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order Decapoda) and action consequential thereon, pp. 43-58. In Hemming, F. (ed.),
Opinions and declarations rendered by the International Commission on Zoological
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London. 690 pp. Kluk, K. 1802. Zwierz. Hist. Nat. Pocz. Gospod. 4:82. LATREILLE, P. A. 1804. Nouvelle Dictionaire d'Histoire Naturelle 24 (Tab.):185, 199.
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14:108.
Linnaeus, C. 1758. Systema Naturae. 10th ed. 464.
---------- 1767. Systema Naturae. 12th ed. 1(2):757. (Microfiche facsimile of Linnaeus'
personal copy. London. British Museum (Natural History) and the Linnean Society, 1991).
Melville, R. V. & J. D. D. Smith (eds.). 1987. Official lists and indexes of names and works in zoology. International Trust for Zoological Nomenclature and the British Museum (Natural History), London. 209.
Milne Edwards, H. 1830. Ann. Sci. Nat., Paris (1) 19:339.
NEUSTETTER, H. 1929. Nymphalididae: subfam. Heliconiinae. Lepidopterorum Catalogs. 36:1-136.
Ride, W. D. L., C. W. Sabrosky, G. Bernardi & R. V. Melville (eds). 1985. International code of zoological nomenclature. International Trust for Zoological Nomenclature and the British Museum (Natural History), London. 338 pp.
Riffarth, H. 1901. Die Gattung Heliconius Latr.: Neu bearbeitet und Beschreibung neuer Formen. Berl. Entomol. Zeit. 46:25-183.
Seitz, A. 1924. Subfamily: Heliconiinae. Macrolepidoptera of the world: The American Rhopalocera. Alfred Kernen, Stuttgart 5:593-597.
Stichel, H. 1906. Lepidoptera Rhopalocera fam. Nymphalidae subfam. Heliconiinae. Genera Insectorum 37:1-74 (6 plates).
Turner, J. R. G. 1967. Goddess changes sex, or the gender game. Syst. Zool. 16:349-350.
Andrew V. Z. Brower, Section of Ecology and Systematics, Cornell University, Ithaca, New York 14853-2701, USA (current address: Department of Entomology, American Museum of Natural History, Central Park West at 79th St., New York, New York 10024-5192).
Received for publication 15 July 1993; revised and accepted 30 October 1993.
Journal of the Lepidopterists' Society 48(2), 1994, 168-170
NATIVE PIERINE BUTTERFLY (PIERIDAE) ADAPTING TO NATURALIZED CRUCIFER?
Additional key words: Brassicaceae, diet breadth.
Native butterflies encounter naturalized plants related to their hosts as one consequence of Palearctic weeds spreading throughout North America. wSometimes these plants are incorporated into the butterfly diet and permit a longer flight season (e.g., Pieris napi microstriata on watercress: Shapiro 1975; Papilio zelicaon on sweet fennel: Sims 1983, Tong & Shapiro 1989, Shapiro in press). In other cases, females do not lay eggs on the naturalized plant so that it is not used, even though it can support complete larval development (e.g., Colias philodice and crown vetch: Karowe 1990). A third alternative
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is that females lay eggs on naturalized plants, but larvae die before completing development (e.g., Pieris napi oleracea, P. n. marginata and P. wrginiensis on garlic mustard: Bowden 1971; P. n. macdunnoughii and P. occidentalis on pennycress: Chew 1977; P. napi oleracea on winter cress: Chew 1981).
Where naturalized plants are attractive to ovipositing females bul: larvae fail to develop successfully on them, the plants can function as a population sink so that eggs laid on these plants are lost from the population. If appropriate genetic variation exists in the population, selection favors both females that discriminate against the unsuitable plant, and feeding larvae that are able to develop on it successfully (Chew 1977). We report here on a population of P. napi oleracea Harris that may be adapting to a biennial weed of Palearctic origin, garlic mustard, Alliaria petiolata (Bieb.) Cavara & Grande (Brassi-caceae) (nomenclature follows Gleason & Cronquist 1991).
Pieris virginiensis and P. napi oleracea fly together in beech-maple-hemlock woods near Lee and Dalton (Berkshire Co., Massachusetts) and Sandgate (Sandgate Co., Vermont). At Lee, Roger W. Pease, Jr. (RWP) previously observed both species ovipositing on garlic mustard and found eggs and small larvae of P. n. oleracea on this plant in July (RWP in litt. and pers. comm.). Rearing these eggs on garlic mustard produced adults with summer brood P. n. oleracea phenotypes (RWP pers. comm.). Garlic mustard stands are dense and extensive at this locality and large stands of toothwort. Cardamine diphylla (Michx.) A. Wood also are present. Occasional plants of watercress, Rorippa nasturtium-aquaticum (L.) Hayek, and cuckoo-flower, Cardamine pratensis L., also occur. This site is 17 km from the Dalton site, where both butterflies fly together (Chew 1980) and utilize C. diphylla. At Dalton, on 19 August 1993, we observed garlic mustard only in two very small stands near a parking lot; one stand lacked rosettes, indicating that no seeds germinated on this spot during the past spring—a probable indication of recent establishment. To our knowledge, garlic mustard has not been reported previously at the Dalton site. At both sites, toothwort is present above-ground in the spring, but by mid-July its leaves are severely yellowed and unsuitable as Pieris food. By contrast, garlic mustard flowering stalks remain green in mid-July, and rosettes remain green throughout the summer.
We confirmed RWP's observations of P. virginiensis and P. n. oleracea females ovipositing on garlic mustard in 1992 and 1993. On 7 May 1993 we collected a single female P. n. oleracea. We attempted to rear some of this female's offspring on garlic mustard. Of 34 newly hatched first instar larvae reared on this plant, 14 pupated (8 female, 6 male). Pupal weights for both sexes were not significantly different from weights for sibs reared on hare's-ear mustard. However, larval developmental times (days from egg hatch to pupation) differed significantly for individuals reared on garlic mustard compared to sibs reared on hare's-ear mustard (range on garlic mustard = 16-30 d compared to 14-17 d for hare's-ear mustard; mean ± SD for females on garlic mustard = 23.4 ± 3.54 d compared to 15.5 ± 1.64 d on hare's-ear mustard; mean ± SD for males on garlic mustard = 19.0 ± 2.90 d compared to 14.3 ± 0.58 d on hare's-ear mustard). All 14 pupae emerged after 6-8 days. Whether these adults were fertile is not known, because they were then placed in a common cage with sibs reared on hare's-ear mustard. The collective cage produced fertile eggs but we cannot be certain whether any came from individuals reared on garlic mustard.
Garlic mustard is a widely used and highly suitable host of P. napi and many related species in Europe (Bowden 1971, A. Porter in litt.). But previous attempts to rear North American pierines on garlic mustard have failed, usually in the first or second instar (Bowden 1971; our unpubl. data). F1 hybrids between North American and English pierines develop successfully on this plant (Bowden 1971). Our only previous success involved 5 P. n. oleracea (3 females, 2 males) derived from a combined breeding stock from Lee and central Vermont (near Hancock, Hancock Co., Vermont). These individuals took longer to develop from egg hatch to pupation, but their pupal weights were similar compared to other members of the colony reared on hare's-ear mustard.
Recent work on the behavior of ovipositing P. n. oleracea from central Vermont shows that these butterflies are more strongly stimulated by alkenyl glucosinolates such as allyl glucosinolate (sinigrin) than by some other glucosinolates (Chew & Renwick in press). Because allyl glucosinolate is prominent in the glucosinolate profile of garlic mustard
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leaves (Chew, F. S., unpubl. data; Renwick, J. A. A., unpubl. data), this plant's attractiveness to ovipositing P. n. oleracea is not surprising. Individuals that develop successfully on garlic mustard would be able to use extensive stands of this naturalized host in addition to their toothwort host, and the two hosts together presumably could support a larger butterfly population. Whether the observed variation in larval success on garlic mustard is a remnant of genetic heritage from a pierine ancestral to both North American and European P. napi lineages, or whether it is newly arisen in the Berkshire Co., Massachusetts region, is unknown.
We thank R. W. Pease, Jr. for introducing us to P. virginiensis and P. n. oleracea near Lee. We thank R. W. Pease, A. M. Shapiro, and A. Porter for sharing their observations and helpful discussion with us. We thank NSF (IBN-91-08987) and the Arabis Fund for financial support.
Literature Cited
Bowden, S. R. 1971. American white butterflies (Pieridae) and English food-plants. J.
Lepid. Soc. 25:6-12. Chew, F. S. 1977. Coevolution of pierid butterflies and their cruciferous food plants.
II. The distribution of eggs on potential hostplants. Evolution 31:568-579.
---------- 1980. Natural interspecific pairing between Pieris virginiensis and P. napi
oleracea (Pieridae). J. Lepid. Soc. 34:259-260.
---------- 1981. Coexistence and local extinction in two pierid butterflies. Am. Nat. 118:
655-672.
Chew, F. S. & J. A. A. Renwick. in press. Hostplant choice in Pieris butterflies. In Carde, R. T. & W. J. Bell (eds.), Chemical ecology of insects II. Chapman & Hall, New York.
Gleason, H. A. & A. CRONQUIST. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. 2nd ed. New York Bot. Gard., Bronx.
Karowe, D. N. 1990. Predicting host range evolution: Colonization of Coronilla varia by Colias philodice (Lepidoptera: Pieridae). Evolution 44:1637-1647.
Shapiro, A. M. 1971. Occurrence of a latent polyphenism in P. virginiensis (Lepidoptera: Pieridae). Entomol. News 82:13-16.
---------- 1975. The role of watercress (Nasturtium officinale) as a host of native and
introduced pierid butterflies in California. J. Res. Lepid. 14:158-168.
---------- in press. From the mountains to the prairies to the oceans white with foam:
Papilio zelicaon makes itself at home. In Walker, R. B. & A. R. Kruckberg (eds.), Ecogeographical races: Turesson to the present. Am. Assoc. Adv. Sci., Washington, DC.
Sims, S. R. 1983. Inheritance of diapause induction and intensity in Papilio zelicaon. Heredity 51:495-500.
Tong, M. L. & A. M. Shapiro. 1989. Genetic differentiation among California populations of the anise Swallowtail butterfly, Papilio zelicaon lucas. J. Lepid. Soc. 43: 217-228.
A. V. Courant, A. E. Holbrook, E. D. Van der Reijden, and F. S. Chew, Department of Biology, Tufts University, Med ford, Massachusetts 02155, USA.
Received for publication 4 September 1993; revised and accepted 1 January 1994.