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Wolcottia (=Isohydnocera) aegra (Coleoptera: Cleridae): association with grasses (Poaceae), native Spartina spp. and the introduced Eragrostis curvula, and resemblance to co-occurring pseudomyrmecine ants.

Wolcottia aegra (Newman) a narrow, elongate, brown clerid beetle about 4.3 mm long (Fig. 1) was described in the genus Hydnocera and later placed in Isohydnocera (Chapin 1917; Kolibac 1998). Kolibac (1998) synonymized Isohydnocera with Wolcottia, but Opitz (2002) did not follow that synonymy. We follow Kolibac (1998) in recognizing Wolcottia (=Isohydnocera).

Known only from the southeastern United States, Florida, Georgia (Peck & Thomas 1998), Mississippi (Lago et al. 2002), North Carolina (Davis & Gray 1966), and South Carolina (Kirk 1969, 1970), W. aegra generally is not well represented in collections, and its habitat and plant associations are little known. In Florida, Shelford (1963) collected it in Dec in semidry prairies of tall sawgrass (Cladium mariscus ssp. jamaicense (Crantz) Kiikenth.; Cyperaceae) marsh near Miami, and Cuda et al. (2007) rarely encountered it during a survey of insects associated with the adventive torpedo grass (Panicum repens L.) near Lake Okeechobee. In Mississippi, an adult was swept from a saltgrass (Distichlis) meadow and another from Schrankia (Fabaceae; probably an incidental occurrence) on Point Clear Island (Lago et al. 2002). The beetle was found in North Carolina from May to Oct on Spartina patens (Ait.) Muhl. in salt marshes in Carteret County (Davis & Gray 1966). In South Carolina, Kirk (1970) swept W. aegra from "salt marsh grass" on Hunting Island, and 5 adults were collected at the Belle Baruch Marine Field Laboratory of the Hobcaw Barony, east of Geogetown, from late Apr to early May 2004, and another adult was taken at the same locality in mid-Sep 2007 (S. M. Paiero, Dept. Environmental Biology, University of Guelph, personal communication).


Here, we report adults from 2 native grasses, sand cordgrass (Spartina bakeri Merr.) and salt-meadow cordgrass (S. patens), and an introduced African species, weeping lovegrass (Eragrostis curuula (Schrad.) Nees), and note the beetle's resemblance to syntopic pseudomyrmecine ants. From 2002 to 2009, an ax handle was used to beat the crowns of the 3 bunchgrass species into a shallow, short-handled net. Voucher specimens of the beetle are deposited in the Clemson University Arthropod Collection (CUAC) and National Museum of Natural History, Smithsonian Institution, Washington, DC; ants are deposited in the CUAC.

We collected adults of W. aegra in Florida, Georgia, and South Carolina from grasses at 14 sites (28 collections) during Jan, Feb, Mar, Apr, Jun, Aug, Oct, and Dec (Table 1). Of the 182 adults we collected, 7 were on S. patens and 71 were beaten from crowns of the more architecturally complex S. bakeri, which grows in dense clumps. The remaining 104 adults of W. aegra were collected in Florida from weeping lovegrass (E. curuula), an African bunchgrass used in the Southeast mainly for erosion control and slope stabilization. Wolcottia aegra can be included among the little-known or seldom-collected native insects that have become associated with weeping lovegrass (Wheeler 1999, 2003; Wilson &Wheeler 2005). We did not observe adults during the sampling of other coastal spartinas, smooth cordgrass (S. alterniflora Loisel.), and big cordgrass (S. cynosuroides (L.) Roth).

At one site, a highway embankment northwest of Loughman in Lake County, Florida, E. curuula and S. bakeri co-occurred. During about 20 min of sampling in mid-Mar 2007, split about evenly between the 2 grass species, 22 adults of the clerid were taken on E. curuula and 1 on S. bakeri.

In salt marshes, Davis (1978) considered W. aegra not abundant on, but "fairly characteristic" of, S. patens, a grass on which we found relatively few adults One could infer from the scattered literature on this clerid that it is restricted to coastal marshes. We did find adults on S. patens in brackish flats and salt marshes and on S. bakeri in brackish and freshwater marshes along the coast. In Florida, however, we also found W. aegra in native populations and landscape plantings of S. bakeri in the Lake Wales Ridge in the center of the peninsula, as well as inland plantings of weeping lovegrass.

We did not find clerid larvae on any of the 3 grass species. Trophic habits of other hydnocerine clerids are little known, but W. aegra has been assumed to be predacious (Davis & Gray 1966). Larvae of 2 other species of Wolcottia (=Isohydnocera) prey on endophages such as gall-inducing and stem-boring insects (Sabrosky 1934; Clausen 1940; Knull 1951). Potential prey of W. aegra on S. bakeri are stem borers known from other spartinas (Stiling & Strong 1984; White et al. 2005), including languriid beetles (Ward et al. 2007). We observed adults of Languria mozardi Latreille in several stands of weeping lovegrass inhabited by W. aegra.

Numerous species of Cleridae mimic aculeate Hymenoptera such as ants. Most hydnocerine clerids are generalized ant mimics, including species currently placed in Wolcottia (Mawdsley 1994).

We collected adults of W. aegra with the similarly colored pseudomyrmecine ants Pseudomyrmex pallidus (F. Smith) and P. seminole Ward (Fig. 1) on E. curuula and S. bakeri. After the presence of pseudomyrmecines began to be recorded in field notes (21 Mar 2007), 16 of 23 collections of the clerid also included one or both species of Pseudomyrmex. The clerid's resemblance to pseudomyrmecines was enhanced by an erratic antlike movement. Clerid males were about the same size as worker ants, whereas the larger females were about the same size as dealated queens. We found P. pallidus in Florida and South Carolina and P. seminole in Florida, Georgia, and South Carolina. Pseudomyrmex pallidus nests preferentially in stems of tall grasses (Van Pelt 1958), including salt marsh grasses (Carter 1962). Sympatric assemblages characterize the P. pallidus group. Pseudomyrmex seminole co-occurs with P. pallidus and might be a facultative social parasite of that species; it nests in dead stems of grasses, such as Andropogon spp. (Ward 1985).

Although the adult of W. aegra exhibits an antlike habitus, use of the more neutral term myrmecomorphy might be preferable to ant mimicry in the absence of data demonstrating that a resemblance to ants enhances survivorship of the clerid. Experimental studies documenting ant mimicry by W. aegra, and examining the possibility that adults are chemically protected, as are certain other myrmecomorphic Cleridae (Mawdsley 2002), are needed. Studies on bionomics of the clerid also are needed, especially information on larval feeding habits. Also desirable would be to determine whether ant densities on native Spartina species differ from those on the adventive weeping lovegrass and whether stems of these grasses differ in their suitability as nesting sites for pseudomyrmecines.

We thank Steven M. Paiero (Dept. of Environmental Biology, University of Guelph, Guelph, Ontario) for allowing us to refer to his collections of the clerid in South Carolina, and David R. Smith (Systematic Entomology Lab., USDA, ARS, Washington, DC) for identifying ants.


Wolcottia (=Isohydnocera) aegra, an antlike or myrmecomorphic clerid beetle typically not well represented in collections, was associated with grasses at 14 sites (28 collections) in Florida, Georgia, and South Carolina. Adults (n -182) were beaten from crowns of bunchgrasses; the introduced South African weeping lovegrass, Eragrostis curuula (n = 104), along highways; sand cordgrass, Spartina bakeri (n = 71), in coastal brackish and freshwater marshes and inland swales, as well as in landscape plantings; and saltmeadow cordgrass, S. patens (n = 7), in brackish flats and salt marshes. The ants Pseudomyrmex pallidus and P. seminole (Formicidae: Pseudomyrmecinae) co-occurred with the clerid.


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Department of Entomology, Soils, and Plant Sciences, Clemson University, Clemson, SC 29634-031
CAROLINA, 2002-2009.

State               County             Locality

Florida           Duval        E of Eastport

Florida           Hamilton     NW of Jennings

Florida           Hamilton     NW of Jennings

Florida           Highlands    NW of Avon Park

Florida           Highlands    NW of Avon Park

Florida           Highlands    NW of Avon Park

Florida           Highlands    NW of Avon Park

Florida           Highlands    NW of Avon Park

Florida           Lake         NW of Loughman

Florida           Lake         NW of Loughman

Florida           Lake         NW of Loughman

Florida           Lake         NW of Loughman
Florida           Lake         NW of Loughman

Florida           Lake         NW of Loughman

Florida           Lake         Altoona

Florida           Lake         S of Clermont

Florida           Lake         S of Clermont

Florida           Lake         S of Clermont

Florida           Lake         S of Clermont

Florida           Nassau       NW of Yulee

Florida           Polk         NW of Loughman

Georgia           Glynn        WSW of Brunswick

Georgia           McIntosh     N of South Newport

South Carolina    Charleston   NW of Edisto Island

South Carolina    Colleton     N of Bennetts Pt.

South Carolina    Colleton     N of Bennetts Pt.

South Carolina    Colleton     Bear Island WMA

South Carolina    Colleton     Bear Island WMA

State                   Date         of adults    Plant species (1)

Florida                27-IV-2008        5        Spartina bakeri

Florida               20-III-2007        1        * Spartina bakeri

Florida                25-IV-2008        9        * Spartina bakeri

Florida               23-III-2007        5        Spartina bakeri

Florida               14-XII-2007        1        Spartina bakeri

Florida               12-III-2008       15        Spartina bakeri

Florida                  4-I-2009        3        Spartina bakeri

Florida                28-II-2009        5        Spartina bakeri

Florida                24-II-2002        3        * Eragrostis curvula

Florida               21-III-2002        6        * Eragrostis curvula

Florida              10-VIII-2002        1        * Eragrostis curvula

Florida              22-III- 2007        5        * Eragrostis curvula

Florida           11, 12-III-2008       23        * Eragrostis curvula

Florida                28-II-2009       12        * Eragrostis curvula

Florida               11-III-2008       15        * Eragrostis curvula

Florida               11-III-2008       17        * Eragrostis curvula

Florida               22-III-2007       13        * Eragrostis curvula

Florida                  3-I-2009        1        * Eragrostis curvula

Florida                28-II-2009        8        * Eragrostis curvula

Florida                27-IV-2008        2        * Spartina bakeri

Florida                 2-VI-2002        1        * Eragrostis curvula

Georgia                27-IV-2008        3        Spartina bakeri

Georgia                27-IV-2008        6        Spartina bakeri

South Carolina         19-IV-2008        3        Spartina patens

South Carolina         19-IV-2008        5        Spartina bakeri

South Carolina         19-IV-2008        1        Spartina bakeri

South Carolina         19-IV-2008       12        Spartina bakeri
                                                  S. patens

South Carolina           4-X-2008        1        Spartina patens

(1) Asterisks indicate landscape or ornamental plantings.
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Author:Wheeler, A.G., Jr.; Stocks, Ian C.
Publication:Florida Entomologist
Article Type:Report
Geographic Code:1USA
Date:Dec 1, 2009
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