Biofouling is the accumulation of microorganisms, plants, algae, and small animals on surfaces where it is not wanted. Biofouling can be found on buoys, ships, pipeworks, docks, etc. Biofouling can interrupt measuring equipment, clog pipes, result in an increase in fuel consumption on vessels, or degrade the purpose of that item. There is also a new problem to consider, biofouling on marine plastics and floating waste.

Plastic debris is currently the most abundant type of litter in the ocean, making up 80% of marine debris, both floating and submerged. We know ocean trash can be ingested or entangle marine life, but floating plastics can also become rafts, providing homes for coastal marine plants and animals. Organism like mussels, barnacles, and seaweed have been known to attach themselves to debris and circulate in the ocean for years. Currents pick up marine trash from one area, and transport it hundreds of miles before depositing it, often on another coastline. The constant movement of marine plastics could contribute to the introduction and transport of invasive and non-native species.

A group of research scientist studying fouling communities on different types of plastic debris found a variety of organisms. Bryozoans were found to be the most diverse group attached to plastics, but deep-water benthic polychaetous annelids, arthropods, brachiopods, bryozoan fossils, chordates, cnidarians, echinoderms, mollusks, sponges, annelid worms, and catshark egg cases were also found. The diversity of organism differed by plastic type: micro vs macro plastic. This is believed to be due to the chemical structure of the plastics and the surface properties. Habitation or biofouling seemed to play a role in causing the debris to sink, as the most abundant types of plastic debris have a lower density than seawater, but were collected from the sediments of the seabed. The bryozoans that were sampled are traditionally found in shallower depths, suggesting the act of biofouling altered their nature. Overall, the research found that a variety of organisms can inhabit marine plastics and move them around the ocean. This could eventually alter the marine ecosystem and/or aid in the transportation and distribution of invasive and non-native species.

Read the research: Subias-Baratau et al., 2022

Red imported fire ants (Solenopsis invicta) have a unique ability to cling together and form a floating raft whenever their underground tunnels flood. This raft can hold together and carry the colony for weeks or until the water recedes. These ants have a hydrophobic cuticle, and the cuticular texture creates an air bubble. These tightly knit bodies create a buoyant, water-resistant foundation for a floating raft. While other species of ant can float on top of water due to their hydrophobic cuticle, Solenopsis invicta is one of few species to exhibit rafting behavior. This behavior is one of many that aid in its successful dispersal.

Ant rafts have a constantly changing shape, and are made up of structural and surface ants. Structural ants are those that pack close together to keep the colony afloat, while surface ants march freely on top of the raft. The queens and eggs are safely tucked in the middle. The everchanging raft shape is caused by a behavior called “treadmilling”, where structural ants circulate to the surface of the raft, while free-walking surface ants burrow into the lower structural levels. Together, this cycle contracts or expands the raft, allowing for the construction of a narrow bridge that branches away from the body of the raft. These extensions are built to help raft riders “feel around” their environment and reach out for land or another such surface where the colony can safely disperse.

There is still a lot left to learn about ant rafting. One study created a series of models in which simulated ant individuals had to follow a simple set of instructions to carry out successful rafting behavior. Researchers hope that understanding rafting behavior and creating successful models will provide inspiration in the design of autonomous active systems such as swarm robotics.

Read the research: Wagner et al, 2021, Wagner and Vernerey, 2022
 

Stories about the joro spider (Trichonephila clavata) in Georgia are passing through social media, where some interesting embellishments have formed. After reading posts about how these “invasive” spiders are going to start falling from the sky or parachute from trees to attack us, it seemed time to squash these exaggerations.

A joro spider has a large football shaped abdomen with yellow and black wavy stripes on the top side, black and yellow pattering and red blotches underneath, and black legs with yellow banding. Females grow up to 3 inches long, while males are typically 1/2 - 3/4 inches. They are orb weaver spiders, like banana spiders (Nephila clavipes) or golden orb weavers (Argiope aurantia) found in Texas.

Currently, there is no evidence to support these spiders are “invasive”. They are more accurately described as introduced non-natives. The terms invasive has a specific definition and should be used cautiously to avoid misunderstanding. To be invasive, one must be non-native and cause harm to the ecosystem. Joros do not seem to affect the local food web, nor do they compete with native species. They build their webs high in trees, on porches, or on telephone lines, while native spiders build their webs lower in shrubs. Joros are an extra food source for native predators and catch invasives in their web, like the brown marmorated stink bug (Halyomorpha halys). Though it is alarming to walk into a spider web, joros are relatively harmless to humans. They are docile with fangs too small to break human skin and will not try to bite unless cornered.

Joros have been present in Georgia since 2013, however their numbers are increasing and their range is growing. Recent studies suggest a continued progression along the east coast. The spider’s high metabolism and ability to withstand colder temperatures removes the geographical limitations that are exhibited on other introduced invertebrates in the southeastern U.S. When compared to a closely related species, the golden silk spider (Trichonephila clavipes), joro spiders had double the metabolism, a 77% higher heart rate, and could survive brief freezes that killed other spiders (Davis and Frick, 2022). Joros can complete an entire lifecycle within a narrow period of suitable weather. These spiders are also very good at hitchhiking rides on vehicles and in transport containers, meaning the possibility for these spiders to spread through human movement is very high.

Now for the part about “falling from the sky to attack”. What is being misconstrued is a parachuting behavior called “ballooning”. It is common in spiders and even some small invertebrates. Spider hatchlings will release silk strands, called gossamer, and use wind currents and electrical fields to lift them up to be transported miles away (Morley and Robert, 2018). Although most commonly performed by spider hatchlings, this behavior can be exhibited by small males or medium sized females of a few different species, but these adults are at max 10cm. Expect joro spider hatchlings to hatch in the spring and float along the wind for dispersal. Large adult spiders will not be flying around or falling from the sky, and they have no desire to attack us. Scientists say they are here to stay and we should all learn to get along.

Some invasive insects may be more resistant to cold weather than was once believed. Dropping temperatures generally restrain invasive species expansion to some degree because many cannot survive the harsh winters, limiting movement north, but invasives like to provide an exception to every rule.

Mosquito surveillance efforts in Iowa uncovered evidence that the invasive Aedes albopictus is surviving the winter in three Iowa counties, allowing the species to establish itself for the first time in these locations. This species has made seasonal appearances in Iowa in the past, but the harsh winters were thought to be keeping the species from establishing. Data shows that not only are A. albopictus present but they seem to be spreading. Aedes albopictus is a vector of human diseases like chikungunya virus, dengue virus, and dirofilariasis. It is present in Texas. Research: Hall et al., 2022.

An invasive beetle is also pushing back against its icy restraints. A recent experiment showed that emerald ash borers (Agrilus planipennis) are more cold-tolerant than believed. They were once though to die when temperatures moved below -30 degrees Celsius, as seen in numerous populations. However, in 2019, an overwintering population of ash borers survived during a polar vortex that hit parts of Canada and midwestern U.S. Further examination showed that some individuals could survive when temperatures dropped to -50 degrees Celsius. Researchers provided two possible explanations: they are evolving to survive harsher winters in areas where they are established, or they can quickly change their physiology to respond to harsh conditions. High levels of cold-tolerance could allow these beetles to survive anywhere an ash tree is found, which is a problem. Research: Duell et al., 2022.

On the plus side, a group of researchers have peeked into the brain activity of fruit flies to see what causes them to sense the cold and alter their behavior accordingly. Many insects and animals restrain reproduction in the winter to protect their offspring from harsh conditions. Circadian and dorsal neurons were examined for an explanation. These neurons are important for sensing and responding to environmental cues. Dorsal neurons were found to be active in warm temperatures and inactive in cold, telling the brain "it is cold, stop egg production". Further examination revealed a neuropeptide, called Allotostatin, that expresses specifically in the circadian neurons, binds with another neuron to activate egg production, and whose expression decreases in the cold. Researchers hope to use this accumulation of knowledge to generate mutant mosquitos or target the neurons/ neuropeptide through chemical intervention to suppress mosquito and agricultural pest populations. Research: Meiselman et al., 2022.

Are You Eating My Crops 11 of 12

Philippine dewy mildew (Peronosclerospora philippinensis) is one of seven plant pathogens that is listed as a select agent by the CDC USDA because it has the potential to pose a serious threat to plant health. The ‘Are you eating my crops?’ series is almost over. Pests highlighted in this series have not yet been reported in Texas, but are on the ‘Watch List’ due to their high level of pest importance or risk due to host availability. So far, we have covered several different crop pests, damage , appearance, and where to find more information. To see previous headliners, visit the TexasInvasives.org iWire page.

Peronosclerospora phillippinensis spreads locally by water and wind through the transfer of spores from infected vegetation. The spread through infected seeds is possible, but only under specific environmental conditions. Symptoms appear on the leaves as long vivid green and yellow stripes or streaks. Downy gray to white fungal-like fuzz may grow on the leaf structure, primarily on the underside of the leaves. This downy covering is the primary site of spore production. As the plants age, the leaves become narrow, appear dried out and become abnormally upright. Corn is the main host, but oats, sugarcane, ornamental grass, and weeds also serve as sources of infestation under natural conditions.

There are other indigenous downy mildews, such as P. maydis and P. spontanea, that cause similar symptoms to plant host. Plant pathogens and various abiotic stresses can also cause similar symptoms in corn. Due to this, molecular identification is necessary to confirm the presence of P. philippinensis.

Philippine dewy mildew pathogen could become established in any area of the U.S. under conductive environmental conditions where the host plants are commercially grown. Texas sugarcane crops are especially at risk. If you believe you have identified a P. philippinensis infestation, please send a picture and the location to invasives@shsu.edu. To read more about false codling moths, see the USDA fact sheet or view the pest tracker to see where it has been detected in the U.S.

Wildlife Forever is proud to release the 2021 Clean Drain Dry Initiative® annual accomplishment report! Through media outreach, communications marketing, and community engagement, the public awareness campaign has generated a record-breaking 117 million impressions in 2021. Implementing a partner-led and consistent best practices campaign empowers users to prevent the spread of aquatic invasive species. Full Press Release.

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 20, 1pm- A Biocultural Approach to Integrating Indigenous Knowledge with Western Science for Invasive Species Management and Policy. REGISTER.
• May 18, 1pm- Using Community Based Social Marketing to Prevent the Spread of Invasive Species. REGISTER.
• June 15, 1pm- Spotted Lanternfly Ecology and Biocontrol Efforts. REGISTER.
• July 20, 1pm- “Jumping Worms:” What We Know Now. REGISTER.

The Entomological Society of America (ESA) announced a new common name for Lymantria dispar. The previously name “gypsy moth” has been replaced with “spongy moth”. The U.S. Department of Agriculture’s Animal and Plant Health Inspection Services (APHIS) supports ESA’s initiative to replace outdated/derogatory names as they work on the “Better Common Names Project”. The name “spongy moth” refers to the distinctive spongy-textured egg masses laid by adults. Egg masses are the part of the moth life cycle that people are most likely to unconsciously move, as they are often laid on outdoor items. "Spongy moths” are a significant invasive forest pest. Infestations into new areas can easily be caused by the transportation of outdoor items containing discrete egg masses. Drawing attention to this hazard is an important step in raising public awareness and reducing the pest’s expansion. See info page for more details. Report possible sightings here, Report It!, or see Full Press Release.

Invasive Spotlight:

Soapberry Borer
(Agrilus prionurus))

Soapberry borer (Agrilus prionurus) is a small beetle that measures about ½ to 1 inch long. They are shiny black with four small distinctive white spots along the elytra. The only known host is the western soapberry trees (Sapindus saponaria var. drummondii). The adults leave a D-shaped exit hole as it emerges from the trunk of a soapberry tree. The exit hole is similar to that of the emerald ash borer (Agrilus planipennis, info page) when it emerges from an ash tree (Fraxinus). Soapberry borer larvae are flat-headed and grow up to an inch in length. Female adults lay their eggs under the bark so the larvae can feed on the cambium layer. The larvae cause damage to the inside of the tree as they bore, feed, and complete development.

Besides the distinct D-shaped exit hole, infested soapberry trees can be recognized by exposed sapwood that results when birds and squirrels chip off the bark to feed on the larvae. This causes bark chips to accumulate at the base of the tree. Infested trees will die back from the top and often produce abundant sprouts along the trunk. Beetles attack and kill all sizes of soapberry trees larger than 2 inches in diameter, which die within 3 years of infestation.

Agrilus prionurus was first reported in Travis County, TX, in 2003, but it is possible that it was present in Texas as far back as 1998. Since then, it has been detected in 49 additional Texas counties including those around Austin, College Station, Corpus Christi, Dallas, Fort Worth, Houston, and Waco. Because of its negative impacts, the soapberry borer is part of the Sentinel Pest Network, a component of Texasinvasives.org. Please Report It! here. For more information regarding management and removal, please see the species info page.

Don’t Move Firewood: Transporting firewood with you when you go on outdoor trips or adventures can unwittingly aid in the movement of tree- killing pests, such as the soapberry borer. Residence and visitors are strongly encouraged to be aware of state firewood regulations to prevent the movement of invasive pests. Following a few simple guidelines can help protect trees everywhere: use firewood purchased locally, gather firewood on site, or buy certified heat-treated wood. To read more about invasive forests pests and the “Don’t Move Firewood” movement, click here.

Opportunities To Get Involved
Looking for participants for the following surveys: 

Citrus Greening Workshops

We need your help to safeguard Texas Citrus, and it can start in your backyard!

TISI is offering educational workshops focused on the Asian citrus psyllid and the pathogen Citrus Greening. The Asian citrus psyllid and the Citrus Greening pathogen is threatening citrus in multiple Texas counties, and we need your help to monitor the spread. The workshop will highlight what you need to look out for, address USDA-APHIS Citrus Quarantines, and offer diagnostic services if you suspect your backyard citrus has either the psyllid pest or Citrus Greening pathogen. This includes providing trapping materials, assisting with management strategies, and more.

Please contact invasives@shsu.edu so we can schedule a workshop (virtual or in-person) for you or your group this year!

Aquarium Watch: Looking for Prohibited Invasive Aquatic Species

Please help texasinvasives.org 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. Texasinvasives.org will contact the appropriate Texas institutions to remove the species for sale.

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

Invasive Fish Destroying Life in Texas Rivers and Waterways
Hypostomus plecostomus, also known as the suckermouth or armored catfish, is rapidly spreading across Texas waters and bodies of water throughout the southern U.S. Researchers are working hard to better understand the fish’s movement and environmental implication. kens5.com

Researchers ID Sex Pheromone of Invasive Giant Hornet
Scientists have developed a method for tracking and trapping the Asian giant hornet (Vespa mandarinia) with the aid of the queen’s sex pheromones, and may be able to use this to accelerate their removal. sciencedaily.com

Field Cage Study Highlights Safety of Classic Biological Control Agent Against Devastating Invasive Fruit Fly
Scientists have led new research which highlights the safety of a classical biological control agent against the devastating invasive fruit fly Drosophila suzukii, which attacks over 150 wild and cultivated fruits. phys.org

Bill To Fight Invasive Species Moves Forward
The bipartisan “Stop the Spread of Invasive Mussels Act” recently advanced out of the U.S. House Transportation and Infrastructure Committee. tradeonlytoday.com

Researchers Create Tool to Help Protect Native Fish from Hybridizing With Non-Natives
Researchers have created a tool to assess the risk of hybridization among native and non-native fish. This development could aid natural resource managers in trying to protect threatened or endangered freshwater fish species. sciencedaily.com

New Feral Swine Research Helps Pinpoint Anthrax Risk Zones
A microscopic anthrax spore can lie dormant in the soil for decades until it ends up in a suitable host. Researchers are examining feral swine blood for anti-anthrax antibodies to use to map out potential regions where the anthrax bacteria might be present, especially in areas inside the anthrax triangle zone in southwest Texas. phys.org

New Research Demonstrates High Value 'Injurious Weeds' Can Bring to Pollinators
New research finds the abundance and diversity of pollinators that visit some 'injurious weeds' are higher than the Department for Environment, Food and Rural Affairs (DEFRA) recommended plants. sciencedaily.com

Adding Fungi to Soil May Introduce Invasive Species, Threatening Ecosystems
Biofertilizers are microbes and mycorrhizal fungi that are grown specifically for application to soil. The introduction of these products involves introducing potentially invasive species that often replace or outcompete native fungi. phys.org

Scientists Estimate Invasive Insects Will Kill 1.4 Million US Street Trees by 2050
A new study estimates that over the next 30 years, 1.4 million street trees will be killed by invasive insects, costing over 900 million dollars to replace. Ninety percent of the tree deaths are predicted to be caused by the emerald ash borer (Agrilus planipennis). 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
Another Successful Brazilian Pepper Tree Workday

Toward the end of February, the Texas Gulf Region Cooperative Weed Management Areas (CWMA) held another successful Brazilian pepper tree removal workday! Seventeen employees and volunteers from the City of Port Aransas, Coastal Bend Bays and Estuaries Program, UT-Marine Science Institute, and the Texas Invasive Species Institute (TISI) gathered to cut down and remove a large batch of Brazilian pepper trees that had been growing alongside a UT-Marine Science Institute dorm in Port Aransas, Tx. The workers removed 6 large trailer loads of the invasive vegetation and cleared about 1/8 acres in the period of one afternoon. Brazilian pepper trees (Schinus terebinthifolious) exhibit a growth process called basal sprouting, which causes each tree to have multiple trunks that intertwine around each other. The interweaving, drooping branches and foliage forms dense thickets that shade out native grasses and smother the native vegetation. A 10-foot-tall batch of invasive guineagrass (Urochloa maxima) was also removed from the property.

Since 2014, the Texas Gulf Region CWMA organization has been working vigorously toward the management and eradication of invasive species, especially the Brazilian pepper trees, that grow along the Texas Gulf coast and in the city of Port Aransas. The group has carried out many Brazilian pepper trees removal projects, replanting, and beach tree restoration projects, and “tree giveaways” that provide city residents with native trees that can be planted in place of invasive trees removed from private property. They currently have multiple projects underway and show no signs of slowing down in their endeavors. We all expect great things from this hard-working group!

Special Shout Out:
Christina Marconi, with the UT-MSI, has served as Coordinator for the Texas Gulf Coastal CWMA program, in Port Aransas, for the past two years. Now that she is leaving to continue pursuing her educational career, we want to take a moment to thank her for all of support in continuing CWMA efforts against Brazilian Peppertree in the area. Her coordination was vital to the success of the Brazilian Peppertree removal and tree replacement efforts throughout 2020 and 2021. We will miss her guidance, but wish her the best of luck on her newest endeavor!