The minute mile-a-minute mitigator

A minute of natural history

Mile-a-minute overtaking trees.
by Furryscaly via Flickr CC

Mile-a-minute (Persicaria perfoliata) is one of the most pervasive and damaging nonnative invasive plant species in the United States.  Mile-a-minute, a member of the Buckwheat family (Polyganaceae), was first introduced to the U.S. in 1890 from its indigenous range of Asian and Southeast Asia.  The plant did not successfully establish a permanent population in the U.S. until a reintroduction in the late 1930s when a Pennsylvanian nursery germinated Holly seeds from Japan and in doing so, the stowaway mile-a-minute seeds.

Approximate U.S. distribution as of July 2013. Source: Eddmaps.

www.eddmaps.org#sthash.Oa4NZqHa.dpuf

www.eddmaps.org#sthash.Oa4NZqHa.dpuf

 

 

 

 

 

 

 

 

Mile-a-minute earned its name

Mile-a-minute is an annual trailing vine with distinctive alternate triangular leaves.  Another identifying trait is the round saucer-shaped structures, or ocreae, which occur at nodes and branching points along the stem.  Self-pollinating flowers and subsequent fruit arise from the ocreae. Recurved barbs along the stem and leaf petioles make this plant particularly unpalatable to most potential herbivores.  Low predation rates in the U.S. coupled with the species’ prolific seed production and readily available dispersal mechanisms (water and birds) are traits characteristic of an exceptionally weedy plant.

Most impressing, and most ecologically damaging, is mile-a-minute’s growth rate of up to six inches a day, or 77’ (33.8 m) in a single growing season.  For perspective, mile-a-minute could cover the Statue of Liberty from heal to torch in two growing seasons.  Methods to control this invasive plant include traditional methods of manual removal and chemical pesticide applications.  However, given the rate at which mile-a-minute spreads, traditional methods are not practical of well-established or remote populations.  In 1996, the U.S. Forest Service began researching possible biological control agents.  

Following annual die-back mile-a-minute leaves and stems continue
to weigh down the plants they have climbed and shade groundcover.
by Leslie J. Mehrhoff, University of Connecticut via Invasives.org

Mile-a-minute leaves and ocreae. 
by Leslie J. Mehrhoff

  

 

Fighting nonnative with nonnative: biological control

Biological control is a way of using an invasive species natural predator or disease, most often from the species’ indigenous region, to reduce the invasives’ proliferation and dominance.  Finding a biological control agent that is truly host-specific to your target species takes a lot of research.  Inadequate research into a control agent’s life history and ecology prior to release may have dire consequences, which are worse than the original cause for their introduction.  A classic example of biological control gone awry is that of Cane Toads introduced to Australia in 1937.  Thankfully, the science of introducing biological control agents has come a long way!

Adult R. latipes are approx. 2mm long.
by Amy Diercks, via Invasives.org

Colpetzer et al. published a study in Biological Control (2004) examining potential biological control agents for use on mile-a-minute.  Results from their study supported the introduction of a small host-specific weevil from Asia, Rhinoncomimus latipes, which feeds on mile-a-minute roots as a larvae and foliage as an adult.  In 2004, the U.S. Department of Agriculture approved the use of the weevil as a biological control agent.  After several regional releases, the introduced weevils have successfully established populations throughout the Mid-Atlantic region. 

Ongoing weevil releases, such as one recently conducted in Union County, New Jersey, help sustain and expand the current weevil populations.  Led by state and county agriculture officials, the recent release of 2,000 weevils in Watchung Reservation, Union County’s largest park, is sure to reduce local mile-a-minute growth in the coming years. 
 

The below video is from a recent weevil release in New York City

Amy Diercks, Bugwood.org

Why does summer have to end?

With today’s heat wave, it is hard to imagine the autumnal equinox will soon be upon us!  Nevertheless, the official end of summer is near.  In honor of this seasonal shift, I thought this TED-Ed talk was very fitting, a good reminder as to why we have seasons.

New omnivorous mammal species describe in the Americas!

An omnivorous mammal species found in the Americas was recently described – the first new omnivorous mammal species to be described in 35 years!   The olinguito (Bassaricyon neblina), a member of the raccoon family (Procyonidae), is indigenous the high-altitude cloud forests of Ecuador and Columbia (map below).  

(Olinguito habitat range (red) and sitings (black dots)
by National Museum of Natural History, via Smithsonian.com)

(Olinguito by Mark Gurney via Smithsonian.com)

The mystery specimen:

("A comparison of olinguito skulls (far right) with those of other
olingos shows their smaller size and slightly different shape."
By Lauren Helgen via Smithsonian.com)

Kristofer Helgen and his team at the Smithsonian National Museum stumbled upon the new species as they worked with clarify known species of olingos (Bassaricyon spp.).  The mysterious specimens differed compared to know species in their fur color (reddish vs. grey), fur length (long vs. short, comparatively), and the elevations at which the specimens were collected (high vs. low).  Olinguitos are also smaller than their olingos kin - hence, their suffix–“ito”, translating as "little" in Spanish. 

To the field!

(Andes Cloud Forest by Slack12 via Flickr CC)

Kristofer Helgen and colleagues observed this new species in its native cloud forest habitat, where they learned it is primarily nocturnal and arboreal, with a diet comprised largely of tree fruit and some insects.  Read more about this neat species at Smithsonian.com.

 

(Andes cloud forest by D. J. Rosen via Flickr CC)