![]() Have you ever seen a coyote roaming in your neighborhood or town before? Or have you noticed that it seems as though coyotes are more common than they used to be? It seems as though coyotes can now be found across all types of biomes and regions in North America. These predators that were once native only to the central part of the United States have now spread across most of the continent. Depending on where they’re spreading to, they can be considered a nuisance or a threat to humans, especially if they find their way into residential areas. Because these coyotes have become so widespread and don’t seem to have many natural predators in the wild, some debate that the coyote should be considered an invasive species. However, there are two sides to this argument: Why Do Some People Consider Coyotes to be Invasive? For one thing, coyotes have definitely expanded their range into areas that they didn’t use to live in. Since wolves are not as abundant as they used to be, this means that coyotes have less competition and are able to grow their populations as well as roam the landscape more freely. One of the biggest signs that a species is invasive is if it has the ability to grow its population without fear of predators, and that’s what the coyote has been able to do across North America. This causes a problem for humans, but it also raises an issue with a species native to North Carolina that is very similar to the coyote: the red wolf. Red wolves are now incredibly endangered, but were once abundant across eastern North Carolina. One reason that red wolves are struggling so much is because they look like coyotes, and humans often will mistake one for the other. Unfortunately, this often leads to a large number of red wolf deaths being attributed to gunshots, and humans are often under the impression that they’ve killed a coyote rather than an endangered animal. For several years, all remaining red wolves were kept in captivity in order to keep them from dying out. Then, in the 1980s, the population was stable enough to be released back into the wild. However, coyotes had since infiltrated the region that the red wolves were originally living in. Since the two species are very similar, many red wolves began breeding with coyotes. As a result, there are virtually no genetically pure red wolves anymore, and the majority of red wolves are actually hybrids between wolves and coyotes. Some scientists worry that red wolves will eventually become extinct because of their assimilation into coyote populations. These are some of the main arguments for coyotes being labeled an invasive species. They can be found in almost every part of North America, they don’t have a lot of competition or predators, and they can cause a lot of problems for other species, such as red wolves. Why Do Others Think Coyotes Aren’t Invasive? On the other side of this argument, many people do not consider coyotes to be invasive at all. In fact, they are native to North America. Some argue that while they are spreading to new areas, they are just expanding their preexisting territory. Some refer to coyotes as a responsive species rather than an invasive species. A responsive species describes a species that is simply responding to environmental factors. In the case of the coyotes, some argue that they are not invading surrounding areas, but are only reacting to stimuli that are causing them to move. Urbanization and efforts by humans to control coyote populations are some of the big reasons why coyotes move into new areas. Additionally, there are some benefits for having coyotes around. Since there aren’t as many wolves as there used to be, along with the fact that humans have spread out and built more urban areas over the years, this leads to a lack of predators. It may seem like having no predators is a good thing, but this lack of balance can cause a lot of issues that coyotes are now able to fix. For example, coyotes are very beneficial to keeping deer populations regulated. Without wolves, deer had very few natural predators, and their populations grew exponentially. Having too many deer can not only cause problems for humans, but it can also lead to overgrazing and other environmental concerns. Some argue that coyotes shouldn’t be considered invasive because they are filling a role that was previously empty due to a lack of wolves. As you can see, there are plenty of arguments to support both sides of this conflict. While coyotes are certainly becoming more common and widespread, they are acting as the top predator that some ecosystems needed. This can help to restore a lot of balance between predators and prey, and it can also allow populations to become better regulated and maintained. On the other hand, the spread of coyotes is causing harm to species like red wolves. These wolves are losing their genetic diversity, and may eventually disappear if the red wolf and coyote populations continue to mix. Whether they are actually invasive or not, there are plenty of pros and cons to coyotes moving into new areas. Sources: Are coyotes a threat to (other) native species? (2017, March 18). Retrieved September 30, 2020, from http://theconservationagency.org/greater-threat-native-species-coyotes-deer/ Eric M. Gese, Fred F. Knowlton, Jennifer R. Adams, Karen Beck, Todd K. Fuller, Dennis L. Murray, Todd D. Steury, Michael K. Stoskopf, Will T. Waddell, Lisette P. Waits, Managing hybridization of a recovering endangered species: The red wolf Canis rufus as a case study, Current Zoology, Volume 61, Issue 1, 1 February 2015, Pages 191–205, https://doi.org/10.1093/czoolo/61.1.191 Hinton, J. W., Brzeski, K. E., Rabon,David R.,,Jr, & Chamberlain, M. J. (2017). Effects of anthropogenic mortality on critically endangered red wolf canis rufus breeding pairs: Implications for red wolf recovery. Oryx, 51(1), 174-181. doi:http://dx.doi.org.prox.lib.ncsu.edu/10.1017/S0030605315000770 Hinton, JW, Gittleman, JL, van Manen, FT, Chamberlain, MJ. Size‐assortative choice and mate availability influences hybridization between red wolves (Canis rufus) and coyotes (Canis latrans). Ecol Evol. 2018; 8: 3927– 3940. https://doi.org/10.1002/ece3.3950 Hody, J. W., & Kays, R. (2018). Mapping the expansion of coyotes (Canis latrans) across North and Central America. ZooKeys, (759), 81–97. https://doi.org/10.3897/zookeys.759.15149 Red Wolf Recovery. (n.d.). Retrieved September 30, 2020, from https://www.nwf.org/Our-Work/Wildlife-Conservation/Red-Wolf United States, USDA, Wildlife Services. (2011). Coyotes in Towns and Suburbs. Retrieved from https://www.aphis.usda.gov/publications/wildlife_damage/content/printable_version/coyote_Dec2011.pdf Wolf, M., Doorn, G. S., & Weissing, F. J. (2008). Evolutionary emergence of responsive and unresponsive personalities. Proceedings of the National Academy of Sciences, 105(41), 15825-15830. doi:10.1073/pnas.0805473105 Photographs: Alfred Viola, Northeastern University, Bugwood.org Rebekah D. Wallace, University of Georgia, Bugwood.org
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. You may have recently seen photos of the hammerhead worm pop-up on your Facebook or Instagram feed and wondered ‘what on Earth is this thing?’ Looking like something that’s escaped the Upside Down from the Netflix series Stranger Things, it’s no doubt that this creepy looking creature would create quite a buzz. You may also be surprised to learn that the hammerhead worm is not a segmented annelid like our beloved earthworms. They are actually in the Phylum Platyhelminthes, and are more closely related to the bright and colorful flatworms found cruising around on the seafloor. So a more appropriate common name for them would be the hammerhead flatworm. Over 910 terrestrial (land living) hammerhead flatworm species have been discovered to date, with many more waiting to be described as a species. Currently, there are four known hammerhead flatworm species that have been introduced in the United States, but the two most commonly encountered are Bipalium adventitium occurring across the northern portion of the US and Bipalium kewense, which is found across the southeast and California. Hammerhead flatworms are easily identified by their distinctive fan or shovel shaped head and their long, flat body. The number of stripes that run along their back and the shape of their head helps researchers determine what species has been encountered. Most species of hammerhead flatworms range in size from 5-8cm, but the Bipalium kewense that has invaded the southeast can reach upwards of 20-cm in length. On the underside of their body, hammerhead flatworms have a large ‘creeping sole’ that they use to glide smoothly through the soil and across the ground. Their motion mimics that of a snake rather than a typical worm, which is why some people confuse the larger species found in the southeast as being a snake. In a study published in 2014, Dr. Amber K. Stokes, an Associate Professor in the Biology Department of CSU Bakersfield, discovered that both Bipalium adventitium and Bipalium kewense possess a potent neurotoxin called tetrodotoxin. This toxin is also found in pufferfish, the blue-ringed octopus, and rough-skinned newts, but remarkably it is not known to occur in any other invertebrate on land. Hammerhead flatworms are considered an apex predator as they have almost no known natural predators. They are known to capture and immobilize prey much larger than themselves by entangling it in slimy secretions of this neurotoxin. Once their prey is mostly immobilized, the flatworm releases digestive enzymes, then consumes the liquefied tissue. Unlike insects, animals and humans, flatworms have only a single orifice, or body opening, so once digestion is complete, the waste goes out the same way it came in. How did they get here?Surprisingly, Bipalium kewense are not a new invasive species in the southeast. They are native to the moist, tropical jungles and temperate woodlands of southeast Asia. With our climate being so similar, they have been able to easily establish themselves here in the southeast, and are commonly found in dark, cool, moist areas under objects such as rocks, logs, and leaf litter. Although an exact date is unclear, it is believed that they were unintentionally introduced through the international ornamental plant trade in the late 1800s. Apparently, they were reported as being so plentiful in New Orleans in the 1960's that they were commonly used as demonstration material in zoology classes. Are they a threat?![]() At one time, researchers were concerned hammerhead flatworms might cause damage to our native plant communities. Over time, it has become apparent that their presence has the potential of causing greater harm to the rich biodiversity that exists in the southeast by endangering our native soil-living species (earthworms, snails, slugs, insect larvae, and several arthropods, including isopods and springtails), which will ultimately impact our native plant and wildlife communities. As of now, there is no known population decline in any of their prey species, including our earthworms. However, this may change as hammerhead flatworms continue to expand their range and their populations continue to grow. What is being done to stop them?![]() Almost every year new sightings of hammerhead flatworms are reported, and in the southeast they have no known natural predators to keep their populations in check. Up until 2012 it appeared as though nothing preyed on these flatworms. Recent experimental work by PhD student Piter Boll at Universidade do Vale do Rio dos Sinos in Brazil discovered that Rectartemon depressus, a carnivorous snail, seeks out and preys on several species of flatworm including Bipalium kewense, the hammerhead flatworm that has invaded the southeast. Although this discovery is encouraging, there is no plan to release this snail into North America. Although the United States’ Animal and Plant Health Inspection Service Agency (APHIS) has set regulations for controlling the transport of ornamental plants and animals to minimize the spread of invasive species, there is no current task force in place focused on controlling the spread of hammerhead flatworms. What can we do?Unfortunately, our present knowledge is limited, and their long term ecological impact is still not well understood. Because of this, curbing their spread will continue to be a challenge in the future if their populations continue to grow. For any budding entomologists out there this may be your shot! Fortunately, some known methods used to control slugs have been found to also work for exterminating hammerhead flatworms. Several flatworm experts have suggested the use of orange essence has proven to be an effective way deter them from taking up residence on your property. Additionally, they can be killed quickly with salt. Another study found that immersing potted plants known to contain a hammerhead flatworm infestation in water heated to 93 degrees for at least five minutes is fully effective, killing them within one hour. Lastly, please avoid cutting them as a method to rid them from your property. Hammerhead flatworms are able to reproduce asexually(without a mate) by a process called fragmentation. During fragmentation, the back end of the hammerhead flatworm separates from the rest of its body. While the front half grows a new tail, the back end moves around headless until it grows a new head, which takes about 10-15 days. Cutting them may inadvertently encourage reproduction. As always, here at Invasive PestWatch NC we encourage you to be careful. If you suspect an infestation on your property you can always seek professional assistance by contacting your local University Extension Department. You can also help scientists that are actively tracking the spread of hammerhead flatworms by uploading images to iNaturalist. Sources:
Ducey, P. K., McCormick, M., & Davidson, E. (2007). Natural history observations on bipalium cf. vagum jones and sterrer (platyhelminthes: Tricladida), a terrestrial broadhead planarian new to north america. Southeastern Naturalist, 6(3), 449-460. doi:10.1656/1528-7092(2007)6[449:NHOOBC]2.0.CO;2 Ducey, P. K., West, L., Shaw, G., & De Lisle, J. (2005). Reproductive ecology and evolution in the invasive terrestrial planarian bipalium adventitium across north america. Pedobiologia, 49(4), 367-377. doi:10.1016/j.pedobi.2005.04.002 Harrison, L. (1 C.E.). Hammerhead worms are an invasive species. http://blogs.ifas.ufl.edu/wakullaco/2019/01/31/hammerhead-worms-are-an-invasive-species/ Gastineau, R., Justine, J., Lemieux, C., Turmel, M., & Witkowski, A. (2019). Complete mitogenome of the giant invasive hammerhead flatworm bipalium kewense.Mitochondrial DNA. Part B. Resources, 4(1), 1343-1344. doi:10.1080/23802359.2019.1596768 Gastineau, R., Justine, J., Thery, T., Gey, D., & Winsor, L. (2019). First record of the invasive land flatworm bipalium adventitium (platyhelminthes, geoplanidae) in canada.Zootaxa, 4656(3), 591-595. doi:10.11646/zootaxa.4656.3.13 Lemos, V. S., Canello, R., & Leal‐Zanchet, A. M. (2012). Carnivore mollusks as natural enemies of invasive land flatworms. Annals of Applied Biology, 161(2), 127-131. doi:10.1111/j.1744-7348.2012.00556.x Sluys, R. (n.d.). Invasion of the Flatworms. American Scientist. https://www.americanscientist.org/article/invasion-of-the-flatworms Stokes, A. N., Ducey, P. K., Neuman-Lee, L., Hanifin, C. T., French, S. S., Pfrender, M. E., . . . Brodie Jr, E. D. (2014). Confirmation and distribution of tetrodotoxin for the first time in terrestrial invertebrates: Two terrestrial flatworm species (bipalium adventitium and bipalium kewense). PloS One, 9(6), e100718-e100718. doi:10.1371/journal.pone.0100718 This beetle may look cool, but it is destructive! The Asian longhorned beetle, Anoplophora glabripennis, is a beetle native to China and Korea. First detected in the U.S. in New York in 1996, this beetle is capable of destroying over 29 species of hardwood trees! It prefers maple and boxelder (Acer) but can also attack birch (Betula), elm (Ulmus), ash (Fraxinus), poplar (Populus), and more. Given this beetle’s talent for destroying a wide range of trees and the fact that maple and boxelder comprise the second-most abundant group of trees in our state, it is important that North Carolinians stay on the lookout for the Asian longhorned beetle. The Asian longhorned beetle (ALB) has travelled to Illinois, Massachusetts, New Jersey, Ohio, and, most recently, South Carolina (discovered near Charleston in June 2020) since its original introduction to New York in 1996. Most infestations in the North came from Asia, but it is unclear if the recently discovered infestation in South Carolina, which has likely existed for about 7 years, came from Asia or another state in the North. More research is needed to understand the Asian longhorned beetle’s life cycle and traits in the Southeastern United States, which could be accomplished by researching the recent infestation in South Carolina. So, how is the ALB destructive? Unlike other wood-boring beetles such as the emerald ash borer, the Asian longhorned beetle larvae burrow deep within the hardwood and cause structural damage. While most longhorned beetles feed on trees that are already stressed or dying, ALB feeding can kill healthy trees! Other pests may only go through to the cambium layer (a layer of a tree just beneath the inner bark that controls growth), but the Asian longhorned beetle larvae burrow deep into the tree where they spend their entire immature life stage. Larvae destroy the quality of the wood, and large numbers of hungry beetles can even kill trees by girdling them and cutting off nutrient and water flow. I spoke with Amy Michael, state survey coordinator for the Cooperative Agricultural Pest Survey (CAPS) with the USDA Animal and Plant Health Inspection Service, to learn more about the Asian longhorned beetle. According to Amy, the discovery of the pest in South Carolina is concerning for our state because, if it came from a northern state, then it would have had to pass through North Carolina to reach the area near Charleston. The beetle poses a risk to health and safety due to its extraordinary ability to kill and weaken the structural integrity of hardwood trees. In this part of the country, strong storms and hurricanes are a threat. If a hurricane came through, high winds could easily knock off large branches of ALB-infested trees, potentially increasing property damage or harming people. Amy says that it is important for North Carolinians to look out for the signs of Asian longhorned beetles. While state and federal agencies complete frequent surveys, many infestations of ALB (including the recently spotted one in South Carolina) were discovered by landowners. Sap flows through a large portion of the beetle’s preferred snacks, maple trees, so it takes time for these trees to die or show symptoms of attack. In fact, it may take several years for symptoms to appear! At first, the trees are just stressed, but eventually they become damaged to the point of no return. According to the NC Forest Service, infested trees do not recover or regenerate. There are several signs and symptoms of the Asian longhorned beetle to watch for. They include:
If you see any of the signs or symptoms listed above, contact your county extension office. Amy says that she would rather receive a call about a false ALB sighting than have ALB go unnoticed in our state. You can also report sightings by using the new reporting tool on the NCDA&CS website or by sending a photograph to [email protected]. Unfortunately, management of the Asian longhorned beetle isn’t pretty. Getting rid of the beetle requires removing and destroying all infested trees. Even though this may seem drastic, it is better to remove the trees and effectively rid the area of the beetle rather than allow it to spread to other areas and kill more unsuspecting host trees. So, if you see signs of ALB, make sure to report them to prevent this tree destruction. Above all, don’t move firewood! Because it is a wood-borer, Asian longhorned beetle can travel through firewood and other wood materials, even if it does not seem like the pesky beetle is present. ALB can live in untreated firewood for months, so moving firewood could help the beetle arrive in new areas. Buy local firewood instead. While the ALB is a scary pest, eradication has been achieved in the past with early detection. Since ALB is closer to NC than ever before, it is important for North Carolinians to be on the lookout so we can detect the pest early if it is indeed in our state. Amy says that, while not moving firewood is the best and easiest way you can help out, it is also great to get involved with your county extension office. Know who they are, where they are, and what they do because they have all the information on pests like ALB. And help them out by keeping an eye on your maple trees! Left: ALB exit holes are perfectly round and about the width of a #2 pencil. Image: Dennis Haugen, USDA Forest Service, Bugwood.org Middle: Adult Asian longhorned beetles gnaw pits before depositing eggs within them. Image: Melody Keena, USDA Forest Service, Bugwood.org Right: Frass, an excrement that looks like sawdust, is often present on trees with Asian longhorned beetle. Image: Kenneth R. Law, USDA APHIS PPQ, Bugwood.org Written by Courtney Smith Edited by Amy Michael References Paine, T., & Hoddle, M. (2020, January 19). Asian Long-Horned Beetle, Anoplophora glabripennis. Retrieved September 23, 2020, from https://cisr.ucr.edu/invasive-species/asian-long-horned-beetle United States, North Carolina Forest Service, Forest Health. (2020, June). Pest Watch: Asian Longhorned Beetle Found in Neighboring State. Retrieved September 22, 2020, from https://www.ncforestservice.gov/forest_health/pdf/FHN/FHN06222020.pdf Cogongrass Imperata cylindrica Photo by Karan A. Rawlins forestryimages.org How Did Cogongrass Get Here?
Cogongrass is a perennial aggressive grass native to southeast Asia. It usually occurs in warm or tropical areas and on all continents except Antarctica and between 45 degrees North and 45 degrees South in each hemisphere. It has become established in the southeastern United States in the last 50 years, mostly in Alabama, Mississippi, and Florida, but its range in the United States extends from Texas to North Carolina. It first appeared in 1912 in Grand Bay, Alabama as packaging material in orange crates. Then, it was intentionally introduced in 1921 in Mississippi as a possible forage plant. In the 1930s and 40s, it was introduced to Florida as a potential forage plant and to help with soil stabilization. Cogongrass was first found in North Carolina in Pender County in May of 2012 and has since been found in Stanly, Martin, Scotland, Wake, and Sampson Counties. The weed was eradicated from Stanly and Martin counties but still remains in the rest. Efforts by the NC Department of Agriculture & Consumer Services are ongoing to eradicate cogongrass from the remaining counties. What Does Cogongrass Look Like? Cogongrass grows mostly in patches and is often in a circular pattern. The height varies from 1 to 4 feet and the leaves are 0.5 to 1 inch wide and 12 to 30 inches long. The leaves have very short stems and appear stemless. They are usually light green and can turn orange-brown in the fall. The leaf margin has tiny serrations. A key identifying feature is the fluffy, white, plume-like seed heads. The seeds have silky white hairs and blow off like dandelion seeds. Threats to Our Native Flora and Fauna Cogongrass is adapted to fire and it actually thrives in areas where fire is a regular occurrence. Fires that contain cogongrass will burn faster, hotter, and higher than native grasses. Because of this, the threat of unmanageable fires greatly increases when cogongrass is present. Cogongrass is not a good foraging plant for our native wildlife because the serrations, which are saw-like toothings on the leaves that can cut animal tongues and the leaves, are very stiff and can damage animals’ teeth. It also has high silica content, and it replaces our native grasses. The grass can get so dense that it makes it hard for ground nesting birds to nest there and for small animals to travel through. Its habitat includes coarse sands in deserts or along shorelines and fine sands or sandy loam soils of swamps and river margins. It has adapted to full sun but can thrive in moderate shade. The pesky weed is a rapid invader of abandoned fields, railroads, highways, utility lines, rights-of-ways, pipelines and other abandoned or disturbed areas. It can also survive dry periods and periods of water-logged soils, and it reproduces asexually and sexually. In a single plant, cogongrass can have up to 3,000 seeds. All of these things help give it the ability to out compete our native species. How it Spreads Cogongrass can be spread by contaminated equipment, so vehicles, equipment, and clothing need to be cleaned after being in a contaminated area. Cogongrass is very difficult to control and just mowing is not an effective control. The rhizomes, which are underground stems that produce shoots and adventurous roots, must be destroyed to avoid regrowth. One thing that seems to prevent or inhibit its establishment is deep and frequent tillage. There are some butterfly species that will feed on cogongrass, but they will also prey upon native grasses. Younger infestations are usually easier to control, and tillage, if continued during the growing season, can eliminate the grass. Dry seasons during the summer can aid in the control and planting of a fall cover crop then the next season plant a perennial or annual grass or broadleaf crop. There are a few herbicides that can help control the grass, but they can also cause harm to non-target plants. How to Prevent the Spread
Sources Bryson, Charles T, and Richard Carter. “Cogongrass, Imperata Cylindrica, in the United States.” Weed Technology 7 (1993): 1005–1009. Web. 12 Sept. 2020. Minteer, C. (2018, October 18). Why should I care about cogongrass?. https://www.invasive.org/101/cogongrass.cfm Troxler, Steve, and Phil Wilson. “Cogongrass.” NC Department of Agriculture & Consumer Services. N.p., n.d. Web. University of Florida. (2020, September 10). Imperata cylindrica. https://plants.ifas.ufl.edu/plant-directory/imperata-cylindrica/ USDA. Cogongrass. https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs141p2_021449.pdf Photos: Karan A. Rawlins, Cogongrass (Imperata cylindrica), forestryimages.org About the Hemlocks and How the HWA Arrived If you’ve ever visited the Appalachian mountains, the chances are that you’ve seen a hemlock tree before. They tower over the landscape and were once incredibly abundant across forests in the eastern United States. There are two main hemlock species found in the Appalachian region: the eastern hemlock and the Carolina hemlock. These endemic species are a vital part of forest communities, and are essential for maintaining and moderating climate as well as providing habitat for wildlife. Unfortunately, these trees are currently being threatened by an invasive species. The hemlock woolly adelgid (HWA) is slowly destroying populations of hemlocks across the eastern United States. This tiny, non-native pest was brought from Japan in the 1920s, and over the course of several years, made its way into the hemlock tree populations in U.S. and Canadian forests. The HWA is able to kill hemlock trees by attaching itself to the base of the needles of the tree’s leaves and feeding on the nutrients while simultaneously restricting the water circulation within the tree. I spoke with PhD student Austin Thomas, who studies eastern hemlock and fraser fir trees, and asked him about how badly damaged the hemlock populations in the Appalachian region are. “To be honest, there's already only about 10% of their original [eastern] hemlock biomass that there was 60 years ago,” Austin explained. “We've already lost American chestnut, which was also primarily a riparian species at least in the southern Appalachians, and now we've lost Eastern hemlock. It hasn't caused a complete collapse yet, but what's the next species to go [extinct], and will that be the one that kind of breaks the whole system and causes the ecological collapse? That's hard to measure. But we're losing diversity, basically.” Unfortunately, the HWA are rapidly making their way through hemlock populations, and the trees have no natural defenses against the pest. What’s Being Done About It? Dr. Benjamin Smith is a research scholar for the Forest Restoration Alliance who oversees the day to day operations of their research program. I spoke with him to find out what’s being done to combat the HWA in the Appalachian region. Dr. Smith oversees “Certainly, there have been enough trees that are chemically treated that we're not going to lose hemlocks,” he began. “But that's going to require ongoing effort. There is bio control that's been utilized for quite a while, and time is going to tell how effective that is. So it may be helping it, but it's really hard to say. "We've also seen the adelgid populations and suffered a little in the last few years with cold winters. And in general, we're tending to see the health of the hemlocks rebounding and bit, just from that that's likely to be just a short term improvement. I don't think there's a risk at this point that we're going to completely lose it. But it certainly is just a very small shadow of its former glory.” “It's a really daunting task,” Austin added while we discussed the challenges in protecting the hemlocks. “And when it's a species that you know has ecological importance, but is not a keystone species or a huge commercial forestry species, it's hard to get funding and get people to care.” How Can You Get Involved? Are there any ways that people can help protect these trees from the HWA in their ordinary lives? As it turns out, there are a few small things that could make a big difference. Many forest pests are spread through human activity, particularly when people move firewood across long distances. “Certainly, the ‘Don't Move Firewood’ type campaigns can help slow down the spread,” Dr. Smith explained. “But it's at this point it's pretty much going to spread everywhere that it can survive.” By purchasing firewood locally, you can ensure that you aren't transporting a forest pest native to one area to another place where it would be considered invasive. PhD student Austin Thomas also works for Hemlock Nature Preserve in Cary, NC, which is a great resource for people who want to learn more about the hemlock trees. This unique park has the eastern-most population of hemlock trees, which typically cannot survive in the Piedmont region. The reason they are able to thrive in a small park in Cary is due to the landscape. The stream at the bottom of the bluffs helps to cool down the area, which mimics the climate of the Appalachians and makes the environment more suitable for hemlocks to thrive in. “This is a very well defined micro climatic niche for the hemlock in this very, very small area,” Austin explained. “But also, it's a pretty small population, there's less than 300 individuals living currently In that hemlock bluffs, and only about 20 of the trees have reached reproductive maturity.” When I asked about some ways that people could help protect the trees when visiting a place like the Hemlock Bluffs Nature Preserve, he responded,“The biggest thing is respect the signs that say, ‘Please don't go off trail,’ because erosion is huge. Walking on and trampling all the soil is going to kill the trees. Respect the trails, because they're there for a reason.” Since this park is such a unique feature in Cary, it has been a very beneficial place for research surrounding hemlocks and HWA to take place. I asked Austin, “And focusing on the Hemlock Bluffs, and then the microclimate and the tiny population that's so far away from, from where the hemlocks naturally grow, why would you say that it's important for those to be preserved?” “I would argue that anything that gets people excited about their local environment is an important thing to preserve and it's an important lesson in the ecology and natural history of the area,” Austin replied. In summary, there’s a lot of challenges involved with trying to preserve the hemlock trees. However, there has been some success in managing the HWA, which means there is still hope that many of the populations can still be saved. If you’d like to get involved, you can always visit the Hemlock Bluffs Nature Preserve in Cary. Also, remember not to move firewood over long distances or plant hemlock trees outside of their natural habitat. Sources: Alexander M. Evans (2008) Growth and Infestation by Hemlock Woolly Adelgid of Two Exotic Hemlock Species in a New England Forest, Journal of Sustainable Forestry, 26:3, 223-240, DOI: 10.1080/10549810701879735 Don't Move Firewood. (n.d.). Retrieved September 16, 2020, from https://www.dontmovefirewood.org/ Forest Disturbance Processes. (2020, March 11). Retrieved September 16, 2020, from https://www.nrs.fs.fed.us/disturbance/invasive_species/hwa/ Forest Restoration Alliance. (n.d.). Retrieved September 16, 2020, from https://threatenedforests.com/ Havill, N. P., Vieira, L. C., & Salom, S. M. (2014). Biology and control of hemlock woolly adelgid. Morgantown, West Virginia?: United States Department of Agriculture, Forest Health Technology Enterprise Team. Thammina, C., Conrad, K.P. & Pooler, M.R. Genetic diversity of the U.S. collection of Chinese hemlock Tsuga chinensis (Franch.) E. Pritz. based on simple sequence repeat markers. Genet Resour Crop Evol 66, 847–855 (2019). https://doi-org.prox.lib.ncsu.edu/10.1007/s10722-019-00752-2 Zoom Interview with Austin Thomas [Online interview]. (2020, September 5). Zoom Interview with Dr. Ben Smith [Online interview]. (2020, September 15). Photos: Bruce Watt, University of Maine, Bugwood.org ![]() If you’ve ever stepped on a fire ant mound by accident, you know how extremely aggressive fire ants are here in the Southeast. Easily confused with our native southern fire ants, red imported fire ants, or Solenopsis invicta, are medium-sized, reddish to dark brown ants. They are typically spotted by the distinctive mounds of exposed soil built up around their nest, which are much larger than the more inconspicuous mounds associated with our native southern fire ant species. Each red imported fire ant nest can have upwards of 200,000 workers and several hundred larvae, winged males and females awaiting their nuptial flight. Yes, red imported fire ants mate in the air! These nuptial flights occur in mid morning when the temperature is above 72°F about 1 or 2 days after a rainfall. After mating, the male dies and the female lands, sheds her now useless wings, and begins searching for a suitable nesting site to establish a new colony. Most ant species have a single queen, but red imported fire ants have a ‘supergene’ which allows them to exist as either a single queen colony (known as monogyny) or a multiple queen colony (known as polygyny). This 'supergene', referred to as the social chromosome, enables them to easily adapt to new environments, and is part of the reason they have been such a successful invasive pest on a global scale. To date, red imported fire ants can be found in eleven states across the southeast (Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, and Texas) with new infestations popping up in Maryland, Arizona, New Mexico, and California. How did they get here? Red imported fire ants, or RIFA for short, are native to South America. As their name suggests, they are thought to have been introduced to the US in the 1930s through the shipping industry in Mobile, Alabama. Since then, the spread throughout most of the southeast and southern US can be traced back to inadvertently transporting infested soil, sod and ornamental plants associated with commercial and residential landscaping. ![]() Why are they a threat? Red imported fire ants are aggressive, and an efficient competitor against our native ant populations. Unlike other ants, RIFA bite only to get a grip on their victim, then they sting repeatedly as they inject a toxic venom called solenopsin. Their sting can cause serious pain or injury in humans, pets, and livestock, but they often kill pollinators and small animals. Not only are they a nuisance, but they are chewing a hole through our pockets. In the US alone, the FDA estimates that more than $6.7 billion is spent annually on control efforts, medical treatment including veterinarian bills and livestock loss, damage to agricultural equipment as well as loss of revenue from crop damage. ![]() What is being done to stop them? In 1958 the U.S. Department of Agriculture (USDA) and Animal and Plant Health Inspection Service (APHIS) established the The Federal Imported Fire Ant Quarantine in an effort to monitor and prevent further spreading of Red Imported Fire Ant invasions across the US. You can view the Imported Fire Ant Quarantine Interactive Map here. In early 2002 the USDA and APHIS in cooperation with the Agricultural Research Service established the Imported Fire Ant Phorid Fly Rearing and Release Program. Phorid Flies are a known natural predator of the Red Imported Fire Ant and are being used as a 'biocontrol agent'. The first 2 species were released from 2002-2009 and have become established in more than 65% of the Red Imported Fire Ant (RIFA) quarantined area. In California, research Entomologist with USDA-ARS, Steven Valles along with other scientists are using a trifecta approach of natural enemies to combat the RIFA spread. The team is using a parasitic fungus called Kneallhazia solenopsae. a virus that occurs naturally in fire ants in South America called Solenopsis invicta, and two species phorid flies to see how these pests respond when faced with a combination of pressures similar to their native environment. Surprisingly, fire ants fear wasabi! Yes that pungent green paste served at the sushi restaurant. In a more recent study, entomologists in Japan and Taiwan are experimenting with a pungent oil extracted from wasabi called AITC as a natural alternative in the fight against red imported fire ants. AITC can also be found in horseradish, radish and mustard. Scientists have discovered that AITC is proving to be a powerful weapon against these pest. Not only was it found to be a powerful repellant, it can be lethal. In fact, scientists found that red imported fire ants died within 40 minutes when placed in a tube with AITC. All of the research discussed is ongoing and some if not all may become important tools in the future for red imported fire ant management programs. Here at Invasive Pest Watch NC we do not recommend introducing non-native species or pathogens on your property to control fire ants. You can always seek out expert advice from your local University Extension Office. ![]() What can we do? The bad news is that they are probably here to stay. The good news is that there are relatively low-cost methods that are useful in managing their impact on your property. The most noninvasive approach is to drown existing nests with a large volume (at least 2 gallons) of hot water (please be careful!). Although this may not remove the nest permanently, it is an effective method to temporarily disrupt the colony, and it does not require chemicals. There are a number of insecticides specifically formulated to eliminate red imported fire ants offered at your local hardware and garden shop. Although insecticides are an effective approach in eliminating a target species, please use as directed. Using more than the suggested amount can have a negative effect on our native wildlife. Lastly, avoid kicking their mounds in an attempt to destroy the nest. This only aggravates them and may encourage new nests to develop on your property. If you're lucky enough to not have these pests on your property the best method of prevention is to simply check any soil, sod or plants you plan to bring home to make sure fire ants have not settled in them. If you suspect a colony on your property you can always contact your local University Extension Department to confirm a suspected red imported fire ant mound. You can also help scientists that are actively tracking Red Imported Fire Ants by submitting sightings to the citizen science project Fire Ant Tracker. Bolton, H. (2020). USDA APHIS| Red Imported Fire Ants. https://www.aphis.usda.gov/aphis/ourfocus/planthealth/plant-pest-and-disease-programs/pests-and-diseases/imported-fire-ants
Hashimoto, Y., Yoshimura, M., & Huang, R. (2019). Wasabi versus red imported fire ants: Preliminary test of repellency of microencapsulated allyl isothiocyanate against solenopsis invicta (hymenoptera: Formicidae) using bait traps in taiwan. Applied Entomology and Zoology, 54(2), 193-196. doi:10.1007/s13355-019-00613-5 Oi, D., Valles, S., Porter, S., Cavanaugh, C., White, G., & Henke, J. (2019). Introduction of fire ant biological control agents into the coachella valley of california. The Florida Entomologist, 102(1), 284-286. doi:10.1653/024.102.0156 Valles, S. M., Porter, S. D., & Calcaterra, L. A. (2018). Prospecting for viral natural enemies of the fire ant solenopsis invicta in argentina. PloS One, 13(2), e0192377-e0192377. doi:10.1371/journal.pone.0192377 Waldvogel, M., & Billeisen, T. (2020). Red Imported Fire Ant. https://entomology.ces.ncsu.edu/red-imported-fire-ant/ While surfing the Internet in 2020, you’ve likely seen all kinds of articles about COVID-19, toilet paper shortages, and, most recently, “murder hornets.” The Asian giant hornet, Vespa mandarinia, was discovered in Washington state in December 2019, and two new workers were found in August 2020. Many in North Carolina are worried about the invasive hornet, which is the largest hornet ever discovered. However, the North Carolina Department of Agriculture and Consumer Services is monitoring for these “murder hornets,” and they have not been discovered in our state. We have several large wasps and hornets (and even some flies) in North Carolina that may fool North Carolinians, but don’t be alarmed! You can easily tell these look-alikes apart with a few defining characteristics. The Asian giant hornet is the world’s largest hornet, measuring up to two inches in length. These hornets are bright orange or yellow in color with a dark brown thorax (the portion where the wings and legs connect). They have notched eyes that are far from the back of the head, and their abdomen is covered in continuous brown and orange stripes. There are a few native wasp species in North Carolina that are comparably large. One example is the cicada killer wasp (Sphecius speciosus), which can reach up to almost two inches in length. But size does not indicate danger - unless you are a cicada (a large, noisy insect in North Carolina), the cicada killer wasp will not harm you! Likewise, there are several other insects, such as the introduced European hornet (Vespa crabro), that are commonly mistaken for “murder hornets.” Even a fly species, the red-footed cannibal fly (Promachus rufipes), deceives people! Still, with a careful eye and a few resources, it is possible to tell the difference. So, why does the Asian giant hornet elicit so much alarm? Besides its large size, many are worried about the hornet because it threatens other insect populations, such as the European honey bee. The European honey bee is not native to the United States, but it is an important pollinator for our agriculture. Asian giant hornets are predators of honey bees, and they are capable of destroying entire hives in just a few hours. These predators send out pheromones, or chemical messages, to other Asian giant hornets, signaling them to attack and rapidly kill honey bees. Japanese honey bees have evolved to fend off Asian giant hornets and respond to these pheromones, but European honey bees haven’t. Without any strong defenses, European honey bees can’t withstand the wrath of Asian giant hornets. It is unknown exactly how the Asian giant hornet would affect other insect populations in the U.S., but it is likely that it would prey upon our native bees, and its impact on European honey bees is enough to worry beekeepers! No one knows for sure how the Asian giant hornet got to Washington state, but some suggest it could have ended up in packing material or been brought illegally for food or medicinal purposes (the nutritious larvae and pupae of the hornet are often eaten in Asia). Researchers in Washington created a model to predict whether the Asian giant hornet could establish itself in the United States. They suggest that the hornet is most likely to occur in areas with low to warm annual temperatures and high precipitation, which exist in most of the eastern part of the country. Since Asian giant hornets are so concerning to beekeepers, professionals across the country are monitoring for these insects. It is understandable that many North Carolinians are worried about the “murder hornet,” but, as of now, these hornets are not in North Carolina. If you see a large wasp, keep in mind that we have several large species in North Carolina, and try to keep your eyes peeled for defining characteristics like colors and patterns. Above all, don’t just kill any large insect you see...most of them are beneficial! Written by Courtney Smith Edited by Dr. Matt Bertone, Director, Plant Disease and Insect Clinic, NCSU References
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AuthorWe are a group of NC State University students committed to spreading awareness about the invasive species that inhabit or threaten North Carolina. Archives
March 2023
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