June 2020
New Discovery of Giant Salvinia in Texas Lake

The Texas Parks and Wildlife Department (TPWD) confirmed the presence of giant salvinia (Salvinia molesta) on Bringle Lake in Texarkana. TPWD says managing the infestation will be challenging because of how large the infestation is, how the invasive plant is mixed in among other aquatic plants, and how the giant salvinia weevils that can be used as control agents in southern lakes can't survive the winter in that part of the state. The discovery has also created concern from Arkansas Game and Fish Commission biologists about the nuisance, since it is so near to that state.

Credit: Texas Parks and Wildlife Department

Banded Bird Challenge Registration Under Way

"Dove hunters in Texas have the opportunity to win a new pickup truck, an all-terrain vehicle or one of a number of prizes in this year’s 2020 Banded Bird Challenge.

"The Texas Dove Hunters Association (TDHA) is now accepting early bird entries for the annual event.

“The Banded Bird Challenge is a research program that we started two years ago in efforts to conduct a more in-depth study of Eurasian Collared-dove [Streptopelia decaocto] in Texas,” Bobby Thornton, co-founder of the Texas Dove Hunters Association, said in an interview with the Texas Farm Bureau Radio Network. “We need three years or more, according to biologists, to start to be able to formulate good research.”

Fewer than three percent of bands placed on mourning doves [Zenaida macroura] and white-wing doves [Z. asiatica] by the Texas Parks and Wildlife Department are reported, so TDHA decided to incentivize hunters who call in their orange bands on the Eurasian Collared-doves.

“If you enter the contest for $20, and you harvest one of the birds with a band on it, the Eurasian Collared Dove, then you are eligible to win anything from a new truck to a Polaris Ranger to shotguns to exotic game hunts,” Thornton said. “When the band says ‘winner’ on it, it encourages people to obviously say, ‘Oh my gosh, what did I win?’ So, they call the phone number on it.”

Learn more at the Brownwood Bulletin.

Eurasian collared dove
Credit: Charles J Sharp, CC BY-SA 4.0

Emerald Ash Borer Found in Bowie County

The emerald ash borer, Agrilus planipennis, has been found in another Texas county, bringing the count of counties in which it has been found to six. The destructive invasive beetle was found in Texas A&M Forest Service traps set in Bowie County, in the northeast corner of the state. As a result, Bowie and Denton counties will now both be added to the Texas Department of Agriculture's wood transportation quarantine list, which restricts movement of any woody ash material exiting the county or quarantined area. The other counties on the list are Harrison County, where the beetles were first discovered in Texas, and Marion and Cass Counties, all of which are also in the northeast corner of the state. For more information, see these articles by the Texas Standard and nbcdfw.com.

EAB adult
Credit: David Cappaert, Michigan State University, Bugwood.org

Invasives in the Time of COVID

Two stories about the effects that the coronavirus pandemic is having on managing invasive species. First, in British Colombia, a company is using its expertise in harvesting invasive species to make fish food in support of aquariums and zoos across the country that are facing financial struggles amid the COVID-19 pandemic. When individuals and organizations purchase a bucket of Piscine Energetics fish food for their personal or office aquarium, the company donates a bucket of food to an institution of the donor's choice. Learn more here.

In the second story, from the Cayman News, the pandemic has halted the culling of as many as 16,000 invasive green iguanas (Iguana iguana) because of shelter-in-place regulations. The invasive lionfish (Pterois volitans) has also enjoyed an extended break from cullers.

green iguana
Credit: Cayambe, CC BY-SA 3.0

The Quest to Purge New Zealand of Invasive Predators

An article in Wired.com describes the local efforts being undertaken to eliminate invasive predators from New Zealand.

"Rats, weasels, and other imported mammals have destroyed native bird populations. Local group Predator Free Wellington wants to turn the tables…

"In a land where the only surviving native terrestrial mammal species are two thumb-sized bats, these invasive species have decimated native bird populations for centuries, causing dozens of extinctions of species found nowhere else on Earth. In 2015, New Zealand’s government launched a nationwide effort called Predator Free 2050 with a $17 million (28 million New Zealand dollars) investment to rid the country’s 164,375 square miles of invasive mammals in the next three decades. It’s an audacious goal: The next largest island to purge itself of predators is tiny South Georgia Island, which covers only 1,450 square miles…

"Miramar, a suburb of Wellington, New Zealand…is out to catch Wellington’s Most Wanted—every last rat, weasel, ferret, possum, and stoat that has invaded the city. They’re doing it to save the birds… In a recent report, Predator Free Wellington noted that 99 percent of Miramar Peninsula residents were willing to participate in the project, and a recent survey found that 92 percent of Wellingtonians supported the citywide effort."

NZ stoat with nestling
Credit: New Zealand Dept. of Conservation

Latest Version of Tool Launched to Help Visualize Invasion Hypotheses

Two years ago, the website hi-knowledge.org was launched, featuring an interactive visualization tool with a network of invasion hypotheses. This tool allows you to zoom into major hypotheses in the field of invasion biology, to explore more specific hypotheses and to find publications addressing them (connected to the book Invasion Biology: Hypotheses and Evidence).

Hi Knowledge 2.0. is now available. In addition to the first tool, it features: (i) an extended hypothesis network with 39 invasion hypotheses structured into five clusters (based on Enders et al. 2020, Global Ecology and Biogeography 29, 978–991 and (ii) a tool allowing you to dive into the different branches of science, as included in Wikipedia.

Hi Knowledge logo 2

Catalog of Federal EDRR Invasive Species Databases and Tools

USGS has released its Catalog of Federal EDRR invasive species databases and tools: Version 2.0 and is available as an excel spreadsheet on ScienceBase. The Texasinvasvies.org website is listed in the Catalog.

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Army Corps of Engineers Summer Invasive Species Webinar Series
Wednesdays from 1:00 - 2:00 CDT
To join: https://usace.webex.com/meet/courtney.e.chambers

July 1: The Triclopyr Shift to Trycera
July 8: Herbicide Residues in Lake Sediments: Understanding Herbicide Fate
July 15: Identification and Management of Invasive Grasses

Spotted Lanternfly: Impacts and Research from the USA and Perspectives from Ontario
Tuesday, July 7, 2020 - 1:00 PM EST

This webinar will give an overview of the Spotted Lanternfly (Lycorma delicatula) and the impacts, management, and research happening in its invasive range in the U.S. Additionally, it will consider perspectives and outreach strategies of stakeholders and agencies in Ontario, and the invasion potential to Canada.
Register here.

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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:

  • July 15 – Gary Lovett, Cary Institute of Ecosystem Science: Invasive forest pests in the U.S.: Impacts and policy solutions – REGISTER
  • August 19 – How biocontrol agents are approved and how to access them for your invasive species management needs (go to NAISMA 2020 Webinar Schedule page to register.
  • September 16 – Leaps and Bounds – How to jump over the barriers to preventing the spread of invasive species – REGISTER


Invasive Spotlight:
Tropical Spiderwort
Commelina benghalensis)

Tropical spiderwort, native to Asia and Africa, is an invasive perennial plant that grows quickly to form dense, pure stands, outcompeting other plants, especially those that are low-growing. Also known as Benghal dayflower, it has been reported recently as a problem in cotton fields in Alabama. In pastures, it can become the dominant species. In rice and other lowland crop it can withstand flooding and waterlogged conditions. It can also be found in cultivated lands, field borders, gardens, grasslands, roadsides, disturbed areas, and waste places. Because it can root from the nodes, light cultivation can break plants and spread them. One plant can produce as many as 1600 seeds.

As a monocot, the leaves of the tropical spiderwort have parallel veins and are lily-like. Unlike grasses, the leaves and stems are thicker and more succulent. The stems are sprawling and will creep along the ground. Leaf blades are alternate, and ovate to lanceolate, 1-3 in (2.5-7.5 cm) long, 0.5-1.5 in (1.3-3.8 cm) wide. Unlike in other dayflowers (or spiderworts), the leaf sheaths often have reddish hairs where the leaf meets the stem. This is a distinguishing characteristic. The stems are sprawling.

Unlike other spiderworts or dayflowers, tropical spiderwort produces both aerial and underground flowers. The aboveground flowers are very small and are present from the spring into the fall. The two prominent upper petals are lilac-to-purple/lavender (not blue), only 0.1-0.2 in. (3-5 mm) across, and are on thin pedicels. The whitish lower petal is even smaller. Underground flowers, which grow on burrowing rhizomes, are white and very small.

Tropical spiderwort is found in 6 states, but has so far not found its way to Texas. Because of its potential for ecological and agricultural harm, it is one of the “Dirty Dozen” pest species identified by the Texas Invasive Plant and Pest Council. It therefore is one of the “Report It!” alert species on the Texasinvasives.org website and reporting app. It is also on the Federal Noxious Weed List.

If you believe you have found tropical spiderwort, please report this species.

Follow this link for more information on the tropical spiderwort and how to distinguish it from its native lookalikes.

Tropical spiderwort flower

Photographer: Herb Pilcher, USDA Agricultural Research Service, Bugwood.org

tropical spiderwort undergroundflower

Underground flowers of tropical spiderwort, which look like swollen nodes.
Photographer: Byron Rhodes, University of Georgia, Bugwood.org

tropical spiderwort map


More News

Puddles the Mussel-Sniffing Dog Saves Washington Waters from Invasive Species
Puddles is the state’s first ever mussel detection dog. It’s her job to sniff out invasive species - such as zebra and quagga mussels (Dreissena polymorpha and D. bugensis, respectively) - before they enter Washington waters on incoming boats. Learn more at YakTri.com.

Invasive 'Rainbow Lizard' Population Is Rapidly Increasing in Florida
African redhead agamas (Agama agama) have spread throughout Florida's Treasure Coast and as far north as Duval County, increasing its population at an unprecedented rate in the past few years. Learn more at USAToday.com.

Red Squirrels Making Comeback in Ireland as Return of Pine Marten Spells Bad News for Invasive Grey Squirrel
The number of red squirrels (Sciurus vulgaris) is on the increase in Ireland thanks to the return of the pine marten (Martes martes), a native carnivore, a new study has found. The study is based on data collected by citizen scientists. Learn more at sciencedaily.com.

Another Asian Giant Hornet Found in Washington, Miles from Previous Sightings
Another Asian giant hornet (Vespa mandarinia) has been found in Western Washington at a location 15 miles farther south than previous sightings. Learn more at komonews.com. Here's another article that describes the first encounter with the hornets in British Colombia.

Invasive Mitten Crabs Threaten Connecticut’s Shores
The crabs (Eriocheir sinensis) migrate up freshwater rivers from saltwater bays and burrow into the banks -- destabilizing shores, weakening dams and levees, clogging screens, pumps and water intake structures and causing hundreds of millions of dollars in infrastructure damage. Learn more at connecticutmag.com.

Alien Frog Invasion Wreaks Havoc on Natural Habitat in Australia
Indiscriminate feeding by an alien population of the carnivorous spotted-thighed frog (Ranoidea cyclorhynchus) could severely affect the native biodiversity of southern Australia, according to a new study. Learn more at sciencedaily.com.

Protected Areas Worldwide at Risk of Invasive Species
Most protected areas across the globe have no invasive animals, but the large majority of them are at risk of invasions. For 89% of the 199,957 protected areas studied, there was an alien animal species resident within 10km of the boundaries. Read more at sciencedaily.com.

Planting Non-Native Trees Accelerates the Release of Carbon Back into the Atmosphere
Recent research shows that non-native plants often grow faster compared to native plants, which sequesters carbon, but they also decompose faster and this helps to accelerate the release of 150% more carbon dioxide from the soil. Learn more at theconversation.com.

Cattle vs. Hippopotamus Dung in Rivers of the Savannah
A recent study examined the effect on the river ecosystems of the African Savannah, of hippopotamuses (Hippopotamus amphibius) being replaced by cattle. This can change aquatic ecosystems due to significant differences in the amount and type of dung input. Read more at sciencedaily.com.

Poorly Designed Tree-Planting Campaigns Threaten the Forest
The first-of-its-kind study reveals that subsidies for the planting of commercially valuable tree plantations in Chile resulted in the loss of biologically valuable natural forests and little, if any, additional carbon sequestration. Learn more at sciencedaily.com.

International Team of Scientists Warns of Increasing Threats Posed by Invasive Species
A new study describes the proliferation of alien invasive species and the dangers they pose. While not surprising, the study also provides examples of how biological invasions can be managed and mitigated. Learn more at sciencedaily.com.

Benchmark Use of eDNA Helps Biologists Find Invasive Snails in Arizona
The recent detection of New Zealand mudnsnails (Potamopyrgus antipodarum) in Oak Creek may be the first time the eDNA has been used to discover a previously unknown population in an ecosystem in Arizona. Learn more at redrocknews.com.

Guam to Get Over $3M to Control Invasive Brown Tree Snake
Guam will get more than $3 million in grant money to suppress and control the highly problematic invasive brown tree snake (Boiga irregularis), federal officials said. Learn more at thehour.com.

Controlling Invasive Milfoil Takes Many Approaches
New research shows that the benefits and costs of methods for controlling water milfoil (Myriophyllum spicatum) and other aquatic invasive plants must be taken into consideration. Learn more at University of Madison-Wisconsin News.

Changing Environment at Home Genetically Primes Invasive Species to Take Over Abroad
New resarch has found that a constantly fluctuating environment can enable some species to invade new areas by helping them maintain the genetic diversity they need to settle into their new homes. Learn more at phys.org.

AI Models to Help Identify Invasive Species of Plants Across the UK
Environmental scientists and artificial intelligence researchers are developing an AI system intended to survey regions like roadsides for the presence of various invasive species. Learn more at UniteAI.com.

Exploring the Use of Cancer to Control Zebra and Quagga Mussels
The result of a 2018 Bureau of Reclamation competition that offered $100,000 for the most environmentally sound and cost-effective theories about how to eradicate quagga and zebra mussels from areas where they are invasive, is a list of three proposals, one of which proposes to enlist cancer. Learn more at westernconfluence.org.


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.


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:

Saturday, August 15, 2020
Sentinel Pest Network Workshop
Location: Virtual (details TBD)
Contact: Teri MacArthur

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