March 2023
What’s the Combination?

Climate change can lead to the creation of a more hospitable habitat for invasive species or it can lead to a destabilization of the environment making it no longer hospitable for native species, but tolerable for hardy invasives. Either way, there have been many studies to show that climate change is mitigating the spread of invasive species.

An interesting new study has discovered that the combination of climate change and invasive species can create a dual threat on biodiversity and native species. Until recently, it was thought that these two factors acted independently upon the environment, as per an argument known as ‘environmental filtering.’ This hypothesis suggests that biotic and abiotic factors act as ‘filters’ to the native species, operating in a scale-dependent top-down manner (abiotic than biotic), with no interaction between each other. This means that abiotic factors, such as those effected by climate change like temperature, would determine broad limits such as species distribution, but would act independently from biotic factors, such as competition, predation, and resource consumption, which would be responsible for the assembly of communities and populations. However, researchers have started to question this hypothesis since ecological complexities of the environment do not seem to work in such synergistic manners, especially when invasive species are introduced to the picture.

To better understand biotic and abiotic interactions, researchers examined the Cuban treefrog (Osteopilus septentrionalis). This invasive species is reported to displace two native treefrogs, green treefrogs (Hyla cinerea) and squirrel treefrogs (H. squirella), through predation and competition. Treefrogs will move around in their environment when their resources or conditions change, such as when a predator is nearby or if there is water available on the ground. A study was set up to determine which factor was more important to the treefrogs, rainfall or predation, if both occurred simultaneously. A climate-controlled container was created where the frogs were introduced, and the position of the water could be altered and observed. The study determined that the presence of the Cuban treefrog restricted the native species from accessing resources. This demonstrated how an invasive can negatively impact native species under unstable conditions, such as those caused by climate change, which challenges the environmental filtering hypothesis.

Read the research: Baecher et al., 2023



 cuban tree frog eating nativeCuban treefrog (Osteopilus septentrionalis) preying on a native green treefrog (Hyla cinerea). Credit: Baecher et al., 2023, photo provided from Kevin R. Messenger.

baecher et al 2023Diagram of treefrog vertical movement experiment in which biotic and abiotic factors were manipulated in a partial factorial design. Credit: Baecher et al., 2023.

Bottoms Up

Beetles are great at surviving in extremely dry environments because they have evolved the ability to survive their entire lives without drinking liquid water. Instead, they absorb water through their butt! Well, not exactly. They are able to open their rectum and take up water through moisture in the air, which is converted into fluid and absorbed into the body. They are also extremely efficient at extracting water from their food, utilizing their rectal complex and kidneys to extract moisture from frass (insect feces) before it is excreted. Until recently, however, no one was sure what mechanisms mediated these water-extraction functions.

An investigation has revealed the molecular mechanisms that allows beetles and most lepidoptera larvae to do this amazing feat of physiology. The research was performed on the red flour beetle (Tribolium castaneum), a global pest of stored food, making it a model organism for this study. Using genetic analysis and electrophysiological studies, researchers were able to isolate the gene responsible for water extraction in the rectal complex. This gene is called NHA1.

NHA1 localizes exclusively to specialized leptophragmata cells. These cells are situated like windows between the beetle's kidneys and the insect circulatory system. They enable hemolymph (or insect blood) to tubule movement of potassium chloride into the kidneys so they are able to absorb water from either frass or moist air through the rectal complex. This moisture is then recycled back into the body. When NHA1 was genetic depleted, excretory water loss was increased and body desiccation increased, suggesting absorption of water through the environment decreased. The findings of this study suggest that NHA1 expression is essential for maintaining the systematic water balance in beetles.

Researchers hope with this new information, ‘eco-friendly’ pesticides can be established to turn off or alter the water balance feature of specific invasive and agricultural pests, alowing for more targeted poisons.

Read the research: Naseem et al., 2023

rectal complex 2Adult red flour beetle (Tribolium castaneum) anatomy highlighting the tissues selected for microdissection and bulk RNA sequencing in order to determine the mechanism that mediates water balance. Credit: Naseem et al., 2023.

sem of rctal complexNHA1 localizes to specialized leptophragmata cells in the PTs of the rectal complex. Scanning electron microscopy, Back-scattered electron, and Maximum projection confocal microscopy images showing the gross morphology of the rectal complex. Credit: Naseem et al., 2023.


Did You Say Chemical Warfare?

Guinea grass (Megathyrus maximun, aka. Urochloa maxima) is an invasive grass that forms dense stands in open pastures and disturbed areas. It is drought resistant with the ability to build up dangerously large masses of vegetation that can suppress and displace local plants. Both attributes can contribute to wildfires. This grass is fire tolerant and thrives in disturbed areas, allowing it will bounce back after a fire where natives are wiped out.

To double the damage, it seems this plant also resorts to chemical warfare to outcompete native plants and turn the soil 'toxic'. Guinea grass releases 2-hydroxyphenylacetic acid into the soil during seeding establishment. This allelopathic compound can inhibit growth and recruitment of competitors in several unrelated species, as well as alters the soil microbial communities. Researchers wanted to determine if the combination of shading out native species and the use of chemical toxins interact to give Guinea grass a competitive advantage in an introduced range. Data was collected using a combination of field testing, greenhouse experiments, and chemical analyses to observe species interactions between Guinea grass and three native species: southwestern bristlegrass (Setaria scheelei), partridge pea (Chamaecrista fasciculata), and Texas sleepy daisy (Xanthisma texanum).

Researchers found that either shading out or the use of chemical toxins was effective at reducing recruitment and growth of native plants, but the combination of both increases the efficiency dramatically. The stressors exacerbated by the shade resulted in shorter plants, lower biomass, and an overall decreased seedling growth and recruitment by native plants. The negative effects of 2-hydroxyphenylacetic acid (2HPAA) were also intensified in the shade. The combination of shading and allelochemical release also lowered the recruitment and growth of Guinea grass’s own seedlings. These finding, in conjunction with previous studies, suggest that Guinea grass seeds and seedlings are more vulnerable to self-shading and allelopathy than fully established stolons, but only seem to slow competition with itself not with the native plants. The data collected demonstrated that resource competition and biochemical interference are not mutually exclusive allowing Guinea grass to thrive in introduced areas. Additional investigation is needed to determine how the combination of these attributes effects plants that Guinea grass comes up against in its native environment. The study also mentions that since 2HPAA seemed to be mildly allelopathic to seed recruitment, perhaps other phenolic acids could also affect seed recruitment and growth.

With a better understanding of how Guinea grass takes over, perhaps we are one step closer to learning how to mitigate and control this invasive in the environment.

Read the research: Morrison et al., 2023

Guinea grass. Dan Clark. USDI National Park Service.
Guinea grass (Megathyrus maximun). Credit: Dan Clark, USDI National Park Service,

dry treated guinea grass. Dan Clark. USDI National Park Service.
Dry and treated Guinea grass. Credit: Dan Clark, USDI National Park Service,

chemicals in guinea grass 2
Metabolite classes that were detected in (a) soil, (b) roots, (c) leaf litter, and (d) leaves and culms. The numbers in the pie slices are metabolite frequencies in each chemotaxonomic class. Credit: Morrison et al., 2023

Free Screening For Your TX Citrus

The Asian citrus psyllid (Diaphorina citri) and the citrus greening pathogen (Candidatus liberibacter asiaticus) are threatening citrus in multiple Texas counties, and we need your help to collect samples and monitor the spread to ensure that you and your neighbors are not affected. This pest and pathogen are extremely detrimental to Texas citrus, both economically and agriculturally. The presence of either can greatly affect citrus yield.

TISI is offering FREE diagnostic services! If you suspect your citrus has either the psyllid pest or the Citrus Greening pathogen, or you would like your citrus plants to be part of our screening survey, contact

We will send you all the instruction you will need. If you are located within 200 miles of our headquarters, we can collect samples, and/or provide traps and monitoring services ourselves. Not only will we share the results and management strategies (where applicable), but you will become part of a multi-county monitoring survey that is striving to improve the health of Texas citrus!

Also Available: TISI offers educational workshops that highlight information about the Asian citrus psyllid, the pathogen Citrus Greening, and what you need to look out for in your own backyard. If you are interested in this, TISI will provide trapping materials, assist with management strategies, and more. Don’t waste another second. Help us stop the spread!

symptoms of citrus greening. Jeffrey W. Lotz. Florida Department of Agriculture and Consumer Services.
Symptoms of citrus greening bacterium. Credit: Jeffrey W. Lotz, Florida Department of Agriculture and Consumer Services,

citrus greening
Leaf mottle on grapefruit, a characteristic symptom caused by citrus greening bacterium but also seen on trees infected by Spiroplasma citri. Credit: J.M. Bove.

Reclamation awards $160,000 for the Veg Out prize competition

The Bureau of Reclamation has selected phase one winners for the Veg Out prize competition seeking sustainable solutions to manage aquatic vegetation in canals. Winning ideas will share in a total prize purse of $345,000. This challenge aims to reduce the cost and labor of aquatic vegetation management in canals throughout Reclamation while minimizing impacts on water quality and downstream users. The challenge seeks to identify, develop, and test novel, sustainable, scalable solutions that can be used across a range of canal types. FULL PRESS RELEASE, including the list of Phase One winners.

 Bureau of Reclamation

America the Beautiful Challenge 2023

The National Fish and Wildlife Foundation (NFWF), through multiple federal cooperative agencies and the private sector, is pleased to announce the America the Beautiful Challenge (ATBC) 2023 Request for Proposals. Applicants are encouraged to develop large-scale, locally led projects that address priorities spanning public and private lands to conserve, connect and restore the lands, waters, and wildlife. Approximately $116 million will be available for 2023 through five categories of grants.

Pre-Proposal Due Date: Thurs, April 20, 2023, by 11:59 PM ET

Some priority project themes include: Benefit at-risk fish, wildlife, and plant species, Expand, provide, and/or strengthen habitat connectivity, ecosystem services, and community resilience, or Expand public and community access and engage local communities.


 National Fish and Wildlife Foundation  copy 


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:

  • April 19, 1pm - Ventenata Identification, Impacts, and Management Options. REGISTER.
  • May 17, 1 pm- Chemical Control of Invasive Weeds: Herbicide Selectivity, Modes of Action, and the Use of Herbicides. REGISTER.
  • June 21, 1pm- Advancing International Invasive Species Prevention Efforts and Developing a Model Legal Framework for Noxious Weed Programs. REGISTER.
  • July 19, pm- Using People Powered Restoration to Manage Invasive Species in an Urban National Park. REGISTER.


Invasive Crayfish Hitchhiking in Aquarium Shipments

Over the last few years, documented cases of invasive animals have been detected when other aquarium related commodities have been purchased. In 2021, zebra mussels were detected in moss balls in pet stores in 46 states. In 2022, multiple states found that invasive crayfish were unintentionally shipped with goldfish or other aquarium fish and were subsequently detected in pet stores.

Multiple Petco stores in Nebraska and Idaho in the last few weeks have reported invasive crayfish in tanks. A few of the specimens retrieved from a Nebraska Petco retail store were four inches or more in length. Although protocols and policies are in place at the supplier and receiver ends of the supply chain, there is still work that needs to be done to minimize the risk of hitchhikers within this pathway. It is uncertain how widespread this issue is at this time.

Please keep an eye out for any potential hitchhikers in Petcos. The National Petco office has been alerted to this issue, but if any reports come up in your state, please contact Kerry Wixted.


petco-logo copy

Invasive Spotlight:

(Limnophila sessiliflora)

Limnophila (Limnophila sessiliflora) is an aquatic plant that forms dense stands of vegetation that reach from the bottom to the top surface of the water. The plant takes root in the substrate and grows a long stem that can reach up to 12 feet (3.7 m) in length, with several inches extending above the water. Submerged stem nodes may also produce roots. Leaves are present in whorls along the stem and may be up to 2 inches (5 cm) in length. Submerged and emergent leaves are distinctly different. Emergent leaves are dark green, lanceolate in shape with slightly serrated margins, and arranged in whorls of 5-8 leaves around the stem. In contrast, submersed leaves are ovate or broadly lanceolate, finely divided and feather-like, and arranged in whorls of 6-10 (or more) around the stem. Small, sessile (without stalks), and solitary flowers grow on the uppermost part of the stems above the water. Flower petals can be blue-violet, pink or lavender in color and the upper lip of the flower is lobed, ovate, and bares two dots.

Limnophila can be found growing in lakes, rivers, springs, streams, and damp soils. It reproduces both asexually and sexually. Asexual reproduction occurs through the regrowing and spreading from plant fragments, which can be spread through water systems via boats, pumps, or other equipment. This plant also produces seeds. The flowers can produce up to 200-300 seeds each with a germination rate as high as 96%. Because this species can rapidly propagate via seeds or fragments, it is very difficult to manage. It can quickly establish, outcompete, and shade/choke out native species. Large stands can also clog irrigation ditches, canals, or pumps.

Despite being listed as a federal noxious weed and a TPWD prohibited exotic species, this plant is often cultivated as an aquarium plant and can be easily obtained online or from sellers. Since its introduction, Limnophila has been reported in Florida, Georgia, and Texas (Comal, Harris, and Hays Counties). For more information distribution or management, visit the TexasInvasives info page. To report Limnophila, please email a picture and location to

Limnophila sessiliflora. M. Grodowitz. 
Limnophila (Limnophila sessiliflora). Credit: M. Grodowitz.
emergent limnophila
Emergent portion of limnophila. Note the slightly serrated leaves and the sessile violet-pink flowers. Credit: Shaun Winterton, Aquarium and Pond Plants of the World, Edition 3, USDA APHIS PPQ,

submerged limnopila
Submerged stems and leaves of limnopila. Credit: Shaun Winterton, Aquarium and Pond Plants of the World, Edition 3, USDA APHIS PPQ,

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 scientists, 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 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. 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, 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 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

Discover the 6 Invasive Birds Invading Texas Skies
Learn about six species of invasive bird reported in Texas that compete with native species for food, shelter, and resources.

Those Seeds Clinging to Your Hiking Socks May Be from Invasive Plants
Temperatures are warming up and outdoor recreation is on the rise. You may be spreading invasive plants on your shoes and sock. Read more about how you can be proactive.

Insecticide Use Against Desert Locust in The Horn of Africa 2019–2021 Reveals A Pressing Need for Change
The large-scale release of organophosphate pesticides to mitigate an alarming number of migrating desert locusts (Schistocerca gregaria) has unforeseen repercussions that could cost billions. A recent study points out what needs to change when faced with pests and invasives, so this doesn’t happen again anywhere.

New Mosquito Species Reported in Florida
The number of invasive mosquitoes is on the rise. A new invasive species of mosquito, identified as Culex lactator, has been reported in at least three counties of Florida. It is currently unknown whether it will be a vector for disease.

Invasive Snails Are Helping an Endangered Bird Make a Comeback in Florida
The endangered snail kite (Rostrhamus sociabilis) population is making a comeback now that the birds are preying on invasive apple snails (Pomacea maculate). What kind of implications will this relationship have moving forward on the kite population, the ecosystem, or the native Florida apple snails (P. paludosa)?

New Study Counts the Environmental Cost of Managing Japanese Knotweed
A research group uses widespread invasive Japanese knotweed (Fallopia japonica) as a model to assess, evaluate, and establish a long-term and sustainable land management method.

Results In for Invasive Impact Survey, Pilot Program Announced
The Pennsylvania Invasive Species Council will be launching the first part of a $3 million pilot program this summer aimed as a statewide response to combat the growing number of invasive species.

Researchers Find Human Transportation Largely Responsible for Spread of Invasive Spotted Lanternfly
A recent study found the spotted lanternfly (Lycorma delicatula) spread is largely due to them hitching rides on cars, trucks, and trains. This data supported some of the long-distance population jumps made by this invasive.

Stefanik, Thompson Call on USPS To Issue Stamp to Combat Invasive Species
A bill has been presented that included a ‘Combating Invasive Species Semi postal Stamp’ that would help raise awareness about the threat of endangered species and help raise research funds through proceeds.

States Are Banning This Invasive Callery Pear Tree and Urging Homeowners to Cut It Down
The Callery pear (Pyrus calleryana) can be found throughout the northeast, Midwest, and southern states. How did this attractive invasive come to be so prolific and what can you do to help?

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:

April 6, 2023, 10am
North Texas Invasive Species
In-person presentation
Contact: Bobbye Hitzfeld,

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