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Use of Two Oviposition Plants in Populations of Euphydryas phaeton Drury (Nymphalidae)

Journal of the Lepidopterists’ Society
67(4), 2013, xx–xx
Additional key words: Baltimore Checkerspot, iridoid glycosides, Vermont
The Baltimore Checkerspot, Euphydryas phaeton
Drury (Nymphalidae: Melitaeini), is a univoltine species
that ranges from Georgia in the south, north to Maine
and southern Canada and west to Kansas (Scudder
1889; Masters 1968; Harris 1972). Its native host plant is
White Turtlehead, Chelone glabra L. (Plantaginaceae),
a denizen of marshy, wetland habitats. In the Ozarks,
another subspecies, E. phaeton ozarkae Masters, was
described as somewhat different in appearance and
using the oviposition plant Aureolaria flava (L.) Farw.
(Orobanchaceae) (Masters 1968). Just over 30 years ago,
a third oviposition plant was described for E. phaeton,
the introduced weed, Ribwort or Narrow-leaved
Plantain, Plantago lanceolata L. (Plantaginaceae)
(Stamp 1979). Plantago lanceolata was introduced into
North America about 200 years ago (Cavers et al. 1980)
and has been incorporated into the diets of many native
North American herbivores (Robinson et al. 2002).
These three different species of oviposition plants are
united by the presence of a particular group of plant
chemical compounds, the iridoid glycosides (Bowers et
al. 1992; Belofsky et al. 1989). Indeed all host plants of
E. phaeton contain iridoid glycosides (Bowers 1980;
Bowers et al. 1992).
Euphydryas phaeton has been declining in numbers
in many areas such as Maryland and Rhode Island
(Durkin 2009); however, in Vermont, there are many
healthy colonies. Specifically, the recent Vermont
Butterfly Atlas Project has documented E. phaeton
populations at nearly 200 sites (McFarland and
Zahendra 2010). Furthermore, the use of Plantago
lanceolata has allowed some populations to get
extremely large; for example, a recent survey of adults
from a population on June 19, 2010, in Bristol, Rhode
Island, in a field of approximately seven acres, revealed
a population estimate of over 3,200 individuals of E.
phaeton (4th of July butterfly count Rhode Island,
2010). A careful search of this site and surrounding
areas revealed no evidence of C. glabra. More recently,
during the 2012 butterfly count in Rhode Island,
another large population (over 1000 individuals
counted) was located on private land near Little
Compton (2012 4th of July butterfly count Rhode
Island, 2012).
Typically, only a single plant species is used as an
oviposition plant by a single population of Baltimore
Checkerspots, although post-diapause larvae may feed
on a variety of plant species, including Penstemon
(Plantaginaceae), Ash (Fraxinus, Oleaceae), Viburnum
(Adoxaceae), false foxglove (Aureolaria) and
honeysuckle (Lonicera, Caprifoliaceae). For example, in
New York (Stamp 1979) and Rhode Island (Bowers and
Schmitt 2013), populations of E. phaeton use solely P.
lanceolata for both oviposition and larval feeding. Other
populations using exclusively P. lanceolata also likely
occur. Most populations, however, still use C. glabra as
the sole oviposition plant.
Here we report the occurrence of two populations in
Vermont that use both C. glabra and P. lanceolata as
oviposition plants at the same sites (Figures 1 and 2). At
both sites, ovipositing E. phaeton females were observed
using both plant species on the same day (although we
did not follow individual females) in 2011 and 2012
(Figure 1 and 2). The two sites were 1) Clark,
Washington County (Figure 1); 2) Connor, Washington
County (Figure 2). There are likely to be other E.
phaeton populations that use both species for oviposition
as well because many Vermont wetlands where C. glabra
occurs are located in or near agricultural landscapes,
where P. lanceolata is a very common weed of old fields,
hay fields and roadsides. Recent studies of E. phaeton in
Massachusetts indicate that populations using both host
plant species as oviposition sites may be relatively
common (G. Breed, E. Crone, personal communication;
h t t p : / / w w w. b u t t e r fl i e s o f m a s s a c h u s e t t s . n e t /
Use of these two host plant species for oviposition by
a single E. phaeton population may have important
consequences for those populations. For example, in
the two populations we studied, there is likely to be
strong selection against oviposition on P. lanceolata:
haying operations destroyed all egg masses we detected
on P. lanceolata. The P. lanceolata plants we observed
occurred almost exclusively in hayfields and these fields
may be cut two or more times in a single summer,
depending on grass growth. Early season (i.e., June)
haying kills post-diapause late instar larvae and pupae,
when Plantago is a common food plant; while later
season haying could kill adults, egg masses, and
prediapause larvae. Because the native host plant, C.
glabra, often occurs near farm fields, use of this non-
native, alternative oviposition host by checkerspots may
be relatively common. There may be other effects on E.
phaeton populations as well. For example, specialist
parasitoids such as Cotesia euphydryidis (Muesebeck)
(Braconidae) and Benjaminia euphydryadis Vierick
(Ichneumonidae) often search for hosts on larval webs
of E. phaeton (Stamp 1982). These webs may be much
less conspicuous when they occur on P. lanceolata
because of the low stature of this species compared to
C. glabra, making them more difficult for parasitoids to
find. Thus larvae from egg masses on P. lanceolata may
better escape parasitoids. Furthermore, larval feeding
on these two different host plant species may also affect
palatability of both larvae and adults. When reared on P.
lanceolata, larvae and adults contain two iridoid
glycosides, aucubin and catalpol, whereas those reared
on C. glabra contain almost exclusively catalpol (Bowers
et al. 1992). Feeding experiments with birds showed
that the C. glabra-reared individuals are much less
palatable than those reared on P. lanceolata (Bowers
1980); thus use of P. lanceolata may affect this important
chemical defense in this species.
In conclusion, use of both the native C. glabra and
the introduced P. lanceolata in individual populations of
E. phaeton may have important consequences for these
insects. As wetlands where C. glabra is found become
less common and agriculture and disturbance become
more common, use of P. lanceolata may increase in this
butterfly, with multiple and potentially long-term effects
on its populations.
Thanks to E. Crone and G. Breed for their observations on
Massachusetts E. phaeton populations.
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M. DEANE BOWERS (corresponding author;, Museum of Natural
History and Department of Ecology and Evolutionary
Biology, UCB 334, University of Colorado, Boulder
Colorado 80309, USA; LEIF L. RICHARDSON,
Department of Biology, Dartmouth College, Hanover,
NH 03755, USA
Submitted for publication 5 February 2013; revised and
accepted 3 May 2013.
FIG. 1
. Egg masses from the Clark site (East Montpelier
County, Vermont). A) Egg mass on C. glabra from this site; B)
egg mass on P. lanceolata from this site. Photographs taken on
July 11, 2011.
FIG.2. Egg masses from the Connor site (East Montpelier
County, Vermont). A) egg mass on C. glabra from this site; B)
egg mass on P. lanceolata from this site. Photographs taken on
July 18, 2011.
... Here, we evaluate the effects of summer and winter heatwaves on the performance of a wetland, oligophagous butterfly, the Baltimore Checkerspot (Euphydryas phaeton phaeton, Drury Nymphalidae: Melitaeini). While northern populations of E. p. phaeton are stable (Bowers and Richardson, 2013), severe declines have been documented in the southern edge, where it is considered endangered (Durkin, 2009;Frye et al., 2013). Because E. p. phaeton have only one generation per year, temperature regimes experienced by each ontogenetic stage differ drastically (Figure 1). ...
... (Smooth Yellow Foxglove, Orobanchaceae, (Robertson, 2015). The incorporation of P. lanceolata to E. p. phaeton's diet has allowed for colony persistence in areas where C. glabra is absent or disappearing (Bowers and Richardson, 2013); however, feeding on P. lanceolata has some potential costs including higher predation risk due to enhanced palatability to birds (Bowers, 1980), lower growth rate and food efficiency conversion (Bowers et al., 1992) and the risk of death by haying due to grass management practices (Bowers and Richardson, 2013). Herbivore host preferences do not necessarily track foliage quality, as generalists often use hosts according to their relative abundance and not their nutritional value (Mason et al., 2011). ...
... (Smooth Yellow Foxglove, Orobanchaceae, (Robertson, 2015). The incorporation of P. lanceolata to E. p. phaeton's diet has allowed for colony persistence in areas where C. glabra is absent or disappearing (Bowers and Richardson, 2013); however, feeding on P. lanceolata has some potential costs including higher predation risk due to enhanced palatability to birds (Bowers, 1980), lower growth rate and food efficiency conversion (Bowers et al., 1992) and the risk of death by haying due to grass management practices (Bowers and Richardson, 2013). Herbivore host preferences do not necessarily track foliage quality, as generalists often use hosts according to their relative abundance and not their nutritional value (Mason et al., 2011). ...
Full-text available
Disruptive effects of climate change include range shifts, phenological mismatches among consumers and producers, and population declines. While these biological alterations have been widely documented, studies identifying specific mechanisms linking climate change to population declines are scarce. Extreme events, such as heatwaves can have devastating effects on living organisms and are increasing in frequency as Earth warms. Hence, understanding the effects of heatwaves on insects is necessary to inform conservation efforts and to develop predictions of population dynamics under future climate scenarios. Here, we experimentally evaluated the effects of heatwaves on the survival and phenology of the Baltimore Checkerspot (Euphydryas phaeton phaeton), a wetland butterfly with imperiled populations that has incorporated a novel host. We performed laboratory manipulations (implementing realistic temperature regimes) to assess the effect of heatwaves during summer and winter on the survival and phenology of E. p. phaeton. In addition, we analyzed historical temperature records to quantify the incidence of heatwaves within E. p. phaeton's range to assess their potential role in the decline of southeastern populations. We found that winter heatwaves with maximum temperatures of 20°C can have more devastating effects on survival than summer heatwaves (up to 41°C). Eggs endured acute heat stress during summer with no significant effects on phenology and survival; similarly, pre-overwintering larvae were robust to heatwave exposure, as only the most intense heatwave treatment reduced their survival (37% reduction compared to control conditions). By contrast, dormant larvae were the most vulnerable stage, as they lost from 2 to 6% of their body mass after a three-day summer heatwave. Furthermore, their exposure to winter heatwaves resulted in 75 to 100% mortality. Feeding on the native host provided higher resilience under thermal stress than feeding on the invasive, recently acquired host. Finally, both heatwave incidence and severity have increased in the southern range of E. p. phaeton in the period from 1894 to 2011. We show that warm winter days induced severe mortality, providing a mechanistic explanation of how climate change can trigger population declines in E. p. phaeton and other insects.
... The site contains ~2 ha of host plant cover, ~30% of which is the native host plant, C. glabra, and ~70% of which is the non-native English plantain, P. lanceolata (estimated by mapping areas containing host plants; Fig. 1). E. phaeton populations using P. lanceolata occur largely in agricultural landscapes, where mowing keeps other vegetation low enough for P. lanceolata to be available to E. phaeton adults, but can also destroy larval nests (Bowers and Richardson 2013). In 2012, G. Breed consulted with the site's land managers to change the timing of mowing to minimize impacts on late summer-early fall E. phaeton larvae on P. lanceolata, when pre-diapause (i.e., fall) larval nests are on host plants and the larvae have not yet dropped to the ground to overwinter (Stamp 1982). ...
... Bowers et al. 1992), which we did not directly measure. Although larger pre-diapause nests should be subject to higher parasitism, P. lanceolata may actually buffer populations from parasitoids (Bowers and Richardson 2013;Van Nouhuys and Hanski 1999), making larger nests adaptive on P. lanceolata but not C. glabra. Overwinter survival was also marginally higher on the non-native host, and led to the largest difference in population growth rates in our sensitivity analysis. ...
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Introduced plants can positively affect population viability by augmenting the diet of native herbivores, but can negatively affect populations if they are subpar or toxic resources. In organisms with complex life histories, such as insects specializing on host plants, the impacts of a novel host may differ across life stages, with divergent effects on population persistence. Most research on effects of novel hosts has focused on adult oviposition preference and larval performance, but adult preference may not optimize offspring performance, nor be indicative of host quality from a demographic perspective. We compared population growth rates of the Baltimore checkerspot butterfly, Euphydryas phaeton, on an introduced host, Plantago lanceolata (English plantain), and the native host Chelone glabra (white turtlehead). Contrary to the previous findings suggesting that P. lanceolata could be a population sink, we found higher population growth rates (λ) on the introduced than the native host, even though some component parameters of λ were higher on the native host. Our findings illustrate the importance of moving beyond preference–performance studies to integrate vital rates across all life stages for evaluating herbivore–host plant relationships. Single measures of preference or performance are not sufficient proxies for overall host quality nor do they provide insights into longer term consequences of novel host plant use. In our system, in particular, P. lanceolata may buffer checkerspot populations when the native host is limiting, but high growth rates could lead to crashes over longer time scales.
... Additional key words: Acacia macracantha, folivorous, host shift, Leucaena leucocephala Although many Lepidoptera species are highly specialized in the use of their hosts, some species are able to colonize exotic plants (Graves & Shapiro 2003, Bowers & Richardson 2013. In butterflies, this capacity may be predicted by the geographic range and the native diet breadth (Jahner et al. 2011). ...
... Host shifts have been acknowledged as extremely important for the survival of the populations of native butterflies in some human-modified environments (Shapiro 2002, Graves & Shapiro 2003, Bowers & Schmitt 2013. Furthermore, host shifts may have a number of effects on phytophagous populations (Bowers & Richardson 2013). The establishment of these new associations could be interesting from an evolutionary perspective, as they open an unexpected window for the understanding of the ecology and evolution of phytophagous insects (Tuda et al. 2014). ...
... Plantago lanceolata also contains IGs , consisting of mainly aucubin with smaller amounts of catalpol (Duff et al., 1965;Fajer, 1989). Where these two host plant species co-occur, E. phaeton may utilize both plants (Bowers & Richardson, 2013), while some populations use P. lanceolata or C. glabra exclusively Stamp, 1979). Despite this host range expansion, E. phaeton prefers the native C. glabra over P. lanceolata for both larval feeding and oviposition . ...
Full-text available
Defense against natural enemies constitutes an important driver of herbivore host range evolution in the wild. Populations of the Baltimore checkerspot butterfly, Euphydryas phaeton (Nymphalidae), have recently incorporated an exotic plant, Plantago lanceolata (Plantaginaceae), into their dietary range. To understand the tritrophic consequences of utilizing this exotic host plant, we examined immune performance, chemical defense, and interactions with a natural entomopathogen (Junonia coenia densovirus, Parvoviridae) across wild populations of this specialist herbivore. We measured three immune parameters, sequestration of defensive iridoid glycosides (IGs), and viral infection load in field-collected caterpillars using either P. lanceolata or a native plant, Chelone glabra (Plantaginaceae). We found that larvae using the exotic plant exhibited reduced immunocompetence, compositional differences in IG sequestration, and higher in situ viral burdens compared to those using the native plant. On both host plants, high IG sequestration was associated with reduced hemocyte concentration in the larval hemolymph, providing the first evidence of incompatibility between sequestered chemical defenses and the immune response (i.e., the "vulnerable host" hypothesis) from a field-based study. However, despite this negative relationship between IG sequestration and cellular immunity, caterpillars with greater sequestration harbored lower viral loads. While survival of virus-infected individuals decreased with increasing viral burden, it ultimately did not differ between the exotic and native plants. These results provide evidence that: (1) phytochemical sequestration may contribute to defense against pathogens even when immunity is compromised and (2) herbivore persistence on exotic plant species may be facilitated by sequestration and its role in defense against natural enemies.
... Although both of these plants contain aucubin and catalpol, C. glabra contains much higher concentrations of the latter, which leads to greater sequestration of catalpol by individuals feeding on C. glabra ). Although it is common for E. phaeton larvae to feed on P. lanceolata following diapause, oviposition on this introduced plant has also been observed in this population (Bowers and Richardson 2013). Females are batch layers and may have laid one or more egg masses at the time of capture. ...
Full-text available
Many insect species sequester compounds acquired from their host plants for defense against natural enemies. The distribution of these compounds is likely to affect both their efficacy as defenses, and their costs. In this study we examined the distribution of sequestered iridoid glycosides (IGs) in two congeneric species of nymphalid butterfly, Euphydryas anicia and E. phaeton, and found that the pattern of localization of IGs differed between the two species. Although IG concentrations were quite high in the heads of both species, the relative concentrations in wings and abdomens differed substantially. Euphydryas anicia had relatively high IG concentrations in their abdomens and low IG concentrations in their wings, whereas the reverse was true in E. phaeton. We interpret these results in light of two current hypotheses regarding where sequestered chemicals should be localized: that they should be found in wings, which would allow non-lethal sampling by predators; and that their distribution is constrained by the distribution of tissue types to which sequestered compounds bind. We also offer the third hypothesis, that costs of storage may differ among body parts, and that the localization of compounds may reflect a cost-reduction strategy. Results from E. phaeton were consistent with all three of these non-mutually exclusive hypotheses, whereas results from E. anicia were only consistent with the notion that tissue bias among body parts plays a role in IG distribution. The finding that these two congeneric butterflies exhibit different patterns of IG localization suggests that they have been shaped by different selection regimes.
... Knowledge about the host range of phytophagous insects is an important aspect for ecological and evolutionary studies (Fiedler 1995(Fiedler , 1996. It is known that egg-laying strategies in butterflies may be locally modified, including differentiation in host use pattern between different populations (Bowers & Richardson 2013;Dolek et al. 2013;Vargas 2013). Thus a detailed documentation of host plant relationships at the local scale is crucial to understand the local biology of butterflies. ...
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Lycaenid caterpillars (Lepidoptera, Lycaenidae) eating flowers of Dalea pennellii var. chilensis (Fabaceae) in the northern Chilean Andes. The shrub Dalea pennellii var. chilensis (Fabaceae) is reported for the first time as a host plant for three Neotropical Polyommatini (Lepidoptera, Lycaenidae, Polyommatinae): Hemiargus ramon (Dognin, 1887), Leptotes trigemmatus (Butler, 1881) and Nabokovia faga (Dognin, 1895), based on two collections performed in the western slopes of the northern Chilean Andes in two consecutive summers. The relative abundance was always above 90% for N. faga while it was always less than 5% for H. ramon and L. trigemmatus. Furthermore, N. faga was not found on inflorescences of other native Fabaceae examined in the study site. This pattern suggests a close relationship between N. faga and D. pennellii var. chilensis, at least at a local scale.
... Introduction Some species of Lepidoptera are able to feed on exotic host plants (Graves & Shapiro 2003, Bowers & Richardson 2013, Vargas 2013. These new host associations may give rise to many consequences for the biology of the respective butterfly or moth. ...
Macaria mirthae Vargas et al (Lepidoptera: Geometridae) is a geometrid moth native to the northern Atacama Desert of Chile. Its oligophagous larvae are associated with native hosts of the plant family Fabaceae, the most important of which is Acacia macracantha. The invasive tree Leucaena leucocephala (Fabaceae) was recently recorded as a host plant for M. mirthae based on morphology. The taxonomic status of larvae collected on A. macracantha and L. leucocephala was assessed using sequences of the DNA barcode fragment of the cytochrome c oxidase subunit I (COI) gene. Genetic divergence between samples from the host plants was found to be 0%-0.8% (Kimura 2-parameter model). Neighbor-joining and maximum likelihood analyses were also performed, including additional barcode sequences of Neotropical geometrid moths from GenBank and BOLD databases. Sequences of the larvae from both host plants clustered in a single clade with high statistical support in both analyses. Based on these results, it is concluded that M. mirthae has effectively expanded its host range and its larvae are currently feeding on the exotic tree L. leucocephala. Additionally, the importance of this new host association in a highly disturbed habitat is briefly discussed in terms of the field biology of this native geometrid moth.
Individual variation in movement can have important consequences for spatial population dynamics. For instance, individual variation increases leptokurtosis in dispersal distance, such that more individuals move very short and very long distances relative to a homogeneous population. We quantified individual variation in movement of the Baltimore checkerspot butterfly (Euphydryas phaeton) to investigate its importance for two conservation-related metrics: the expected dispersal distance and the critical minimum patch size, or the smallest area within which a population can persist based on loss due to emigration. All movement parameters showed among-individual variation, with the greatest variation in move lengths and time spent resting. Correlations in among-individual movement parameters indicated that some butterflies were generally more mobile than others. We incorporated empirically estimated movement and demographic parameters into two individual-based models (IBMs), one with homogeneity in movement among individuals, and one with heterogeneity in movement. As expected, individual variation in movement increased the leptokurtosis of lifetime movement distance; the maximum difference in distance moved was substantial (~850 m vs. ~5800 m) and is likely of significance for conservation. Individual variation also affected the critical minimum patch size, but the difference (~0.7 ha vs. ~0.5 ha) is unlikely to be ecologically significant. Notably, populations with individual variation had higher growth rates in small patches and lower growth rates in large patches, a logical consequence of increased leptokurtosis. Individual variation in movement is fairly straightforward to quantify using mixed effects models and is important for spatial population dynamics, thus we encourage its inclusion in studies of other systems.
Narrow-leaved plantain (Plantago lanceolata L.) is particularly abundant in southern areas of British Columbia, Ontario and Quebec, and the coastline of Prince Edward Island and Nova Scotia. It is a serious weed of lawns, dry grasslands and roadsides, although it is a palatable species to livestock in dry pastures. This account is a summary of the most recent biological information on P. lanceolata including data heretofore unpublished.
Grey jays were fed a set of six species of lepidopterans, predicted to be palatable or unpalatable based on their coloration and the fate of ingested host plant allelochemicals. Each of four birds received the entire series of insects. Junonia coenia (Nymphalidae) and Ceratomia catalpae (Sphingidae) were highly palatable as predicted based on their relatively cryptic coloration and lack of chemical defence. Three Euphydryas (Nymphalidae) species were predicted to be unpalatable: larvae and adults are warningly coloured and they sequester iridoid glycosides. However, Euphydryas gillettii was quite palatable, E. anicia was intermediate and E. phaeton was unpalatable. These differences may be due to differences in the iridoid glycoside content of these butterflies. Eumaeus atala (Lycaenidae) sequesters cycasin from its hostplant in the Cycadaceae and larvae and adults are warningly coloured. Adult E. atala were unpalatable.
Braconid wasps, Apanteles euphydryidis, attended webs of their lepidopteran hosts, Euphydryas phaeton, for hours, with one-third of each hour spent searching for caterpillars. Encounters with larvae on the outside of webs were frequent and usually resulted in parasitoids turning away. Head-jerking exhibited by caterpillars was effective in knocking parasitoids away. Ichneumonid wasps, Benjaminia euphydryadis, traveled from web to web, spending less than 1 min per web. Overall, the defensive mechanisms exhibited by the caterpillars and their distribution on and in webs were effective in deterring parasitoids.
Four iridoid glycosides were isolated and identified from Aureolaria flava (Scrophulariaceae): aucubin, gardoside methyl ester, 8-epiloganin, and 8-O-acetylharpagide. The iridoid glycoside content of Euphydryas phaeton (Nymphalidae), a principal herbivore of A. flava, was quantitatively determined by gas chromatography. In general, only aucubin was found in the butterflies, and amounts of this compound were low and variable among individuals.