Pathogens as Biological Weapons of Invasive Species By Lindsey Rieck

Based on the article “Pathogens as Biological Weapons of Invasive Species” written by Andreas Vilcinskas in 2015 published to PLOS Pathogens.

What are invasive species? An invasive species is a plant, fungus, or animal that is not native to a specific location (an introduced species), and which has a tendency to spread to a degree believed to cause damage to the environment, human economy or human health

What are “Biological weapons”? Biological weapons are complex systems that widely disperse disease- causing organisms or toxins to harm or kill humans, animals or plants. They generally consist of two parts – a weaponized agent and a delivery mechanism.

Pathogens as biological weapons of invasive species Some species have mechanisms to help them be more competitive against similar species Sometimes invasive species will carry with them diseases and they are immune to that pathogen but that disease or pathogen kills off the similar species The result of these pathogens can be devastating to native species

Red Squirrels

Red Squirrels Used to be very common in the United Kingdom Their natural threats are birds of prey Red squirrels are known and identified by their russet red fur They enjoy eating seeds from pine cones, but you can also find them eating seeds from larch and spruce They also eat fungi, shoots and fruits of shrubs and trees, and occasionally they will munch on some birds’ eggs.

Release of the Greys Thomas Brocklehurst, a Victorian banker who lived at Henbury Park in Cheshire, is the one who introduced grey squirrels into the UK. In 1876, he released pair of Native American grey squirrels into his gardens Other landowners saw this and they decided grey squirrels were very fashionable so they also released them into their gardens

Grey Squirrel

Squirrel parapoxvirus The grey squirrels brought with them the pathogen “Squirrel parapoxvirus” The grey squirrels act as a carrier to this disease When red squirrels get this disease, it is fatal to them and they die within the week

Squirrel parapoxvirus What does this disease look like? Visible symptoms of red squirrels with poxvirus include -wet, discharging lesions or scabs around the eyes, mouth, and feet - squirrels generally become increasingly lethargic as the disease progresses.

What are the effects of this biological pathogen? There are now only 160,000 red squirrels left while there are now 2.5 million grey squirrels in the UK Those grey squirrels used this pathogen as a biological weapon They greatly outnumber the competition (red squirrels)

Noble Crayfish

Noble Crawfish Noble crawfish also is native to Europe It’s population has greatly declined in recent years because of a biological weapon used against it

Signal Crawfish

Signal Crawfish This is an North American species that was brought to Europe It’s population has increased immensely since the 1800’s

Aphanomyces astaci Signal crawfish used a biological weapon a fungal pathogen, Aphanomyces astaci, which greatly decreased the amount of the native noble crawfish This fungal pathogen has spread by birds, boats, but most importantly by the signal crawfish

Conclusion Invasive species using biological weapons can be very dangerous Thankfully there is a lot we can do to prevent invasive species in general

What can we do?–Taken from the Nature Conservancy website The best way to fight invasive species is to prevent them from occurring in the first place. Verify that the plants you are buying for your yard or garden are not invasive. Replace invasive plants in your garden with non-invasive alternatives When boating, clean your boat thoroughly before transporting it to a different body of water. Clean your boots before you hike in a new area to get rid of hitchhiking weed seeds and pathogens.

What can we do? Don't "pack a pest" when traveling. Fruits and vegetables, plants, insects and animals can carry pests or become invasive themselves. Don't move firewood (it can harbor forest pests), clean your bags and boots after each hike, and throw out food before you travel from place to place. Don't release aquarium fish and plants, live bait or other exotic animals into the wild Volunteer at your local park, refuge or other wildlife area to help remove invasive species. Help educate others about the threat.

Works Cited "Red Squirrel." Red Squirrels (England). Forestry Commission England, 15 Sept. 2015. Web. 2 Dec. 2015. Vilcinskas, A, 2015. Pathogens As Biological Weapons Of Invasive Species. Plos Pathogens. [accessed 2015 Nov. 17]: 11(4): 1-5. http://eds.b.ebscohost.com/ehost/pdfviewer/pdfviewer?vid=3&sid=2ad31cea- 17b2-4da5-b27c-212f66c432c2%40sessionmgr113&hid=104. "Invasive Plant Species Invasive Species Education." Invasive Plant Species Invasive Species Education. The Nature Conservancy. Web. 5 Dec. 2015. <http://www.nature.org/ourinitiatives/habitats/forests/help/invasive-plant- species-invasive-species-education-1.xml>.