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