TAES 143: 95-99 RESEARCH NOTE ISSO 0002-8320 http://taes.entomology-aes.org/ Platte Prairies Ants (Hymenoptera: Formicidae) in restored and remnant prairie tracts in central Nebraska JAMES C. TRAGER1, LAURA WINKLER2, CHRIS HELZER3, 1Shaw Nature Reserve of the Missouri Botanical Garden, Gray Summit, MO 63039 Corresponding author email: [email protected] 2South Dakota State University 3The Nature Conservancy of Nebraska ABSTRACT In July 2012, we sampled ant species in remnant and restored prairie tracts in the Platte River Prairies, managed by The Nature Conservancy of Nebraska. The sampling period coincided with TNC’s July 2012 “Week of Insects”, an event which involved both general public and invited expert participation, and was an opportunity for both education and citizen science. In four days of sampling, even under severe drought conditions, we encountered 22 species of ants. Fifteen species were found in never-plowed, remnant prairies, and four species were found only in them. Thirteen species were found on restored (planted) prairies, with three of these found only in the planted prairies. Four species were exclusively associated with mature cottonwood trees near the site headquarters. INTRODUCTION of remnant and planted prairie tracts were mostly similar, but considering the harsh weather conditions “Plant it and they will come.” From the of the sampling period, and observed differences in beginnings of the ecological restoration movement their ant species, there is need for more thorough and in central United States, practitioners have held the longer-term study of ants in both the precious and hypothesis - some might call it the hope - that the highly fragmented prairie remnants and the prairie development of diverse vegetation, modeled after habitat expansion through restoration plantings remnant reference sites and including native plants nearby. in naturalistic species assemblages and proportions, would eventually attract the associated fauna of the STUDY SITE AND METHODS reference sites. Most terrestrial fauna are insects, yet tests of the hypothesis using insects are relatively The Central Platte River ecosystem of central few. First indicated by Trager (1990) several studies Nebraska includes the Platte River channel and its of species composition of ants in restored grasslands long-term floodplain. The highest ground studied, in this decade generally concur that older restorations a sandhill prairie which was one of the remnant come to resemble, though slightly imperfectly, prairies, has been likely above the floodplain reference ant assemblages in remnant habitats. See: during most of the Holocene, and was also the most (Fagan et al. 2010, Majer et al 2007, Menke, et al. biotically distinctive. The plots studied included two 2015, Nemec, 2014, Orlofske, et al. 2010, Peters et rather different remnant prairie areas (Fig. 1A-B), al. 2016, Phipps 2006, Wodika et al. 2014). and three also somewhat distinctive planted prairies This note compares the ant species assemblages (Fig. 1C-D) on former agricultural fields in corn- of three planted prairie sites and two nearby, never- soybean rotation. Soils range from loamy alluvium plowed remnant prairie sites in central Nebraska, to sandy alluvium parent material, to deep sand on where the western tallgrass prairie meets the the upper reaches of the sandhill. At the time of the sandhills prairie. We found that the ant assemblages study, there had been no measurable rain in recent Publication date: 31 January 2017 96 PLATTE PRAIRIE ANTS weeks, and daily thermal maxima were at or above parasite, Aphaenogaster tennesseensis, of which 95 F/ 35 C, so many plants were wilted or stunted the queen must invade and become accepted by a and except in the lowest portions of the topography. colony of another congeneric species for new colony Daytime ant activity was largely compressed into establishment. No other such potential host species the 2-3 hours after sunrise and the 2-3 hours before was found in the grove, but A. “rudis” (in quotes sunset. However, ants were attracted to baits at all because now known to be a complex of closely hours, especially if baits were placed in a modicum related, cryptic species) was encountered in the of shade. No nocturnal sampling was conducted. vicinity by K. Nemec, and our inability to discover it We collected ants with a combination of may be reflective of the drought conditions. Dispersal tuna fish bait transects and general collecting. of grassland ants into the planted prairies seems less Bait transects consisted of 20 bait stations, 10 remarkable, as there were remnant sites in proximity paces apart, placed at the edge of mowed trails to the planted habitats, and because some native through the management units. General collecting grassland ants exist in infrequently mowed roadside included observing the ground while walking vegetation that partially connects the sample areas. trails, inspecting nest entrances and turning cover Two of the three species found only in objects, as well as searching for ants on plants while restorations - Camponotus novaeboracensis and searching or foraging, tending honeydew-producing Formica subsericea are species characteristic of a hemipterans, or visiting extrafloral nectaries. Trager variety of open, mesic and wet-mesic habitats. True also searched for ants at the base and on trunks in to form, these were found in the moister, higher- a small group of cottonwoods near the preserve water-table portions of restorations. F. pergandei headquarters. We preserved, in 95% ethanol, one to is a dulotic parasite of F. subsericea and a variety a few voucher specimens from at least one species- of other Formica species. (At this site, the live- occurrence from each site, then identified them under in host population consisted of workers of both F. a dissecting microscope or with hand lenses, using subsericea and F. montana (Figs. 1E-F), another Creighton (1950) and Wheeler and Wheeler (1963). mesic prairie species.) Often found in highly drained, Nomenclature is updated according to www.antcat. sandy areas in southern Canada and New England, F. org. Voucher material is currently stored in the pergandei is more characteristic of mesic grasslands personal collection of Trager. in the southern half of its distribution. In any case, F. pergandei is always found with abundant host species RESULTS colonies nearby from which to acquire brood, which is stolen and matures into the host work force of the A total of 30 ant species are known from the area F. pergandei colony. – this number derived from combined records of K. Among the ants found only in remnants, Nemec (Nemec 2014), and of Trager and Winkler in Dorymyrmex flavus and F. dolosa are psammophilic this study. We encountered 22 species. Four of these ants, and as might be expected, were found only near were arboreal species. Of the remaining 18 species, the summit of the sandhill. Drainage conditions in 15 were sampled in remnants, with four of these the restorations and in the other, more mesic remnant unique to the remnants, while 13 were collected in the are not suited to these sand-inhabiting species. planted prairies, with three unique to the plantings. On the other hand, F. lasioides and F. incerta are The results are tabulated by species in Table 1. characteristic of mesic grassland and grassland- woodland interfaces. It seems certain they will be DISCUSSION found in the restorations with further searching, as they, especially F. incerta, often are in prairie The four arboreal species are of some interest plantings elsewhere. for their demonstrated ability to disperse to an island Looking at these early results in a larger context, of suitable nesting trees over what amounts to a sea there are about 120 ant species known to occur in of unsuitable agricultural land and prairie habitat. A Nebraska. We’ve found fewer than 20% of those particularly interesting case is that of the temporary species in the Platte River Prairies so far. Given the TRAGER, WINKLER, & HELZER 97 diversity of habitats of the preserve, from wetland to LITERATURE CITED sandhills, it seems likely we’ll find more ant species in these sites. In particular, we were surprised not Fagan, K. C et al. (2010) Are ants useful indicators to find three species that one of us (Trager) nearly of restoration success in temperate grasslands? always sees both in remnant and planted prairies, and Restoration Ecology. 18: 373–379. which are in the Nebraska myrmecofauna. Those Majer, J. D., et al. (2007) Ants (Hymenoptera: species are Crematogaster lineolata, Monomorium Formicidae) pass the bioindicator scorecard. minimum and Temnothorax ambiguus. Maybe Myrmecological News 10: 69–76. they’re here, maybe they’re not, but not seeing those Menke, S.B. (2015) The effects of restoration age and three otherwise common grassland species may be prescribed burns on grassland ant community taken as resulting from the brief and preliminary structure. Environmental. Entomology 44: 1-12 nature of this study. Nemec, K. T. (2014) Tallgrass prairie ants: Their species composition, ecological roles, and ACKNOWLEDGEMENTS response to management. Journal.of Insect Conservation. 18: 509–521. We appreciate the funding for the Orlofske, J.M., et al. 2010. Potential terrestrial “Week of Insects” provided through a grant arthropod indicators for tallgrass prairie from Prairie Biotic Research of Madison restoration in Iowa. Ecological Restoration 28: Wisconsin. Room and board for Trager and 250–253. Winkler (and some other guest experts) in the Peters, V.E., Campbell, K.U., Dienno, G. et comfortable conditions of the Derr House were al. (2016) Ants and plants as indicators covered by this grant. The house doubles as of biodiversity, ecosystems services, and the headquarters of TNC’s Platte River Prairies conservation value in constructed grasslands. Preserve, to which we are also grateful for the Biodiversity Conservation 25: 1481-1501. hospitality. Phipps, S. J. 2006. Biodiversity of ants (Hymenoptera: Formicidae) in restored grasslands of different ages.