|Emery, 1895d PDF: 333 (q.m.); Wheeler & Wheeler, 1951 PDF: 196 (l.); Crozier, 1970a PDF: 119 (k.); Taber & Cokendolpher, 1988 PDF: 95 (k.).|
|Senior synonym of Tapinoma parva, Tapinoma boreale Roger (and its junior synonym Tapinoma boreale Provancher): Mayr, 1886d PDF: 434; Creighton, 1950a PDF: 353; of Tapinoma gracilis: Emery, 1895d PDF: 337; Wheeler, 1902g PDF: 20; Creighton, 1950a PDF: 353; of Tapinoma dimmocki: Shattuck, 1992c PDF: 153.|
Regularity: Regularly occurring
Type of Residency: Year-round
Regularity: Regularly occurring
Type of Residency: Year-round
Diagnosis of worker among Antkey species. Antenna 12-segmented. Antennal scape length less than 1.5x head length. Eyes medium to large (greater than 5 facets). Antennal sockets and posterior clypeal margin separated by a distance less than the minimum width of antennal scape. Dorsum of mesosoma with metanotal groove, but never with a deep and broad concavity; lacking erect hairs. Propodeum and petiolar node both lacking a pair of short teeth. Propodeum with dorsal surface distinctly shorter than posterior face; lacking posteriorly projecting protrusion. Waist 1-segmented (may be hidden by gaster). Petiolar node appearing flattened. Gaster armed with ventral slit; with four plates on its dorsal surface, and with the fifth plate on the ventral surface. Distinct constriction not visible between abdominal segments 3+4. Hairs not long thick and produced in pairs. Color uniformly dull brown.
Tapinoma sessile can be distinguished from Brachymyrmex species, with which it bears superficial resemblance, by the 12-segmented (versus 9-segmented) antenna, and by the presence of a ventral slit (versus acidopore) on the gaster tip. It can be differentiated from Technomyrmex species by the absence (versus presence) or erect hairs on the mesosoma, and by the gaster which has 4 plates on the dorsal surface and 6 on the ventral surface (versus 5 plates on both surfaces). It is most easily differentiated from Tapinoma melanocephalum by the uniform brown color (versus bicolored with dark head and light body, gaster and appendages).
Brachymyrmex species, Technomyrmex species, Tapinoma melanocephalum
Molecular Biology and Genetics
Statistics of barcoding coverage: Tapinoma sessile
Public Records: 93
Specimens with Barcodes: 466
Species With Barcodes: 1
Barcode data: Tapinoma sessile
There are 42 barcode sequences available from BOLD and GenBank. Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species. See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
NatureServe Conservation Status
Rounded Global Status Rank: GNR - Not Yet Ranked
Tapinoma sessile is a species of ant that goes by the common names odorous house ant, stink ant, and coconut ant. Their colonies are polydomous (consist of multiple nests) and have a characteristic dominance hierarchy system. Like many social insects, T. sessile employs complex foraging strategies, allocates food depending on environmental conditions, and engages in competition with several other insect species.
These are both indoor and outdoor ants. They eat honeydew, which is made by aphids and scale insects, and other sugary foods. Due to the vast variety of food they eat and their commonality, they are a common household ant.
As with most other ants (the exception being some socially parasitic species), T. sessile is eusocial. This is characterized by reproductive division of labor, cooperative care of the young, and overlapping generations.
Little is known about the lifespan of the ant, though it has been shown that queens live at least 8 months (and probably much longer), workers at least a few months (and show every indication of living as long as queens), while males appear to live only approximately a week.
This odorous house ant is tough; injured workers have been observed to continue living and working with little hindrance. Some queens with crushed abdomens still lay eggs, and there are documented instances of T. sessile queens surviving without food or water for over two months. They also appear highly tolerant to heat and cold. These ants are difficult to remove from the home. When killed, these ants leave an odorous smell which leads to their nickname "Stink Ant."
The gaster portion of the abdomen sits directly on top of the petiole in the abdomen of this ant species. A comparison of the diagram of a normal ant body and the side view of the T. sessile shows how the gaster sits atop the petiole.
This also leads to a very small petiole and to the gaster being pointed downward. The anal pore then open ventrally (toward the abdomen) instead of distally.
This species of ant demonstrates a dominance hierarchy system, consisting of a queen and subordinate workers. The larger colonies themselves vary in size from a few hundred to tens of thousands of individuals. The bigger colonies usually have multiple queens. The queens lay the eggs and then incubate between 11–26 days. The larva stage then lasts between 13–29 days, and the pre-pupal and pupal stages last between 10–24 days.
In this species, foragers collect food that is around the nesting area and bring it back to the colony to share with the other ants. The T. sessile has polydomous colonies, meaning that it has multiple nests. Because it is polydomous, the T. sessile is very good at foraging for food where there is a great variance in the distribution of resources. Instead of always going back to the nest to deliver food, they move workers, queens, and the brood to be closer to the food, so that they can reduce food transport costs. This is called dispersed central-place foraging. It was also found that the nest half-life for the ant was about 12.9 days.
Buczkowski and Bennett also studied the patterns of food moving within a nest. They labeled sucrose with Immunoglobin G (IgG) proteins, and then identified them using an enzyme-linked immunosorbent assay (ELISA) to track the movement of food. They were able to find that food was spread through trophallaxis, which is when one animal regurgitates food to another. Despite this trophallactic spread of food, the workers kept most of the sucrose. They also found that some queens received more food than others, suggesting a dominance hierarchy even within the queens. They also found that the nests were located in a system of trails, and that their distribution depended on where food was found and the distance between these patches of food.
It is also found that the rate of trophallactic feeding depends on the number of ants per nest, and the quality of food available. When the number of donors is kept constant, but the number of total individuals in increased, more individuals test positive for the food marker. This indicates that more individuals are eating, but the amount they eat is less. If the number of donors was doubled, and the size of the overall population increased, the number of individuals receiving food more than doubled, again indicating that the number of individuals fed increased, but that the per capita amount of food consumed decreased. The ants prefer sugar and protein food sources, over lipids, and this preference did not change seasonally. When specific sugar sources were studied the ants preferred sucrose over other sugars, such as fructose and glucose.
When searching for food, primary orientation is when ants are exploring a new terrain without the guidance of odor trails. Secondary orientation is when terrain is explored, and there are pre-existing odor trails which ants use to orient themselves. When the T. sessile ants are orientating themselves for the first time they often rely on the topography to orientate themselves. The major types of elements they rely on are bilaterally elevated, bilaterally depressed, unilaterally elevated, and unilaterally depressed. They use these types of surfaces to orient along, and lay the first odor trails, which can then be followed in the future, the food source, by other ants.
It was also found that the polydomy, having multiple colonies to have access to multiple food sources is seasonal in this ant species. The colony will overwinter in a single nest, and then during the spring and summer when resources are more abundant they will form multiple nests. This allows them to better utilize food sources that might be spread out. Then during the winter they will return to the same nest location. Seasonal polydomy is pretty rare, and only found in 10% of all polydomous species. Although season polydomy is rare and not found in many ant species there are many ant species, including T. sessile, which move even within a season. Immigration is common and allows them to forage for better food.
Seasonal activity patterns of the ants were also studied, and corresponding to the seasonal polydomy, it was observed that the ants displayed the most activity between March and September and displayed almost no activity from October to December. Daily activity patterns were also studied. In March T. sessile foraged during the day, but in April that pattern changed and the ant began to forage during both day and night. Throughout most of the summer the ant has low levels of activity during all twenty-four hours.
Competition with other ant species
Competition between species is often classified as exploitation or interference. Exploitation involves finding and using limited resources before they can be used by other species, while interference is the act of preventing others from getting resources by more direct force or aggression. When it comes to these behaviors, a species is considered dominant if it initiates an attack and subordinate if it avoided other species. In comparison with eight other ant species, the T. sessile was more subordinate on the dominant to subordinate scale. The ant does not show a large propensity for attack, preferring to use chemical secretions instead of biting.
When the T. sessile, a subordinate species, was in the presence of dominant ant species such as C. ferrugineus, P. imparis, Lasius alienus, and F. subsericea, they reduced the amount of time that was spent foraging. This was tested with the use of bait, and when the subordinate species, such as T. sessile, encountered a dominant species they would leave the bait. It would then make sense that the subordinate species would forage at a different time than dominant species, so that they could avoid confrontation, but there is sizable overlap in foraging period on a daily and seasonal basis. Because the T. sissile forages at the same time as dominant species, but does not want to interfere, they must have excellent exploitative abilities to survive.
One of the invasive species that T. sessile has had to contend with is the Linepithema humile, or Argentine ant. Studies of its interactions with L. humile has helped researchers better understand the aggression of T. sessile. T. sessile ants do not fight with their nest mates, and it was found that they only fought collectively in six of forty interactions. This often caused T. sessile to lose in interactions with other ants, such as the L. humile, even when they have more individuals. This is because species like the L. humile work together while the T. sessile does not. The T. sessile is however more likely to win in one-on-one interactions because they have effective chemical defenses.
This species is a scavenger/predator ant that will eat most household foods, especially those that contain sugar, as well as other insects. Indoors they will colonize near heat sources or in insulation. In hot and dry situations, nests have been found in house plants and even in the lids of toilets. Outdoors they tend to colonize under rocks and exposed soil. They appear, however, to form colonies virtually anywhere, in a variety of conditions.
They appear to be more likely to invade homes after rain (which washes away the honeydew they collect).
Odorous house ants appear to be highly tolerant of other ants, with compound nests consisting of multiple ant species (including T. sessile) having been observed.
Predators and parasites
Isobrachium myrmecophilum (a small wasp) appears to parasitize odorous house ants.
Some birds and toads will also eat odorous house ants on occasion.
Sessile translates to "sitting" which probably refers to the gaster sitting directly on top of the petiole in the abdomen of the ant species. The common names "odorous house ant" and "coconut ant" come from the odor the ants produce when crushed, which is very similar to the pungent odor of a coconut, bleu cheese, or turpentine.
These ants are not hard to control, and most ant killers will solve problems, especially if controlled as soon as the problem is noticed. At this point, they could be put under control in just a few days. However, the longer someone waits, the larger the population is and the longer it will take to control the situation, possibly a few weeks. Standing water should be eliminated, as odorous house ants are attracted to moisture. Plants should be trimmed back so they cannot be used to get inside. Cracks, holes and joints should be sealed with polyurethane foam or caulk, especially those that are near the ground. Firewood, rocks and other materials should not be stored next to a home because it encourages nest building. People should be on the lookout for these ants in late winter and early spring (particularly after rain), as this is when they most commonly appear.
|Wikimedia Commons has media related to Tapinoma sessile.|
- Davies, Nicholas B., John R. Krebs, Stuart A. West (2012). Introduction to Behavioural Ecology. Chichester, West Sussex: Blackwell Publishing. p. 363.
- Marion R. Smith, "Biology of Tapinoma Sessile Say, an Important House-Infesting Ant". A. & M. College, Mississippi, 1928. Retrieved 2011-03-29.
- "Tapinoma sessile (Say)". Texas A&M University. Retrieved 2013-10-22.
- Buczkowski, G.; G. W. Bennett (August 2006). "Dispersed central-place foraging in the polydomous odorous house ant, Tapinoma sessile as revealed by a protein marker". Insectes Sociaux 53 (3): 282–290. Retrieved 2013-10-22.
- Smallwood, J. (1982). "Nest relocations in ants". Insectes Sociaux 29 (2): 138–147.
- Buczkowski, G.; G. Bennett (2009). "The inﬂuence of forager number and colony size on food distribution in the odorous house ant, Tapinoma sessile". Insectes Sociaux 56: 185–192.
- Barbani, Laura Elise. "Foraging Activity and Food Preferences of the Odorous House Ant (Tapinoma sessile Say) (Hymenoptera: Formicidae)". Digital Library and Archives. Retrieved 2013-10-22.
- Klotz, J.H.; B. L. Reid (January 1992). "The use of spatial cues for structural guideline orientation in Tapinoma sessile and Camponotus pennsylvanicus (Hymenoptera: Formicidae)". Journal of Insect Behavior 5 (1): 71–82.
- Buczkowski, G.; G. Bennett (2008). "Seasonal polydomy in a polygynous supercolony of the odorous house ant, Tapinoma sessile". Ecological Entomology 33: 780–788.
- Fellers, Joan H. (1989). "Daily and seasonal activity in woodland ants". Oecologia 78: 69–76.
- Fellers, Joan H. (October 1987). "Interference and Exploitation in a Guild of Woodland Ants". Ecology 68: 1466–1478.
- Buckowski, G.; G.W. Bennett (October 2008). "Aggressive interactions between the introduced Argentine ant, Linepithema humile and the native odorous house ant, Tapinoma sessile". Biological Invations 10 (7): 1001–1011.
- Odorous House Ants Fact Sheet National Pest Management Association data highlighting habits, habitats and threats
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