January 2021
Do the Locomotion With Sssssme

A fifth type of snake locomotion, called ‘lasso locomotion’, was recently discovered by a group of researchers while they were observing the climbing behaviors of the invasive brown tree snake (Boiga irregularis). Until now, there were only four known modes of snake locomotion: rectilinear, lateral undulation, sidewinding, and concertina. Only concertina locomotion was known to generate a friction grip required for climbing cylindrical objects, like trees.

Lasso locomotion involves the snake looping its body around a cylinder or tree, crossing part of its body or tail around itself (at least once), and pointing the head and neck in an uphill direction. Throughout the ‘body loop’, small bends form to provide the propulsive mechanism that moves part of the body uphill, while simultaneously shifting grip. The extended head and neck may be used to help maintain balance. Upward movement is a slow, calculating process and downward slipping does occur. The snakes are recorded pausing frequently and exhibit heavy breathing, suggesting this behavior is quite demanding.

The brown tree snakes have been recorded climbing smooth, vertical cylinders (between 15–20 cm in diameter) that other snake species have difficulty climbing. However, lasso locomotion enables the snake to climb cylinders that are not only smooth and 'difficult to grip' but more than twice the diameter otherwise possible for other tree snakes. Example: the single gripping region required by lasso locomotion only needs to be a little longer than the snake's body length, while the two gripping regions seen in concertina locomotion are each as long as the circumference of a tree trunk. This behavior could contribute to the success of the invasive brown tree snake. With this new discovery, new barrier mechanisms can be designed to help reduce the brown tree snake dispersal and deleterious effects.

To read the research paper mentioned above: Savidge et al. (2021)

The brown tree snake has also been reported in Alaska, Hawaii, Oklahoma, and Texas. For more information about the brown tree snake click here.

If you believe you have identified a suspected brown tree snake, please take a picture and REPORT IT! to invasives@shsu.edu.

Brown tree snake (Boiga irregularis)
Brown tree snake (Boiga irregularis). Credit: Dickinson College.
Example of brown tree snake lasso locomotion 3
Infrared video images showing the posture of lasso locomotion by the brown tree snake. White arrows indicate crossover regions. Credit: Savidge et al. (2021)

Doing Things the eDNA Way

Environmental DNA, or eDNA, techniques have been increasingly studied over the last decade, with many of them focused on determining the presence/absence of target species in an ecosystem. As an organism interacts with its environment, DNA accumulates in their surroundings, which can then be targeted for thorough DNA sequencing. Environmental DNA analysis can be performed on air, soil, snow, and water samples. These methods have become extremely helpful in situations involving limiting sampling, like with endangered or threatened species, or in areas where direct contact with the organism(s) is limited or difficult, such as aquatic ecosystems.

Cornell researchers have established new eDNA methods that they believe will allow one to determine which invasive species are present in the environment, predict how many individuals there are, and possibly determine where the individuals came from. The researchers established these methods by identifying the genetic diversity in the water samples taken from Cayuga Lake, New York, while gathering information about the invasive round goby fish (Neogobius melanostomus). Round goby fish are camouflaged bottom dwelling fish that are difficult to find and catch. They have been displacing native fish populations, and impacting fisheries in the Great Lakes and Finger Lakes. Knowing how many of an invasive species there are in the environment, how many in each population, and the genetic variation within that population would be useful in conservation efforts. The researchers believe the genetic signature collected through this method could be used to match the goby fish DNA with populations from other areas, narrowing down the likely means of introduction, whether via international vessels or other.

As the time and cost associated with molecular research continues to decline, this method, in conjunction with already established eDNA methods, could extend to all organisms that are difficult to monitor, i.e. invasive, elusive, endangered, and threatened species. Environmental DNA allows for interspecies analysis, and eliminates the need for direct contact. Maybe one day soon, it could be used to minimize the impact of mass collections required for some organism monitoring. It is exciting to see how science continues to advance, amaze, and marvel.

To read the research paper mentioned above: Andres et al. (2021)

Environmental DNA. credit FISHBIO
round goby (Neogobius melanostomus). Center for Great Lakes and Aquatic Sciences
Round goby fish (Neogobius melanostomus). Credit: Center for Great Lakes and Aquatic.

Invasive Cellar Spider Sensing Chemical Cues

Spiders taste and smell through special sensory organs on their legs and pedipalps, and they hear, or sense, vibrations through hairs and tiny slits distributed over most of their body. Many spiders, including web-builders, have poor eyesight, and rely on chemical cues laid down in the environment to guide them when finding and attracting mates, and evaluating competitors. The chemical cues attach to the silk of a spider’s web, and allow for communication in a wide range of body sizes. An individual’s success often weighs heavily on the ability to evaluate or avoid competition for webs and/or the best web sites, and size is often linked to competitive ability.

A recently published research paper, Berry and Rypstra, 2021, examined whether two invasive web-building cellar spiders, Pholcus manueli and P. phalangioides, used chemical cues present on webs to evaluate territory risk, the size and body condition of a web owner, and if this information affected their decisions when invading a foreign web. These two species not only compete with other conspecifics (others of the same species), but with each other for similar web sites. Pholcus manueli and P. phalangioides are found in the midwestern U.S.

Results suggested P. manueli can judge the conspecific size from both an empty and occupied web using chemical cues, while P. phalangioides was less affected by them. The research found that P. phalangioides invaded webs faster than P. manueli, no matter the size of the web owner. Pholcus manueli displayed a more cautious approach to occupied webs, varying its behavior based on the size of a web-building spider, and entering webs more slowly. This more tentative approach likely results in the avoidance of unnecessary or unequally matched territorial disputes. The research also found that when the webs were washed with ethanol and all chemical cues were removed, their behaviors adjusted. The findings suggesting that P. manueli priorities may lean toward safety, while P. phalangioides may lean toward resource acquisition. Additional literature has demonstrated that competition for webs or web sites may influence invasive spider success. Pholcus manueli is actively displacing P. phalangioides across some of its territory. Research such as this will allow us to further understand how invasives are able to thrive and displace natives and other invasives.

cellar spiders (Pholcus sp.). Credit Joseph Berger
Cellar spiders (Pholcus sp.). Credit: Joseph Berger.
 Closer image of Pholcus manueli. credit Steve Nanz 
Dorsal view of Pholcus manueli. Credit: Steve Nanz.

Pholcus phalangioides. credit Christopher E. Smith
Dorsal view of Pholcus phalangioides. Credit: Christopher E. Smith.

Global Insect Decline! What to Do? What to Do?!?

The term “insect apocalypse” may seem overly dramatic to some, but to many it perfectly personifies the real problem that is at our door. There is a rapid global decline in the number of insects, and loss in insect diversity. Why should we care? As prey, they are critical to the survival of other species. As herbivores, predators, and parasites, they aid in the distribution and abundance of plants and animals. As decomposers and consumers, they contribute to various nutrient systems. As pollinators, many flowering plants depend on them for reproduction. Insects have become essential in the consumer industry, as well as the medical and biological research fields.

A thorough publication called ‘Insect decline in the Anthropocene: Death by a thousand cuts’, Wagner et al. (2021), compiled the information from world experts in order to better analyze the threat to the world’s insect population. The research notes that while some insects are declining, other lineages have not changed or have increased in abundance, and others are lacking the data required to form a full picture. Insect decline is due to a combination of things: nitrification, fire, global warming, drought, deforestation, climate change (which also causes storm intensity and interaction distribution), pollution, insecticides, agriculture intensification, introduction of invasive species, and urbanization. Population declines and territory/range decrease can also be seen in terrestrial vertebrates, aquatic organisms, amphibians, birds and more. Scientists, state, and governments will need to work together to adopt new collection techniques, technologies, methods, and increase information sharing. Some interesting things are already in development (Hoye et al., 2021).

But what can you do?

1) Convert lawns into diverse natural habitats: Even partial conversion of lawns to a minimally disturbed natural area could significantly aid insect conservation.
2) Grow native plants: Native plants are typically more beneficial to all wildlife compared to non-native ornamentals.
3) Reduce pesticide and herbicide use: all the ‘-cides’ can harm nontarget, natural insect populations, and reduce beneficial arthropod populations. See if alternative non-chemical methods are available.
4) Limit use of exterior lighting: Lights can indirectly kill nocturnal insects via exhaustion, or result in predation before sunrise.
5) Lessen soap runoff from washing vehicles and building exteriors, and reduce use of driveway sealants: Pollutants and heavy metals found in some soaps drain into water ways which contain aquatic insects. Consider using biodegradable soaps.
6) Counter negative perceptions of insects: Learn more about insects so that you might learn to better appreciate what you don’t understand.
7) Become a Citizen Scientist: Learn how to identify and report your local invasive species. Learn how to properly remove invasives from your yard to prevent accidental spread.
8) Report invasive species: If you think you have spotted an invasive species, take a picture, record your location, and email it to invasives@shsu.edu OR REPORT IT!

To read Kawahara et al. (2021) and his 8 simple ways you can help: click

Examples of insects that are beneficial to humans and environment
Examples of insects that are beneficial to humans and environment: (A) Pollinator: Honey bee (Apis mellifera). Credit: Michael J. Raupp. (B) Decomposer: Dung beetle (Scarabaeidae: Scarabaeinae). Credit: L.E.R. (C) Parasite and pollinator of fig trees: Fig wasps (Blastophaga psenes). Credit: W. P. Armstrong 2009. (D) Vaccine development, including coronavirus: Alfalfa looper moth (Autographa californica). Credit: iNaturalist/Anita Sprungk, licensed under CC BY-NC 4.0. (E) Visual defense, scares predators: Hawkmoth caterpillars (Hemeroplanes triptolemus). Credit: André Victor Lucci Frietas. (F) Agriculture, fungi farmers: Leaf cutter ants (Atta sp.). Credit: L.E.R.

Death by a thousand cuts. Wagner et al (2021)
Death by a thousand cuts. Credit: Wagner et al. (2021)

Gulf of Mexico Marine Sanctuary Expansion

The Flower Garden Banks National Marine Sanctuary in the Gulf of Mexico was expanded this month to cover 14 additional reefs and banks (total 17), and 104 additional square miles (total 160 sq. mi.), almost tripling the size of the sanctuary. The sanctuary is located 100 miles off the Texas and Louisiana coasts, and is the only sanctuary in the Gulf of Mexico.

On January 19, National Oceanic and Atmospheric Administration (NOAA) issued the final rules, which applies existing sanctuary regulations to all of the new areas, providing protection from fishing with bottom-tending gear, ship anchoring, oil and gas exploration and production, and salvage activities on sensitive biological resources.

The expansion areas will be the subjects of future conservation work and support resource protection, research, recreation, and stewardship for local communities and the country. The extension areas also include habitats for threatened and endangered fish, as well as some of the healthiest coral reef systems in the Caribbean. Scientists will study the healthy reefs as potential sites to seed and restore reefs in the Gulf of Mexico and the Caribbean in the future. Aquarium-Sanctuary Partnerships for America’s Keystone Wildlife Project conducts fish and coral recovery, invasive species and marine debris removal, sea turtle rehabilitation, and maintain mooring buoys that deter boats from anchoring on reefs.

Flower Garden Banks National Marine Sanctuary Map. Credit: NOAA.gov

Expansion area of the Flower Garden Banks National Marine Sanctuary. NOAA
Expansion area of the Flower Garden Banks National Marine Sanctuary. Credit: NOAA.gov

Department of the Interior - Invasive Species Strategic Plan

Interior is pleased to announce its new Invasive Species Strategic Plan, developed pursuant to the John D. Dingell Jr., Conservation, Management, and Recreation Act (Public Law 116-9). The Plan sets out a vision for effectively managing invasive species through collaborative conservation to protect our nation’s environment and natural and cultural resources; economy and infrastructure; and public health. It both reflects ongoing work by Interior and its partners and leverages opportunities to respond to emerging issues. For the next five years, this Plan will guide work to prevent, control, and eradicate invasive species that damage the nation's lands and waters. The final Plan is available here.

Department of the Interior copy

National Invasive Species Awareness Week

Participate in the largest invasive species awareness effort! National Invasive Species Awareness Week is right around the corner. In fact, this event is so full of great opportunities and great advice, we are celebrating twice! Go to NISAW website for more information, as it becomes available. The NISAW 2020 webinar series are now available to watch on YouTube here.

NISAW Part I – Information and Advocacy:
February 22-28, 2021

• Promotion of national and local legislative actions
• Tools and resources for communicating with policy makers
• Action toolkit and resources
• FREE Webinar 2021 series (schedule TBA)

NISAW Part II – Outreach and Education:
May 15-22, 2021

• Find or add local invasive species prevention, removal, and educational events
• Action toolkit and resources

North American Invasive Species Virtual Forum:
May 18-20, 2021

This is an international event encompassing the interests of professionals and organizations involved in invasive species management, research, and regulation across North America that is being held in conjunction with NISAW Part II. Click here to learn more and register.

How will you get involved? If you are an Invaders of Texas Citizen Scientist, consider doing some mapping, perform some removal or restoration, or contact your Satellite Group to see what can be done locally. Not part of a Citizen Scientist program, but would like to be? Here is your first stop.

NISAW_Social-Media-Posts_Jan21_Final_FB-Banner-copy-2 copy

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:

  • February 17, 1pm- Raising the Awareness of Invasive Species Management Among State Legislators. REGISTER
  • March 24, 1pm- Non-native Invasive Earthworms 101: From the Nightcrawler to the Jumping Worm. REGISTER



Invasive Spotlight:
Air Potato
(Dioscorea bulbifera)

The air potato (Dioscorea bulbifera) is an herbaceous, fast growing, high climbing vine that can grow up to 8 inches (20cm) per day and reach lengths of 65 feet (20 m). Vine growth will typically wrap around and cover native plant life, climb to the tops of tree canopies, and cover branches with trellises that allow for regrowth year after year. The air potato vine prefers tropical, warm temperatures. It prospers in disturbed areas, hammocks, and along the forest edge in open to semi-shady sites.

The vines twine and twirl in a counter-clockwise direction. The leaves are heart-shaped with leaf veins that all arise from the leaf base and long petioles (stalks) that alternately attach to round stems. The leaves can grow up to 8 inches (20cm) long and 8 inches (20cm) wide.

Flowers are inconspicuous, green to white in color, and small, arising from leaf axils in loose clusters up to 4 inches (10cm) long. Air potatoes do not produce fruit. The primary mechanism of reproduction is through potato-like tubers (or bulbils), found along the leaf axils of aerial vines. Bulbils can be as small as marbles or as large as softballs. They are typically roundish, but some are warty while others are smooth. Colors can range from light tan to dark brown. A secondary form of reproduction is performed via large underground tubers formation, some reaching over 6 inches (15cm) in diameter.

Bulbils typically grow in the fall, drop in the winter (December to February), and sprout in the spring. The aerial stems die back in winter. Bulbils can sprout from even a very small stage, and can be carried over long distances by water, making control difficult. The complete removal and destruction of both aerial and underground reproductive elements is required to prevent spread: Read more about prevention and management information here.

Despite the name, air potatoes are not potatoes and are not safe to eat. Both the underground and aerial bulbils contain a variety of toxic compounds not safe for consumption. They are a member of the yam family (Dioscoreaceae), and not at all related to the white potato (Solanum tuberosum), which is in the nightshade family (Solanaceae).

The air potato is native to eastern and tropical Asia and sub-Saharan Africa, but since its introduction in 1905, it can be found throughout Florida, Hawaii, Louisiana, Mississippi, Texas, and Puerto Rico. If you believe you have identified a suspected air potato, please take a picture and REPORT IT! to invasives@shsu.edu.

air-potato (Dioscorea bulbifera) vine. credit Dan Clark 2
Air potato (Dioscorea bulbifera) vine taking over native vegetation. Credit: Dan Clark.
air-potato (Dioscorea bulbifera) leaf and flowers. credit Karen Brown
Heart-shaped leaves with leaf veins all arising from leaf base, and inconspicuous white flowers. Credit: Karen Brown.
air-potato (Dioscorea bulbifera)2 bulbil. credit Karen Brown
Aerial bulbil growing out of a leaf axil. Credit: Karen Brown.


Zebra Mussel Watch

Zebra mussels (Dreissena polymorpha) have been successfully eradicated from Lake Waco in Central Texas, south of Dallas. The successful eradication of an invasive species is very rare, which makes this a thrilling way to start 2021. The zebra mussel infestation in Lake Waco was first detected in late 2014. Thanks to early detection and rapid response, adults and larvae were located, removed, and killed, preventing further spread. Over an acre of benthic barriers (plastic sheeting placed on the shoreline and lake bottom to eliminate the favorable oxygen conditions) were installed to impede reproduction and prevent establishment. Benthic barriers were removed in early 2015, and eradication efforts were successful.

TPWD and the City of Waco have continued to monitor the lake, but after five years of no larvae, settled adults, or DNA detection in Lake Waco, it will now be downgraded from ‘positive’ to ’undetected/negative’ status. 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

Strike Team’ Dropped onto Small Texas Island to Eradicate Poisonous Invasive Plant
An Invasive Species Strike Team spent three days trying to eradicate the Brazilian peppertree (Schinus terebinthifolia) from Padre Island National Seashore between the Gulf of Mexico from the Laguna Madre. Star-telegram.com

Figs Show That Nonnative Species Can Invade Ecosystems by Forming Unexpected Partnerships
All figs (Ficus spp.) on Kauai are non-native. However, if each fig species is known to only be pollinated by a specific parasitic wasp, how are these non-native figs settling in? phys.org

Researchers Find Nonnative Species in Oahu Play Greater Role in Seed Dispersal Networks
University of Wyoming researchers study shows nonnative species, especially non-native birds, play a greater role in shaping the structure and stability of seed dispersal networks in Oahu, Hawaii, than native species. sciencedaily.com

Deal Reached on Project to Protect Lakes from Invasive Fish
Michigan, Illinois, and U.S. Army Corps of Engineers have agreed on funding the next phase of a multi- million-dollar initiative to keep Asian carp (made up of 4 different species) out of the Great Lakes by strengthening defenses on a Chicago-area waterway. phys.org

Quagga Mussel Found to Be Primary Regulator of Phosphorus Cycling in Lower Four Great Lakes
Invasive quagga mussels (Dreissena bugensis) are now the primary regulator of phosphorus runoff from fertilizer introduced to the Great Lakes. Researchers create a model to represent the impact of the invasive mussels on the Great Lakes. phys.org

Invasive Tawny Crazy Ants Have an Intense Craving for Calcium – With Implications For Their Spread In the US
Micronutrients, such as calcium, in the ground can control populations of invasive crazy ants (Nylanderia fulva). theconversation.com

Conservation Corner: Saltwater, Freshwater, Plastic Doesn’t Care
Plastic pollution can negatively impact the environment whether it is floating along in saltwater of freshwater. Plastic pollution not only causes injury to the surrounding wildlife, but it can block out surface sunlight, decreasing oxygen levels, transport invasive species, and cause a bottom-up effect on the food web. goupstate.com

International News

Honeybees Reveal How Our Floral Landscape Has Changed Over the Last 65 Years
Using cutting-edge DNA barcoding techniques, scientists at the Botanic Garden of Wales, UK, identified which plants modern-day honeybees (Apis spp.) visited most often by looking at the pollen grains trapped within honey, and how honeybee preference has changes since the 1950s. Results reveal a controversial preference towards a highly invasive species. phys.org

Risk of Extinction Cascades from Freshwater Mussels to Bitterling Fish
Reproduction of native and invasive bitterling fishes (Tanakia lanceolata and T. limbate respectively) and their hybridization was studied in Japan. The rapid decline of the host unionid mussels (include 3 different species) and artificial introduction of invasive bitterling fish interacted to cause the rapid decline of a native fish and increase competition. sciencedaily.com

Warming Driving Eastern Mediterranean Species Collapse
Populations of marine mollusks have collapsed in recent decades in parts of the eastern Mediterranean as warming waters have made conditions unsuitable for native species. While native populations are on the decline, non-native tropical mollusk species seem to be thriving. phys.org

Aphids Suck: Invasive Aphid Found on Danish Apple Trees
The invasive spirea aphid (Aphis spiraecola) has been discovered for the first time in Denmark by University of Copenhagen researchers and could become problematic for apple orchards. phys.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.

Citizen Scientists Spotlight

Heartwood Invaders Have Heart, Dedication… And Potatoes?

We would like to shine the spotlight on The Woodlands Township Task Force and the Heartwood Invaders of Texas, and congratulate them on their very successful Martin Luther King National Day Service workday!

On January 16, a group of 22 Woodlands Township Task Force volunteers marched along one of the public pathways in Grogan’s Mill Village (the oldest of 8 villages in The Woodlands). This group was made up of made up of 16 dedicated Task Force members, 4 new volunteers and 2 Student Ambassadors with the Woodlands Green. The primary focus was to remove air potatoes (Dioscorea bulbifera) vines that have become overgrown along the public pathways throughout several of the Villages. These invasive plants can require a lot of vine maintenance. Air potatoes are high climbing, long vines, growing up to 65 feet long and up to 8 inches a day. They typically intwine themselves around native trees and bushes, covering them completely (Read article above ‘Invasive Spotlight: Air Potato’ to learn more). The Task Force spent the day cutting the vines away from native plants, and pulled vines down to get to the aerial bulbils (potato-like tubers) tucked on top of and beneath the native vegetation. The Citizen Scientists filled 35 40-gallon black trash bags with invasive plant debris. They also picked and dug up 57.4 lbs of bulbils, which were removed in buckets for later destruction.

The Woodlands Township Task Force is made up of city employees and local volunteers of all ages, in conjunction with the Heartwood Invaders of Texas. The Woodlands Township Task Force came together and started their training through the Invaders of Texas program at the end of 2019, with their first official work day in February 2020. They work closely with the city to remove invasive vegetation from public areas around the township. The Task Force has focused on the removal of air potatoes, however, they have also removed Japanese climbing fern (Lygodium japonicum), heavenly bamboo (Nandina domestica), elephant ears (Colocasia esculenta), and Chinese privet (Ligustrum sinense), all invasive and troublesome plants. In 2020, the Task Force completed 1,004 volunteer hours, but it looks like they will quickly surpass that number. Throughout January, the group has completed 80.5 volunteer hours, with another workday scheduled on Jan. 30.

“The group has far surpassed the amount of work expected when the Task Force began…Now, 2021 promises to set new records for these hard working and dedicated volunteers. They are amazing!” says The Woodlands Township Task Force coordinator, Terrilyn MacArthur.

  Feb-2020-Woodlands Task Force in GM
The Woodlands Task Force, February 2020 workday.
Invasive plant debris removed by The Woodlands Task Force MLK workday
Invasive plant debris removed by The Woodlands Task Force, MLK workday, January 2021.

Bulbils in a bucket- removed by The Woodlands Task Force
Air potato bulbils removed by The Woodlands Task Force, MLK workday, January 2021.


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, February 20, 2021 (8:30am-12:30pm)
Invaders of Texas Workshop
Location: Virtual
Contact: Terrilyn MacArthur

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