Research Article |
Corresponding author: Kaloyan Ivanov ( kal.ivanov@vmnh.virginia.gov ) Academic editor: Jack Neff
© 2016 Kaloyan Ivanov.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Ivanov K (2016) Exotic ants (Hymenoptera, Formicidae) of Ohio. Journal of Hymenoptera Research 51: 203-226. https://doi.org/10.3897/jhr.51.9135
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The worldwide transfer of plants and animals outside their native ranges is an ever increasing problem for global biodiversity. Ants are no exception and many species have been transported to new locations often with profound negative impacts on local biota. The current study is based on data gathered since the publication of the “Ants of Ohio” in 2005. Here I expand on our knowledge of Ohio’s myrmecofauna by contributing new records, new distributional information and natural history notes. The list presented here contains 10 species with origins in a variety of geographic regions, including South America, Europe, Asia, and Indo-Australia. Two distinct groups of exotics, somewhat dissimilar in their geographic origin, occur in Ohio: a) 3 species of temperate Eurasian origin that have established reproducing outdoor populations; and b) 7 tropical tramp species currently confined to man-made structures. Only Nylanderia flavipes (Smith, 1874) is currently seen to be of concern although its effects on local ant communities appear to be restricted largely to already disturbed habitats. A systematic sampling of disturbed areas, urban sites, plant nurseries and conservatories, where new arrivals can be expected, would extend and build upon our current knowledge of Ohio’s exotic ant fauna.
Formicidae , non-native species, distribution, natural history, eastern US, Ohio
People rarely travel alone and the worldwide human-mediated transfer of organisms is well documented. In the current era of enhanced commerce, improved transportation and globalization, more and more species are being transported to areas where they did not occur previously. A large number of plant and animal species have been transferred to new locations either purposefully (for food, medicine, landscaping, or as pets) or unintentionally (in ballast water, via potted plants, top soil, or fire wood) (
Owing to their small body size, social behavior and often pronounced tolerance to, and association with, human-altered habitats, many non-native ants now are widely distributed across the globe and have become an integral part of their new homes (
Many established non-native species (i.e., species that have completed the second step of the dispersal process; “exotic established species” in
The Global Invasive Species Database shows that five ant species currently are listed among the World’s 100 worst invasives (
In the context of this paper, I apply the term “exotic species” to designate any species detected outside the confines of its known native range. As such this definition includes both species with well-established populations in natural or human-altered settings as well as species which have been encountered only infrequently, or in low numbers, and whose current status therefore is uncertain. The focus of this paper, accordingly, is on the species that have concluded the first, fundamental, step in the invasion process, namely the completion of human-aided dispersal.
The first known record of an ant exotic in Ohio is from 1917 when Monomorium pharaonis (Linnaeus, 1758) was collected by M.R. Smith in Columbus (unpublished material housed at the Ohio State University Collection; in
Here I extend the current knowledge of the ant fauna of Ohio and provide a summary of the exotic species known to occur in the state at present. I expand the list with the inclusion of species newly discovered or species not included in
The work for this study began in late 2005, following the publication of
During my work I concentrated on documenting as many species as possible at each survey site primarily through the use of hand collecting. I divided my sampling time between natural and human altered habitats alike as disturbed areas are often prone to the accumulation of ant exotics. A substantial part of my sampling was conducted in human-modified habitats including parks, gardens, yards and other urban landscapes. In addition, various man-made structures such as greenhouses, conservatories, plant nurseries and people’s homes also were examined. At each site I inspected the ground and vegetation (including flowers and seed pods) looked under bark, stones, logs and other cover objects. I also broke open stems and branches that have fallen on the ground and inspected them for the presence of ant colonies. On a number of occasions I augmented this sampling scheme by checking lights on buildings or by using black light for the collection of alate reproductives. New materials accumulated in the invertebrate collection at the
Voucher specimens of all recorded species are in the invertebrate collections at
All species included here can be identified using the taxonomic keys in
As a result of the current work three non-native ant species are newly recorded from the state – Nylanderia flavipes (first record in
Taxa are arranged alphabetically by subfamily, genus and species. Each species name is followed by the taxon’s currently known Ohio distribution, habitat, known area of origin and brief natural history notes. Precise distributional records of these species for North America and elsewhere can be found in
Northern Ohio. Counties: Cuyahoga (Cleveland, 27.x.2005 [KI 1176], 15.xi.2005 [KI 1177], and 01.iii.2015 [observed, not coll.], same locality, leg. K. Ivanov, in a greenhouse) and an unspecified Ohio record in
Indoors, in greenhouses and conservatories.
The Paraná River drainage basin of South America.
The Argentine ant is amongst the world’s most successful invasive species and is a nuisance everywhere it occurs. It is established primarily in regions with Mediterranean climate where it has been shown to have profound negative impacts on native biota (
This cosmopolitan species often thrives in disturbed habitats with abundant moisture. Nests are most often in soil, but also under cover objects, refuse piles and more rarely under tree bark. The main dietary component is honeydew from hemipterans, although these ants will also take other sweet substances including household food items, and occasionally will feed on insects (
Throughout its introduced range Argentine ant colonies are polygynous with pronounced unicoloniality (i.e., the formation of large colonies with multiple nests). A key attribute to the ecological success of this species thus is the absence of intraspecific aggression within the large colony (
Ohio’s only confirmed record of this species comes from a greenhouse in Cleveland where I have observed large numbers of ground foragers on paved surfaces, exposed soil, and on tropical plant debris on the ground. In many cases foragers were accumulating around sugar syrup stations, banana, apple and other fruit pieces used for feeding tropical butterflies. Due to logistical limitations, I was not able to conduct nest searches at this location. The very high worker densities observed, however, suggest that this species now has well-established indoor colonies at this site. At present, this species can survive in the north only in heated buildings, where occasionally it can be a persistent and troublesome pest.
Widespread in Ohio. Counties: Butler (material examined: Oxford, Miami University, Belk Greenhouse, 25.ii.2014, leg. S. Mays), Cuyahoga (material examined: Cleveland, 07.ii.2008, leg. K. Ivanov, and 04.iii.2008, leg. B. Poynter, same locality, in an animal care zoo facility), and Franklin (photographs examined: Columbus 25–29.ii.2008, photos by S. Heideman, in a conservatory), (Fig.
Indoors, abundant in greenhouses, conservatories and zoo buildings.
Indo-Pacific.
This widely distributed tramp species is more prevalent in disturbed areas but also has been encountered in natural habitats in its introduced range (
Colonies are moderate to large in size, and polygynous, with queens distributed in multiple nests. Additional features characteristic of this ant include unicoloniality, intranidal mating, and colony formation via budding (
Where it occurs this ant is a major nuisance pest, both indoors and outdoors, that tends mealybugs and scale insects and scavenges for dead insects and food scraps (
I have only seen this species at a single animal care facility in the greater Cleveland area where I observed multiple nests in wall spaces and crevices. In addition, numerous foragers were noted near and at reptile feeding stations. In Ohio, this ant is a known conservatory and zoo pest, likely distributed via potted plants or animal feed. Unpublished observations suggest that this ant has been present in the state since at least the early 2000s (B. Poynter and M. Vincent pers. communication).
Northern Ohio. Counties: Cuyahoga (material examined: Cleveland Heights, 12–14.x.2004 and 22–24.x.2004, leg. H. Clebsch, yellow pan traps in residential area; Cleveland, 19.v.2013 [KI 2319] and 23.iv.2014 [KI 2345], leg. K. Ivanov, in a greenhouse; Cleveland, Case Western Reserve University, main campus, 17.v.2015, leg. A. Perez, pitfall trap, mulch bed adjacent to a concrete path; Shaker Heights, Doan Brook Gorge, multiple records since original discovery in 2005 with last collection event on 06.v.2014 [KI 2346], leg. K. Ivanov, hand collecting, Winkler litter extraction, and baiting in open woodlands; Euclid Creek Reservation, Wildwood Park, 16.ix.2014 [KI 2348], leg. K. Ivanov, open woodland), Franklin (Columbus 17.viii.2015, leg. A. Perez, Winkler litter extraction, flower bed adjacent to public library), Lake (material examined: Kirtland, multiple records from July and August 2009 and 2010, leg. T. Webster, suburban lawn) and Lucas (
This species is abundant in urban and suburban areas including forested green spaces, gardens, yards and vacant lots. It is also found indoors, in conservatories.
Temperate Asia.
This temperate formicine was first reported for Ohio based on material collected at the Doan Brooke Gorge of Shaker Heights in July 2005 (
This is a monogynous species that frequently develops polydomous colonies (
In Ohio I have observed and collected this species in a variety of different situations including urban woodlots, residential lawns, flower gardens, on concrete/pavement, as well as inside a greenhouse where I have seen foragers on Oncidium flowers. In all outdoor situations nests were in the soil, and were rather small and inconspicuous. Colonies most often were found under small rocks and less frequently under bark and tree limbs on the ground. On few occasions, workers readily came and took tuna in oil placed in open, rather degraded, mesic urban woodlots. Nylanderia flavipes maintained high abundance at the baits in the absence of native ants. However, when baits were discovered by native species, N. flavipes workers were displaced quickly. Our observations suggest that this species does not engage in aggressive interactions with native ants, and does not recruit to defend food resources.
Southern Ohio. Counties: Hamilton (
Ohio’s single record is from a warehouse in Cincinnati, although this species is undoubtedly more widespread in the state where it should be sought after in heated buildings.
Southeast Asia or Melanesia.
Along with Monomorium pharaonis and Tapinoma melanocephalum, this is one the most widespread tramp ant species and perhaps the most widespread ant in the world (
Longhorn crazy ants are highly adaptable and exhibit pronounced ability to survive even in extremely anthropogenically modified environments including nesting sites with very low humidity (
A contributing factor to the colonizing success of this species is its mode of reproduction with lack of nuptial flights. Wings of queens are removed while still callow. Dealate queens and winged males usually gather around the nest entrance, where mating occurs (
This species is a known household and garden pest across tropical and subtropical areas, where it can also attain a significant agricultural pest status via its symbiotic relationships with sap feeding Hemiptera (
Indoors, in a conservatory.
Australasia.
This is an Old World genus of small, omnivorous ants that contains several cosmopolitan tramp species (
Lateral view of Cardiocondyla obscurior worker (www.antweb.org, specimen CASENT0103429, photo: A. Nobile).
This is a species with arboreal nesting habits and its small colonies (usually <500 individuals) are typically located in nest cavities on low (2–5m) vegetation, or in folded leaves above ground. Similar to many other ants with small colonies, workers of this species do not defend foraging areas or food resources thus colonies can reach very high densities (
It appears that colonies of all tramp Cardiocondyla species are polygynous and new colonies are formed via budding (
Due to their small colony size, and the fact that workers forage mostly solitary, members of Cardiocondyla are generally not considered pest species (
Widespread in Ohio. Counties: Cuyahoga (material examined: Cleveland, iii.2007, leg. J.B. Keiper, inside a building,
Indoors, in heated buildings.
Asia.
The pharaoh ant is arguably one of the world’s most widespread house-infesting ants and there is a large body of literature on the pest status of this species. According to
Like other tramp species Monomorium pharaonis possesses features that facilitate its transport and establishment including highly polygynous and extensively polydomous colonies with little intercolony aggression (
In northern temperate regions, this small ant is highly synanthropic and depends on humans for food and shelter (
Single record from south-central Ohio. Counties: Franklin (
Indoors. The single Ohio record was discovered in a greenhouse in Franklin Co.
Neotropics.
This is a synanthropic species with pronounced tolerance to disturbed habitats.
According to
This species has a history of human-mediated dispersal, which is not surprising given its abundance and synanthropic habitat preferences. In northern regions, both in North America and in Europe, this species occasionally is found in greenhouses, and other heated buildings (
Records from western and northeastern Ohio. Counties: Ashtabula (material examined: North Kingsville Sand Barrens, 20.vii.–11.viii.2007, leg. T. Pucci., Malaise trap,
Along with host Tetramorium caespitum (see habitat description below).
Europe.
This workerless inquiline social parasite is rarely observed and collected in both its native and introduced ranges, presumably because of its parasitic lifestyle or simply because it is indeed rare. This species’ known distribution includes Europe and North America broadly following that of its host Tetramorium caespitum. In North America it is mostly found in the eastern part of the continent (
Colonies consist of males and females that live with their hosts on which they rely for work and food. Unlike many other obligate social parasites, queens of this species are adopted by queen-less host colonies (
My only encounter with this species in Ohio was in downtown Cleveland in early May 2007 when my attention was attracted by a single dealate queen which was swiftly running on the soil surface exploring exposed entrances to what later turned out to be Tetramorium cf. caespitum colonies. I was unable to observe any interactions between the two species in the short period of time before I collected the specimen. The location where this observation occurred is urban and heavily dominated by impervious surfaces, including pavement and mowed grass, interspersed with a multitude of non-native flowering plants and few scattered crab apples (Malus sp.), serviceberries (Amelanchier sp.), and tulip trees (Liriodendron tulipifera L.).
Statewide in Ohio. Counties: Listed for 74 of Ohio’s 88 counties in
Along roadsides, in cracks in driveways, pavement and roads, under rocks and logs in open woodlands and wood edges, in grassy fields and many disturbed areas. Also in gardens, lawns and inside residences.
Europe.
A temperate species commonly found in urban habitats and adjacent natural settings in Ohio. Tetramorium cf. caespitum has been continuously documented in the state since its first discovery and undoubtedly occurs in all of Ohio’s counties. In North America this species has been reported as an agricultural pest, and shown to expand into natural habitats where it displaces native ants (
Pavement ant colonies are large to very large and usually monogynous. Nests are initiated by a single reproductive queen that carries out reproduction for the lifespan of the colony. In North America nuptial flights most commonly occur in mid-summer and generally one sex predominates in the reproductives produced by a particular colony (
I have observed this species in every Ohio County in which I have had the opportunity to collect material. This is undoubtedly one of the most common ants I have encountered in the state although it is largely restricted to human-modified environments where workers are nearly ubiquitous on paved surfaces, near and inside buildings and in open grass situations (including mowed lawns). I have rarely encountered this ant in natural, relatively undisturbed, settings in Ohio. Nearly all colonies I have seen were located in open situations usually under some type of cover object, most commonly large rocks, or at the bases of grasses. Notable exceptions include two rather large colonies from northeastern Ohio, the first of which [KI 1375] was found in a naturalized open grass field at Eldon Russel Park in Geauga County and comprised a large, de-vegetated, soil mound akin to those of young Formica exsectoides Forel, 1886 colonies. The second colony [KI 2332] was found inside a very large rotten stump in the park manager’s service area of Acacia Reservation in Cuyahoga County.
Southern Ohio. Counties: Jackson (
The following quote from
Old World, with assumed African origin. The current confirmed distribution includes Europe, Africa and India (
The genus Hypoponera includes small cryptic ants with global distribution, although the highest diversity of the group occurs in the tropics. Hypoponera ragusai is a species with known tramping ability widespread in most parts of the world (
The success of this ant as a tramp species is attributed to the presence of unusual ergatoid males which remain in their natal nest where they mate with virgin queens (
This species often has been refferred to as Hypoponera gleadowi (Emery, 1895) in the literature (including
Biological invasions by plants and animals are an ever increasing problem for global biodiversity and ants are no exception. Many ant species have been transported to new locations with often profound negative impacts on local biota (e.g., Linepithema humile, Solenopsis invicta Buren, 1972). The collection of precise distributional records is the first, fundamental, step in establishing the extent of the current spread of these species. Such data are critical if we are to better understand the factors that govern the spread and establishment of these exotics and their potential to disturb native ecosystems.
In general, the majority of the world’s known established non-native ants come from tropical and subtropical areas and the spread of temperate ant exotics is rather limited (
As a result of the current work three ant exotics are added to the state’s species list (but see Paratrechina longicornis comments above) thus increasing the number of known ant taxa in Ohio to 135 (
Species | First record (year, source) |
Last record (year, source) | # localities | Where found |
---|---|---|---|---|
Dolichoderinae | ||||
Linepithema humile (Mayr) | 1993, Arnett | 2015, this study | 1 | Indoors only |
Tapinoma melanocephalum (Fabricius) | 2008, this study | 2014, this study | 2–5 | Indoors only |
Formicinae | ||||
Nylanderia flavipes (Smith) | 2004, this study | 2015, this study | 6–9 | Outdoors, occasionally indoors |
Paratrechina longicornis (Latreille) | 1998, Hedges | 1998, Hedges | 1 | Indoors only |
Myrmicinae | ||||
Cardiocondyla obscurior Wheeler | 2008, this study | 2008, this study | 1 | Indoors only |
Monomorium pharaonis (Linnaeus) | 1917, |
2007, this study | 6–9 | Indoors only |
Pheidole bilimeki Mayr | 2005, Coovert | 2005, Coovert | 1 | Indoors only |
Tetramorium atratulum (Schenck) | 2005, Coovert | 2010, this study | 2–5 | Outdoors |
Tetramorium cf. caespitum (Linnaeus) | 1940, Wesson and Wesson | 2015, this study | >10 | Outdoors/indoors |
Ponerinae | ||||
Hypoponera ragusai (Emery) | 1940, Wesson and Wesson | 1940, Wesson and Wesson | 1 | Unspecified, likely indoors |
Two rather distinct groups of ant exotics with somewhat dissimilar geographic origin occur in Ohio. The first group comprises species of temperate Eurasian origin (Nylanderia flavipes, Tetramorium cf. caespitum, and Tetramorium atratulum) that have established outdoor populations in the state. The first two of these species were found to be common inhabitants of street medians in New York City by
Published accounts suggest that only a handful of temperate species have established outdoor populations in northeastern US. These include: Brachyponera chinensis (Emery, 1895), Formica paralugubris Seifert, 1996, Lasius cf. niger (Linnaeus, 1758), Nylanderia flavipes, Myrmica rubra (Linnaeus, 1758), M. scabrinodis Nylander, 1846, Tetramorium atratulum, Tetramorium cf. caespitum, Tetramorium tsushimae, and Vollenhovia emeryi Wheeler, W.M., 1906 (
Tropical and subtropical exotic ants are more widespread and a larger number of species have been reported from more northerly states. However, given physiological restrictions all of these species currently are confined to indoor situations, being unable to survive the cold, harsh winter conditions. Although I do expect that the number of these species in Ohio will increase, it is difficult to predict which of these warmer climate species will turn up in the state. However, given the astonishing amount of personal and commercial transport in the US, it is relatively easy to foresee that we have not yet seen the last members of these exotics in Ohio. It is most likely that the first individuals to arrive in Ohio will be members of some of the most abundant and widespread among the synanthropic species (i.e., Technomyrmex difficilis Forel, 1892, Brachymyrmex patagonicus Mayr, 1868), Nylanderia bourbonica (Forel, 1886), Cardiocondyla emeryi Forel, 1881, Monomorium floricola (Jerdon, 1851), M. destructor (Jerdon, 1851), Pheidole anastasii, P. megacephala (Fabricius, 1793), P. moerens Wheeler, W.M., 1908, Tetramorium bicarinatum (Nylander, 1846), Wasmannia auropunctata (Roger, 1863)). Future survey efforts should focus on plant nurseries, botanical gardens, zoo facilities and other heated buildings to document the arrival and establishment of these species.
In eastern US, there is a clear pattern of increasing number of both native and non-native ant species from north to south, with the peak in the number of ant exotics reached in the southeastern US. In total, only 10 of Ohio’s ant species are non-native with even a smaller number of these established in the state at present (including indoor and outdoor populations). These records are comparable with the number of ant exotics known from other northerly states, such as Illinois (8 species;
Ants often are inconspicuous immigrants, and may remain unnoticed until many years after their arrival in an area. This is most likely the case with the recent finding of Nylanderia flavipes in Ohio. This species has been present in the eastern US since at least the 1930s when it was first discovered in Philadelphia, PA (
Despite nearly ten years of surveying, I have sampled a rather small portion of the potential habitats in the state and thus many “exotic-ant-friendly” areas remain unexplored. This work is not complete and there is still much to do. A more extensive systematic sampling of disturbed areas, urban and suburban sites, plant nurseries and conservatories would be worthwhile and undoubtedly reveal the presence of yet undiscovered species in Ohio.
I thank H. Clebsch, M. Gates, R. Gibson, S. Heideman, A. Perez, B. Poynter, T. Pucci, M. Vincent, and T. Webster for providing specimens, photographs and/or information concerning the distribution of Ohio’s nonnative ants. I also thank the Nature Center at Shaker Lakes for permitting me to conduct field work at their site. Comments and suggestions from R. Gibson, J. Keiper, O. Lockhart, J. Milligan, J. Trager, and two anonymous reviewers improved the manuscript. This research was partially supported by the Ohio Biological Survey small grants program.