Great Basin Naturalist Volume 58 Number 3 Article 11 7-1-1998 Fish predation on giant water bug (Heteroptera: Belostomatidae) eggs in an Arizona stream Robert L. Smith University of Arizona, Tucson Chris Horton University of Arizona, Tucson Follow this and additional works at: https://scholarsarchive.byu.edu/gbn Recommended Citation Smith, Robert L. and Horton, Chris (1998) "Fish predation on giant water bug (Heteroptera: Belostomatidae) eggs in an Arizona stream," Great Basin Naturalist: Vol. 58 : No. 3 , Article 11. Available at: https://scholarsarchive.byu.edu/gbn/vol58/iss3/11 This Note is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Great Basin Naturalist 58(3), © 1998, pp. 292-293 FISH PREDATION ON GIANT WATER BUG (HETEROPTERA: BELOSTOMATIDAE) EGGS IN AN ARIZONA STREAM Robert L. Smithl and Chris Horton2 Key words: Abedus herberti, brooding, egg predation, aquatic insect, fWh diet, stomach contents. We caught 3 brown trout (Salrrw trotta) in water bug subfamily Belostomatinae, females the White Mountains of east central Arizona glue their eggs to the backs oftheir mates, and just after daybreak on the morning of20 April the males then actively brood the eggs in a 1997. The fish were taken in the South Fork of variety of ways (Smith 1997). Most belostoma­ the Little Colorado River, elevation ca 2350 m, tines inhabit lentic habitats, but species in the ca 10 km southeast of Springerville, Arizona. New World genus Abedus are stream dwellers The 3 fish ranged in size from 18 to 20 cm TL. (Menke 1960). Abedus herberti occurs in Ari­ The brown or German trout, a European zona streams at elevations of ca 1000-3000 m. species, has been widely distributed in the Males of this species brood their eggs by United States since its introduction to North exposing them to the atmosphere while resting America in the late 19th century (Carlander on vegetation or rocks such that the bug is 1969). This species was introduced to the submersed with the tops of the eggs exposed White Mountains of Arizona sometime in the to the air. When below the surface of the water, 1920, (Miller 1972). Brown trout are pro­ encumbered A. herberti males aerate their eggs duced in hatcheries and released in Arizona by "brood-pumping," i.e., rocking longitudi­ streams including the Little Colorado River to nally about once per second to circulate water provide a sports fishery. over the eggs for embryonic respiration (Smith Pooled stomach contents of the 3 fish con­ 1976). tained 27 Trichoptera (Helicopsychidae and When Abedus spp. eggs are first laid, tlley Limnephilidae) larvae in their cases, 5 mayfly are white in color with tan caps. As the eggs nymphs (Baetidae), 3 Plecoptera (nymphs and develop, they take on a grayish color and adults), 2 aquatic Heteroptera (a naucorid and enlarge. Near hatching time the dorsal portion an early instar belostomatid), plus a variety of of the chorion becomes ash gray. In all stages terrestrial insects. In addition to these items, of development, eggs are highly conspicuous one of the trout stomachs contained 10 giant against the male's dark brown back. Giant water water bug (Abedus herberti Hidalgo) eggs. The bug ova are among the largest insect eggs. eggs, white in color with tan apices, were in Fully developed Abedus herberti eggs can reach good condition and contained mucilage on 6 mm in length and 2 mm in width. Adult their distal ends, From this evidence we infer Abedus herberti bugs range from 24.5 to 40 that the ova had recently been laid and, soon mm in length and 12.5 to 22 mm wide (Menke after their deposition, consumed by the fish. 1960). Thus, the size of adult bugs substan­ Brown trout are able to feed at starlight (10-4 tially exceeded the gape of the small trout we foot Lamberts) intensities (Robinson 1978); caught. thus, the eggs were probably eaten during the Prior to this observation there have been night. no reports of predation or parasitism of any Giant water bugs, aquatic Heteroptera in kind on giant water bug eggs, nor have these the family Belostomatidae, are found in tropical huge insect eggs ever been noted in the stom­ and temperate freshwater habitats through­ ach contents of fish. It seems possible that out most ofthe world. In members ofthe giant fisheries biologists who routinely sample sports 1Deparlment ofEnlomology, University Qf!ulU)1la, Tucson, AZ 8572L zS"hoo! ofR'.mewahle Natural Re~oun;"s, Univer:;ity ofAriZOllV, TucsQn. AZ 86721. 292 1998] NOTES 293 fish stomach contents might not have recog­ MENKE, A.S. 1960. A taxonomk study of tho genus nized giant water bug eggs for what they are. Abedus 51:<11 (Hemiptera, Belostomatidae). University ofCalifornia Publications in Entomology 16:393-440. it However, is not surprising that these con­ MILLER, RH. 1972. Classification of the native trouts of spicuous eggs attached to actively brooding Arizona with the description ofa new species, Salmo giant water bugs would attract the interest of apache. Capcia 1972:401-422. foraging fish who might regularly snatcb eggs ROBINSON, RW 1978. Feeding by brown trout (Sal:mo fn.dta) from encumbered male bugs' backs. 1£ this is and Arizona trout (Saltrw apache) at various light lev­ els. Unpublished master's thesis, University of Ari­ the case, fish could be significant predators of zona, Tucson. AbedW! spp. eggs thronghout the range of the SMITH, R.L. 1976. Male brooding behavior of the water genus from southern Utah through Arizona hug Abedus luwberti (Heteroptera; Belostomatidae). and Mexico to Central America. It is also pos­ Annals of the Entomological Society of America 69: sible that the eggs were inadvertently ingested 740-747. 1997. Evolution of paternal care in the hriant water when the small fish attempted to eat a very --\C'1UgS (Hcteroptera: Belostomatidae). In: J.C. Choe large bug. Tbe authors would be grateful for and B.J. Crespi, editors, The evolution of social be­ any additional accounts of giant water bug havior in insects and arachnids. Cmnbridge University eggs found in fish stomachs. Press. Received 28 August 1997 LITERATURE CITED Accepted 27 Septembe1' 1997 CARLANDER, K.D. 1969, Handbook of freshwater fishely biology. Volume 1. Iowa State University Press, Amos. 752 pp..