Tag: Galls

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Symbiosis in the Desert

Summer temperatures in the Red Cliffs Desert Reserve may often exceed 100 degrees with only a 15 degree drop at night. This is not uncommon in this portion of the Mojave Desert. Over the millennia, amazing adaptations have been made by plants and animal alike to enhance their survival here. Anatomical, physiological and behavioral adaptations are on display every day. Some are quite obvious like cacti, whose leaves have been reduced to spines. What is not as obvious are the remarkable symbiotic relationships that have evolved to enhance survival in these extreme conditions

A symbiotic relationship is best defined as two organisms living together where one or both benefit from the relationship and neither is harmed

Lichen on Rock, Courtesy & Copyright Marshall Topham, Photographer
Lichen on Rock
Courtesy & Copyright Marshall Topham, Photographer
Anyone who has hiked in the deserts of Utah has encountered rocks splashed with a dazzling display of every color in the rainbow. We call them Lichens, but you may not be aware that they are examples of a mutualistic symbiosis where two organisms live together and both benefits from the relationship. Lichens are actually a partnership between a fungus and a photosynthetic organism, usually an alga or cyanobacterium. The fungus provides a protective structure and absorbs water and minerals from rain, dew, or dust. They also offer shelter from harsh desert conditions such as intense sunlight and temperature extremes. The alga or cyanobacterium are the source of color as they contain Chlorophyl, Carotenoids, Anthraquinones, Uric acid and Melanin’s. They produce food by photosynthesis, supplying life sustaining energy for both organisms

Desert Trumpet with Wasp Exit Holes, Courtesy & Copyright Marshall Topham, Photographer
Desert Trumpet with Wasp Exit Holes
Courtesy & Copyright Marshall Topham, Photographer
Another symbiotic relationship known as commensalisms, where one organism is benefited and the other is neither harmed or benefited, can be found associated with Desert Trumpet plants. These tall slender plants have hollow and dynamic inflated stems. The inflated portions of the stems are penetrated by Cynipidae wasps as they lay their eggs inside the hollow cavity where their larvae develop in a protected environment. The resulting hole left when the larvae emerge as adults, allows access inside the chamber, sometimes for years. a student of mine cataloged over 20 species of insects, spiders and mites that were secondary inhabitants of the hollow stems.

Rabbit Brush Gall, Opened Below Showing Occupant, Courtesy & Copyright Marshall Topham, Photographer
Rabbit Brush Gall
Opened Below Showing Occupant
Courtesy & Copyright Marshall Topham, Photographer

Creosote Gall, Courtesy & Copyright Marshall Topham, Photographer Creosote Gall
Courtesy & Copyright Marshall Topham, Photographer

Perhaps the most interesting of all symbiotic relationships found in the desert is the creation of insect galls. Galls are remarkable cancerous like plant growths, produced as a reaction to chemicals injected by insects. This is most commonly initiated by gall wasps, midges, and aphids. Galls come in all shapes, sizes and architectural design and serve as a protective capsule for insects eggs and developing larvae. Some look like cotton balls others resemble land mines or satellites or simple cupping protuberances on a leaf. These galls provide both food and shelter for the insect’s developing larvae. Despite the harshness of arid landscapes, deserts host a surprising diversity of galls. Each insect species typically induces a highly specific gall on a particular host plant. Chemicals secreted by the insect or its larvae manipulate the plant’s hormonal pathways, redirecting growth to form a unique structure that supports the insect’s life cycle. I am not averse to stopping and dissecting galls to examine the larva inside. I am occasionally surprised to find secondary inhabitants such as spiders, mites and the like. While insects benefit from the galls protection the host plants generally do not seem to Any significant harm.

I’m professor Marshall Topham and I’m Wild about Utah’s Mojave Desert.

Credits:

Images Courtesy & Copyright Marshall Topham, Photographer
Featured Audio: Courtesy & © Bob Holmes, Composer, Hugh Jones, Producer, Rubber Rodeo-Before I Go Away, 1984, https://www.discogs.com/release/9698183-Rubber-Rodeo-Scenic-Views
Text: Marshall Topham, https://ees.utahtech.edu/faculty-staff/
Additional Reading: Lyle Bingham, https://bridgerlandaudubon.org/

Additional Reading

Wild About Utah pieces by Marshall Topham https://wildaboututah.org/author/marshall-topham/

Cane, Jim & Kervin, Linda, Gall Insects, Wild About Utah, January 13, 2011, https://wildaboututah.org/gall-insects/

“Sagebrush is an important member of an ecosystem that helps support many birds, reptiles, amphibians, and mammals, as well as an abundance of insects and microbes. One study found nearly 300 arthropod species directly living on just a few plants including- 72 spider, 237 insect, 42 of which were gall-forming, amongst many other species.”
Greene, Jack, Sage Steppe, Wild About Utah, June 15, 2015, https://wildaboututah.org/sage-steppe/

“Pests and Potential Problems Some ecotypes of rubber rabbitbrush are infected by stem galls, which are caused by two species of tephritid flies (Aciurina species) (McArthur 1979). There are no reports of negative effects caused by the galls. ”
Rubber Rabbitbrush, NRCS, USDA, https://www.nrcs.usda.gov/plantmaterials/mtpmcpg9696.pdf

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Gall Insects

Gall Insects: Click to view Rabbit Brush Galls made by a tephritid fly (Aciurina trixa.) Image courtesy and copyright Jim Cane
Rabbit Brush Galls
made by a tephritid fly Aciurina trixa
Image courtesy and Copyright Jim Cane
Fly identification courtesy Gary Dodson

Does Utah have more Gauls than Caesar conquered? Certainly not Gaulish peoples of the ancient Roman Empire, but yes, galls of the vegetal kind we have aplenty. Galls are small protuberant growths on plants that are induced hormonally by insects, nematodes, and microbes. For its resident juvenile insect, the gall is a sort of edible fortress.

Some plant galls made by insects persist into winter, when they are more apparent to the naturalist’s eye. Looking at just rabbitbrush, you can find a menagerie of galls shaped like peas, pineapples and spindles that were formed from leaves, buds and stems. No growing tissue is immune to galling. The morphology of a gall is often diagnostic for the species of juvenile insect within. Gall-making insects are all tiny and include gall midges and tephritid flies, cynipid gall wasps, various nondescript moths, and any number of aphids and their kin.

One aphid causes the unsightly brown galls on branch tips of blue spruce, a bane to homeowners. Another aphid forms the pea-shaped galls that swell leaf petioles of aspens and cottonwoods. On sagebrush can be found a leaf gall whose soft surface surpasses that of a puppy’s ear. Oaks and willows host a remarkable diversity of galls. One oak gall was formerly used for tanning leather and making inks because it is rich in tannic acids. The Hessian fly is of grave agricultural importance today because its stem galls weaken wheat stems, causing them to lodge over.

Click to view Tephritid fly (Aciurina bigeloviae) galls on Rabbitbrush. Image courtesy and copyright Jim Cane
Tephritid fly Aciurina bigeloviae
galls on Rabbitbrush
Image courtesy and Copyright Jim Cane
Fly identification courtesy Gary Dodson

But these are exceptions; most galls are of little or no ecological or economic importance. For that reason, most galling insects remain understudied by all but a handful of passionate specialists. Finding plant galls is easy, and once you begin to notice them, you will find it hard to stop. There is no guide to Utah’s plant galls, but we list several starting references for you on our web site.

This is Linda Kervin for Bridgerland Audubon Society.

Credits:

Photos: Courtesy and Copyright Jim Cane
Text: Jim Cane, Bridgerland Audubon Society
Additional Reading:
Sagebrush Gall made by the fly Rhopalomyia pomum, https://bugguide.net/node/view/200946
Robert P. Wawrzynski, Jeffrey D. Hahn, and Mark E. Ascerno, Insect and Mite Galls, WW-01009 2005,
University of Minnesota Extension, https://www.extension.umn.edu/distribution/horticulture/dg1009.html

Click to view Willow Cone Gall Midge. Image courtesy and copyright Jim Cane
Willow Cone Gall Midge
Image Courtesy and Copyright Jim Cane

Field Guide to Plant Galls of California and Other Western States by Ron Russo
ISBN: 978-0-520-24886-1 https://www.amazon.com/California-Western-States-Natural-History/dp/0520248864
Gall, Wikipedia, Wikimedia Foundation, Inc., https://en.wikipedia.org/wiki/Gall (Accessed Dec 2010)
Gagné R (1989) The plant-feeding gall midges of North America. Cornell University Press, Ithaca
https://www.amazon.com/Plant-Feeding-Midges-North-America-Comstock/dp/0801419182

Posted on

Gall Insects

Rabbit Brush Galls
made by a tephritid fly Aciurina trixa
Image courtesy and Copyright Jim Cane
Fly identification courtesy Gary Dodson

Does Utah have more Gauls than Caesar conquered? Certainly not Gaulish peoples of the ancient Roman Empire, but yes, galls of the vegetal kind we have aplenty. Galls are small protuberant growths on plants that are induced hormonally by insects, nematodes, and microbes. For its resident juvenile insect, the gall is a sort of edible fortress.

Some plant galls made by insects persist into winter, when they are more apparent to the naturalist’s eye. Looking at just rabbitbrush, you can find a menagerie of galls shaped like peas, pineapples and spindles that were formed from leaves, buds and stems. No growing tissue is immune to galling. The morphology of a gall is often diagnostic for the species of juvenile insect within. Gall-making insects are all tiny and include gall midges and tephritid flies, cynipid gall wasps, various nondescript moths, and any number of aphids and their kin.

One aphid causes the unsightly brown galls on branch tips of blue spruce, a bane to homeowners. Another aphid forms the pea-shaped galls that swell leaf petioles of aspens and cottonwoods. On sagebrush can be found a leaf gall whose soft surface surpasses that of a puppy’s ear. Oaks and willows host a remarkable diversity of galls. One oak gall was formerly used for tanning leather and making inks because it is rich in tannic acids. The Hessian fly is of grave agricultural importance today because its stem galls weaken wheat stems, causing them to lodge over.

Tephritid fly Aciurina bigeloviae
galls on Rabbitbrush
Image courtesy and Copyright Jim Cane
Fly identification courtesy Gary Dodson

But these are exceptions; most galls are of little or no ecological or economic importance. For that reason, most galling insects remain understudied by all but a handful of passionate specialists. Finding plant galls is easy, and once you begin to notice them, you will find it hard to stop. There is no guide to Utah’s plant galls, but we list several starting references for you on our web site.

This is Linda Kervin for Bridgerland Audubon Society.

Credits:

Theme: Courtesy & Copyright Don Anderson as performed by Leaping Lulu
Photos: Courtesy and Copyright Jim Cane
Text: Jim Cane, Bridgerland Audubon Society
Voice: Linda Kervin, Bridgerland Audubon Society

Additional Reading:

Sagebrush Gall made by the fly Rhopalomyia pomum, https://bugguide.net/node/view/200946
Robert P. Wawrzynski, Jeffrey D. Hahn, and Mark E. Ascerno, Insect and Mite Galls, WW-01009 2005,
University of Minnesota Extension, https://www.extension.umn.edu/distribution/horticulture/dg1009.html

Willow Cone Gall Midge
Image Courtesy and Copyright Jim Cane

Field Guide to Plant Galls of California and Other Western States by Ron Russo
ISBN: 978-0-520-24886-1 https://www.amazon.com/California-Western-States-Natural-History/dp/0520248864
Gall, Wikipedia, Wikimedia Foundation, Inc., https://en.wikipedia.org/wiki/Gall (Accessed Dec 2010)
Gagné R (1989) The plant-feeding gall midges of North America. Cornell University Press, Ithaca
https://www.amazon.com/Plant-Feeding-Midges-North-America-Comstock/dp/0801419182