation of European Wildlife and Natural Habitats, and thus serve as umbrella species for the protection of natural aquatic habitats: Dytiscus latissimus and Graphoderus bilineatus.
Cultural significance
The diving beetle plays a role in a Cherokee creation story. According to the narrative, upon finding nowhere to rest in the "liquid chaos" the beetle brought up soft mud from the bottom. This mud then spread out to form all of the land on Earth.[11]
Ethnobiology
Adult Dytiscidae, as well as Gyrinidae, are collected by young girls in East Africa. It is believed that inducing the beetles to bite the nipples will stimulate breast growth.[11] The effect of that habit has not been tested, but it is notable that the defense glands of diving beetles contain many types of bioactive steroids.[14]
Parasites
Dytiscidae are parasitised by various mites. Those in genera Dytiscacarus and Eylais live beneath the elytra of their hosts,[15][16] those in genus Acherontacarus attach to the mesosternal regions[17] and those in genus Hydrachna attach to various locations.[18] These mites are parasitic as larvae with the exception of Dytiscacarus, which are parasitic for their entire life cycle.[15]
Systematics
The following taxonomic sequence gives the subfamilies, their associated genera.[19][20][21][22]
Subfamily Agabinae Thomson, 1867
Agabinus Crotch, 1873
Agabus Leach, 1817
Agametrus Sharp, 1882
Andonectes Guéorguiev, 1971
Hydronebrius Jakovlev, 1897
Hydrotrupes Sharp, 1882
Ilybiosoma Crotch, 1873
Ilybius Erichson, 1832
Leuronectes Sharp, 1882
Platambus Thomson, 1859
Platynectes Régimbart, 1879
Subfamily Colymbetinae Erichson, 1837
Anisomeria Brinck, 1943
Senilites Brinck, 1948
Carabdytes Balke, Hendrich & Wewalka, 1992
Bunites Spangler, 1972
Colymbetes Clairville, 1806
Hoperius Fall, 1927
Meladema Laporte, 1835
Melanodytes Seidlitz, 1887
Neoscutopterus J.Balfour-Browne, 1943
Rhantus Dejean, 1833
Rugosus García, 2001
Subfamily Copelatinae Branden, 1885
Agaporomorphus Zimmermann, 1921
Aglymbus Sharp, 1880
Copelatus Erichson, 1832
Exocelina Broun, 1886
Lacconectus Motschulsky, 1855
Liopterus Dejean, 1833
Madaglymbus Shaverdo & Balke, 2008
Rugosus García, 2001
Subfamily Coptotominae Branden, 1885
Coptotomus Say, 1830
Subfamily Cybistrinae
Austrodytes Watts, 1978
Cybister Curtis, 1827
Megadytes Sharp, 1882
Onychohydrus Schaum & White, 1847
Regimbartina Chatanay, 1911
Spencerhydrus Sharp, 1882
Sternhydrus Brinck, 1945
Subfamily Dytiscinae Leach, 1815
Acilius Leach, 1817
Aethionectes Sharp, 1882
Austrodytes Watts, 1978
Dytiscus Linnaeus, 1758
Eretes Laporte, 1833
Graphoderus Dejean, 1833
Hydaticus Leach, 1817
Hyderodes Hope, 1838
Megadytes Sharp, 1882
Miodytiscus Wickham, 1911
Notaticus Zimmermann, 1928
Onychohydrus Schaum & White, 1847
Regimbartina Chatanay, 1911
Rhantaticus Sharp, 1880
Sandracottus Sharp, 1882
Spencerhydrus Sharp, 1882
Sternhydrus Brinck, 1945
Thermonectus Dejean, 1833
Tikoloshanes Omer-Cooper, 1956
†Ambarticus Yang et al. 2019 Burmese amber, Myanmar, Late Cretaceous (Cenomanian)
↑ 1.01.11.21.3G.N. Foster; D.T. Bilton (2014). "The Conservation of Predaceous Diving Beetles: Knowns, Unknowns and Anecdotes". in D.A. Yee. Ecology, Systematics, and the Natural History of Predaceous Diving Beetles (Coleoptera: Dytiscidae). pp. 437–462. ISBN 978-94-017-9109-0.
↑"Dytiscidae - Hurdan, the answer engine". http://www.hurdan.com/search?q=dytiscidae.
↑G.C. McGavin (2010). Insects. pp. 86–87. ISBN 978-1-4053-4997-0.
↑Nilsson, A.N. (2013). "A World Catalogue of the Family Dytiscidae, or the Diving Beetles (Coleoptera, Adephaga)". University of Umeå. http://www2.emg.umu.se/projects/biginst/andersn/WCD_20130101.pdf.
↑Yee, D.A. (2014). "An Introduction to the Dytiscidae: Their Diversity, Historical Importance, Cultural Significance, and Other Musings". Ecology, Systematics, and the Natural History of Predaceous Diving Beetles (Coleoptera: Dytiscidae): 1–16. doi:10.1007/978-94-017-9109-0_1. ISBN 978-94-017-9108-3.
↑ 6.06.1Lundkvist, E.; Landin, J.; Karlsson, F. (2002). "Dispersing diving beetles (Dytiscidae) in agricultural and urban landscapes in south-eastern Sweden". Annales Zoologici Fennici.
↑ 7.07.1Law, A.; Baker, A.; Sayer, C.; Foster, G.; Gunn, I.D.; Taylor, P.; Blaikie, James; Willby, N.J. (2019). "The effectiveness of aquatic plants as surrogates for wider biodiversity in standing fresh waters". Freshwater Biology64 (9): 1664–1675. doi:10.1111/fwb.13369. https://research.tees.ac.uk/ws/files/7865012/The_effectiveness_of_aquatic_plants_as_surrogates_for_wider_biodiversity_in_standing_fresh_waters.pdf.
↑ 8.08.18.2Liao, W.; Venn, S.; Niemelä, J. (2020). "Environmental determinants of diving beetle assemblages (Coleoptera: Dytiscidae) in an urban landscape". Biodiversity and Conservation29 (7): 2343–2359. doi:10.1007/s10531-020-01977-9.
↑Liao, W.; Venn, Stephen.; Niemelä, J. (2023). "Microhabitats with emergent plants counterbalance the negative effects of fish presence on diving beetle (Coleoptera: Dytiscidae) diversity in urban ponds". Global Ecology and Conservation41: e02361. doi:10.1016/j.gecco.2022.e02361.
↑Nilsson, A. N.; Holmen, M. (1995). The Aquatic Adephaga (Coleoptera) of the Fennoscandia and Denmark. II. Dytiscidae. Leiden, the Netherlands: Brill.. ISBN 9004104569.
↑ 11.011.111.2Miller, Kelly; Bergsten, Johannes (3 October 2016). Diving Beetles of the World: Systematics and Biology of the Dytiscidae. Baltimore: Johns Hopkins University Press. p. 20.
↑De Foliart (2002), Jäch (2003), CSIRO (2004)
↑Liao, W.; Venn, S.; Niemelä, J. (2022). "Diving beetle (Coleoptera: Dytiscidae) community dissimilarity reveals how low landscape connectivity restricts the ecological value of urban ponds". Landscape Ecology37 (4): 1049–1058. doi:10.1007/s10980-022-01413-z.
↑ 14.014.1Konrad Dettner (2014). "Chemical Ecology and Biochemistry of Dytiscidae". in D.A. Yee. Ecology, Systematics, and the Natural History of Predaceous Diving Beetles (Coleoptera: Dytiscidae). pp. 235–306. ISBN 978-94-017-9109-0.
↑ 15.015.1Mortazavi, Abdolazim; Hajiqanbar, Hamidreza; Lindquist, Evert E (2018-10-20). "A new family of mites (Acari: Prostigmata: Raphignathina), highly specialized subelytral parasites of dytiscid water beetles (Coleoptera: Dytiscidae: Dytiscinae)". Zoological Journal of the Linnean Society184 (3): 695–749. doi:10.1093/zoolinnean/zlx113. ISSN 0024-4082. https://doi.org/10.1093/zoolinnean/zlx113.
↑Aiken, R. B. (1985-02-01). "Attachment sites, phenology, and growth of larvae of Eylais sp. (Acari) on Dytiscus alaskanus J. Balfour-Browne (Coleoptera: Dytiscidae)" (in en). Canadian Journal of Zoology63 (2): 267–271. doi:10.1139/z85-041. ISSN 0008-4301. http://www.nrcresearchpress.com/doi/10.1139/z85-041.
↑Aykut, Medeni; Esen, Yunus; Taşar, Gani Erhan (2016-07-03). "New host-parasite association of Acherontacarus rutilans (Acari, Hydrachnidia, Acherontacaridae) on Scarodytes halensis (Coleoptera: Dytiscidae)" (in en). International Journal of Acarology42 (5): 242–246. doi:10.1080/01647954.2016.1174304. ISSN 0164-7954. http://www.tandfonline.com/doi/full/10.1080/01647954.2016.1174304.
↑Arjomandi, Elham; Zawal, Andrzej; Hajiqanbar, Hamidreza; Filip, Ewa; Szenejko, Magdalena (2019-07-22). "New record of a parasitising species of Hydrachna (Acari, Hydrachnidia) on water beetles Eretes griseus (Fabricius, 1781) (Coleoptera, Dytiscidae, Dytiscinae, Eretini)". ZooKeys (865): 31–38. doi:10.3897/zookeys.865.34532. ISSN 1313-2970. PMID 31379442. PMC 6663934. https://zookeys.pensoft.net/article/34532/.
↑"Dytiscidae". https://www.gbif.org/species/7824.
↑Nilsson, A.N.. A World Catalogue of the Family Dytiscidae, or the Diving Beetles (Coleoptera, Adephaga) (Report). http://www2.emg.umu.se/projects/biginst/andersn/World catalogue of Dytiscidae 2015.pdf. Retrieved 2019-06-18.
↑Bouchard, Patrice; Bousquet, Yves; Davies, Anthony E.; Alonso-Zarazaga, Miguel A. et al. (2011). "Family-group names in Coleoptera (Insecta)". ZooKeys (88): 1–972. doi:10.3897/zookeys.88.807. ISSN 1313-2989. PMID 21594053. PMC 3088472. https://zookeys.pensoft.net/articles.php?id=4001.
↑Prokin, A.A.; Petrov, P.N.; Wang, B.; Ponomarenko, A.G. (2013). "New fossil taxa and notes on the Mesozoic evolution of Liadytidae and Dytiscidae (Coleoptera)". Zootaxa3666 (2): 137–159. doi:10.11646/zootaxa.3666.2.2. https://www.zin.ru/animalia/coleoptera/pdf/Prokin_Petrov_Wang_Ponomarenko_2013_Mesozoic_Liadytidae_Dytiscidae_z03666p159p594.pdf.
Commonwealth Scientific and Industrial Research Organisation (CSIRO) (2004): Water for a Healthy Country - Family Dytiscidae. Version of 2004-JUL-02. Retrieved 2008-AUG-04
De Foliart, Gene R. (2002): Chapter 26 - Eastern Asia: China, Japan, and other countries. In: The Human Use of Insects as a Food Resource: A Bibliographic Account in Progress.
Jäch, Manfred A. (2003): Fried water beetles Cantonese style. American Entomologist49(1): 34-37. PDF fulltext
Larson, D.J., Alarie, Y., and Roughley, R.E. (2000): Predaceous Diving Beetles (Coleoptera: Dytiscidae) of the Nearctic Region, with emphasis on the fauna of Canada and Alaska. NRC Research Press, Ottawa. ISBN:978-0-660-17967-4.
External links
Wikidata ☰ Q327149 entry
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