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.
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).
Through 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)
Found 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.
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.
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.
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