Wednesday, November 25, 2015

Tales of the Turkey Tail

Thanks to very successful conservation efforts, you may be lucky enough to see a wild turkey if you take a walk in the woods after your Thanksgiving dinner. But it would not take much luck at all to encounter the turkey tail fungus, Trametes versicolor on your walk. This subtly beautiful fungus probably is the most common wood rotting fungus on dead hardwoods throughout North America (Gilbertson & Ryvarden, North American Polypores, 1987). In fact, you may not need to leave your neighborhood to see turkey tails on old stumps like these flowering cherries we removed a couple of years ago.

New fruiting bodies of the turkey tail fungus Trametes versicolor on a flowing cherry stump

The common name of the turkey tail fungus refers to the semicircular rosettes of varying colors in the fruiting bodies (the spore producing part) of this fungus. The species name versicolor describes both the multicolored bands seen at different times within an individual specimen and the color variations seen among different specimens.
Bands of color variations in an old fruiting body

  T. versicolor can be distinguished from similar species by the tiny pores visible on the underside of the fruiting bodies. Like mushrooms, this fungus belongs to the basidiomycetes, but unlike the button mushrooms you may have had with your Thanksgiving dinner, T. versicolor is a polypore, a basidiomycete that produces spores within pores rather than on gills. Also unlike many mushrooms, the fruiting body is somewhat leathery (not fleshy) and long lived. The fruiting bodies first appeared on our cherry stumps in September and have been expanding and changing color since then.

Small pores covering the lower side of the fruiting body

 Trametes versicolor is one of the white rot fungi, indicating that the fungus can decay lignin, which along with cellulose, is a main component of wood. White rot fungi such as T. versicolor break down the dark lignin in wood, leaving the lighter colored cellulose behind. Other so-called brown rot fungi break down cellulose, leaving behind dark lignin. Many species of both white rot and brown rot fungi cause rots in living trees, but T. versicolor is not a pathogen and decays only nonliving materials. When you gather up piles of leaves and fallen sticks and branches in the fall, you can begin to appreciate that decay organisms such as T. versicolor perform a very necessary function in nature. Without them, we’d soon be inundated with layers and layers of plant debris. In fact, a recent theory proposes that the evolution of white rot fungi brought about the end of the massive accumulation of plant materials characteristic of the coal age.

As you might guess, T. versicolor has been studied for its potential to remove lignin in various industrial processes. It also is has been studied for medicinal purposes and is used in traditional Chinese medicine. Not surprisingly, the dried fruiting bodies have been used as dyes of protein based fibers like wool and silk (Binion et al, Macrofungi Associated with oaks of Eastern North America, 2008). The turkey tail fungus is commonly sold in craft stores for use in seasonal floral arrangements, and if you would like to add a touch of turkey to your Thanksgiving decor, the source may be as close as your own backyard. 

Tuesday, November 24, 2015

Kissing Bugs and Chagas Disease in NC

The causative agent of Chagas disease is a protozoan called Trypanosoma cruzi, seen here at center among human blood cells. Image courtesy of Public Health Image Library (PHIL)/CDC/ Dr. Mae Melvin

News reports out of Texas, and now North Carolina, have been stirring up fears about "deadly" insects and a lesser known, but potentially serious illness: Chagas disease. Most people in the United States have never heard of this malady, yet it affects millions of people every Central and South America.

The vast majority of Chagas disease cases are from rural areas in the New World tropics. Cases in the United States are rare, and most have been diagnosed from people who traveled here from outside the country. In fact there are at present only seven verified cases of natively-infected (termed "autochthonous") Chagas in the United States since 1955, and none of these was from North Carolina (see Reference 2). To put this in perspective, malaria -- a mosquito transmitted protozoan disease often thought of as exotic -- has been recorded as autochthonous 63 times since 1957.

Since I am an entomologist and not a medical pathologist I will not be writing about the disease itself, including its forms of transmission, symptoms and treatment. However, there are many great resources that describe the disease including the Centers for Disease Control and Prevention (CDC), the World Health Organization (WHO), and Wikipedia. I would, however, like to discuss the biology, identification, methods/risks of bites, and prevention in relation to the bugs themselves.

On that note, let's start off with a real kissing bug found right here in NC:

The Eastern blood-sucking conenose (AKA kissing bug), Triatoma sanguisuga, is native to NC and much of the southern and middle U.S.

Kissing bugs are true bugs (Hemiptera) in the family Reduviidae, most of which are referred to as assassin bugs. With ~7,000 species worldwide, the family Reduviidae is among the largest in the order. Most species in the family are predators, feeding on other insects and arthropods. However, the subfamily Triatominae, and the subject of this post, has largely abandoned the predatory lifestyle for one of blood-feeding. These bugs feed on a wide variety of vertebrate hosts, including reptiles, amphibians, birds, and mammals. In all there are over 130 species of kissing bugs, the majority being found in the Western Hemisphere.

Although most species are tropical, kissing bugs are native to North Carolina and have been for as long as humans have been here. At least two species can be found in the state: Triatoma sanguisuga and T. lecticularia. T. sanguisuga is more common, but even it is not frequently encountered. The reasons why they are so rarely found are two-fold. First, they are nocturnal, preferring to hide during the day. They may be seen at lights at night after dispersing (they have wings and can fly) but otherwise it's not often that you will see them in your daily lives. Second, they are often associated with small mammal nests, especially species of Neotoma (woodrats); the Eastern woodrat (Neotoma floridana), for example, can be found in North Carolina where it builds nests out of sticks and other debris. These nests are a perfect habitat for kissing bugs to hide before feeding on the inhabitants. Other mammal hosts of particular importance are opossums (Didelphis virginiana), raccoons (Procyon lotor), and armadillos (Dasypus novemcintus), but they will feed on a variety of mammals including livestock, pets, and humans.

As true bugs, kissing bugs undergo incomplete metamorphosis: after the egg, there are eight nymphal stages (instars) before they become an adult. All free-living stages feed on vertebrate blood, although they have been known to take other insects as food. The name "kissing" bug comes from the fact that when the bugs feed on humans at night, they prefer the face, especially the lips and eyes. Kissing bugs swell greatly when engorged, usually taking 20 minutes or so to feed. Their bites do not initially hurt, so as not to wake their victims, but often become itchy, swollen and painful. The bites can last for weeks and in some cases allergic reactions to the saliva can occur, even resulting in anaphylaxis.

The Chagas disease cycle begins when a bug feeds on an infected host, drinking blood containing the parasites. Many mammals that are fed on by kissing bugs (but not typically birds) can harbor the pathogen that causes the disease, but these animals rarely show symptoms. In fact, researchers at Wake Forest University (North Carolina), found that 1 of 12 (8.3%) opossums and 3 of 20 (15%) raccoons they trapped locally had the parasite. The parasite then grows and multiplies in the bug until it is ready to infect another organism. Unlike mosquitoes and many other blood-sucking arthropods, the disease is not transmitted directly through the bite. Instead, the parasites are found in the feces which may be deposited while feeding or somewhere near the bite. Intense itching causes the person to rub the feces into the eyes, mouth or wound where the parasites can enter the new host to complete the cycle. Thus an important factor for getting the disease is not the bite itself, but the likelihood of the feces getting into open wounds or mucous membranes. In this sense our native kissing bugs are rather courteous and discreet with their excreta -- they most often wait until they leave the host before defecating. This is thought to be the main reason why the disease is not common in the United States despite the bugs, disease and reservoir animals being present. In fact many kissing bugs that are tested for the disease have it, as do local mammals. But humans are not a preferred host and are not typically exposed to the parasite-riddled feces. Thus, the species native to most of the United States are not considered vectors of the disease to humans.


As far as identification, kissing bugs are like most other Hemiptera in that they have a long, straw-like rostrum used to suck liquids. Therefore, if the insect you have has mandibles or chewing mouthparts, it's not a kissing bug. True bugs will also never have more than five true antennal segments, and never more than three tarsal segments (the parts of the "feet").

Side view of an Eastern conenose kissing bug.
Kissing bugs themselves are around one inch in length when fully grown and somewhat flattened (when not fed). The sides of their abdomen (termed connexivum) and thorax are striped, alternating black and orange/red (sometimes even pink in hue). The legs of kissing bugs are thin compared to most assassin bugs, likely because they do not need to grab prey but instead must be able to move quickly. The name conenose comes from the fact that the front of the head is elongate and the rostrum is long and thin. The antennae are placed well in front of the eyes along the "nose". They also have a prominent spine on the back of the thorax.

Often, other true bugs have similar shapes or markings and can be difficult to tell apart from kissing bugs. The following are NOT kissing bugs:

Other assassin bugs

At well over an inch long, wheel bugs (Arilus cristatus) are our largest assassin bugs. They are very easily recognized by the large cog-shaped crest on the pronotum. They lack red stripes and have a much stronger beak than kissing bugs.
Microtomus purcis is a large, primitive assassin bug species that enjoys hunting under bark, likely for woodroaches (Parcoblatta sp.). The large white patches on the wings and half red hind femora are diagnostic for the species.
Milkweed assassins (Zelus longipes) are medium sized, distinctively red/orange and black assassin bugs with long legs. They are often found out on plants where they wait to capture prey with their sticky forelegs.
Massive front legs and a spiny head are characteristics of spined assassin bugs (Sinea sp.). They are generally smaller than many of the previous assassins (around half an inch) and typically lack bright colors.
Black corsairs (Melanolestes picipes) are often attracted to lights and may specialize in capturing scarab beetles with their large, padded fore legs. Black corsairs are obviously black, but other close relatives, like the genera Rasahus and Sirthenea, can be red/orange or striped. The masked bed bug hunter (Reduvius personatus) is a similarly black species found around homes.
Members of the genus Pselliopus are small, common assassin bugs with distinct rings around their appendages and along the body. This nymph, found crawling around a home, shows the typical orange color of the genus.

Other bugs

Leaf-footed bugs, like this Leptoglossus corculus (Coreidae), are similar to assassin bugs (and thus kissing bugs) but have enlarged hind legs rather than enlarged forelegs. The leaf-like hind legs are also a good trait for distinguishing between the groups, but not all Coreidae have them. These bugs have a long, needle-like rostrum for piercing plants that does not fit in a groove on the underside of the body (as in assassin bugs). 
Stink bugs (Pentatomidae) are another group of true bugs that may be mistaken for kissing bugs, but are generally wider and shield-shaped; they also have a much shorter head that is broadly attached to the thorax (i.e. they lack a distinct neck). Shown here is a rough stink bug (Brochymena sp.), a common plant feeding genus.
Florida predatory stink bugs (Euthyrhynchus floridanus) are brightly colored, metallic cobalt and orange/red bugs. As their name implies, they are predators of other insects.
There are many brown stink bugs, including this Euschistus sp. Some feed on plants, while others are predators. Most have distinct "shoulders" or pointed lateral edges of the thorax.

Now infamous throughout their ever expanding range, brown marmorated stink bugs, or BMSBs (Halyomorpha halys) are native to Asia but were introduced over a decade ago into the northeast of the United States. As plant feeders they can be pests, but are most often pestiferous when they enter homes during the fall and winter in large numbers. Their scent can be strong and their presence annoying. They resemble other brown stink bugs, but are unique in having striped antennae.

If you think you have a kissing bug, this short pictorial key should help you identify similar bugs that may bite. If you are still unsure and would like to have a photograph or specimen identified, please visit our website for information on how to submit such a sample.

Finally, how do you control kissing bugs? In the tropics where the bugs live in large numbers among cracks in mud homes or in thatched roofs (and the threat of disease transmission is high), applying pesticides is a good idea. However, here in North Carolina prevention is the key and applying pesticides is not advised, as there are no definitive sites to apply the pesticides. The following are some strategies that can greatly reduce the chances of kissing bugs entering homes, especially in rural areas where there are more mammal hosts:

  • reduce the amount of debris and vegetation directly around the home; wood and leaf piles, stacked rocks and other habitats that attract rodents can also harbor the bugs
  • repair cracks and gaps in homes; use weather stripping on points of entry like windows and doors and make sure window screens are intact and holes are repaired
  • if you suspect kissing bugs are in your home, inspect cracks and tight spaces, especially in bedrooms
  • lights will sometimes attract kissing bugs; minimizing the amount of lights on at night will help to "cloak" homes

Although these preventative measures will help reduce the chances of coming into contact with kissing bugs, in reality it is very unlikely you would ever come into contact with one of these insects anyway. In fact I have never seen one myself in the wild, even after 15 years of living in the state. Of course that is anecdotal, but I think most entomologists in the area would agree that they are uncommonly encountered.

So in conclusion, yes these bugs can carry a deadly disease. But here in the United States, especially North Carolina, you have almost no chance of contracting the disease from these native bugs.

  1. Kissing Bugs in the United States
  2. Trypanosoma cruzi and Chagas' Disease in the United States
  3. Triatominae at
  4. The Eastern Blood-Sucking Conenose, UFL