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An additional natural hostplant of Pieris virginiensis (W. H. Edwards) (Pieridae) in Ohio
... Most studies on this species have been conducted on populations throughout New England, Pennsylvania, and Ohio, but the range of P. virginiensis extends throughout the Appalachians southward into Virginia and North Carolina (Mather 1964). The native ephemeral forb Cardamine diphylla is the most common larval host plant of P. virginiensis, but there are also occasional small populations that use Cardamine concatenata, Cardamine dissecta, or Boechera laevigata when C. diphylla is absent (Calhoun and Iftner 1988;Shuey and Peacock 1989). C. diphylla emerges in early April, completes leaf expansion by May, and senesces by early June when the tree canopy begins to shade out the lower understory. ...
In invaded environments, formerly reliable cues might no longer be associated with adaptive outcomes and organisms can become trapped by their evolved responses. The invasion of Alliaria petiolata (garlic mustard) into the native habitat of Pieris virginiensis (West Virginia White) is one such example. Female butterflies oviposit on the invasive plant because it is related to their preferred native host plant Cardamine diphylla (toothwort), but larvae are unable to complete development. We have studied the impact of the A. petiolata invasion on P. virginiensis butterflies in the Southeastern USA by comparing oviposition preference and larval survival on both plants in North Carolina (NC) populations without A. petiolata and West Virginia (WV) populations where A. petiolata is present. Larval survival to the 3rd instar was equally low in both populations when raised on A. petiolata. Mean oviposition preference on the two plants also did not differ between populations. However, we found a seasonal effect on preference between early and late season flights within WV populations. Late season females laid 99% of total eggs on A. petiolata while early season females utilized both host plants. Late season females were also less likely to lay eggs than early season females. This change in preference toward A. petiolata could be driven by the early senescence of C. diphylla and suggests a seasonal component to the impact of A. petiolata. Therefore, the already short flight season of P. virginiensis could become further constrained in invaded populations.
... or Boechera laevigata (Muhl. ex Willd.) when C. diphylla is absent ( Calhoun and Ifter 1988;Shuey and Peacock 1989;Finnell and Lehn 2007). In addition to interactions with larval host plants, P. virginiensis pollinates early springtime herbs in the genera Claytonia, Erythronium, Mertensia, Phlox, Trillium and Viola ( Bess 2005). ...
Pieris virginiensis is a rare, univoltine butterfly that inhabits Eastern deciduous forests and normally uses Cardamine diphylla (Brassicaceae) as its larval host plant. In areas invaded by the European biennial garlic mustard (Alliaria petiolata; Brassicaceae), P. virginiensis females prefer to oviposit on the novel host. When P. virginiensis eggs hatch on A. petiolata, caterpillars often die after only a few days. We investigated how two candidate chemicals, sinigrin and alliarinoside, contributed to P. virginiensis larval mortality.
Sinigrin is the predominant glucosinolate in A. petiolata. Pieris spp. butterflies use the tactile signals of glucosinolates to decide where to oviposit, and Pieris caterpillars possess a special enzyme, the Nitrile Specifier Protein (NSP), which converts the normally toxic glucosinolates into harmless nitriles. We painted sinigrin onto two different acceptable host plants, C. diphylla and Brassica juncea. We found that sinigrin was not the primary reason for neonatal death, but may serve as a feeding deterrent or obstacle to successful development.
Alliarinoside is a chemical unique to A. petiolata that was identified as a feeding deterrent for a related Pieris spp., P. oleracea by Renwick et al. (2001). We painted alliarinoside onto B. oleracea to test the effects on newly hatched P. virginiensis caterpillars. We found that alliarinoside treatment severely reduced survival of P. virginiensis larvae. Alliarinoside may be the primary driver of P. virginiensis larval mortality on the novel host A. petiolata.
... or Boechera laevigata (Muhl. ex Willd.) when C. diphylla is absent (Calhoun and Ifter 1988;Shuey and Peacock 1989;Finnell and Lehn 2007). In addition to interactions with larval host plants, P. virginiensis pollinates early springtime herbs in the genera Claytonia, Erythronium, Mertensia, Phlox, Trillium and Viola (Bess 2005). ...
Alliaria petiolata is a European biennial herb that invades North American forests and has direct negative effects on associated flora and fauna. In some places, A. petiolata has invaded the habitat of Pieris virginiensis, a rare, univoltine butterfly that normally uses native spring ephemeral crucifer hosts. There are occasional observations of P. virginiensis laying eggs on A. petiolata, but the frequency and effects of these “mistake oviposition events” are not yet known. We investigated P. virginiensis oviposition preference through field observations in three locations (NY, OH, PA), and also through laboratory experiments measuring egg deposition of adult females on either a native or invasive crucifer. In addition, we examined neonate larval performance through no-choice feeding assays on both A. petiolata leaves and cabbage leaves painted with A. petiolata leaf extracts. We found that P. virginiensis lays significantly more eggs on the exotic A. petiolata than on its native host Cardamine diphylla in both field and laboratory experiments. Caterpillars fed either A. petiolata leaf tissue or its ethanol extract did not survive to pupation, and most died after only a few days. Continual invasion and persistence of A. petiolata in P. virginiensis habitats may lead to genetic bottlenecking and possibly local extinctions without human intervention.
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