Abedus

Abedus is a genus of giant water bugs (family Belostomatidae) found in freshwater habitats in southern United States, Mexico and Central America.[1][2] Sometimes called ferocious water bugs,[3] these brown insects typically are between 2.3 and 4 cm (0.9–1.6 in) long,[1][4] although A. immaculatus only is about 1.3–1.4 cm (0.51–0.55 in), making it the smallest North American belostomatid and possibly worthy of separation in its own genus.[5] Otherwise the different Abedus species are very similar and can often only be separated with a microscope.[6] They will bite in self-defense, which is painful but not dangerous.[6]

Abedus
Abedus herberti (male with eggs) at the Cincinnati Zoo
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hemiptera
Family: Belostomatidae
Genus: Abedus
Stål, 1862

Behavior

Members of this genus generally do not fly,[7] and at least some species, including A. herberti, have a greatly reduced flight apparatus and are completely flightless.[8][9] Despite being essentially aquatic Abedus may travel some distance overland and have been known to abandon streams after heavy rainfalls, allowing them to avoid being swept along in flash floods.[7]

Breeding
Several Abedus herberti, including both males with eggs on their back and individuals without eggs

Giant water bugs exhibit male parental care. In Abedus and other species in the subfamily Belostomatinae (but not subfamily Lethocerinae), the female glues the eggs onto the male's back and the male tends them until the eggs hatch.[4][10] The eggs are initially yellow-white but gradually change to gray-brown.[4][11] They can be quite large compared to the size of the adult; in the up to 4 cm-long (1.6 in) A. herberti of highland streams in Arizona and northwestern Mexico each egg can measure as much as 6 mm × 2 mm (0.24 in × 0.08 in) when fully developed.[4][12] After hatching, the nymphs go through five instar stages before adulthood.[11]

Because of the unusual breeding behavior, especially A. herberti is often displayed in zoos, sometimes together with the sunburst diving beetle.[13] These two species also occur together in the wild.[14]

Feeding

Abedus are sit-and-wait predators that catch small animals, especially invertebrates such as other aquatic insects and snails, but also small vertebrates such as young fish and tadpoles.[3][14] Small and medium-sized prey items are caught with their strong front legs and stabbed with the proboscis, which injects a saliva that both incapacitates the prey and dissolves it.[14] The largest food category (in A. herberti, animals 1.2 cm (0.5 in) or more in length) are mostly scavenged. The only prey they regularly catch alive (not just scavenge) in the largest category is nymphs of their own species.[14] Adults are generally highly cannibalistic towards their nymphs and older nymphs often eat younger; adults however only rarely cannibalize other adults.[11][14]

Species

List of species:[15]
Subgenus Abedus

  • Abedus breviceps Stål, 1862
  • Abedus ovatus Stål, 1862
  • Abedus parkeri Menke, 1966

Subgenus Deinostoma

  • Abedus decarloi Menke, 1960
  • Abedus dilatatus (Say, 1832)
  • Abedus herberti Hidalgo, 1935
  • Abedus immensus Menke, 1960
  • Abedus indentatus (Haldeman, 1854)
  • Abedus stangei Menke, 1960

Subgenus Microabedus

Subgenus Pseudoabedus

  • Abedus signoreti Mayr, 1871
  • Abedus vicinus Mayr, 1871

References
  1. Roland F. Hussey; Jon L. Herring (1950). "A Remarkable New Belostomatid (Hemiptera) from Florida and Georgia". The Florida Entomologist. 33 (2): 84–89. doi:10.2307/3492076. JSTOR 3492076.
  2. Capinera, J.L., ed. (2008). Encyclopedia of Entomology (2 ed.). Springer. p. 1620. ISBN 978-1-4020-6242-1.
  3. "Ferocious Water Bug". Saint Louis Zoo. Retrieved 6 April 2018.
  4. R.L. Smith; C. Horton (1998). "Fish predation on giant water bug (Heteroptera: Belostomatidae) eggs in an Arizona stream". Great Basin Naturalist. 58 (3): 292–293.
  5. J.H. Epler (2006). "Identification manual for the aquatic and semi-aquatic Heteroptera of Florida" (PDF). Florida Department of Environmental Protection. Retrieved 6 April 2018.
  6. "Species Abedus herberti". BugGuide. Retrieved 6 April 2018.
  7. Lytle, D.A. (1999). "Use of Rainfall Cues by Abedus herberti (Hemiptera: Belostomatidae): A Mechanism for Avoiding Flash Floods". Journal of Insect Behavior. 12 (1): 1–12. doi:10.1023/A:1020940012775.
  8. J.H. Thorp; D.C. Rogers, eds. (2015). Thorp and Covich's Freshwater Invertebrates: Ecology and General Biology. 1 (4 ed.). Elsevier. pp. 954–955. ISBN 978-0-12-385026-3.
  9. Phillipsen. I.C.; Kirk, E.H.; Bogan, M.T.; Mims, M.C.; Olden, J.D.; Lytle, D.A. (2015). "Dispersal ability and habitat requirements determine landscape-level genetic patterns in desert aquatic insects". Mol. Ecol. 24 (1): 54–69. doi:10.1111/mec.13003. PMID 25402260.
  10. Robert L. Smith (1997). "Evolution of paternal care in the giant water bugs (Hemiptera: Belostomatidae)". In Jae C. Choe & Bernard J. Crespi (ed.). The Evolution of Social Behavior in Insects and Arachnids Sociality. Cambridge University Press. pp. 116–149. doi:10.1017/CBO9780511721953.007. ISBN 978-0-511-72195-3.
  11. R.L. Smith (1974). "Life History of Abedus herberti in Central Arizona (Hemiptera: Belostomatidae)". Psyche: A Journal of Entomology. 89 (2): 272–283. doi:10.1155/1974/83959.
  12. M.T. Bogan; O.G. Gutiérrez-Ruacho; J.A. Alvarado-Castro; D.A. Lytle (2013). "New Records of Martarega, Graptocorixa, and Abedus (Heteroptera: Notonectidae, Corixidae, Belostomatidae) From Northwestern Mexico and Arizona, Including the First Record of Graptocorixa emburyi In the United States". The Southwestern Naturalist. 58 (4): 494–497. doi:10.1894/0038-4909-58.4.494.
  13. O’Sullivan, T. "Captive rearing study of the Thermonectus marmoratus" (PDF). St. Louis Zoo. Retrieved 9 April 2018.
  14. J. Velasco; V.H. Millan (1998). "Feeding Habits of Two Large Insects from a Desert Stream: Abedus herberti (Hemiptera: Belostomatidae) and Thermonectus marmoratus (Coleoptera: Dytiscidae)". Aquatic Insects. 20 (2): 85–96. doi:10.1076/aqin.20.2.85.4500.
  15. "Abedus Stål, 1862". Integrated Taxonomic Information System. Retrieved 2020-11-09.
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