Microrhopala xerene (Newman)

Eiseman, Charles S., Feldman, Tracy S. & Palmer, Michael W., 2024, New larval host records, parasitoid records, and DNA barcoding data for North American leaf-mining leaf beetles (Coleoptera: Chrysomeloidea), Zootaxa 5549 (1), pp. 1-60 : 25

Microrhopala xerene (Newman)

( Figs. 14 , 63–64 , 141)

Reared specimens. MASSACHUSETTS: Essex Co., Rockport , 42.682890, -70.623997, 11.viii.2019, em. 26.viii– 5.ix.2019, C.S. Eiseman & J.A. Blyth, ex Symphyotrichum cordifolium , # CSE5854 (6 adults, MLBM); Franklin Co., Ashfield, 2.ix.2014, em. 19.ix.2014, C.S. Eiseman, ex Symphyotrichum , # CSE1388 (1 adult, ZFMK) .

Hosts. Asteraceae : Boltonia asteroides (L.) L’Hér., Sericocarpus asteroides (L.) Britton, Sterns & Poggenb., Solidago caesia L., S. canadensis L., S. juncea Aiton , Symphyotrichum chilense (Nees) G.L. Nesom , S. cordifolium (L.) G.L. Nesom, S. lanceolatum (Willd.) G.L. Nesom , S. novae-angliae (L.) G.L. Nesom, S. patens (Aiton) G.L. Nesom , S. puniceum (L.) Á. Löve & D. Löve ( Chittenden 1902; Clark 1983; Clark et al. 2004). Possibly not all of the Symphyotrichum records refer to larvae, but this genus is the preferred host in our experience and according to Clark (1983).

The record of Doellingeria umbellata (Mill.) Nees given by Eiseman (2015) and repeated by Staines (2015) referred to a failed rearing; the mine (including egg placement) was consistent with those from which we have since reared M. excavata on the same host, and the larva had the sclerotized body parts dark brown to black rather than testaceous as should be the case for M. xerene according to Ford & Cavey (1985), so we consider this record to represent a misidentification of M. excavata .

Goeden & Ricker (1974, 1976c) reported Microrhopala xerene from Ambrosia chamissonis Greene and A. psilostachya DC. in southern California. Although these records were repeated by Clark et al. (2004) and Staines (2015), M. xerene does not occur in California and the records in fact refer to M. rubrolineata (Mannerheim) ( Staines 2015) .

Biology. The leaf mines ( Figs. 63–64 ) were described by Chittenden (1902) and Eiseman (2015). Eggs are deposited singly or in clusters in pits chewed on the lower leaf surface, typically away from the leaf margin, and coated in dark, liquid excrement as in other Microrhopala species ( Fig. 14 ). Chittenden (1902) reported one instance of an egg cluster being deposited on the upper leaf surface. Pupation takes place in a circular, blisterlike swelling in which the ceiling and floor are thickly plastered with long strips of frass.

Parasitoids. All of the parasitoid records for Microrhopala xerene are derived from Chittenden (1902), and some of them are problematic. The type series of Oenonogastra microrhopalae (Ashmead) ( Braconidae : Alysiinae ) was composed of swept specimens plus one that Chittenden stated was “reared July 6 from a white cocoon in a mine of this beetle” ( Ashmead 1896). Evidently some mistake was made, since members of this subfamily are Diptera specialists that pupate within the host puparia; the other three recorded hosts of this wasp are all agromyzid flies ( Yu 2012). Chittenden reported “ Eurytoma albitarsis Ashm. ” from mines in Solidago , but no such species was ever described, and we have yet to rear a eurytomid from any leafminer. Chittenden’s record of Closterocerus trifasciatus Westwood ( Eulophidae ) from a mine in Sericocarpus asteroides was not repeated by Hansson (1994), but it is not particularly suspicious since C. trifasciatus is extremely polyphagous. Chittenden himself expressed some doubt about the origin of his single specimen of Zagrammosoma multilineatum Ashmead ( Eulophidae ), based on the fact that this species was known to parasitize microlepidoptera and had not been observed to attack beetles. Given that we have reared Z. multilineatum from Odontota horni (below) and it has also been reared from a leaf-mining buprestid ( Perry & Heraty 2021), M. xerene may well have been the true host of Chittenden’s wasp. Finally, Baryscapus microrhopalae (Ashmead) ( Eulophidae ) was described from specimens Chittenden reared from dried larval skins of M. xerene ( Ashmead 1896) .

Figures

FIGURES 1–22. Eggs of Chalepini spp.; 1: Anisostena californica; 2: A. lecontii; 3: Baliosus californicus; 4: B. nervosus; 5: same; 6: Brachycoryna hardyi (photo by E. LoPresti); 7: B. pumila; 8: Chalepus bicolor; 9: C. walshii walshii; 10: Glyphuroplata pluto; 11: Microrhopala excavata excavata; 12: M. laetula; 13: M. vittata; 14: M. xerene; 15: Odontota dorsalis; 16: O. floridana; 17: O. horni (top view); 18: same (side view); 19: O. scapularis; 20: Sumitrosis ancoroides; 21: S. inaequalis; 22: S. rosea.

FIGURES 58–64. Leaf mines of Microrhopala spp.; 58: M. laetula on Silphium laciniatum, with excrement-covered egg at far right; 59: other side of same leaf; 60: M. laetula on Silphium integrifolium× perfoliatum; 61: M. vittata on Solidago sp.; 62: M. vittata on Solidago rugosa; 63: M. xerene on Symphyotrichum cordifolium; 64: same.