Species in the family Myrmecophilidae (Orthoptera) are small, apterous, inquiline inhabitants of ant nests, and a number of species are known to strigilate and engage in trophallaxis with their ant hosts (Wheeler 1900, Schimmer 1909, Carter 1939, Henderson & Akre 1986). Several studies indicate that the ant hosts are typically aggressive toward the crickets, but that the crickets mimicked the mutual grooming and trophallactic behavior of their hosts thereby getting close to them, and usually avoided attack by using their superb jumping ability (Wheeler 1900, Henderson & Akre 1986).
Four species are known from the United States; however, only the eastern ant cricket (Myrmecophilus pergandei Bruner), occurs in the southeastern United States (Blatchley 1920, Hebard, 1920, Capinera et al. 2004, MacGown & Hill 2006). Myrmecophilus pergandei has been recorded as an inquiline from numerous species of native ants including Aphaenogaster treatae Forel, Camponotus castaneus (Latreille), C. chromaiodes Bolton, C. herculeanus (L.), C. pennsylvanicus (DeGeer), C. novaeboracensis (Fitch), Crematogaster lineolata (Say), Formica fusca L., F. obscuriventris Mayr., F. pallidefulva Latreille, F. subsericea Say, F. truncorum Fab., Lasius umbratus (Nylander), and Paratrechina parvula (Mayr) (Hebard 1920, Carter 1939). It has also been successfully kept with captive ant colonies, including Crematogaster lineolata, C. missuriensis Emery, Neivamyrmex nigrescens (Cresson) and Pheidole dentata Mayr (Carter 1939).
Though M. pergandei has been reported to inhabit colonies of Solenopsis geminata, a purported exotic ant species in North America, it has not been recorded from colonies of Solenopsis xyloni McCook, another purported exotic species, or colonies of the imported fire ants, Solenopsis invicta Buren, S. richteri Forel, or their hybrid S. invicta × richteri (Travis 1941). Carter (1939) introduced several M. pergandei into a laboratory colony of S. xyloni and found that the crickets were met with aggressive behavior and were unable to approach the ants for feeding. In most cases the Solenopsis captured and devoured the crickets within 24 h of their introduction into the nest.
However, on 9 September 2008, several individuals of M. pergandei were observed within a colony of the hybrid imported fire ant, Solenopsis invicta × richteri. This colony was not the typical mound in an open area for which imported fire ants are well known, but instead the colony was nesting in a rotting log in an open bottom-land hardwood forest in the Noxubee National Wildlife Refuge (lat 33° 16′ 17″N, long 88° 47′ 17″W). Also found in the colony was an individual of Myrmecosaurus ferrugineus Bruch (Staphylinidae), a beetle that is native to South America and associated with imported fire ant colonies. Voucher specimens of M. pergandei and S. invicta × richteri are both pinned and stored in alcohol. The specimen of M. femigineus is pinned. All specimens are deposited in the Mississippi Entomological Museum.
This finding represents a new host record for M. pergandei, and it is the first report of it occurring with an ant truly known to be exotic. It is interesting that M. pergandei has not yet been documented as occurring in colonies of the imported fire ant, given the amount of research conducted on these exotics since their introduction to North America in the early part of the 20th century. However, it is not overly surprising that M. pergandei finds imported fire ants a suitable host, as a related species, Myrmecophila nebrascensis Bruner, has been reported to occur in the colonies of Solenopsis xyloni McCook and S. invicta Buren (Neece & Barteli 1981, 1982).
Acknowledgements
This research was supported by the Mississippi Forestry Experiment Station Project MIS-311080, USDA-ARS Areawide Management of Imported Fire Ant Project, R. L. Brown (PI), and a grant from Noxubee National Wildlife Refuge, R. L. Brown, J. A. MacGown, and J. G. Hill (Co PIs). This is publication J-11529 of the Mississippi Agricultural and Forestry Experiment Station.