April 2021
Fuel for the Fire

Invasive grasses and plants, such as buffelgrass (Pennisetum ciliare), lovegrass (Eragrostis curvula), red brome (Bromus rubens), and stinknet (Oncosiphon pilulifer) are overwhelming U.S. deserts and providing fuel for wildfires. Not only do the invasive grasses shade the ground, preventing the growth of native species, they grow between cactus, trees, bushes, and rocks creating dense mats of vegetation in spaces that would normally be void of plants. The additional vegetative growth provides fuel for fire to spread and continue spreading. The native desert plants are not fire-adapted and do not survive these fires.

In 2020, Arizona experienced one of its worst wildfire seasons in a decade. Authorities say that invasive grasses and plants fed many of the fires, including one that spanned 193,000 acres. Recent research examined 14 American states to determine a vulnerability index for places at high risk of wildfire (read more here). Arizona and New Mexico pose the greatest vulnerability, while Texas, Florida, and California pose the least (California was ranked low due the high adaptive capacity measures in place to withstand its vulnerability, even though it has one of the highest exposures and sensitivities to wildfire). Although there are benefits to wildfires in some ecosystems, deserts of the southwestern U.S., such as the Sonoran Desert, are not as fire-adapted and do not benefit as much as other ecosystem. As fires continuously burn down vegetation and change the soil, it becomes more easily erodible and loses its capacity to absorb rain and retain water flow. This can result in more flash floods and heavy debris-flows during monsoon season.

Buffelgrass in particular is spreading across large areas of the desert landscape in Arizona. This exotic grass is a perennial grass adapted to arid climate, and was introduced to Arizona, Texas, and Mexico in the 30’s to control soil erosion and provide cattle forage. In the 80’s, the grass started to take over the Sonoran Desert. Buffelgrass can be managed with herbicide or by manual removal. Herbicides are only effective during the summer when the plant is green, which coincides with the hottest days in the desert, so year-round manual buffelgrass pulls have become critical for management. Volunteers on solo missions or in groups often venture out to tackle the relentless buffelgrass and other invasive vegetation. Buffelgrass has well-anchored roots which requires a crowbar or pickaxe in order to excavate the plant and roots completely. The seeds that linger remain viable for years, requiring cleared areas to be revisited year after year. Some signs of success are evident in cleared areas of Catalina State Park, Tucson, AZ, that have remained free of buffelgrass and are now full of wildflowers in the spring.

buffelgrass in sonoran desert. Travis Bean
Buffelgrass (Pennisetum ciliare) in Sonoran Desert. Credit: Travis Bean.

buffelgrass regrowing after fire. no natives survived. mpsaz.org
Buffelgrass (Pennisetum ciliare) regrowing after fire. No natives survived. Credit: mpsaz.org

Wildfire in the Mojave Desert fueled by the invasive exotic grass red brome (Bromus rubens). Photograph- Kimberleigh J. Field.
Wildfire in the Mojave Desert fueled by the invasive exotic grass red brome (Bromus rubens). Credit: Kimberleigh J. Field.


Lazy Ants or Workers Working Hard

Most social Hymenotera (bees, wasps, and ants) have a caste system that consists of a reproductive queen (or multiple queens, depending on the species) that produce offspring, and non-reproductive female workers that contribute to the colony in different ways. Males arise parthenogenetically from unfertilized eggs and are haploid, whereas females arise from fertilized eggs and are diploid. This is referred to as a haplodiploid sex determination system. In a monogynous colony (one queen), this system results in an asymmetrical genetic relatedness among the colony where workers are more genetically related to their sisters (queens’ offspring) than they would be to their own offspring. The workers in most colonies retain functional ovaries and are capable of producing viable male eggs and/or unfertilized tropic eggs, but different reproductive constraints impair the workers from reproducing, sometimes resulting in workers with underdeveloped ovaries. Tropic eggs are essentially nutrient packets that can be an important source of food for the colony.

The yellow crazy ant (Anoplolepis gracilipes) is a highly aggressive tramp ants, is polygynous (multiple queens), forms supercolonies, and is on the list of the 100 world’s worst invasive species. The caste systems contain reproductive (physogastic) workers with well-developed ovaries, as well as non-reproductive workers. However, the reproductive workers seem to act more like queens than workers. They are less active, remaining immobile and sheltered inside their nest, and spend only a small fraction of time foraging. They are also slow to react or move when the nest is disturbed, less aggressive, and less likely to start fighting to defend of the colony. However, having reproductive workers can also be advantageous because they can produce tropic eggs, reproductive eggs, and males, which allows mating to take place in the absence of a queen, extending the life of the colony until a virgin queens emerges, or another queen is adopted. Yellow crazy ant workers are not able to lay worker eggs due to their lack of spermatheca, so the only chance for a queenless colony to survive is for the colony to merge with another colony or adopt a queen. When a queen is present, the reproductive workers stop producing reproductive eggs and produce trophic eggs, until worker-produced males are needed. The plasticity and reproductive behavior of the yellow crazy ant workers may contribute to its success as an invasive species.

Read the research: Lenancker et al. (2021), Lee et al. (2017)

adult yellow crazy ant (Anoplolepis gracilipes). Eli Sarnat
Adult yellow crazy ant (Anoplolepis gracilipes). Credit: Eli Sarnat.
Eggs produced by A. gracilipes workers.  lee et al (2017)
Eggs produced by A. gracilipes workers. Light micrograph of a (a) worker laid reproductive egg and a (b) worker laid trophic egg. Credit: Lee et al. (2017).

Invasive Art Installation

As we fight to control invasive species population, it is sometimes easy to get lost in the monotony of the battle. Remove, treat, dispose, repeat. However, a group of volunteers, a Wareham Land Trust staff member, and a local artist launched an invasive removal and art build program at the Marks Cove Conservation Area in Wareham, MA, reminding us that there are also creative ways to fight back against invasive species.

The program started toward the end of April when the volunteers worked to pull and cut down the invasive species growing in the area. The Conservation area's primary invasive species are Autumn Olive (Elaeagnus umbellata) and Russian Olive (Elaeagnus angustifolia), which are large shrubs that can quickly choke out the surrounding vegetation. The vegetative debris was then brought together to be shaped, intwined, and weaved together into sculptures. The group is forming two serpents along the walking path, so they appear to be emerging from and disappearing into the land itself. By creating the sculptures out of the invasive vegetation, and allowing it to desiccate at the site of removal, the volunteers reduce the chance of accidental seed spread from one location to another that can occur when debris is transported for disposal. The sculpture and cleared areas will be treated with herbicide to prevent regrowth. The sculptures are not finished yet, and they don’t know how long the Wareham Land Trust plans to keep them up, but the esthetically pleasing sculptures can last for years.

Click to see Full Article.

Serpents take shape. by Madison Czopek
Serpents take shape. Credit: Madison Czopek.
 TerraCorps member with the Wareham Land Trust and Mass Audubon working on serpents. Madison Czopek 
TerraCorps member with the Wareham Land Trust and Mass Audubon working on serpents. Credit: Madison Czopek.

Bio-concrete from Invasive Waste

Graduates from the Central Saint Martins College of Art, in London, have created concrete-like tiles, or bio-concrete, made from Japanese knotweed (Reynoutria japonica) and the shells from American signal crayfish (Pacifastacus leniusculus). These two invasive species are among the most detrimental to the UK. The project was commissioned as part of the Maison/0 graduate programme by the LVMH group with the aim of developing a sustainable alternative to current building materials that could be used in luxury store interiors.

When invasive species are removed, the harvested material is incinerated, burned or trashed. In producing the bio-concrete, the creators hope to relocate the harvested waste material into something sustainable. Both invasive species waste removal and the creation of concrete are major carbon emissions culprits, whereas the bio-concrete is created in a fashioned similar to that used by the ancient Romans when developing volcanic ash concrete. Incinerated knotweed acts as a binder, while pulverized crayfish shells are used as the aggregate, instead of the traditional rock or sand. This mixture is added to water and gelatin to create a strong homogeneous material that cures and hardens without the aid of heat. By experimenting with different cure times and aggregate-binder-water mixtures, different colors and textures were created, ranging from pale mint green to dark burgundy. The finished product can have the appearance of raw concrete, stone, or marble. The project is still in its infancy and there are many hurdles that prevents larger production of the regenerative material, such as building regulations and invasive species disposal rules. Currently in the UK, invasive species are labelled as hazardous waste material once removed, making it difficult to repurpose into raw materials.

Click to see Full Article.

Bio-concrete. Credit: dezeen.com
Close up of bio-concrete
Close up of bio-concrete. Credit: dezeen.com

Update- Zebra mussels found in Moss Ball

Zebra mussels (Dreissena polymorpha) infested moss balls have been confirmed in pet stores in 34 states, including Texas. Moss ball are squishy, aquatic balls of green algae, about 2 to 5 inches in diameter. TPWD officials have alerted pet stores and retailers, who are working to remove the products from their shelves and discontinue further sales.

According to authorities, anyone that has recently purchased moss balls should consider them contaminated and dispose of them appropriately. Aquarium owners are encouraged to inspect their aquarium and follow the U.S. Fish and Wildlife Service’s “Destroy, Dispose, Drain” strategy. For more information and instruction on how to dispose and report moss balls with zebra mussels, please visit: www.fws.gov

Pet Industry Joint Advisory Council (PIJAC) has been engaging on this threat with state and federal regulatory bodies led by the U.S. Fish and Wildlife Service (USFWS). These regulatory bodies have identified a need for more comprehensive guidance for use by the aquarium trade. PIJAC has developed an enhanced guidance document for use by retailers and suppliers, as well as aquarium and water garden hobbyist. Download the PDF here.

Moss ball and Zebra mussel. Photo by IDFW
Moss ball and Zebra mussel. Credit: IDFW.

Aquatic Invasive Species Research Grants
  • Proposal Deadline: May 31, 2021

Texas Parks and Wildlife Department (TPWD) announces a Request for Proposals (RFP) for state fiscal years 2022–2023 under the Aquatic Invasive Species program. Research grants that span one or two years may be awarded. Prior to proposal submittal, it is suggested that investigators contact the TPWD Senior Scientist for Aquatic Invasive Species or other TPWD biologist(s) with expertise in the study area to discuss and refine potential proposals. Applicants must demonstrate a proven track record of publications or previous work (e.g., unpublished project reports) in an applicable field. For more information, please see tpwd.texas.gov.


National Invasive Species Awareness Week

National Invasive Species Awareness Week is back! Participate in Part 2 of the largest invasive species awareness effort in North America. Go to NISAW website for more information about local events, a resourse toolkit, and more.

  • NISAW Part II: May 15-22

  • Outreach and Education Webinars:
    • May 17, 1pm- The Climate Crisis and Invasive Species. REGISTER.
    • May 18, 1pm- The Model Legislative Framework for State Aquatic Nuisance Species (ANS) Programs and Resource Toolkit for Local Governments. REGISTER.
    • May 19, 1pm- The Regulatory Process for Classical Weed Biological Control. REGISTER.
    • May 20, 1pm- Aquatic Plant Management Priorities. REGISTER.
    • May 21, 1pm- A Comparison of State Noxious Weed Lists and an Overview of the Western Weed Action Plan. REGISTER.


North American Invasive Species Management Association Training Webinars

The program is designed to provide the education needed for professionals and students who are managing or learning to manage invasive species. The courses include the most current invasive species identification, control and management techniques, and how to comply with local and federal regulations.

Participants may register and enroll at any time, and will receive a certificate of invasive species management from NAISMA upon completion of the program.

All live webinars are open to the public. Recorded webinars are available to members of NAISMA.

NAISMA 2020 Webinar Schedule:

  • May 5, 1pm- PlayCleanGo Awareness Week and How to Integrate PlayCleanGo Outreach Tools. REGISTER.
  • June 16, 1pm- Healthy Trees, Healthy Cities. REGISTER.
  • July 21, 1pm- Best Management Practices for Pesticide Applications. REGISTER.
  • August 18, 1pm- Racial Equity & Environmentalism. REGISTER.


USGS' Comprehensive List of Non-Native Species Established in Three Major Regions of the U.S.

A comprehensive list of non-native species established in three major regions of the United States: Version 3.0. A compilation and analysis of authoritative assertions of the nonindigenous established status of taxa in Alaska, Hawaii, and the contiguous United States of America.

Version 3.0 of the non-native species list, as of 2020-09-15, contains 13,391 records and 11,478 unique names: 537 taxa for Alaska, 5,996 taxa for Hawaii, and 6,818 taxa for the conterminous United States. It is taxonomically refined, has tighter control of establishment status and non-native status, and includes approximate dates of introduction for 28% of its records.


National Agricultural Library: Learn to Edit Wikipedia And Help Improve Articles About Invasive Species
  • May 20, 2021; 10:00am- 2:00pm

Join the National Agricultural Library’s National Invasive Species Information Center to learn more about invasive species, their effects, and their control. This free event will begin with an introduction and information about the Information Center and invasive species from Joyce Bolton, head of the National Invasive Species Information Center, and other guest speakers from USDA Then, Jamie Flood, Wikipedian-in-residence of National Agricultural Library and Ariel Cetrone of Wikimedia D.C. will lead a one-hour training on Wikipedia editing and we will spend the rest of the day updating invasive species articles on Wikipedia. During the event experienced editors and Invasive Species experts will be on hand to assist and answer questions. REGISTER HERE.

Texas invasive. modification of image from sporcle.com
Example of Texas invasive. Modification of image from sporcle.com

Invasive Spotlight:

Black Velvet Leatherleaf Slug
(Belocaulus angustipes)

The black velvet leatherleaf slug (Belocaulus angustipes) is typically jet black with an inconspicuous tan stripe down the underside, and two ocular tentacles that are also black. The mantle covers the entire length of the body and has a velvety/wrinkled appearance. The ventral portion of the mantle that runs along either side of the tan strip has black flecks along the margins. Both the breathing pore (pneumostome) and anus are located posteriorly. The slugs can measure up to 3.5 inches in length when fully extended. Juvenile slugs are not as dark and have a much lighter underside. These slugs are typically nocturnal, but will often emerge following a rainstorm. They live underneath fallen trees, planks, or similar places that will keep them out of the sun.

Their diet consists of both live and decaying plant matter. The slugs have a large appetite, which can be detrimental to many types of grasses, plants, and agricultural crops. Outside the U.S., the black velvet leatherleaf slug has been reported as an important vector of the nematode parasite Angiostrongylus costaricensis, which causes abdominal angiostrongyliasis in humans. Although abdominal angiostrongyliasis has not yet been reported in the U.S. where the slug has been detected, it is recommended that latex gloves be worn, or at least samples handled using a plastic bag. After handling live slugs, hands should be washed thoroughly in hot soapy water and rinsed in alcohol or hand disinfectant.

For more information about the black velvet leatherleaf slug, click here.

If you believe you have identified a suspected black velvet leatherleaf slug, please take a picture and REPORT IT! to invasives@shsu.edu.

Ideally, someone from Texas Invasive Species Institute (TISI) would like to pick up specimen(s), but sometimes this isn't feasible. If you are interested in sending the suspected specimen to TISI, where the team checks them for Angiostrongylus nematodes, please use the above-mentioned email and instructions will be provided. Specimens can be stored in 70% ethanol.

black velvet leatherleaf slug. jexshells.org
Black velvet leatherleaf slug (Belocaulus angustipes). jexshells.org
black velvet leatherleaf slug. Photo B. Frank. Jacksonville
Black velvet leatherleaf slug. Note tan strip down underside and black flecks along margins of the mantle. Credit: B. Frank, Jacksonville.


Zebra Mussel Watch

TPWD has detected invasive zebra mussels (Dreissena polymorpha) larvae at Lake Brownwood, which has now been classified as suspect. The larvae were detected in plankton samples at two sites at the lake in November. In March, intensive shoreline and substrate surveys were conducted at both sites where larvae were previously detected. No adult mussels have been found. This is the second lake in the Upper Colorado River Basin where zebra mussels have now been detected, indicating this species is continuing to spread westward.

The public is asked to be on the alert for zebra mussels at Lake Brownwood on rocks, docks, boats, and other hard surfaces. Anyone who spots zebra mussels should immediately notify TPWD at AquaticInvasives@tpwd.texas.gov with photos.

The department emphasized the importance of continued help from boaters, marina operators, and others to Clean, Drain, and Dry all boats and water craft equipment before moving them, and remain vigilant to stop the spread of aquatic hitchhikers.

mussel signal KK
Credit: Kylee N. Kleiner, TRIES.

More News

The American Public is Responsible for Identifying Over a Quarter of New Invasive Species
New research by a team at Resources for the Future (RFF) has found that at least 27% of new pests in the United States were initially detected by members of the general public. phys.org

Texas Marks 5 Years of Enhanced Efforts Against Aquatic Invasive Species
After five years of enhanced funding from state legislature for efforts to protect lakes, rivers, water recreationists, and industry from non-native invasive species, the Texas Parks and Wildlife Department (TPWD) and its partners are reporting significant achievements. tpwd.texas.gov

Major Fly Pest Genetically Modified in the Lab to Produce More Males
Mediterranean fruit flies (Ceratitis capitata), an agricultural pest, have been modified in a lab experiment so more males are born than females, reducing their numbers. phys.org

Lanternfly's Attraction to Vertical Silhouettes Could Help Monitor, Trap It
Spotted lanternflies (Lycorma delicatula) are visually drawn toward vertical objects, such as buildings and utility poles, a behavior that could be valuable in predicting where the pests might be heading, and even trapping. phys.org

Lehua Island is Rat Free- Decade Long Eradication Effort at State Sea Bird Sanctuary is Complete
Lehua Island, the tiny, but mighty island off Kaua‘i’s west shore has been declared free of damaging, introduced rats (Rattus sps). After many decades, the island is free of invasive vertebrates, enabling Hawaii’s seabirds to safely nest on the steep rocky shores, and native plants to flourish once again. governor.hawaii.gov

Roadside Invader: The Higher the Traffic, the Easier the Invasive Common Ragweed Disperses
Common ragweed (Ambrosia artemisiifolia) is an annual plant native to parts of the United States and southern Canada, but an invasive species that has spread to Europe. This plant is particularly well-adapted to living at road networks. New research found high population growth along high-traffic roads and less disturbed road sections, suggesting that seed dispersal by vehicles and by road maintenance can partially compensate for less favorable habitat conditions. sciencedaily.com

Frequent fire too hot to handle for invasive plants
Research shows frequent fires can help keep invasive plants in check by reducing nitrogen availability in soils. A connection was made between fire frequency, invasive plant growth, and microbial nitrogen cycling by comparing forest stands with different fire histories in southern Illinois. phys.org

Global Warming Helps Invasive Species Flourish
New research has shown that increased global temperatures help invasive species establish themselves in ecosystems. The study gives an insight into the probable combined effects of species invasions and global warming. sciencedaily.com

The Unforeseen Consequences of Eradicating Invasive Species
A new study has shown how the eradication of non-native invasive species from islands doesn't necessarily lead to an entirely positive outcome for the native species that live there. The ecosystems need time to recover and some show little sign of doing so. birdguides.com

Seaplanes at Low Risk of Transporting Aquatic Invasive Species
Seaplane pilots are strong advocates for the protection of those waterways. Pilots are required to acquire annual certification training that teaches prevention of contamination and invasive species removal. ndcmontana.com


If you would like to highlight a successful invasive species project or nominate a special person to be highlighted in an upcoming iWire, please send the details to iwire@texasinvasives.org.

Citizen Scientists Spotlight

Port Aransas Brazilian Pepper Tree Removal Workday

In mid-April, a group of volunteers and various entities got together to remove several Brazilian pepper trees (Schinus terebinthifolia) from an acre of land that backs up to the Port Aransas Nature Preserve, in Port Aransas, TX. The workday was run by the Texas Gulf Region of the Cooperative Weed Management Area program in Port Aransas. The group consisted of volunteers that were permanent residents, "winter Texans", the City of Port Aransas, the Mission-Aransas National Estuarine Research Reserve with the UT-Marine Science Institute, the Texas Invasive Species Institute (TISI), and the Texas A&M Forest Service.

Keeping an eye out for snakes in the tall grass, the group worked together to cut back the tangle of branches that grows away from the multiple trunks of each tree and out into a twisted array of vegetation. Because of a growth process called basial sprouting, Brazilian pepper trees can have dozens of trunks instead of one. The intertwining, drooping branches and foliage forms dense thickets that shade out native grasses and smother the native vegetation. Although the trees can grow up to 30-40 feet high, the group only had to tackle some 20 footers. Once the bramble was cleared and there was access to the trunks, workers with chainsaws cut the trees down to short stumps and herbicide was quickly applied to prevent regrowth. Thanks to the freeze, the trees were bare of leaves and berries. This reduced the likelihood of accidental seed spread during the removal process. The foliage can also cause an irritation of the skin similar to that of poison ivy. By the end of the workday, six trailers worth of Brazilian pepper trees material was removed and hauled away.

Port Aransas BPT removal work day. before
Brazilian pepper trees (Schinus terebinthifolia) on land that backs up to the Port Aransas Nature Preserve, Port Aransas, TX. Beginning of work day.

Rae Mooney spraying hernicide on BPT
Rae Mooney with Texas Gulf Region of the Cooperative Weed Management Area spraying herbicide on cut trunks of Brazilian pepper trees.


Sentinel Pest Network and Invaders of Texas Workshops

Invaders of Texas workshops train volunteers to detect and report invasive species as citizen scientists. Workshops, which are free, are designed to introduce participants to invasive species and the problems they cause, cover aspects of invasive species management, and teach identification of local invasive plants, and to train participants to report invasive plants using the TX Invaders mobile application. The workshop is 7 hours long (usually on a Saturday, but scheduling is arranged with each individual host group). The workshop satisfies Master Naturalist training requirements.

Sentinel Pest Network workshops serve to increase the awareness and early detection of a set of particularly important invasive species to help prevent their spread into Texas or their further spread within Texas. Participants learn to identify species such as the Emerald Ash Borer, Cactus Moth, Asian Longhorned Beetle, and other pests of regulatory significance, and to report them. The workshop is 3.5 hours long. The workshop satisfies Master Naturalist training requirements.

Upcoming Workshops:

Thursday, May 6, 2021 (10:30am-11:15am)
Invasive Species talk with Highland Lakes Birding and Wildflower Society based out of Spicewood, TX.
Location: Virtual
Contact: Maria Whitsett

For more information or to register to attend a free workshop, please visit the Workshop Page.