This research guide gives information on invasive species and their impact on the local environment and agriculture. The purpose of this research guide is to offer students access to primary and secondary source materials found within the University of Texas Rio Grande Valley library as well as external resources.
Invaders entered Estero Llano Grande State Park in 2016. Staff of the park noticed the absence of local insects and reptiles. And something was blinding the baby rabbits. While the invasion was large, the invaders themselves were no bigger than 2.4 mm long.
Known as the tawny crazy ant, these small creatures are just one of the many invasive species that consider the Rio Grande Valley home. According to House Bill 865, the 81st Texas Legislature defined invasive species as any “species that is not native to an ecosystem and whose introduction to the ecosystem causes or has caused economic harm, environmental harm, or harm to human health.”
Invasive species have the power to transform ecological landscapes, endangering native species, and potentially causing agricultural and economic harm. In some small cases, can be a potential threat to human safety and border security.
While the definition of an invasive species includes mammals, the focus of this research guide is on invasive plants and insects and the threats that arise when these invaders are introduced to Lower Rio Grande Valley.
![Color image of water hyacinth]("https://commons.m.wikimedia.org/wiki/File:Pontederia_crassipes,_Tunga,_Mumbai,_India_%28405613458%29.jpg)
The water hyacinth (Pontederia crassipes – formerly Eichhorinia crassipes) is a freshwater, tropical and subtropical aquatic plant native to South America. It was first introduced to the United States in 1884 as an ornamental plant before spreading across freshwater in the Southeastern states. It can now be found as far as California and Washington (Image Source: Wikimedia Commons).
In the Lower Rio Grande Valley, the noxious weed is known to clog irrigation pipelines which makes it difficult irrigate fields. Its rapid propagation can overcrowd its freshwater source, pushing out indigenous plants thus reducing a food supply to native wildlife and aquatic creatures. The overcrowding can also slow the natural flow of the Rio Grande River, creating a breeding ground for pests, fungi, bacteria, and biofilms in the stagnant waters.
In her 1928 book, Texas Wild Flowers: A Popular Account of the Common Wild Flowers of Texas, Ellen D. Schulz describes the water hyacinth (then Piaropus crassipes) as "[a] floating mass of blue, resembling a bit of Texas sky fallen to earth... To the dreamer, it is a scene of beauty. To the practical minded, it is a menace to transportation..."
Indigenous to Brazil, the tawny crazy ant (Nylanderia fulva) were once used as a biological control agent used to combat pests in Colombia, and have since become a major pest in the country. They were first discovered in 2002 by Tom Rasberry, an exterminator. He was working a job in Pasadena, Texas when he noticed the ants increase in population between his first and second visit to a location.
It is unknown how they were introduced to the United States, but it can be speculated that they traveled aboard a commercial ship. Since their first discovery, the ant has spread across several Texas gulf coast counties. By 2012, they had reached Florida.
Their attraction to electrical equipment makes them a burden for both rural and urban households. They are known to cause damage and shortages in electrical outlets, air conditioning units, and several common household electronics.
Their negative impact on agriculture can also raise issues. Tawny crazy ants are a nuisance to livestock, which can asphyxiate smaller creatures while attacking the larger cattle’s eyes, feet, and nostrils. The ants are also known to assist in destroying crops themselves or pushing out natural predators of other pests who may invade fields (Image Source: Flickr).
Hydrilla (Hydrilla vericillata) can be found on every continent except Antarctica. It first arrived in the United States through Florida where it was imported as an aquarium plant in the 1950s. Its invasive status happened when the plant was dumped into canals nearby Tampa Bay.
Hydrilla creates many of the same issues the water hyacinth (Pontederia crassipes) does. It is known to push out native aquatic plants by robbing them of nutrients, but it can also alter the pH in and remove oxygen from the water. This, in turn, can also affect the local wildlife by killing off a food source as well as harming any aquatic species that may call the Rio Grande River home. Like the water hyacinth, hydrilla can also cause issue with irrigation pipelines (Image source: Flickr).
Triploid Grass CarpThrough its Parks and Wildlife, the state of Texas allows residents to apply for a permit to stock triploid grass carp to combat hydrilla. Grass carp (Ctenopharyngodon idella) is native to Pacific Far East; however, to prevent it from becoming an invasive species itself, a sterile form of grass carp is used. (Image source: Wikimedia Commons)
New World Screwworm flyFound in tropical and subtropical locations in the Western Hemisphere, the New World Screwworm fly (Cochliomyia hominivorax) is a parasitic fly whose larva, the screwworm, became a particular nuisance among farmers in the Lower Rio Grande Valley as well as across the United States (Image source: Wikimedia Commons).
Unlike maggots of other flies which feed on dead flesh, the screwworm infects living hosts through various means including opens wounds brought on by accidents or other pests, and the navels of newborn animals. This could lead to tissue damage or even death.
In 1960, Texas pushed for a screwworm eradication program. In Mission, Texas, the program began to produce sterile male screwflies to be released and “mate” with female screwflies, which reduced the number of fertilized eggs. By 1964, the USDA announced the pest had been eradicated from Texas. While the last reported case occurred in Starr County in August 1982, the screwworm continues to appear occasionally in the United States.
Carrizo Cane (Arundo Donax)Arundo Donax is known by many names: Giant reed, Spanish reed, elephant grass, Colorado river reed, Spanish cane, giant cane, wild cane. In the Rio Grande Valley, it is known as carrizo cane or, simply, carrizo. While it is thought to be an indigenous plant from eastern Asia, it was introduced to the United States from the Mediterranean when it was brought into California in the 1820s. Its original purpose in the United States is to assist in soil erosion control, but the reed proved used for as thatching, making musical instruments, and walking sticks. It spread along the United States throughout warm coastal freshwater, reaching as far as Maryland (Image source: Wikimedia Commons).
Growing along the Rio Grande River, carrizo cane not only causes issues with native plants and animals, but with border security too. The invasive weed can grow around 4 inches a day, which can crowd out native plants. It’s also an ideal habitat for cattle fever ticks as it helps them from being detected by predators and the like.
Carrizo cane is also seen as a border security threat as it can assist undocumented immigrants from being detected by border security. In 2015, the 84th Texas Legislature passed Senate Bill 1734, which directed the Texas State Soil and Water Conservation Board to create a program to eradicate the weed.
Africanized Honeybees (aka Killer Bees)The Africanized honeybee is a hybrid subspecies of the Western honeybee (Apis mellifera), or European honeybee, and the East African lowland honeybee (Apis mellifera scutellata). The East African lowland honeybee was first introduced to Brazil in the 1950s after a failed attempt with the imported European honeybees which were brought into the country to increase honey production. The spread of Africanized honeybees began when the East African lowland honeybee escaped quarantine and began crossbreeding with the European subspecies (Image source: Wikimedia Commons).
Their introduction to the United States happened in 1990 when they arrived in Texas from Mexico. Most fears of the hybrid subspecies centered around their defensive behavior. Unlike the common Western honeybee, the Africanized honeybees quickly defend their hive and will pursue potential threats for longer distances. Because of their unpredictable behavior, they are also difficult to work with. An entire colony will abandon its hive, reducing honey production and causing crop pollination to drop.
Collection contains articles, clippings, flyers, brochures, maps, and other ephemera collected by the Library Special Collections on topics concerning the Lower Rio Grande Valley Collection pertaining to the geographic region of southern Texas and northeastern Mexico. Many of these materials are protected by U.S. Copyright Law.
The Congressional Papers of Eligio "Kika" de la Garza consist of approximately 425 linear feet of materials dating from 1965 - 1996. The bulk of the papers date from 1965-1980 and 1989-1996. The papers were created during Kika de la Garza's time as an elected official in the U.S. House of Representatives from 1965 - 1996, representing the 15th Congressional District in South Texas.
The Congressional Papers of Rubén Hinojosa consists of 291 linear feet of materials dating from 1997 - 2016. The papers were created during Rubén Hinojosa's time as an elected official in the U.S. House of Representatives from 1997 - 2016, representing the 15th Congressional District in South Texas. The collection consists of legislative material as well as casework of local projects and issues.
The collection consists of twenty-eight document cases containing research Dr. Howard T. Dulmage conducted on Bacillus thuringiensis (Bt) microbial insecticides while he was stationed at the Insect Pathology Research Unit, U.S. Department of Agriculture in Brownsville, Texas (1967-early 1990s).
Selected newsletters and news releases from the Kika de la Garza Congressional Papers. Kika de la Garza served as Congressman for the 15th Congressional District of Texas from 1965-1996. This digitization project was funded by a grant from the National Historical Publications and Records Commission.
Guillermo Corona earned a Bachelor of Arts in English with a minor in philosophy at the University of Texas Pan American in 2007. During his final year of college, he was the local chapter president of Sigma Tau Delta, the international English honor society. He worked at the Dustin Michael Sekula Memorial Library in Edinburg, Texas for nine years in technical services and the children’s department. He joined the UTRGV Special Collections & Archives in 2021.
Calculating evapotranspiration of Arundo donax along the Rio Grande [Thesis] by
Invasive species have been recorded to cause large economic and ecological impacts on various ecosystems and their services. Locally, giant reed ( Arundo donax L.), a woody grass native to the Mediterranean, adversely impacts riparian ecosystems in southwestern United States by aggressively displacing their native flora and fauna. Giant reed also has become a cause of concern for national water security, especially in water-limited areas of the arid southwestern United States. The main objective of this study is to provide the first, landscape-level estimates of water use by giant reed in the United States. Evapotranspiration was monitored using the eddy covariance method concurrently with the implementation of a biological control program targeting giant reed. Daily maximum ET reached 7.7 and 6.07 mm day -1 in 2014 and 2015, respectively. Our study suggests that this reduction in ET may be attributed to the presence of stem-galling specialist insect biological control agents at relatively higher density in 2015 than in 2014. Additional studies are needed to quantify the long term water conservation and economic benefits of the biological control program in the Rio Grande Basin.
Ecological and socio-economic impacts of invasive water hyacinth (Eichhornia crassipes): a review [Article] by
1. Water hyacinth (Eichhornia crassipes) is one of the world's most invasive aquatic plants and is known to cause significant ecological and socio-economic effects. 2. Water hyacinth can alter water clarity and decrease phytoplankton production, dissolved oxygen, nitrogen, phosphorous, heavy metals and concentrations of other contaminants. 3. The effects of water hyacinth on ecological communities appear to be largely nonlinear. Abundance and diversity of aquatic invertebrates generally increase in response to increased habitat heterogeneity and structural complexity provided by water hyacinth but decrease due to decreased phytoplankton (food) availability. 4. Effects of water hyacinth on fish are largely dependent on original community composition and food-web structure. A more diverse and abundant epiphytic invertebrate community may increase fish abundance and diversity, but a decrease in phytoplankton may decrease dissolved oxygen concentrations and planktivorous fish abundance, subsequently affecting higher trophic levels. 5. Little is known about the effects of water hyacinth on waterbird communities; however, increases in macroinvertebrate and fish abundance and diversity suggest a potentially positive interaction with waterbirds when water hyacinth is at moderate density. 6. The socio-economic effects of water hyacinth are dependent on the extent of the invasion, the uses of the impacted waterbody, control methods and the response to control efforts. Ecosystem-level research programmes that simultaneously monitor the effects of water hyacinth on multiple trophic-levels are needed to further our understanding of invasive species.
Effects of Patch Size, Fragmentation, and Invasive Species on Plant and Lepidoptera Communities in Southern Texas [Article] by
Habitat loss, fragmentation, and invasive species are major threats to biodiversity. In the Lower Rio Grande Valley (LRGV) of southern Texas, a conservation hotspot, few studies have examined how land use change and biotic disturbance influence biodiversity, particularly among Lepidoptera. We surveyed 24 habitat fragments on private lands in the LRGV and examined how patch size, edge to interior ratio (EIR), prevalence of invasive, exotic, and pest (IEP) plant species, and other environmental factors influenced plant and Lepidoptera communities within four habitat classes. Biotic disturbance was widespread and intense. IEP plants represented three of the four most common species in all but one habitat class; yet, classes largely had distinctive plant and Lepidoptera communities. Larger habitat patches had lower IEP prevalence but also lower plant richness and lower Lepidoptera richness and abundance. Conversely, patches with higher EIRs had greater IEP prevalence, plant richness, and Lepidoptera richness and abundance. IEP prevalence was negatively related to plant diversity and positively related to woody dominance, blooming plant abundance, and, surprisingly, both plant cover and richness. However, plant richness, abundance, and diversity were higher where a greater proportion of the plants were native. Lepidoptera diversity increased with plant cover, and Lepidoptera richness and abundance increased with plant richness. More individual Lepidoptera species were influenced by habitat attributes than by availability of resources such as host plants or nectar sources. Our results illustrate extensive landscape alteration and biotic disturbance and suggest that most regional habitats are at early successional stages and populated by a novel species pool heavy in IEP species; these factors must be considered together to develop effective and realistic management plans for the LRGV.
Encyclopedia of Entomology by
The Encyclopedia of Entomology provides a detailed, global overview of insects and their close relatives, including taxonomy, behavior, ecology, physiology, history, and management. It covers all the major groups of arthropods, as well as many important families and individual species. The encyclopedia also covers physiology, genetics, ecology, behavior, insect relationships with people, medical entomology, and pest management.
Encyclopedia of Invasive Species [2 Volumes] by
This two-volume set provides a one-stop resource on invasive plants, animals, fungi, and microorganisms that are threatening native ecosystems, agriculture, economies, and human health in the United States.Kudzu vine and field bindweed. Eurasian collared-doves, Burmese pythons, and black rats. The northern snakehead and the gypsy moth. All of these are examples of invasive species that have taken over or are threatening certain ecosystems--places where these organisms never naturally occurred. This two-volume work contains 168 entries on plants, animals, fungi, and microorganisms that are invasive in the United States, providing a complete examination of the variety of organisms, pathways, distribution patterns, and impacts of non-native species introduced to this country.Encyclopedia of Invasive Species: From Africanized Honey Bees to Zebra Mussels begins with a background essay that illuminates the complexities of dealing with invasive animals and plants. Each entry provides information on the origins and invasion history of the species in question as well as a general description of the biology and ecology of each organism. Impacts--actual and potential, as well as management strategies--are addressed. Every species is depicted via photographs as well as maps that show its place of origin and invaded regions in the United States. This unique work presents fascinating scientific information as well as valuable insights about how seemingly minor events can drastically alter our environment.
Evidence of plant-soil feedback in South Texas grasslands associated with invasive Guinea grass [Article] by
Plant-soil feedback (PSF) processes play an integral role in structuring plant communities. In native grasslands, PSF has a largely negative or stabilizing effect on plant growth contributing to species coexistence and succession, but perturbations to a system can alter PSF, leading to long-term changes. Through changes to soil abiotic and biotic properties, invasion by non-native plants has a strong impact on belowground processes with broad shifts in historical PSFs. Guinea grass, Megathyrsus maximus , an emerging invasive in South Texas, can efficiently exclude native plants in part due to its fast growth rate and high biomass accumulation, but its impacts on belowground processes are unknown. Here, we provide a first look at PSF processes in South Texas savannas currently undergoing invasion by Guinea grass. In this pilot study, we addressed the question of how the presence of the invasive M. maximus may alter PSF compared to uninvaded grasslands. Under greenhouse conditions, we assessed germination and growth of Guinea grass and the seed bank in soil collected from grasslands invaded and uninvaded by Guinea grass. We found that Guinea grass grown in soil from invaded grasslands grew taller and accumulated higher biomass than in soil from uninvaded grasslands. Plants grown from the seed bank were more species rich and abundant in soil from uninvaded grasslands but had higher biomass in soil from invaded grasslands. In South Texas savannas, we found evidence to support shifts in the direction of PSF processes in the presence of Guinea grass with positive feedback processes appearing to reinforce invasion and negative feedback processes possibly contributing to species coexistence in uninvaded grasslands. Future work is needed to determine the mechanisms behind the observed shifts in PSF and further explore the role PSF has in Guinea grass invasion.
A Handbook of Global Freshwater Invasive Species by
Invasive non-native species are a major threat to global biodiversity. Often introduced accidentally through international travel or trade, they invade and colonize new habitats, often with devastating consequences for the local flora and fauna. Their environmental impacts can range from damage to resource production (e.g. agriculture and forestry) and infrastructure (e.g. buildings, road and water supply), to human health. They consequently can have major economic impacts. It is a priority to prevent their introduction and spread, as well as to control them. Freshwater ecosystems are particularly at risk from invasions and are landscape corridors that facilitate the spread of invasives.nbsp; This book reviews the current state of knowledge of the most notable global invasive freshwater species or groups, based on their severity of economic impact, geographic distribution outside of their native range, extent of research, and recognition of the ecological severity of the impact of the species by the IUCN.nbsp;As well as some of the very well-known species, the book also covers some invasives that are emerging as serious threats. Examples covered include a range of aquatic and riparian plants, insects, molluscs, crustacea, fish, amphibians, reptiles and mammals, as well as some major pathogens of aquatic organisms.nbsp; The book also includes overview chapters synthesizing the ecological impact of invasive species in fresh water and summarizing practical implications for the management of rivers and other freshwater habitats.
Myrmecomorba nylanderiae gen. et sp. nov., a microsporidian parasite of the tawny crazy ant Nylanderia fulva [Article] by
We describe a new microsporidian genus and species, Myrmecomorba nylanderiae.•M. nylanderiae is the first known parasite of N. American invasive ant, Nylanderia fulva.•M. nylanderiae produces 3 spore types (Type 1 DK, Type 2 DK and octospores).•Infections are found in all stages of ant host development and reproductive castes. A new microsporidian genus and species, Myrmecomorba nylanderiae, is described from North American populations of the tawny crazy ant, Nylanderia fulva. This new species was found to be heterosporous producing several types of binucleate spores in both larval and adult stages and an abortive octosporoblastic sporogony in adult ants. While microsporidia are widespread arthropod parasites, this description represents only the fifth species described from an ant host. Molecular analysis indicated that this new taxon is phylogenetically closely allied to the microsporidian family Caudosporidae, a group known to parasitize aquatic black fly larvae. We report the presence of 3 spore types (Type 1 DK, Type 2 DK, and octospores) with infections found in all stages of host development and reproductive castes. This report documents the first pathogen infecting N. fulva, an invasive ant of considerable economic and ecological consequence.
Progress and potential of two biological control agents of the invasive giant reed (Arundo Donax L.) [Dissertation] by
This work reports on the progress and potential of two biological control agents of
Arundo donax, an invasive, noxious weed dominating riparian habitats globally and along the
Rio Grande River. The arundo wasp, Tetramesa romana, released in 2009, is having significant
impacts. The introduced ranges of Texas and South Africa had T. romana population densities 20
and 7 times that of the native range, respectively. Percent parasitism of T. romana in Texas and
the native range of Thessaloniki, Greece were 2.0% and 24.6%, respectively. Field research was
conducted on the arundo leaf miner, Lasioptera donacis in its native range of Greece. Lasioptera
donacis feeding damage was documented on 40.4 and 67.8 % of dead and decaying leaf sheaths
respectively and showed a slight preference for sites near running freshwater sources (R = -
0.514, p = 0.001) and lower densities adjacent to salt water sources (R = 0.463, p = 0.001)
South Texas Natives: a collaborative regional effort to meet restoration needs in south Texas [Article] by
South Texas Natives (STN) is an initiative started in 2001 to develop and promote native plants for the restoration and reclamation of public and private lands in south Texas. At the urging of concerned conservationists and private landowners, STN has developed commercially viable sources of native seed and conducted research to discover effective restoration strategies that can be used by private landowners and government agencies to restore native plant communities. STN grew out of a strong partnership among the USDA Natural Resources Conservation Service E "Kika" de la Garza Plant Materials Center, Texas AgriLife Research, Rio Farms Inc, Caesar Kleberg Wildlife Research Institute, and private landowners of south Texas. Plant development efforts center on the release of commercially viable, multiple origin germplasms selected with an awareness of the commercial requirements for production but grounded in genetic and ecosystem function parameters. In addition to plant development efforts, extensive restoration and revegetation research is conducted by STN to develop usable methodology and much-needed guidelines for restoration in south Texas. Current restoration research emphasis centers on providing techniques for the diversification of areas dominated by invasive exotic grasses.
Texas wild flowers; a popular account of the common wild flowers of Texas by 
Water Hyacinth by
The water hyacinth is a disruptive factor in aquatic ecosystem management and ecosystem services, and causes problems in fisheries, transportation waterways, irrigation, hydropower generation, and water resources. To address these concerns, it is necessary to integrate past studies with current research and innovations to identify where the knowledge gap is and to creatively assess and solve the problems in a global context. This book provides comprehensive coverage of new research and technological innovations for the application of controlling, managing, harvesting, postharvest processing and utilizing the water hyacinth.
Weeds of the South by
Weeds threaten the safe, efficient, and sustainable production of food, feed, fiber, and biofuel throughout the world. Featuring more than fifteen hundred full-color photographs, this handy guide provides essential information on four hundred of the most troublesome weedy and invasive plants found in the southern United States. Drawing on the expertise of more than forty weed scientists and botanists, the guide identifies each plant at various stages of its life and offers useful details about its origin, habitat, morphology, biology, distribution, and known toxic properties. The book also includes illustrations of the most common characteristics of plants and the terms used to describe them, a key to plant families, a glossary of frequently used terms, a bibliography, and an index of scientific and common plant names. Each species account includes:Up to four full-color photographs showing seed, seedling, plant, flower, and other unique plant featuresDistribution mapFor grasses, a line drawing of the collar (where the leaf joins the stem), an important identifying characteristicScientific names, common names, and local synonyms of common namesVegetative characteristics for seedlings and leavesSpecial identifying features, reproductive characteristics, and toxic properties States covered (species distribution maps also show occurrences across the United States and Canada):AlabamaArkansasFloridaGeorgiaKentuckyLouisianaMarylandMississippiMissouriNorth CarolinaOklahomaSouth CarolinaTennesseeTexasVirginiaWest Virginia
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