Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Invasive species: Those who live together invade better

13.09.2002


While the spread of imported fire ants has received much public attention, another invader has been quietly sucking the juices from plants in our lawns and fields: a legless mealybug. In a recent study published in the September issue of the peer-reviewed journal Ecology, scientists have discovered that these bugs may be a possible key to the success of the infamous invasive fire ants.



"Widespread association of the invasive ant Solenopsis invicta with an invasive mealybug," a study by Ken R. Helms and S. Bradleigh Vinson of Texas A&M University, started after the scientists noticed mealybugs and aphids living in underground shelters close to fire ant colonies.

"It seemed clear that there was potentially something important to it all," said Helms.


Helms and Vinson studied grasses and plants from four sites in east Texas, looking for mealybugs and aphid colonies on or near the base of plants. They took samples of mealybugs and aphids from over 2100 shelters around 86 fire ant mounds throughout the spring, summer, and fall, when the ants are most active. With the mass of bugs they collected, they went to work determining how many and what types of aphids and mealybugs were present. During their study, Vinson and Helms also noticed the ants built the shelters for the other insects out of nearby materials on the ground. The researchers found that almost 70% of the biomass collected from the underground shelters near the ant colonies was the invasive mealybug Antonia graminis.

Of Asian origin, these legless creatures were first noticed in the US in the 1940’s. How exactly they entered the United States and spread is unclear. A. graminis, currently exists in over 80 countries around the world, a successful and well traveled invader. Native aphids and other native varieties of mealybugs, some with legs, others without, were found in the shelters too, but nowhere near the amount of the legless invader.

The researchers aren’t sure why the ants build the shelters for these other insects. Some of the colonies of imported fire ants were observed tending these insects on plants, without shelters. Such a symbiotic relationship may allow the ants to feed without the dangers associated with crossing across the ground outside to reach aphid and mealybug colonies on exposed plants, as well as protect the aphids and mealybugs from predation. Avoiding higher temperatures and inclement weather could also be a benefit for all the species involved. Yet, whether the ants create the shelters so aphids and mealybugs can be attended more safely, or whether the ants are exhibiting a general habit of covering and exploiting long-lived food sources, remains unstudied.

The mealybugs do appear to add to the success of the ants however. Using previous studies of other ant-aphid relations, Helms and Vinson determined approximately how much honeydew, or energy, the aphids and mealybugs would produce for the ants. They discovered that an average of 32% of the daily energy for a fire ant colony comes from A. graminis alone. Vinson and Helms investigated this link further by surveying sites throughout the southeastern US. They discovered similar relationships between the ants’ shelter building and mealybugs.

"Associations between some invasive species might be crucial to their success. Because of human commerce, species are frequently transported outside their native ranges, but very few actually become established at their new location, and of those, very few become successful enough to be considered invasive," stated Helms in a recent interview. "Both S. invicta and A. graminis are major invasive species, and our study shows that their association could be an important factor in explaining their success in the southeast United States."

The imported fire ant’s track through the US is well recorded. Native to South America, they entered the US between 1933 and 1945 in Mobile, Alabama and then spread throughout the southeastern US and California. Unlike the legless mealybug, imported fire ants have only managed to gain a strong foothold in the US, Puerto Rico and the Virgin Islands, and are starting to spread into Australia. A. graminis may be an important food source for the ants, and part of the reason they have been so successful in the southeastern US.

According to the researchers, other successful invasive ant species have also been seen tending aphids and mealy bugs, including invasive ant species that live in similar ranges to the invasive mealybug. Few studies have really delved into any possible links, however.

Fire ants have long been a problem, disabling native ant populations and harming humans, pets, livestock, and other living organisms. The mealybugs pose a problem by feeding upon and damaging agriculturally important grasses such as those used for cattle grazing, as well as those used in lawns and on golf courses. The relation between invasive species doesn’t just end with the ants and mealybugs, though.

According to Helms, "One interesting thing about where these invasive mealybugs is that they live on grasses that are mostly non-native. In fact, Bermuda grass is a major, if not the major, grass used in pastures, lawns, and golf courses in the southeast US, and the greatest recorded density of the invasive mealybug on grasses in the US is on Bermuda grass."

Annie Drinkard | EurekAlert!
Further information:
http://www.esa.org.

More articles from Ecology, The Environment and Conservation:

nachricht Dune ecosystem modelling
23.06.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht Understanding animal social networks can aid wildlife conservation
23.06.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>