Sumitrosis inaequalis (Weber)

Eiseman, Charles S., 2014, New Host Records and Other Notes on North American Leaf-Mining Chrysomelidae (Coleoptera), The Coleopterists Bulletin 68 (3), pp. 351-359 : 356-357

Sumitrosis inaequalis (Weber)

Ford and Cavey (1985) stated that “In Odontota ,

Sumitrosis , Microrhopala , and Baliosus , eggs are laid in clusters of 3–7 on a leaf or leaflet.” Wheeler and Snook (1986) reported that this statement is inaccurate for Sumitrosis rosea (Weber) “and may not hold for any member of the genus.” They describe how females of that species instead gnaw into the upper leaf surface and deposit a single egg in the resulting wound (just as observed in Stenopodius texanus ). Based on a rearing of S. inaequalis from Eurybia divaricata (L.) G.L. Nesom ( Asteraceae ) in Pelham, Massachusetts, I can confirm that oviposition in this species is identical, except in this case the wound and egg were in the underside of the leaf, with a corresponding brown, necrotic spot on the upper leaf surface ( Fig. 13 ). The egg was similar in size to that of S. rosea , about 0.8 mm by 0.5 mm. I collected the mine on 21 June 2013, and the adult emerged by 8 July, having completed its development in the original leaf. The egg situation was the same in a mine on Symphyotrichum cordifolium (L.) G.L. Nesom ( Asteraceae ) from which I reared S. inaequalis taken in Burlington, Vermont in July 2012.

The two hosts noted above are among the known larval hosts of S. inaequalis ( Staines 2012) , but I have also reared this beetle from a new host genus. On 22 July 2012, an adult emerged from a mine in Ambrosia artemisiifolia L. ( Asteraceae ) I had collected on 11 July in Northfield, Massachusetts. The mine was found among several superficially similar blotches from which I reared Calycomyza platyptera (Thomson) (Agromyzidae) . The most obvious difference was that the leaf containing the beetle mine lacked the stippling that was invariably present on the other leaves, caused by the female flies puncturing the epidermis with their ovipositors to feed on plant juices. On close inspection, the characteristic strips of frass were visible in the beetle mine, compared with the more irregular or indistinct deposits in the fly mines; also, whereas the newer portions of the fly mines were whitish, the beetle mine was more uniformly brown.

Figures

Figs. 13–17. 13) Young Sumitrosis inaequalis larva mining in white wood aster (Eurybia divaricata) leaf; egg at upper right; 14) Mine of Sumitrosis rosea in leaf of Oriental bittersweet (Celastrus orbiculatus); 15) Detail of presumed Dibolia chelones mine in leaf of white turtlehead (Chelone glabra), showing squiggly strings of frass; 16) Leaf of climbing false buckwheat (Fallopia scandens) mined by four Mantura floridana larvae; 17) Mines of Monoxia angularis in Atriplex prostrata leaf.