December 2022
Patience Is a Virtue

Argentine ants (Linepithema humile) are agriculturally invasive ants that have multiple queens and can construct super colonies that easily outnumber and displace native species. Recent research has discovered an interesting foraging strategy that might contribute to the success of this invasive ant.

All ants require carbohydrates, which they obtain from plants and animals, and protein to nourish their offspring, which they gather from dead animals. Ants adjust their foraging behavior according to the needs and availability of these nutrients, as well as the presence or threat of competition and/or predators. Well-fed Argentine ants are bold and aggressive when foraging for carbohydrates and show little to no hesitation when predators and competitors are around.

One might expect that a starving animal would go to great lengths to acquire food, especially when the good of the colony is at stake. However, after analyzing a series of experiments, researchers found instead of starving Argentine ants increasing their foraging in high-risk situations as expected due to having “little to loose and everything to gain,” the opposite happened. Starving Argentine ants were more likely to show caution during foraging, especially when risk of competition was high. This suggests that they are unwilling to expose themselves to danger when weakened by hunger, which in turn preserves their colonies' foraging capabilities. This complies with a behavior called the state-dependent safety hypothesis, which explains that animals in good condition are more likely to take risks because they are more likely to survive dangers they encounter.

A lack of foraging can lead to a reduction of food stores, and if those stores are already low, i.e. the ants are already weakened and starving, foraging in a high-risk environment could lead to the loss of foragers. To that end, if the foragers show an increased degree of caution or reduced foraging, it could result in lowering unnecessary risk which would result in fewer foragers lost while the need for them is greatest. This foraging strategy could give them a competitive edge.

Read the research: Barbee and Pinter-Wollman 2022



 Argentine ant. Eli Sarnat. USDA APHIS PPQ. Bugwood.orgArgentine ant (Linepithema humile). Credit: Eli Sarnat, PIAkey: Invasive Ants of the Pacific Islands, USDA APHIS PPQ.

*These ants are often mistaken for others and usually require an entomologist for official verification and identification.

Screen Shot 2022-12-30 at 7.38.28 PM copySchematic (A) and photo (B) of the experimental set up with a housing area/cup connected to two foraging areas with plastic tubes, with one foraging area provided protein-rich food and the other providing carbohydrate-rich food. Credit: Barbee and Pinter-Wollman, 2022.


I’ll Take That Iron, Thank You

Pectobacterium spp. are necrotrophic gram-negative bacterial pathogens that causes soft-rot and other types of rotting disease in a range of plant types, including some invasive weeds, all over the world. Strains of Pectobacterium are known to pirate iron from their host plant by directly extracting certain iron-loaded proteins in order to survive and replicate. Until recently, researchers did not understand how Pectobacterium was able to carry out this important species-specific protein transport pathway.

According to research, the soft-rot of host tissues depend on protein-secretion systems to deliver proteins into the tissues, and growth and replication of bacteria in this rot are dependent on access to iron from rotting tissue. Resent examination found that Pectobacterium spp pirate ferredoxin, a protein loaded with iron, by importing it into the bacterial cell through a membrane channel called FusA. When it arrives in the cell interior, an area called FusC grabs it and dismembers the ferredoxin to release the iron. This is the first observed example of a bacterium carrying out this process. The study also found that it is likely that the bacterium evolved, or re-evolved, this important countermeasure alongside the host plant in order to get past the natural host mechanisms that are in place to prevent pathogens from tapping into host plant iron stores. This would explain the species-specific parallel between the iron-importing mechanism of the bacterium and the protein-import pathways evolved in the mitochondria and chloroplasts of the host plants.

Some strains of Pectobacterium are known to infest invasive weeds, giving it potential as a biological control agent. A better understanding of the bacterium's ability to obtain iron is an important step in maximizing the practical application of a biocontrol.

Read the research: Grinter et al., 2022

bacterial soft rot (Pectobacterium carotovorum ssp. carotovorum) (Jones 1901). Gerald Holmes Strawberry Center Cal Poly San Luis Obispo Bugwood.orgBacterial soft rot (Pectobacterium carotovorum ssp. carotovorum). Credit: Gerald Holmes, Strawberry Center Cal Poly San Luis Obispo,

Grinter et al 2022 FusC copyA Brownian ratchet model of ferredoxin, an iron-loaded protein being imported into Pectobacterium. Credit: Grinter et al., 2022

Water Encyclopedia

Getting samples from the upper heights of the canopy can be physically demanding, time-consuming, environmentally invasive, and often expensive. A group of scientists have utilized the wonders of eDNA, or environmental DNA, to design a new method of canopy collection that is non-invasive, cost efficient, and simply designed. Where once large cranes or tree climbing equipment was needed, now all one needs to do is collect rainwater.

In a recent study, a group of researchers collected rainwater runoff from the canopy in four 1m sq. rain samplers that were placed beneath four tree types (beech, oak, larch, and pine). The collected water was filtered, and eDNA metabarcoding was performed to profile the canopy invertebrate community. Physical specimens present in the water runoff samplers were also collected and identified in order to compare it to the eDNA analysis. This was done in order to determine if eDNA analysis detected the presence of species other that those physically present in the collection trays. Fifty invertebrate species were detected by eDNA metabarcoding, of which 43 were not physically present in the water sample. These results likely represent a peek into the true biodiversity of the canopy. The study findings also observed species occurrence patterns corresponding to the four trees; 88% of species detected were tree host specific. This suggests that ecological patterns, such as host specificity, might be assessable using this method.

Forest canopies are highly diverse ecosystems. Despite decades of study and observation, there is still a lot left to learn about the diversity and the ecological interactions of canopy life. This new technique is an innovative way to start filling in some of these knowledge gaps. The researchers understand this is a small sample size, but the potential for this non-invasive method is yet to fully be explored.

Read the research: Macher et al., 2022

Macher et al 2022 sample collection
Example of setup of the rain sampler prototype at sampling one of the sample sites. Water was collected, transferred into a sterile bottle, and filtered before eDNA analysis. Credit: Macher et al., 2022

rainwater-edna Scientists from the UDEs working group Aquatic Ecosystem Research taking samples. Credit- UDE Till Macher
Scientists from the UDEs Aquatic Ecosystem Research taking Rainwater-eDNA samples. Credit: UDE, Till Macher.


Texas Citrus Need Your Help

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 and samples to monitor the spread. 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 diagnostic services if you suspect your backyard citrus has either the psyllid pest or the Citrus Greening pathogen.

Contact for instruction to send a plant or pest sample. If you are located within 200 miles of our headquarters, we can collect samples, and/or provide traps and monitoring services. 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 back yard. Your citrus can also become part of a TISI survey that is monitoring Texas citrus for pests and pathogens. If you are interested in this, TISI will providing trapping materials, assist with management strategies, and more.

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.

Virtual Watercraft Inspection Training Opportunities

Virtual watercraft inspection training classes are available, free of charge. Classes are known to fill up fast, so it is recommended that if you are interested in attending any virtual classes, you get your registration in soon. All class levels are offered on three different dates in January, February, and March 2023.

WIT Level - Inspector Training (3 days, 8am - 12pm PST)

WIT Level - Inspector & Decon Training (3 days, 8am - 12pm PST)

WIT Level - Trainer Training (3 days, 9am - 4pm PST)


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:

  • January 18, 1pm – The Blue Ribbon AIS Commission – Process, Participation and Final Report. REGISTER
  • 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.


Back In Action

At, we believe public education regarding invasive species prevention is as important as the research we do on distribution and biology. Our Director of Research & Education, Ashley Morgan-Olvera, returned from maternity leave with determination! She has spent the past couple of months traveling to various groups across the state to spread the word about invasive species and what YOU can do about them! She was able to connect with Master Naturalists at the Annual Conference in Houston, the Texas Aquatic Plant Management Society Conference in San Marcos, and presented to over 100 engaged citizens as part of the District 5 Garden Club meeting in Georgetown, TX. It was an honor and a pleasure to reach so many citizens from different districts. If you are interested in a workshop about invasive species management, specific pest identification, or just an introduction to Invasive Species, CONTACT US TODAY at! We would love to present to your area, either virtually or in-person!


Ashley Morgan-Olvera presenting at the District 5 Garden Club meeting in Georgetown, TX. Credit: Gelasio Olvera.

Invasive Spotlight:

Pink Hibiscus Mealybug
(Maconellicoccus hirsutus)

The pink hibiscus mealybug (Maconellicoccus hirsutus) sucks juices from its host plants and injects toxic saliva while it feeds. This can lead to a malformation of leaves and fruit, stunted terminal and leaf growth (called bunchy top), or host plant death. Severe mealybug infestation is often noticeable by heavy cotton-like white waxy build up on the terminals, stems, and branches.

Adult females are 3mm long, wingless, and have no lateral wax filaments. The males are smaller than the females, have one pair of wings, and two long wax caudal filaments. Their bodies and body fluids are reddish, but males can be more reddish brown. The males have no mouthparts because they do not feed and only live for a few days. Eggs are small and pink and contained in an egg sack of white wax. Newly hatched nymphs, called crawlers, are highly mobile and will quickly disperse over the host, target new growth, and are displaced via wind, human, or animal transport. Like most mealybugs, the nymph stages look similar to the female in form, however the female nymphs have three instars (stages) and the males have four instars. The entire life cycle can be completed in 23-30 days and there can be as many as 15 generations in a year.

The primary host of these mealybugs is hibiscus, but they are also known to infest citrus, coffee, sugar cane, plums, guava, mango, okra, sorrel, teak, mora, pigeon pea, peanut, grapevine, maize, asparagus, chrysanthemum, beans, cotton, soybean, cocoa, and many other plants.

The natural spread of these mealybugs is slow because they are not strong fliers and are primarily facilitated by human activity or the transportation of ornamental plants. The movement of infested plants and plant material is not advisable as this may spread the pink hibiscus mealybug to new areas. Pink hibiscus mealybugs can be easily mistaken for other mealybugs and require an entomologist for positive verification/identification.

While not currently in Texas, there is a potential that the pink hibiscus mealybug will rapidly spread throughout Texas, as well as the southern and southeastern states, due to the mealybugs semi-tropical habitat preference. Be sure to observe imported plants from the nursery for the signs of infestation. For more information about the pink hibiscus mealybug, visit the TexasInvasives species info page.

pink hibiscus mealybug Maconellicoccus hirsutus. Jeffrey W. Lotz. Florida Department of Agriculture and Consumer Services. 
Pink hibiscus mealybug (Maconellicoccus hirsutus). Credit: Jeffrey W. Lotz, Florida Department of Agriculture and Consumer Services,
pink hibiscus mealybug male. Florida Division of Plant Industry. Florida Department of Agriculture and Consumer Services.
Male pink hibiscus mealybug. Credit: Florida Division of Plant Industry, Florida Department of Agriculture and Consumer Services,

pink hib mealybug infestation. effrey W. Lotz. Florida Department of Agriculture and Consumer Services.
Pink hibiscus mealybug infestation. Credit: Effrey W. Lotz, Florida Department of Agriculture and Consumer Services,

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 and natural habitats by looking for 14 prohibited invasive aquatic species being sold in your local aquarium store. With just one photo you can assist us in finding and documenting which stores are selling prohibited species. will contact the appropriate Texas institutions to remove the species for sale.

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

Opinion: Bill Would Invest Millions in Texas Wildlife
Congress may pass the Recovering America’s Wildlife Act (RAWA), which would send nearly $1.3 billion to the states annually and bring as much as $50 million per year for the next five years to the Texas Parks and Wildlife Department (TPWD).

No Northern Giant Hornets Found In 2022 in Washington State
Trapping in Washington for the northern giant hornet (Vespa mandarinia) ended November 30th without any confirmed sightings for the first year since trapping was initiated.

Findings For Invasive Insect's Life Cycle Could Aid Management in Southeast
New research findings could help scientists control the emerald ash borer (Agrilus planipennis), an invasive pest ravaging native ash trees in North America, and aid in timing the release of important biocontrols.

Invasive Species Handbook: A Resource for Educators
A great resource for educators, grades 3-8, and anyone looking to learn all about invasive species, including environmental, economic, health impacts, pathways and movement, as well as monitoring and control methods.

Invasive Species Policy Must Embrace a Changing Climate
Existing policy and management may be too slow to incorporate climate change observations and mitigations into environmental policy and practice. These missed opportunities could exacerbate the negative effects seen by climate change because proactive response management based on observations is not being initiated.

Ancient Invention May Safely Move Fish Across Barriers While Blocking Invaders, Study Finds
Recent studies find that a device from 234 BC could be the answer as to how to lift native fish over low-head barriers that are in place to keep invasive species out of the Great Lakes.

Giant Goldfish Hybrid as Heavy as A 10-Year-Old Is A Reminder Not To Dump Your Pets
A giant goldfish was caught in Champagne, France, from Blue Water Lakes. The carp fishery released the behemoth 20 years ago and it has since grown to be one of the largest in the world, weighing in at 30-kilogram (67-pound).

Study Examines Feeding Damage Caused by Spotted Lanternflies on Young Maples
Short-term, heavy feeding by adult spotted lanternflies (Lycorma delicatula) on young maple trees inhibits photosynthesis, potentially impairing the tree's growth by up to 50 percent.

Political Geography Key to Assessing Economic Costs of Invasive Pests on Islands
Islands are highly susceptible both economically and environmentally to invasive species. A recent study established an extensive database to correlate the economic cost of invasive species compared to recorded cost.

New Research Shows People, Wildlife, And Marine Environment Benefit When Island-Ocean Connections Are Restored
Linking land and sea through coordinated conservation efforts may offer benefits for biodiversity, human wellbeing, climate resilience and ocean health, and provide a microcosm for the untapped potential of ecosystem restoration on a larger scale.


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:

January 18, 2023, 6:30pm
Invasive Species in Central Texas
Virtual Workshop
Contact: Bob Morris,

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

March 9, 2023, 7pm
Invasive Pests near You
In-Person Workshop
Contact: Beth Erwin,

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.