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Potential Herbivory on the Wintergreen Orchids Aplectrum hyemale and Tipularia discolor by the Spur-throated Grasshopper Melanoplus acrophilus
Peter F. Menzies1 and Irene M. Rossell

Southeastern Naturalist, Volume 16, Issue 3 (2017): N36–N39

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2017 Southeastern Naturalist Notes Vol. 16, No. 3 N36 P.F. Menzies and I.M. Rossell Potential Herbivory on the Wintergreen Orchids Aplectrum hyemale and Tipularia discolor by the Spur-throated Grasshopper Melanoplus acrophilus Peter F. Menzies1 and Irene M. Rossell1,* Abstract - Aplectrum hyemale (Puttyroot) and Tipularia discolor (Cranefly Orchid) are wintergreen orchids native to the eastern and central United States. Plants of both species produce leaves in the fall, photosynthesize during the winter, and persist as underground corms during the summer. Odocoileus virginianus (White-tailed Deer) are implicated as the main predator of both orchids, although little information is available regarding herbivory of these or other wintergreen species. We observed early emerging overwintering nymphs of the spur-throated grasshopper Melanoplus acrophilus on leaves of Puttyroot and Cranefly Orchids in a forested site in western North Carolina. This is the first account of potential insect herbivory on these winter green orchids. Aplectrum hyemale (Muhl. ex Willd.) Torr. (Puttyroot) and Tipularia discolor (Pursh) Nutt. (Cranefly Orchid) are the only 2 orchids in the eastern forest with the wintergreen phenology (Whigham and McWethy 1980). In the fall, each produces a single leaf that photosynthesizes until senescing in late spring, after which plants persist as underground corms during the summer. Reproduction is mainly clonal, but a single leafless flowering stalk may be produced in the summer. Both species are considered secure in North Carolina (North Carolina Native Plant Society 2016) and surrounding states, but neither is secure throughout its entire range (North American Orchid Conservation Center 2016). There is little information regarding herbivory of either species, though Odocoileus virginianus (Zimmermann) (White-tailed Deer) are known to consume Cranefly Orchid leaves (Whigham and O’Neill 1988), and deer and rodents are suspected as the greatest threats to Puttyroot in some regions (Richburg 2003). Herein, we provide the first account of potential insect herbivory on both orchids. We observed Puttyroot and Cranefly Orchid in a south-facing mesic hardwood forest (elevation 900–1000 m) in the Big Ivy area of Pisgah National Forest near Barnardsville, NC. Dominant overstory trees include Liriodendron tulipifera L. (Tulip Poplar), Quercus rubra L. (Northern Red Oak), and Fagus grandifolia Ehrh. (American Beech). The forested slope is adjacent to an early successional clearing dominated by grasses, legumes, asters, and other forbs. On 12 March 2016, we observed a large number of grasshopper nymphs emerging from soil in the clearing, as well as nymphs resting on Puttyroot leaves in the forest. We subsequently observed grasshopper nymphs on Cranefly Orchid leaves on 15 March 2016, and on leaves of both orchid species on 28 March 2016. During our observations, multiple nymphs (sometimes 10 or more) were typically present on each orchid leaf. In most cases, leaves showed signs of feeding damage, though we did not directly observe nymphs feeding on leaves (Figs. 1, 2). Grasshopper nymphs were not observed on leaves of evergreen species common in the area, including Goodyera pubescens (Willd.) R.Br. (Rattlesnake Plantain), Chimaphila maculata (L.) Pursh (Striped Wintergreen), and Cardamine diphylla (Michx.) Alph. Wood (Crinkleroot), and leaves of these evergreens showed no signs of insect herbivory. 1Environmental Studies Department, University of North Carolina Asheville, Asheville, NC 28804. *Corresponding author - irossell@unca.edu. Manuscript Editor: JoVonn Hill Notes of the Southeastern Naturalist, Issue 16/3, 2017 N37 2017 Southeastern Naturalist Notes Vol. 16, No. 3 P.F. Menzies and I.M. Rossell On 9 April 2016, leaves of both orchid species were no longer present in the study area. We collected adult grasshoppers on 16 May 2016, which were identified by Dr. Timothy Forrest (Professor of Biology, University of North Carolina, Asheville, NC) as the spurthroated grasshopper Melanoplus acrophilus Hebard in the Viridipes species group (family Acrididae). Voucher specimens were deposited in the Environmental Studies Department, University of North Carolina, Asheville, NC. Melanoplus acrophilus is endemic to montane forests of the southern Appalachians (LeGrand et al. 2014). In a comprehensive review of Melanoplus, Otte (2002) reported it as the largest genus of grasshoppers, with most species in the Viridipes group inhabiting forest gaps, edges, or open woods where a sparse canopy allows sufficient sunlight penetration for some species to overwinter as nymphs; these are among the first grasshoppers to emerge in the spring, with adults generally present in May and June (we collected adults in mid-May). In North Carolina, M. acrophilus is listed as watch category 3 (W3), which includes species that are poorly known, but not necessarily declining (Legrand et al. 2014). Its rank is listed as S2/S3, an uncertain conservation ranking of category S2 (imperiled, 1000–3000 individuals) or S3 (vulnerable, 3000–10,000 individuals). Capinera et al. (2004) indicated spur-throated grasshoppers are largely phytophagous and feed on grasses, forbs, shrubs, and trees. They also noted some species may scavenge on insect cadavers or dead plant material. Interestingly, when nymphs were emerging at our study site in March, we observed some densely clustered on dog droppings in the early successional clearing where few green plants were available. Figure 1. Nymphs of the spur-throated grasshopper Melanoplus acrophilus on leaves of Aplectrum hyemale (Puttyroot) in western North Carolina on 15 March 2016. 2017 Southeastern Naturalist Notes Vol. 16, No. 3 N38 P.F. Menzies and I.M. Rossell A wintergreen phenology allows plants such as Puttyroot and Cranefly Orchid to benefit from higher levels of sunlight on the forest floor as well as minimize losses to phytophagous insects, which are typically inactive in forested ecosystems during the winter. Defoliation has been shown to significantly impact growth and reproduction of Cranefly Orchid (Whigham 1990). In fact, Whigham (1984) suggested one purpose of its large underground Figure 2. Nymphs of the spur-throated grasshopper Melanoplus acrophilus on leaves of Tipularia discolor (Cranefly Orchid) in western North Carolina on 15 March 2016. N39 2017 Southeastern Naturalist Notes Vol. 16, No. 3 P.F. Menzies and I.M. Rossell corms might be to enable plants to survive bouts of intense herbivory. At our study site, we observed M. acrophilus nymphs on Puttyroot and Cranefly Orchid within a month of leaf senescence, so the impacts of grasshopper feeding on corm reserves are unclear. As there are few wintergreen species in the temperate deciduous forests of eastern North America (Neufeld and Young 2003), it would be interesting to know whether these 2 orchids are a significant food source for M. acrophilus nymphs, which emerge from overwintering at a time when few other palatable green leaves are available on the forest floor. Acknowledgments. We thank Tyler Clabby for his participation in a larger study that led to these observations, Dr. Timothy Forrest for identifying grasshopper specimens, and C. Reed Rossell Jr. for helpful comments on an earlier version of the manuscript. Literature Cited Capinera, J.L., R.D. Scott, and T.J. Walker. 2004. Field Guide to the Grasshoppers, Katydids, and Crickets of the United States. Cornell University Press. Ithaca , NY. 249 pp. Legrand, H.E., Jr., J.A. Ratcliffe, and J.T. Finnegan. 2014. Natural Heritage Program list of the rare animal species of North Carolina, revised 14 May 2015. North Carolina Department of Environment and Natural Resources, Raleigh, NC. 172 pp. Neufeld, H.S., and D.R. Young. 2003. Ecophysiology of the herbaceous layer in temperate deciduous forests. Pp. 38–90, In F.S. Gilliam and M.R. Roberts (Eds.). The Herbaceous Layer in Forests of Eastern North America. Oxford University Press, New York, NY. 408 pp. North American Orchid Conservation Center. 2016. Aplectrum hyemale. Available online at http://goorchids. northamericanorchidcenter.org/species/aplectrum/hyemale/. Accessed 20 September 2016. North Carolina Native Plant Society. 2016. Aplectrum hyemale. Available online at http://ncwildflower. org/plant_galleries/details/aplectrum-hyemale. Accessed 20 September 2016. Otte, D. 2002. Studies of Melanoplus. 1. Review of the Viridipes Group (Acrididae: Melanoplinae). Journal of Orthoptera Research 11:91–118. Richburg, J.A. 2003. Aplectrum hyemale (Muhl. ex Willd.) Nutt. (Puttyroot) conservation and research plan for New England. New England Wild Flower Society, Framingham, MA. 14 pp. Whigham, D.F. 1984. Biomass and nutrient allocation of Tipularia discolor (Orchidaceae). Oikos 42:303–313. Whigham, D.F. 1990. The effect of experimental defoliation on the growth and reproduction of a woodland orchid, Tipularia discolor. Canadian Journal of Botany 68:1812–1816. Whigham, D.F., and M. McWethy. 1980. Studies on the pollination ecology of Tipularia discolor (Orchidaceae). American Journal of Botany 67:550–555. Whigham, D.F., and J. O’Neill. 1988. The importance of predation and small-scale disturbance to two woodland herb species. Pp. 243–252, In M.J.A. Werger, P.J.M. van der Aart, H.J. During, and J.T.A. Verhoeven (Eds.). Plant Form and Vegetation Structure: Adaptation, Plasticity, and Relation to Herbivory. SPB Academic Publishers, The Hague, The Netherlands.