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(Stonefly)
Soil & Water Conservation Society of Metro Halifax (SWCSMH)
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Updated: October 09, 2013 
Contents:
- Superphylum Arthropoda
- (jointed-legged metazoan animals [Gr, arthron = joint; pous = foot])
- Phylum Entoma
- Subphylum Uniramia
- (L, unus = one; ramus = branch, referring to the unbranched nature of the appendages)
- Superclass Hexapoda
- (Gr, hex = six, pous = foot)
- Class Insecta
- (L, insectum meaning cut into sections)
- Subclass Ptilota
- Infraclass Neopterygota
Introduction
The Plecoptera (stoneflies), all of which
are aquatic as nymphs, are considered to be the most primitive order of
living Neoptera. Plecopterans number about 1718 species in 239 genera
belonging to 15 families. Nymphs feed on fresh or decayed vegetable
matter, but may be carnivorous in later instars.
The order Plecoptera belongs to
the infraclass Neoptera because stoneflies' wings fold over their backs
at rest. Wings develop in external wingpads, a characteristic that
places Plecoptera in the division Exopterygota. North American
stoneflies are generally divided into two groups, Euholognatha and
Systellognatha, based on major differences in mouthpart morphology and,
hence, feeding biology.
The taxonomy of this order, like that of
the Ephemeroptera, is poorly known because the larvae of many species
have not been associated with adults.
Modern plecopterans are thought to have
been derived from the Protoperlaria of the Permian (360-286 million
years B.P.) and the fossil record is quite respectable with more than
30 species described from the different strata of the Permian to the
middle Tertiary.
Life History
The stoneflies are terrestrial as adults,
but in the nymphal stages they are strictly aquatic, and most are
restricted to flowing waters of relatively high oxygen concentrations.
Fertile eggs, laid over or in the water, requite two to three weeks for
hatching in many species, and several months among some larger forms.
The nymphal instars, from 10 to over 30 moltings, occur in one to three
years. Adults live from 1 to 4 weeks. Most adults are winged, although
a few species are wingless (apterous) or have short wings
(brachypterous). None fly well and this has prevented them from
crossing even small geographical barriers. Thus, like the mayflies, stoneflies are useful tools in studies of historical biogeography.
Temperate species that overwinter
as nymphs often do not stop growing even in water temperatures close to
0°C. It seems that it is warm water temperatures rather than cold ones
that punctuate stonefly life cycles. The ability to spend the summer in
diapause enables some species to live in temporary streams.
Feeding
Generally, stonefly nymphs are either
shredders or predators. Some groups that are predaceous as late instars
have been reported to be herbivorous or detritivorous in early instars,
while late instars of large detritivores may consume some prey.
Predators are engulfers, that is, they swallow their prey whole or bite
off and swallow parts of prey. They are active search or pursuit
predators, using their long filamentous antennae to locate prey using
tactile, wave disturbance, and chemical cues. Many species are
opportunistic feeders, consuming prey in proportion to their relative
abundance. Other species are selective for prey species or sizes. In
some families adults feed, and in others they do not.
Habitat and Ecological preference
Plecopteran nymphs are restricted to cool,
clean streams with high dissolved oxygen content. some species,
however, may be found along the wave-swept shores of large oligotrophic
lakes. When subjected to low dissolved oxygen concentration, the nymphs
of many species exhibit a characteristic "push-up" behaviour that
increases the rate of movement past the gills. The gills are variously
placed among species on the neck, thorax and abdomen. However, some
species have no gills and respiration in these is assumed to be across
the cuticle surface.
The high water quality
requirements of the nymphs bars all but a very few species from
habitats subject to low oxygen levels, siltation, high temperatures and
organic enrichment, and this has led to their effective use as
biological indicators of environmental degradation.
Field surveys clearly show that the
nymphs of many species are associated with particular sections of a
stream bed or lake shore. The specific microhabitat occupied depends on
a variety of environmental factors such as the nature of the substratum
(particle size and configuration), current regime, presence of other
organisms, and local variations in water chemistry and temperature.
Habitat preference often changes as the nymphs develop and with season.
Prior to emergence, final instar nymphs tend to migrate towards the
bank where they crawl out of the water to shed their skins.
Most stoneflies are classified as
clingers or sprawlers, as they are closely associated with the
substrate or leaf litter. A few species have been reported from the
hyporheic zone.
Some physiological and ecological tolerances and requirements (Mackie, 2001)
| Species | General habitat | Feeding | pH | Oxygen %
|
|---|
| Acroneuria lycorias | rocks, streams | predator of insects | <7 - >7 | approx. 100
|
| Allocapnia spp. | rocks, streams | shredder | >7 | approx. 100
|
| Amphinemura delosa | gravel, rocks, streams | gatherer, shredder | <7 - 7 | 100
|
| Isoperla bilineata | plants, rocks, streams | predator of insects, gatherer | >7 | 100
|
| Isoperla clio | plants, streams | predator of insects | >7 | 100
|
| Isoperla fulva | plants, rocks, streams | predator of insects, scraper, gatherer | ≥7 | 50-100
|
| Nemoura trispinosa | plants, rocks, streams | shredder | <7 - >7 | 100
|
| Peltoperla maria | leaf litter, streams | shredder | ≥7 | approx. 100
|
| Perlesta placida | rocks, leaves, streams | predator of insects, gatherer | >7 | approx. 100
|
| Pteronarcys spp. | rocks, logs, leaves, streams | predator, scraper, shredder | ≥7 | approx. 100
|
| Taeniopteryx maura | rocks, logs, leaves, streams | gatherer, shredder | <7 - >7 | approx. 100
|
References and web URLs:
- Hutchinson, G.E. 1993. A Treatise on Limnology. Vol. IV, The Zoobenthos. Ed. Y.H. Edmondson. John Wiley & Sons, Inc. Xx, 944pp.
- Mackie, G.L. 2001. Applied Aquatic Ecosystem Concepts. Kendall/Hunt Publishing Company. xxv, 744 pp. ISBN 0-7872-7490-9
- Narf, R. 1997. Midges, bugs, whirligigs and others: The
distribution of insects in Lake "U-Name-It". Lakeline. N. Am. Lake
Manage. Soc. 16-17, 57-62.
- Peckarsky, B.L., P.R. Fraissinet, M.A. Penton, and D.J. Conklin,
Jr. 1990. Freshwater Macroinvertebrates of Northeastern North America.
Cornell Univ. Press. xii, 442pp.
- Wetzel, R.G. 1983. Limnology. 2nd ed. Saunders College Publishing. Xii, 767pp, R81, I10.
- Williams, D.D., and Feltmate, B.W. 1992. Aquatic Insects. CAB International. ISBN: 0-85198-782-6. xiii, 358p.
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