January 2023
Invasive Species Management- The Game

Prevention of invasive species introduction and establishment is cheaper than management and eradication. However, many invasive species remain unnoticed or unrecognized by the general public, allowing them to spread unchecked. Education about their identification, prevention, and management can play a vital role in limiting the cascading effects of invasive species. What better way to teach than with a game?

A recent publication outlines a fun and simple game that introduces invasive species management and the economic issues associated with preventing spread. This game is targeted for high school and college students, but can be enjoyed by anyone eager to learn more about the complexities of invasive species mitigation. This is a team based, turn style game that can be played in one or more rounds. Each group starts with a predetermined amount of money and pretends that they are on an island. Before the game begins, each group must decide how much they would like to spend to prevent, manage, or ignore invasive species (each a predetermined cost), and which ones they choose (list provided). The groups are intentionally not provided with enough money to prevent every invasive in order to mimic the choices politicians, conservationists, and environmental officials must make with limited resources. To start the game, a group draws an invasive species card, showing the vector(s) of arrival on the island (provided). Based on their decision to prevent/manage/ignore, they must pay money to “manage” the problem (prices vary by beginning decision). The invasive species then has the potential to move on to the next island where the next group faces the same financial fate until it reaches an island where the group chose the “prevent.” The round ends when each group has drawn a card. The winner is the group with the most money. Having a negative sum is common. The purpose of the game is to help people understand invasive species management and impact, spread and vectors, the complexities of economic factors, and spark discussions about why this is important.

Read about the game: Lord, 2023



 invasive game table 1Example of invasive species and vectors that each group must choose how to financially manage. Credit: Lord, 2023.

invasive game figure 1Example of trade routes between islands when five groups play. Credit: Lord, 2023.


How Experts Kill the Tree of Heaven

The tree-of-heaven (Ailanthus altissima) was first introduced as an ornamental plant in the 1780s. The history of these trees in their native land of China is as beautiful and ancient as the written word. Regardless of its fruitful history, it is now a widely distributed invasive species across the United States, occurring in forty-two states, including Texas. It can be found sprouting up just about anywhere in rural, urban, natural, and disturbed areas. These trees have many unique properties that make them experts at propagation, but especially difficult to manage.

Full grown trees can grow to 80 feet, with large compound leaves that reach 1-4 feet in length. The leaves leech toxins into the soil when they fall from the trees, which suppress germination in native plants. The trees create thick canopies that choke out native trees, shrubs, and grasses. These trees reproduce both sexually and asexually. One study reported that an individual tree can produce as many as 325,000 seeds, or samaras, per year. The tree of heaven also reproduces by sending up numerous suckers from the roots, cut stumps, and root fragments. This double reproductive method allows these trees to pop up in a new area by the hundreds, quickly out competing natural vegetation.

Seasoned experts suggest that you battle these trees with a sneak attack. If you cut down or prune these trees out right, dozens of saplings with spring up from the cut stumps and root systems in a 25 feet radius from where you cut. Instead, they recommend that you use a method called “hack and squirt.” This involves making several shallow notches into the trunk of the tree, trying to keep the damage to a minimum, so the tree does not think it is under attack and start sprouting underground suckers and saplings. Then, spray the notches with an herbicide, like Triclopyr. This particular herbicide infiltrates the vascular system, travels to the roots, mimics growth hormones, and forces the cells to divide themselves to death. Gruesome, but effective. Saplings are too small to be notched, so a small bit of bark should be shaved off for the herbicide to be applied. Sometimes areas must be treated and retreated as these trees are resilient and pervasive, but the experts stand by the ways of the sneak attack.

Read the article: wired.com
Read about the tree of heaven: texasinvasive.org

Tree of heaven growing in the city. Ian Trueman. University of Wolverhampton. Bugwood.orgTree of heaven (Ailanthus altissima) growing in the city. Credit: Ian Trueman, University of Wolverhampton, Bugwood.org

tree of heaven seeds. Annemarie Smith. ODNR Division of Forestry. Bugwood.orgTree of heaven seeds. Credit: Annemarie Smith, ODNR Division of Forestry, Bugwood.org

hack and squirtExample of "hack and squirt" method on an an invasive hard wood tree. Credit: University of Florida, bugwoodcloud.org

Bees Out Matched

Bees can contract viruses just like we can. Deformed wing virus (DWV) is a RNA virus that most commonly affects the western or European honey bees (Apis mellifera), but can affect many other bee species and some types of wasps. These symptoms include damaged appendages, particularly stubby wings, shortened abdomens, discoloration, and paralysis of the legs and wings. Symptomatic bees will usually die within 48 hours and are typically expelled from the hive. The virus can be transmitted orally between adults as a covert infection. However, the main vector of DWV is an invasive ectoparasite known as Varroa destructor.

Varroa mites harbor a greater level of the DWV virus than that found in severely infected bees. A recently published research paper (Lamas et al., 2023) examined varroa mite infestations to determine how they spread DWV throughout a honeybee colony so effectively. Without the presence of mites, the virus will only spread across horizontal and vertical vectors. During an infestation, the mites will move from host to host, bringing the virus along for the ride. Observations found that varroa mites switched hosts at a very high frequency, making them responsible for 3x as many parasitized hosts as lower switching mites. It is not understood why these mites switch hosts at such a high rate.

Another research paper (Dobelmann et al., 2023) reported that a secondary vector of DWV has been introduced to the scene. The Argentine ant (Linepithema humile) is an invasive ant species capable of constructing super colonies with multiple queens that can easily outnumber and outcompete the native competition. Argentine ants are known to raid beehives and steal honey, often killing bees in the process. Recent data suggests that these ants are carrying substantial levels of DWV and either directly infect the bees while raiding the hive or that the stress from the raid is introducing a higher viral infection load.

DWV is linked to millions of beehive deaths worldwide. Pesticides, insecticides, or moving the hives are currently the only options available to beekeepers, but even these options are not always effective. Experts are looking for different ways to control the effects of DWV. There is some research being conducted with immunotherapy and antibiotics that could hold promise. We will all have to wait and see.

DWV in bees due to ants
Top: Western honey bee hive infested with Argentine ants (Linepithema humile). Bottom: Honey bee with Deformed wing virus. Credit Dobelmann et al., 2023.

He Can’t Hear You

Overuse of common mosquito sprays are not only detrimental to the environment, but are becoming less effective as mosquitoes develop resistances to them. A promising new method is singing a different tune.

Female mosquitoes create the familiar high pitched buzzing sound as they fly around looking for blood. Males have a specially designed hearing organ comprised of a hairy flagellum which acts as a sound sail, as well as a Johnston’s organ. The flagellum vibrates at the same frequency as a female’s wings. When a female flies by, the males detect this frequency and resonate, sending a signal to their brain that helps them identify a potential mate. A new method aims to control the mating behavior of male mosquitoes by altering the frequency at which they listen.

As a recap, female mosquitoes are the ones that bite humans and consume blood. They do this to nourish their brood/eggs. Male mosquitoes feed on nectar. The purpose of this research is to reduce successful mating pairs and in return reduce future populations, i.e. fewer females in the future to bite/feed on humans. They tested this method using Aedes aegypti (yellow fever mosquito), a mosquito that is invasive in many areas around the US and a vector to many transmittable diseases. Researchers identified the involvement of serotonin in the auditory system of the mosquitoes. Serotonin plays an important role in the nervous system and brain. Altering levels can cause a wide range of behavioral changes. Manipulating serotonin levels in different ways affected the male hearing organ and auditory response. The team hopes that further research will allow them to create an auditory birth-control that can administer a targeted compound that will be able to alter the male auditory receptors and disrupt mating behavior. This research would allow for species specific targeting, something commercial insecticides cannot currently promise.

Read the research: Xu et al., 2022

Aedes aegypti. Pest and Diseases Image Library. Bugwood.org
Aedes aegypti. Credit: Pest and Diseases Image Library, Bugwood.org

mosquito hearing
Serotonin distributed throughout male and female Ae. aegypti flagellar ears. Schematic diagrams of male (left) and female (right) brains and ears (Johnston's organ and flagellum). See paper for more information. Credit: Xu et al., 2022.

CWMA Brazilian Peppertree Workday and Meeting

Texas Gulf Coast Cooperative Weed Management Area’s annual Brazilian peppertree workday and meeting is coming up soon. It is a chance to join a group that will be removing invasive peppertrees in Port Aransas Nature Preserve at Charlie's Pasture to help restore the native habitat. The workday may include cutting peppertrees, hauling away vegetation, and treating plants or stumps with herbicide. Remember to dress for the weather. It is best to wear long sleeves and pants when working with Brazilian peppertrees. Please bring water, any tools you have, and gloves. CWMA will have some tools and gloves to borrow.

Workday: Thursday February 23, 9 - 11:30 a.m.
Nature Preserve at Charlie's Pasture South, 2650 St Hwy 361, Port Aransas, TX

Following the workday, CWMA is meeting to discuss accomplishments, current and upcoming projects, partnership opportunities, and future outreach events. The public is encouraged to attend.

Fall Meeting: Thursday February 23, 1:30 - 3:30 p.m.
Estuarine Research Center at UTMSI
750 Channel View Drive, Port Aransas, TX
or Zoom (register at link to receive Zoom meeting information)

Workday and/or Meeting Registration Link
Email Katie for additional information: katie.swanson@utexas.edu

 CWMA logo
Texas Gulf Coast Cooperative Weed Management

2023 Annual Invasive Species Forum

The virtual 2023 Invasive Species Forum is an annual event that brings attention to invasive species issues, research, and advances in prevention and management occurring across Canada, and in neighboring U.S. States.

Date: February 7-9, 2023

The theme is “Invasive Species Action in a Changing Climate” The event will feature may dedicated sessions such as Vectors, Ecosystem Resilience Developments in Research and Management, Municipalities, Indigenous Communities, Outreach, and more. Registration is free!

 invasive species forum 
Credit: Invasive Species Centre.

North American Invasive Species Management Association Training Webinars

This 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:

  • February 15,1pm - Miller Creek Watershed Restoration: The value of partnership during a pandemic. REGISTER.
  • March 15, 1pm - Preventing the Spread of Invasive Species through PlayCleanGo and WorkCleanGo. REGISTER.
  • April 19, 1pm - Ventenata Identification, Impacts, and Management Options. REGISTER.


Celebrating 20 Years of Fishy Plates

The largemouth bass license plate is celebrating not only its 20th anniversary, but its success in generating $893,005 for 93 conservation projects through TPWD’s Inland Fisheries Division. With the help of largemouth bass conservation license plates, TPWD Conservation License Plate Program (CLPP) has helped generate funds to support state parks, outdoor recreation, wildlife management and research, and conservation projects in Texas. These funds also help with invasive species control and fish habitat enhancement in Texas’ rivers and streams, among many, many other things. In addition to the largemouth bass and Texas rivers plates, other plates in the collection include horned lizard, rattlesnake, monarch butterfly and hummingbird plates benefiting wildlife diversity, white-tailed deer and bighorn sheep plates benefiting big game management, camping and bluebonnet plates benefiting state parks, and a roadrunner plate benefiting nature tourism and habitat conservation.

Read the full press release HERE. To buy the largemouth bass or Texas rivers plates or one of the other available designs, visit www.conservationplate.org or your local county tax assessor-collector’s office.


largemouth bass conservationplate.org
TPWD largemouth bass conservation plate. Credit: conservationplate.org

Invasive Spotlight:

Bastard Cabbage
(Rapistrum rugosum)

Bastard cabbage (Rapistrum rugosum) has many common names, such as turnip weed, common giant mustard, ball mustard, wild turnip, wild rape, and tall mustard-weed. It is an herbaceous annual plant that can grow up to 5 feet or more in height. It has many branches and deep green leaves that are lobed, wrinkled, and sometimes have a reddish cast, with a terminal lobe that is larger than the lateral lobe, especially on the basal leaves. Younger leaves growing higher up on the plant are less lobed and more elongated. Bastard cabbage has a strong taproot that can become large and deep-rooted. These plants typically flower from early spring into summer, bearing clusters of small, yellow flowers at the tips of its branches, resembling those of broccoli or cabbage. Bastard cabbage can be identified easily by its unusually shaped fruit - a two-segmented seed capsule, or silique. The seed capsule is stalked, with a long beak at the tip, and contains 1-2 seeds. The seeds are oval-shaped, dark brown, smooth, and about 1/16-inch.

Bastard cabbage seeds germinate early in the growing season (late fall or early winter) and quickly cover the ground with a blanket of leafy rosettes that block sunlight from reaching seeds and seedlings of native plants. The ability to quickly establish basal leaves allows for this plant to easily out complete native plants. In areas where bastard cabbage becomes established, it often forms a monoculture (a vegetative cover of mostly one species). Bastard cabbage grows mostly in agricultural fields, along roadsides, and throughout disturbed lands, but are spreading into natural areas such as open forests and along streams.

Bastard cabbage is documented to grow in 16 states, including Texas, where it is designated a terrestrial noxious-weed seed. It is believed that seeds of these plants are spread through contaminated grass seed mixtures and mulching materials. The seeds are similar in size to wheat and rye seeds, and seed screening may fail to remove the invasive seeds from seed mixtures before packaging and distribution. For more information about the bastard cabbage, visit the TexasInvasives species info page.

bastard cabbage infestation 
Bastard cabbage (Rapistrum rugosum) infestation. Credit: Karan A. Rawlins, University of Georgia, Bugwood.org
bastard cabbage
Bastard cabbage. Credit: Karan A. Rawlins, University of Georgia, Bugwood.org

bastard cabbage seeds. Cesar Calderon Cesar Calderon Pathology Collection USDA APHIS PPQ Bugwood.org
Bastard cabbage seeds. Credit: Cesar Calderon, Cesar Calderon Pathology Collection, USDA APHIS PPQ, Bugwood.org

Get Involved Today!!

The Texas Invasive Species Institute (TISI) and The Texas Research Institute for Environmental Studies (TRIES) have many surveys and projects underway. These facilities strive to provide yearly invasive species presence and absence data to the authorities. Pre-screening is one of the first lines of defense in the war against invasives. However, sometimes it is hard to do it alone.

With the aid of the public and citizen scientist, we could cover a much wider area, and gather a more substantial amount of data. When it comes to protecting our environment, there is an opportunity for everyone! Together we can make a difference, one research project at a time.

See how you can get involved by reading the projects listed below or see all the available projects on the Texas Invasives website HERE.

Aquarium Watch: Looking for Prohibited Invasive Aquatic Species

Please help texasinvasives.org and natural habitats by looking for 14 prohibited or invasive aquatic species that might be for sale in your local aquarium store(s). With just one photo you can assist us in finding and documenting which stores are selling prohibited or invasive species. Texasinvasives.org will use this information to contact the appropriate Texas institutions to ensure the appropriate steps are taken for each case.

If you would like more information please email invasives@shsu.edu, and mention you want to assist with our Aquarium Watch.

Air Potato Survey

Help Texas Research Institute for Environmental Studies conduct an air potato survey by actively reporting any infestations seen in your area. The air potato (Dioscorea bulbifera) is a fast growing, high climbing vine. Potato-like tubers are the primary means of reproduction for this vine. They can be as small as a marble or as large as a softball. Native yams are often confused for air potatoes. To avoid this confusion, please refer to the key below:

- Plants rhizomatous; bulbils never produced in leaf axils; petiole base never clasping the stem; Native D. villosa
- Plants tuberous; bulbils produced in leaf axils; petiole base sometimes clasping the stem; Invasive D. bulbifera

For additional information, please refer to the TexasInvasives information page.

If you believe you have identified an air potato vine, please email invasives@shsu.edu and include the following information: an image, an approximate number of vines present, the location (including whether it is on public or private land), and if bulbils are present (the potato-like tubers that emerge from the stem).

Participation opportunities
Participation Opportunities. Credit: KNKleiner, TRIES.

Armorded catfish. Photographer United States Geological Survey
Armored catfish (Hypostomus plecostomus). Credit: United States Geological Survey.

air-potato (Dioscorea bulbifera)2 bulbil. credit Karen Brown
Air-potato (Dioscorea bulbifera), bulbil emerging from leaf axil. Credit: Karen Brown.

More News

‘Early Detection, Rapid Response’: Invasive Axis Deer Spotted at Big Thicket
Axis deer have been spotted roaming the Big Thicket Natural Preserve. It is believed they escaped from a private ranch nearby. Axis deer are an invasive species originally from India and it is unknown what impact this herd animal will have on the reserve, but the situation is being monitored. kut.org

UH Coastal Center Takes to The Air in Effort to Restore Coastal Prairie
The University of Houston Coastal Center, in La Marque, Texas, is using aerial spraying to target invasive tallow trees (Triadica sebifera) growing in dense stands throughout the coastal prairie habitat. Targeted spraying alleviates unnecessary spraying of surrounding plants, while being less physically and economically demanding. uh.edu

Native Eastern Fence Lizards Change Their Bodies and Behavior in Response to Invasive Red Imported Fire Ants
Last month, there was an article that mentioned how the consumption of red imported fire ants (Solenopsis invicta) could change the immune system of the eastern fence lizard (Sceloporus undulatus). This article talks a little more about the other ways these lizards have changed in response to fire ants. phys.org

Tweets, News Offer Insights on Invasive Insect Spread
A new study shows using Twitter and online news articles has the potential to track invasive insect spread in the United States and around the world. These sources could fill in gaps where official data is not available, as well as track the timing and location of spread. sciencedaily.com

Outdoor Cats Are an Invasive Species and A Threat to Themselves, Scientists Say
We all know this is a controversial subject, but new research reveals the dangers of letting house cats roam around outdoors. Some suggest keeping them in completely, others suggest a belled collar or a catio. salon.com

Most Plastic Debris on Seychelles Beaches Comes from Far-Off Sources
Islands in the western Indian Ocean aren’t responsible for all the plastic waste accumulating on their beaches. A significant amount of land-based plastic debris comes from Indonesia, India, and Sri Lanka, while marine-based debris comes from fisheries and shipping lanes. sciencedaily.com

Alien Land Snail Species Are Increasing Exponentially, Says Study
The number of invasive land snails has increased steadily and become more widespread since the 19th century. Information about invasive land snails that have been introduced to Europe and the Mediterranean from other continents could be a bases for control and eradication. phys.org

Invasive Nutria Rats Declared Officially Eradicated in Chesapeake Bay Area
After 20 years of trapping and euthanizing invasive nutria (Myocastor coypus), wildlife experts announce that they have been eradicated from the Delmarva area, a 170-mile stretch that crosses Delaware, Maryland, and Virginia. wset.com

Active Matter Theory Explains Fire-Ant Group Behavior
Red imported fire ants (Solenopsis invicta) social interactions are explained with a theory called “Active Matter”, which annotates the ants' group behavior as a reaction to the intrinsic mechanisms in the system. sciencedaily.com

Invasive Rats Transform Reef Fish Behavior
Invasive black rats (Rattus rattus) on tropical islands are affecting the territorial behavior of jewel damselfish (Microspathodon Chrysurus) on surrounding coral reefs. The presence of the rats is disturbing the delicate nutrient cycle. sciencedaily.com



Citizen Scientists Spotlight
Apple Snail Removal Champion

San Antonio River Authority awarded Alamo Area Master Naturalist David Mullins an “Apple Snail Removal Champion” award after removing more than 2,000 apple snails and over 1,700 egg cases from San Antonio River.

Invasive apple snails (Pomacea maculate) have infested the San Antonio River. The river authority hires employees and contract workers to remove snails from the River Walk every week, but there are still many snails left in surrounding water ways. That is where Mullin, along with a number of other trained volunteers come in. They have all been working with the San Antonio River Authority to diligently remove as many snails and egg cases as they can. These invasive snails will likely never be eliminated because there are tens of thousands present throughout the water systems. Mitigation can be managed by regular removal of apple snails and egg cases. Here is a special thanks to everyone working hard to keep our waters clean.

Just shows you that anyone and everyone can help their local and state agencies in the fight against invasive species.

  apple snail
Alamo Area Master Naturalist David Mullins hunts for apple snails (Pomacea maculate) along the San Antonio River Walk. Credit: Jerry Lara, Staff, San Antonio Express-News.

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, teach identification of local invasive plants, and 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:

February 4, 2023, 8am-12pm
Invasive Species & Citizen Scientists
In-Person Citizen Scientist Training, TBD in The Woodlands
Contact: Terrilyn MacArthur, tmacarthur@thewoodlandstownship-tx.gov

March 9, 2023, 7pm
Invasive Pests near You
In-Person Workshop
Contact: Beth Erwin, thearborlady@gmail.com

April 6, 2023, 10am
North Texas Invasive Species
In-person presentation
Contact: Bobbye Hitzfeld, Bobbye55@outlook.com

CITRUS WORKSHOPS: Stay tuned for upcoming 2023 virtual weekend presentations about Citrus diseases and FREE testing we offer at Texas Invasive Species Institute.