Aflexia rubranura (DeLong, 1935)
Red-tailed Prairie Leafhopper
Basis for Listing
The Red-tailed Prairie Leafhopper (Aflexia rubranura) is endemic to the tallgrass prairie of the western Great Lakes basin and oak savanna from Illinois to Manitoba, and it is limited to small patches throughout its range. This species is an obligate to its host plant, Sporobolus heterolepis (prairie dropseed) and is usually found only in relatively large mature stands of this plant (>20 tussocks). Surveys of most of Minnesota’s better-quality prairie remnants in the 1990s found this species in only a small number of scattered locations (Prairie Parkland and Eastern Broadleaf Forest provinces), indicating that it is quite rare in the state.
All of the known populations of the Red-tailed Prairie Leafhopper in Minnesota are on land that is protected by government or private conservation ownership. However, in addition to protection from destructive activities, prairies require active management to suppress nonnative invasive species and to prevent the encroachment of trees and eventual succession to woodland. The principal tool for this purpose is prescribed fire and this, in itself, poses some threat to the persistence of this species in remnant habitat patches, especially small ones. In most cases, extirpation would not be reversed by recolonization, since prairie remnants are too far apart in an inhospitable agricultural landscape for this flightless species. Given its rarity, as well as the loss, degradation, and fragmentation of habitat, the Red-tailed Prairie Leafhopper was listed as a species of special concern in 1996.
The Red-tailed Prairie Leafhopper is a small, less than 4.0 mm (0.16 in.) long, flightless insect, with wings reduced to small pads that leave most abdominal segments exposed. It is yellowish in color and has a distinctive, dark, ladderlike marking extended down the middle of its head and thorax. Males have a red spot on either side of their ninth abdominal segment ('red-tailed'). Fully winged forms of this species have been reported, mainly from a spring brood found only in Illinois, but appear to be very rare elsewhere (<0.5%).
In Minnesota, the Red-tailed Prairie Leafhopper is found predominantly in dry hill prairie and dry bedrock bluff prairie (less frequently in mesic prairie) in which its host plant, priaire dropseed, is common.
Biology / Life History
The Red-tailed Prairie Leafhopper completes a single generation per year in Minnesota, with the adult stage being present from July to early August. All stages of the life cycle live on the above-ground parts of ther host plant. Females insert their eggs into the stems of prairie dropseed in late summer, where they remain dormant until spring, probably hatching in late May. Nymphs feed on the phloem sap of prairie dropseed and undergo five molts before reaching the adult stage in mid-summer.
Conservation / Management
The small number of locations for this species and the apparent isolation of the populations due to past habitat loss, are the primary threats facing the Red-tailed Prairie Leafhopper in Minnesota. This is aggravated by continuing prairie habitat destruction. Any habitat that is not protected by permanent dedication for conservation is at risk of destruction. Small colonies of the leafhopper are vulnerable to extirpation mainly as a result of human caused events such as insecticide application and drift from neighboring agricultural areas, dumping in 'wasteland', and limestone mining as well as from the vagaries of normal population processes (genetic bottlenecks). Because this species of leafhopper is a flightless insect, its dispersal capabilities are limited. The isolation of the current colonies in a landscape of non-habitat suggests that immigration is unlikely to help sustain colonies or to reestablish them in suitable habitat after extirpation events.
Even where protected, prairie in Minnesota is strongly susceptible to woodland encroachment (succession). Invasion by nonnative herbaceous species such as smooth brome (Bromus inermis) and leafy spurge (Euphorbia virgata) is also a serious threat. Prescribed burning to replicate the natural fire regime that created and maintained the tallgrass prairie is the usual management tool for preventing succession and for suppressing nonnative species. That said, the Red-tailed Prairie Leafhopper is sensitive to prescribed burns, and full population recovery can take 2-4 years (Hamilton 2014). Dormancy in the egg stage, as well as the fact that eggs are laid above ground on host plants, makes this species particularly vulnerable to fall and early spring burns. Accordingly, the use of prescribed fire as a habitat management tool must be judicious (Hamilton 2014). A site needs to be subdivided and the units burned in a rotation that leaves enough habitat containing prairie dropseed unburned to assure population survival and recolonization of burned areas between burns. The prescribed burning of any given area should be several years apart, which may be difficult for small sites. The Red-tailed Prairie Leafhopper can be negatively affected by grazing, as dropseed has been shown to decrease when subjected to prolonged heavy grazing. Mowing, however, has not been shown to have a negative effect on this species and can be used to reduce woody plant encroachment on sites known to harbor Red-tailed Prairie Leafhoppers.
Conservation Efforts in Minnesota
All known populations of this species in Minnesota occur in prairies that are partly or completely protected by the Minnesota Department of Natural Resources (MN DNR) as Scientific and Natural Areas or State Parks; by the U.S. Fish and Wildlife Service (USFWS) as Waterfowl Production Areas; by The Nature Conservancy; or by Clay County. Information about known occurrences of this species is available to land managers, most of whom are knowledgeable about the potential negative impacts of prescribed burning on the arthropod fauna of prairies and follow guidelines to ameliorate threats. There has been an effort to educate all land managers in this regard.
An extensive survey of Minnesota’s prairie remnants was completed in the 1990s, and the information about occurrences of the Red-tailed Prairie Leafhopper is incorporated into the MN DNR's Natural Heritage Information System database. These data are routinely consulted for environmental review, which helps in preventing negative impacts to the species. However, very little survey or monitoring for this leafhopper has been conducted in Minnesota since the 1990's and remedying this is an important task if conservation of this species is to be successful.
References and Additional Information
Hamilton, K. G. A. 1993. Survey for the Red-tailed Leafhopper Aflexia rubranura (DeLong) (Rhynchota: Homoptera: Cicadellidae). Preliminary report submitted to the Minnesota Department of Natural Resources. 7 pp. + Figures.
Hamilton, K. G. A. 1995. Evaluation of Leafhoppers and their relatives (Insecta: Homoptera: Auchenorrhyncha) as indicators of prairie preserve quality. Pages 211-226 in Proceedings of the 14th Annual North American Prairie Conference.
Hamilton, K. G. A. 2014. Canadian grasslands and their endemic leafhoppers (Hemiptera: Auchenorrhyncha: Cicadellidae). Pages 311-345 in H. A. Carcamo and D. J. Giberson, editors. Arthropods of Canadian Grasslands. Volume 3. Biodiversity and Systematics Part 1. Biological Survey of Canada, Ottawa, Ontario.