Parnassius smintheus sayii description and field notes.
Observations of a population of Parnassius smintheus sayii at mount Evans Summit trail
(12,000-14,000ft), Colorado, September 9, 2022 from 11:00 AM to 4:00 PM: Oliver Blunt
Description/Background, (Field notes on pg. 3): Parnassius smintheus, known colloquially as the
“Rocky Mountain Parnassian '' is one of the 6 Nearctic Parnassius species. It is a medium-sized
butterfly with significant variation in patterning both within and across sexes. Males and females
range in horizontal length from ~2-2.5 inches and are dimorphic. Males are white with 2 narrow
submarginal hyaline borders on the forewings; each separated by a narrow line of white scales, with
two pairs of large transverse black spots located discally, and a subdiscal black spot. In most cases,
males possess 1-2 FW postdiscal red spots with black bordering, though these are often reduced to
smaller black dots. Male HWs possess thick black bordering along the dorsum; occasionally the black
bordering will curve upwards along the discal cell from the dorsum, creating a “hooked” appearance.
The black scaling also appears basally on the forewings. Males can display 2 pairs of red HW ocelli,
one located subcostally along the discal cell, the other subdiscally. While females can still appear
white, they have much larger hyaline portions of their wings, which can (in rare cases) extend fully
across the wing, leaving the female almost entirely translucent with diffused gray scaling. Females
have larger and more exaggerated red ocelli/spots and may display a third FW spot located
subdiscally; and can have up to four large red ocelli on their Hindwings, (2 located in the same
position as the males, the latter 2 along the dorsum subdiscally. Both sexes have antennae with
alternating black/white segments and have heavily sclerotized exoskeletons. Larvae are
approximately 1.5 inches long at L5 and are black, with dorsal rows of small yellow dots contrasted
against a black body. Like all papilionids, they possess defensive osmeteria, though it is undeveloped
in the genus Parnassius. (Tanaka, et al, 1983)
Above: cohort of 12 P. smintheus specimens (3 P. clodius on the top right). Collected at Mt. Evans Summit Park on 9/9/22.
Behavior/Characteristics: P. smintheus resides in alpine/subalpine meadows and tundra and is
univoltine, overwintering as eggs. In some areas, smintheus can be observed from late June until
early September. After overwintering, the larvae hatch in spring and feed on sedum lanceolatum,
sequestering the glycoside sarmentosin from the plants as a chemical defense against predation.
Because lanceolatum releases excess sarmentosin as a defense against larval feeding, larvae are
forced to wander to more nutritional plants after 1⁄2-1 hours, as high levels of sarmentosin can reduce
larval growth rates (Doyle, 2017). The need to continuously alternate host plants is a potential reason
these larvae move much faster than other Papilionid counterparts. The aposematic coloration
imparted by the sarmentosin serves a dual function in thermoregulation; the larvae absorb heat via
light by resting exposed rock during the day (Shepard, et al., 2011), a behavior that hastens their
growth across the 10-12 week larval development period.
Above: Parnassus smintheus habitat at Mt. Evans, 9/9/22.
At the end of the 5th instar in the late spring/early summer, larvae spin loose silken cocoons and
pupate. Adults eclose after 10-14 days. The immediate goal of emerging males is to copulate with
females; males are conspicuous and can be seen patrolling their territory, “hilltopping” to find females.
This species has no courtship rituals; once a female is located, a male dives towards her and
subdues her, forcing an attempt to pair. After mating, the male secretes a waxy plug over the female’s
genitalia (Sphragis) which serves to prevent other males from pairing with her (Shepard, et al., 2011).
Sphragi are found in almost all Parnassiinae, as well as other groups of Papilionidae, including the
birdwing genus Ornithoptera. Once gravid, the female will search for Sedum lanceolatum, though she
will not always oviposit on the plant, but regularly scatter ova in the close vicinity of hosts, as the
plants can be chemically detected by her antennae.
Larvae develop fully within their eggs before winter, allowing them to eclose almost
immediately after the temperature rises above 75°-80°F in the early summer. The eggs are facultative
diapausers and will emerge under warm conditions in captivity after at least 3 months inside a freezer.
Parnassius smintheus has higher than average levels of glycerol in its hemolymph, a sugar
associated with lowering the freezing point of water. In Park, et al., 2017 the related species
Parnassius bremeri was found to have hemolytic glycerol levels that were positively associated with
supercooling tolerance, indicating that the presence of glycerol in P. smintheus may be a large factor
in the species’ ability to tolerate sub-zero winter conditions. Adults and larvae also possess high
glycerol levels, the effects of which can be observed during the late-summer subzero flashes that
adults seem to tolerate.
Field notes: During the time I spent hiking along the summit trail at Mt. Evans, Clear Creek
County, CO (around 12,000-13,000ft), I observed a late-season population of Parnassius smintheus
sayii. Around 600 individuals were observed from 11:00 AM to 4:00 PM; the temperature ranged from
75-31*F from the beginning to the end of the day, respectively. During that time, I observed the typical
behaviors of Parnassius smintheus. Males were patrolling areas of tundra, while females were
generally more restricted to the ground, where they crawled around ovipositing near sedum. Sp. Both
sexes were observed nectaring frequently on Fremont’s Ragwort (Senecio fremontii). Females were
better camouflaged against ground due to their wing transparency, which is less exaggerated in
males.
The most novel behavior that I observed occurred during the end of the day around 3:30 PM;
as it had started snowing and raining at various elevations on the mountain. As the temperature
dropped to 33-31*F, the butterflies stopped patrolling and took shelter amongst the tundra brush,
which was predictable given the conditions. Notably, smintheus was observed sheltering in
higher-than-average concentrations amongst the Ragwort plants. Ragwort was among one of several
foliated flowering plants growing in the local biotope; plants including Rhodiola integrifolia, Sedum
lanceolatum, and Geum rossii, and at times a single 1^3’’ bush of fremontii could contain up to 6
lethargic smintheus. Among a group of 12 ragwort bushes distributed across the trail, 32 smintheus
were found, averaging 2.66 individuals per bush. Among other plants and rocky terrain, fewer than 5
sheltering smintheus could be found across a 1.5 hour period of cold. While I have no current means
to test using more data, I hypothesize that the concentration of smintheus in ragwort is likely due to
consumption favoritism (as individuals were observed frequenting these throughout the day),
combined with the temperature drop, causing already-feeding smintheus to shelter in their nearest
resting location in higher concentrations than could be observed in open terrain and non-flowering
plants.
Above: P. smintheus male sheltering on Senecio fremontii
Image Gallery:
Above: Rhodiola integrifolia: potential hostplant for P. smintheus at Mt. Evans.
Above: Male P. smintheus at rest.
References:
[1] Masahiro Tanaka, Yukimasa Kobayashi, Hiroshi Ando,Embryonic development of the osmeteria of papilionid caterpillars, Parnassius glacialis butler and Papilio machaon hippocrates C. et R. felder (Lepidoptera : Papilionidae), International Journal of Insect Morphology and Embryology, Volume 12, Issues 2–3, 1983, Pages 79-85, ISSN 0020-7322, https://doi.org/10.1016/0020-7322(83)90001-6.(https://www.sciencedirect.com/science/article/pii/0020732283900016)
[2] Doyle, Amanda. "The roles of temperature and host plant interactions in larval development and population ecology of Parnassius smintheus Doubleday, the Rocky Mountain Apollo butterfly" (PDF). University of Alberta. Retrieved 24 October 2017.
[3] Shepard, Jon; Guppy, Crispin (2011). Butterflies of British Columbia: Including Western Alberta, Southern Yukon, the Alaska Panhandle, Washington, Northern Oregon, Northern Idaho, and Northwestern Montana. UBC Press. ISBN 9780774844376.
[4] Youngjin Park, Yonggyun Kim, Gi-Won Park, Jung-Ok Lee, Kang-Woon Lee, Supercooling capacity along with up-regulation of glycerol content in an overwintering butterfly, Parnassius bremeri, Journal of Asia-Pacific Entomology, Volume 20, Issue 3, 2017, Pages 949-954, ISSN 1226-8615, https://doi.org/10.1016/j.aspen.2017.06.014(https://www.sciencedirect.com/science/article/pii/S1226861517301528)
Comentarios
Agregar un comentario