Transcript of audio, notes on the audio, photo, and additional information follow below. All Web addresses mentioned were functional as of 5-28-15.
TRANSCRIPT OF AUDIO
From the Cumberland Gap to the Atlantic Ocean, this is
Virginia Water Radio for the week of June 1, 2015.
This week, we feature another mystery sound. Have a listen
for about 15 seconds, and see if you can guess what kind of mostly-aquatic
insect is making these sounds. And
here’s a hint: small, but with big impacts, there’s nothing “MIDdling” about
these creatures—except part of their name.
SOUND – 14 SEC – Buzzing of swarming
non-biting midge adults, Blacksburg, Va., 5/13/15
If you guessed midges, you’re right! Specifically, those were swarming adults of
one species of non-biting midges,
technically called chironomids
[pronounced chi-ro-NOM-ids]. Chironomids’
immature forms—egg, larva, and pupa—develop in water; winged adults emerge from
water to live only a few days or weeks to form mating swarms—as you heard—and to
lay eggs. Scientists classify
chironomids as a family within the
group of insects called “true flies,” which also includes mosquitoes, house
flies, and many other familiar insects. Chironomids
aren’t as well-known as those everyday flies, but the family’s aquatic
significance is huge. With over 1000
species, chironomids are North America’s most diverse family of aquatic
insects; they live on the bottom of all kinds of aquatic habitats, both
freshwater and marine; and the number of individuals can reach the tens of
thousands per square meter on the bottom of some water bodies, especially deep
lakes. These and other factors make
chironomids a key component of aquatic food webs, as they eat small organisms
and bottom debris and in turn are eaten by larger animals, including many kinds
of fish.
Chironomids can also help indicate the health of aquatic systems, because certain species are tolerant of poor environmental conditions, such as low dissolved oxygen. For example, bright red chironomids called “bloodworms” have blood hemoglobin that allows them to survive low dissolved oxygen.
On land, chironomid adults don’t bite humans or anything else, as the name “non-biting midges” indicates. But dense mating swarms can sometimes create a human nuisance, such as in July 2010 near Baltimore, Maryland, where a large swarm led one person to claim that “Every leaf of every tree was covered with...midges.” If you look underwater, you might be similarly impressed by nearly countless chironomids.
Chironomids can also help indicate the health of aquatic systems, because certain species are tolerant of poor environmental conditions, such as low dissolved oxygen. For example, bright red chironomids called “bloodworms” have blood hemoglobin that allows them to survive low dissolved oxygen.
On land, chironomid adults don’t bite humans or anything else, as the name “non-biting midges” indicates. But dense mating swarms can sometimes create a human nuisance, such as in July 2010 near Baltimore, Maryland, where a large swarm led one person to claim that “Every leaf of every tree was covered with...midges.” If you look underwater, you might be similarly impressed by nearly countless chironomids.
SOUND – ~1-2 SEC - Appomattox River underwater recording, 4/18/14.
For more Virginia water sounds, music, and information, visit
us online at virginiawaterradio.org,
or call us at (540) 231-5463. Virginia
Water Radio is produced by the Virginia Water Resources Research Center, part
of Virginia Tech’s College of Natural Resources and Environment. Thanks to Stewart Scales for his banjo
version of Cripple Creek to open and close the show. In Blacksburg, I’m Alan Raflo, thanking you for listening, and wishing you
health, wisdom, and good water.
AUDIO NOTES AND
ACKNOWLEDGEMENTS
The sound of a
swarm of non-biting midge adults was recorded on May 13, 2015, at a residential
lawn in Blacksburg, Va. Thanks to Eric
Day, Virginia Tech Department of Entomology, for identifying a sample of these
insects and for providing other information.
The underwater
sound was recorded by Raven Harris on the Appomattox River on April 18, 2014. Thanks to Mr. Harris for providing this
sound.
PHOTO
 |
| Larvae of chironomid species sampled from Eastland Creek in Wise County, Va., in October 2012. Specimens courtesy of Tony Timpano and Kriddie Whitmore, Virginia Tech Department of Forest Resources and Conservation. Photo by Eric Day, Virginia Tech Department of Entomology. |
 |
| Adult of the chironomid species recorded for this episode. The animal was captured from a swarm over a
residential lawn in Blacksburg, Va., on May 13, 2015. Photo by Eric Day, Virginia Tech Department
of Entomology. |
MORE INFORMATION ON NON-BITING MIDGES/CHIRONOMIDS
Here are some other bits of information about non-biting
midges, family Chironomidae in the insect order Diptera (true flies). The last name(s) of the sources for each item,
with relevant page number(s), are listed in parentheses at the end of each item;
for full source information, please see the Sources section below.
Species Diversity
The insect order of the true flies, known as Diptera,
includes some 17,000 species in North America, making it second only to the
order of beetles (Coleoptera) in the number of species, also referred to as its
diversity. Most true flies are terrestrial, but 29
families with about 3500 species in North America have aquatic larvae. (Voshell, p. 396)
There are several other families of dipterans with “midge”
in the common name. The chironomid
family has by far the largest number of species in North America, but the other
families still have species with significant ecological and human impacts. Other “midge” families include the biting
midges (also called “no-see-ums” or “punkies”), dixid midges, mountain midges, net-winged
midges, and phantom midges. (Voshell,
pp. 412-425)
Chironomid species may constitute as much as 50 percent of
the species present in some communities of aquatic macroinvertebrates. (Voshell, p. 421)
Modes of Living
Some chironomid species “roam freely,” but most construct
tubes of fine particles of sediment and organic detritus, held together by
silk. Some attach these tubes to rocks,
plants, logs, or other objects, but some species attach to other insects in a commensal
relationship (commensalism is a type of symbiosis, in which one organism
benefits but the other is not harmed).
(Voshell, p. 420)
As a group, chironomid larvae feed primarily by collecting
or filtering organic material (plant debris, animal debris or wastes,
decomposed materials) from the substrate or from water; some are predators. (Voshell, p. 420-422)
Tolerance of Environmental Conditions
Because of the great diversity of species in this family,
there’s a correspondingly great range of tolerance for various environmental
conditions, such as temperature, dissolved oxygen, salinity, and chemical
pollutants. “In general [however], if
midge larvae are very numerous and account for the majority [of individuals or
species] in a community, that is an indication of poor environmental health
caused by some type of pollution. ...Some kinds [of midges] are very tolerant
of toxins, such as petroleum or heavy metals.”
(Voshell, p. 422)
Hemoglobin is found in the blood of other animals that live
on the bottoms of water bodies (known as the benthic area or zone), but “[t]he
bright red species of Chironomus [a
chironomid genus] are especially characteristic....” (Cole, p. 66)
The ability of chironomids (as a group) to inhabit a very
wide range of environmental conditions is “the product of a very wide array of
morphological, physiological, and behavioral adaptations.” An example of morphological (body structure)
adaptations is “extreme variation” shown in mouthparts. An example of physiological adaptation is
hemoglobin in the blood of some species.
And behavioral adaptations include variations in the activities (timing,
etc.) of the life stages of different species.
(Merritt and Cummins, pp. 551-552)
SOURCES
Used for This Episode
W.P. Coffman and L.C. Ferrington, Jr., “Chironomidae,” in R.W.
Merritt and K.W. Cummins, eds., An
Introduction to Aquatic Insects, 2nd Edition, Kendall/Hunt
Publishing Company, Dubuque, Ia., 1984.
Gerald A. Cole, Textbook of Limnology (2nd
Edition), C.V. Mosby Company, St. Louis, Mo., 1979.
J. Reese Voshell, Jr. Guide
to Common Freshwater Invertebrates of North America, McDonald &
Woodward Publishing, Blacksburg, Va., 2002.
Timothy Wheeler, Midge
infestation in Back River a mystery, Baltimore
Sun, 7/3/10.
For More Information about Non-biting Midges and Other Insects
P.D. Armitage, Peter Cranston, and L.C. Pinder, The Chironomidae: Biology and Ecology of Non-Biting Midges, Chapman and Hall, London, 1997, accessed online at https://books.google.com/books?id=bQyvnx4x6toC&dq=midges&source=gbs_navlinks_s.
Iowa State University Department of Entomology, “BugGuide,”
online at http://bugguide.net/node/view/15740.
McCafferty, W. Patrick, Aquatic
Entomology: The Fishermen's and Ecologists' Illustrated Guide to Insects and
Their Relatives, Jones and Bartlett Publishers, Toronto, 1998.
“Mosquitoes and Water,” Virginia
Water Central, June 2009, pp. 6-15 (Virginia Water Resources Research
Center, Blacksburg, Va.), online at http://vtechworks.lib.vt.edu/handle/10919/49357.
University of Florida Department of Entomology, “Featured
Creatures” Web site, http://entnemdept.ufl.edu/creatures/.
Virginia Tech Department of Entomology Insect Identification
Lab, online at http://www.insectid.ento.vt.edu/.
RELATED VIRGINIA WATER RADIO EPISODES
For previous episodes on aquatic insects, please see the “Insects”
category at the Index link above (http://www.virginiawaterradio.org/p/index.html). In addition, Episode
81 (9/26/11) focuses on the use of aquatic insects in monitoring the
quality of stream water and habitat.
SOLS INFORMATION FOR
VIRGINIA TEACHERS
This episode may help with the following Virginia’s 2010 Science Standards of Learning (SOLs).
Grades K-6 Earth
Resources Theme
3.10 - impacts on survival of species.
4.9 - Va. natural resources, including watersheds, water
resources, and organisms.
Grades K-6 Life
Processes Theme
2.4 - life cycles.
3.4 - behavioral and physiological adaptations.
Grades K-6 Living
Systems Theme
2.5 - living things as part of a system, including habitats.
3.5 - food webs.
3.6 - ecosystems, communities, populations, shared resources.
4.5 - ecosystem interactions and human influences on
ecosystem.
5.5 - organism features and classification.
6.7 - natural processes and human interactions that affect
watershed systems; Va. watersheds, water bodies, and wetlands; and water
monitoring.
Life Science Course
LS. 4 - organisms’ features and classification.
LS.6 - ecosystem interactions, including cycles and energy
flow.
LS.8 - community and population interactions, including food
webs, niches, symbiotic relationships.
LS.9 - adaptations for particular ecosystems’ biotic and
abiotic factors.
LS. 10 - changes over time in ecosystems, communities, and
populations, and factors affecting those changes.
LS.11 - relationships between ecosystem dynamics and human activity.
Earth Science Course
ES.8 - freshwater resources, including groundwater, and
influences by geologic processes and the activities of humans.
Biology Course
BIO.6 - bases for modern classification systems, including structures,
biochemistry, and developmental stages.
BIO.8 - dynamic equilibria and interactions within populations,
communities, and ecosystems; including analysis of the flora, fauna, and microorganisms
of Virginia ecosystems.
Virginia’s SOLs are available from the Virginia Department of Education, online at http://www.doe.virginia.gov/testing/.
Virginia’s SOLs are available from the Virginia Department of Education, online at http://www.doe.virginia.gov/testing/.
