Inventory & Monitoring: April-May, 2009

The invasive needle ant is 5 mm long with a dark brown body & reddish legs.

Photo by Lloyd R. Davis, Jr., 2002. Courtesy of Antweb.org.

Ant Awareness: Invasive Needle Ant at Oconoluftee

When you’re at the Mountain Farm Museum at Oconoluftee, keep an eye out for a certain unwelcome ant. Eric Payson, who completed his studies at Clemson University last year, discovered the Asian Needle Ant (Pachycondyla chinensis) at the Mountain Farm Museum in 2001. The park is looking forward to receiving specimens to add to its natural history collection this summer. Since the ant’s discovery, the population doesn’t seem to have spread, but visitors, educators, and park staff should be aware of the potential sting that this insect inflicts. While merely painful for most people, a few do suffer from a severe allergic reaction (just as some people do with bee stings). The ant is not overly aggressive (unlike another invasive insect, the fire ant), but will sting if it’s trapped between layers of clothing or in a closed fist.

The first indicator that an ant is indeed the needle ant is its small size: at 5 mm (less than the diameter of a pencil eraser or pen cap), this insect is among the smallest ants you will find here. You can also look for its distinctive dark brown body with lighter, reddish brown legs. Needle ant nests are often in damp soil below stones, rotting logs, stumps, or debris, according to the Mississippi Entomological Museum.

Researchers found the ant during inventory studies to list and describe all of the species in the park as part of the All Taxa Biodiversity Inventory. While it hasn’t been found yet in other places in the Smokies, it could potentially invade forested areas (it is one of the only invasive ants that likes forests) and displace native ant species. This would further alter native forest communities that have already changed significantly due to tree pests, invasive plants, and invasive earthworms. Park scientists and partners, including Mississippi State entomologist JoVonn Hill, will investigate the ant’s range and spread more thoroughly beginning this summer. Such information would us better understand threats to human and forest health in southeastern forests.

 

Park curator Adriean Mayor with the new biohazard cabinet at Twin Creeks Science Center.

NPS photo.

New biohazard cabinet protects scientists from disease

This spring, researchers at the Twin Creeks Science Center added a new science tool to their supplies: a biohazard cabinet. The cabinet is a 600 pound, glass-sided case that can attach to a hood (a vent that carries away, purifies the air, and releases it outside). Researchers will use it when they find animals in the Park that they need to dissect or inspect; the cabinet is specially designed to protect them from any zoonotic (animal-spread) diseases. Wildlife here can pass rabies, pseudorabies, hantavirus, Rocky Mountain Spotted Fever (via ticks) and other diseases on to people and their pets.

Freezes, fire, & worms: research on new possibilities for managing invasive earthworms

Jimmy Blackmon and Paul Hendrix of the University of Georgia have completed research in two studies in the Park on the biology of invasive earthworms. The Chinese Jumping Worm (Amynthas agrestis) is a common bait worm sold at sporting goods stores, and raised in large commercial worm farms throughout the southeast. It comes into the Park’s forests when anglers release their unused bait (which is prohibited within the Park’s boundaries). These worms devour leaf litter at a very fast rate, and in much larger quantities, than native worms, millipedes, and other decomposers do, stripping the forest floor of essential duff (decaying plant and leaf matter) layers. Since the introduction of the invasive Jumping Worm, native worms and millipedes have died off at alarming rates. Park managers need to find a way to control the worm, and to figure out how it spreads in a climate that is much colder than the one in which they evolved.

To answer these questions, researchers measured the effect that cold temperatures had on worm hatching rates, and the effect that fire had on worm survival. They expected that worm hatching rates would be much lower with colder temperatures (below 10 degrees C, or about 50 degrees), since the worms came from subtropical parts of the globe. However, this cool temperature proved to be the optimal hatching climate, indicating that the spread of worms through the Smokies could happen more quickly than scientists initially thought and also that this worm may not actually be from the subtropics, but rather from cooler parts of Asia.

Another project used soil scorching—similar to what forests would experience during lightning or controlled burns—to measure the impact of fire on these invasive earthworms. While there was no decrease in worms at first (the worms dug deeper down to protect themselves), over time many did die, probably from starvation. This tells managers that fire is an effective way to control invasive worms, because it limits their food supply. What effect it has on native animals that depend on that same food supply needs further investigation. It may be that millipedes and native worms have evolved to deal with regular, low intensity fires, because these were a regular part of Smoky Mountain ecology before humans began suppressing fires.

Return to Resource Roundup: April-May, 2009.