OCCURRENCE OF A LATENT POLYPHENISM IN PIERIS VIRGINIENSIS (LEPIDOPTERA: PIERIDAE) 1 Arthur M. Shapiro 2 3 "Seasonal polymorphisms" are well-known in insects of several orders. They are better called polyphenisms to emphasize the lack of genetic differences among the "morphs" ( phenotypes ) , which are pro-duced by developmental switch mechanisms under environmental control. The control mechanisms for the seasonal polyphenisms of two Nearctic Pieris, P. protodice Boisduval and LeConte and P. napi olcracea Harris, have recently been shown to be photoperiodic (Sha-piro, 1968; Oliver, 1970). (These belong to different species-groups or subgenera.) This is known to be true also for two Palaearctic stocks of the P. napi group, P. n. napi from England and P. "adal-winda" from northern Scotland and Orkney (Shapiro, unpublished data). This paper reports a hitherto unsuspected polyphenism in an-other member of the napi group, P. virginiensis Edwards. Throughout its range, P. virginiensis is believed to be strictly uni-voltine although the partly sympatric, closely related P. n. oleracea is trivoltine in the overlap zone. Forbes ( 1960 ) mentions a "rare second brood" of P. virginiensis at the southern end of its range, but no speci-men data are cited. The normal phenotype of P. virginiensis is similar to the vernal phenotype of P. n. oleracea, but has the vein-lines less in-tensely dark and contrasting. In long series some variation in the in-tensity of the pattern is evident, but at least traces are always present. 'Accepted for publication: November 29, 1970 [3.0083]. 2 Division of Science and Engineering, Richmond College, 130 Stuyvesant Place, Staten Island, NY 10301. 3 Thanks are due Mr. George Patterson of Wellsboro, Pa. for providing access to a population of P. vir^inicn.sis, and to Mrs. Adrienne R. Shapiro and Mr. Frank Slansky for their help in the field. Ent. News, 82: 13-16, 1971 13
BioStor
