Journal of Threatened
Taxa | www.threatenedtaxa.org | 26 January 2023 | 15(1): 22440–22447
ISSN 0974-7907 (Online) | ISSN 0974-7893
(Print)
https://doi.org/10.11609/jott.7393.15.1.22440-22447
#7393 | Received 03 May 2021 | Final received
06 December 2022 | Finally accepted 11 December 2022
Biology
of Bhutanitis ludlowi
Gabriel, 1942 (Lepidoptera: Papilionidae) Bumdeling Wildlife Sanctuary, Bhutan
Tshering Dendup
1 , Namgay Shacha
2, Karma Tempa 3 & Tez Bdr Ghalley 4
1 Pemagatshel Divisional Forest Office, Department of Forests
and Park Services, Ministry of Energy and Natural Resources, Royal Government
of Bhutan.
2,4 Bumdeling Wildlife Sanctuary, Trashiyangtse,
Department of Forests and Park Services, Ministry of Energy and Natural
Resources, Royal Government of Bhutan.
3 Mongar Territorial Division, Mongar,
Department of Forests and Park Services, Ministry of Energy and Natural
Resources, Royal Government of Bhutan.
1 tsheringdendup@moaf.gov.bt,
2 nshacha@moaf.gov.bt (corresponding author), 3 ktempa@moaf.gov.bt,
4 tbghalley@moaf.gov.bt
Editor: Kushal Choudhury,
Bodoland University, Kokrajhar, India. Date of publication: 26 January
2023 (online & print)
Citation: Dendup,
T., N. Shacha, K. Tempa
& T.B. Ghalley (2023). Biology of Bhutanitis ludlowi
Gabriel, 1942 (Lepidoptera: Papilionidae) Bumdeling Wildlife Sanctuary, Bhutan. Journal of Threatened
Taxa 15(1): 22440–22447. https://doi.org/10.11609/jott.7393.15.1.22440-22447
Copyright: © Dendup et al. 2023. Creative Commons Attribution 4.0 International
License. JoTT
allows unrestricted use, reproduction, and distribution of this article in any
medium by providing adequate credit to the author(s) and the source of
publication.
Funding: Bhutan for Life (BFL); Green Climate
Fund (GCF); World Wildlife Fund (WWF).
Competing interests: The authors
declare no competing interests.
Author details: Mr. Tshering Dendup, Deputy
Chief Forestry Officer currently working under Pemgatshel Divisional Forest Office, Department of Forests and Park Services (DoFPS),
Bhutan. Mr. Namgay Shacha, Forestry Officer working under Bumdeling Wildlife Sanctuary, DoFPS, Bhutan. Karma Tempa,
Chief Forestry Officer currently working under Mongar Territorial
Division, DoFPS, Bhutan. Tez Bdr Ghalley, Forestry Officer working under Bumdeling Wildlife Sanctuary, DoFPS,Bhutan
Author contributions: All the
authors have contributed equally in edition and revision of the paper. Tshering Dendup (main author),
Namgay Shacha (corresponding author), Karma Tempa & Tez Bdr Ghalley (coauthors)
Acknowledgements: We, the authors,
would like to thank the management of Bumdeling
Wildlife Sanctuary (BWS) (DoFPS, Royal Government of
Bhutan) for the support and guidance in publishing this paper. We would like to
thank Bhutan for Life (BFL) for their financial support in publishing the
paper. Lastly we would like to thank all
the staff of BWS involved in the study and who have provided helping hand
during the study period.
Abstract: It was in 1933–34
that the first discovery of Bhutanitis ludlowi was made by plant explorer Frank Ludlow and
George Sheriff at Tobrang, upper part of Trashiyangtse valley, Bhutan. It was rediscovered after a
lapse of 76 years in 2009 by Bhutanese forester Karma Wangdi.
Bhutanitis ludlowi
is native to Trashiyangtse and occurs in few pockets
of areas in northeastern part of Bumdeling Wildlife
Sanctuary (BWS). There has been no report which described complete life cycle
of Bhutanitis ludlowi
till date. Listed in CITES appendix II, the endemic species is also the first
butterfly species to be included under Schedule I of FNCRR of Bhutan, making it
a totally protected species in Bhutan. For the first time a complete life cycle
stages of Bhutanitis ludlowi
was recorded at BWS on the host plant Aristolochia
griffithii Hook.f.
& Thomson ex Duch in ex situ environment. A
greenhouse with dimensions of 12 X 5 X 3 m was constructed and a thriving
habitat was created artificially through establishment of Aristolochia
griffithii nursery inside the greenhouse. The
eggs were brought down to the new environment at an elevation of 1,752 m from
their natural habitat (elevation of 2,200 m). The eggs were incubated in the
greenhouse with host plants in ex-situ conditions. Eggs incubated inside the
greenhouse were examined at eight hour intervals daily (twice a day: 0900 h and
1700 h) to record physical changes in eggs such as colours.
Bhutanitis ludlowi
is univoltine brood where the life cycle completes in
365–367 days with egg hatching (Average = 16 days; SD = 2), larva (Avg. of 174
days SD 3), pupa (174 days, SD 1.53)) and adults emerged after 366 days.
Predators of Bhutanitis ludlowi
include spider, wasps, praying mantis, snails, and ants. Bhutanitis
ludlowi protects themselves by avoiding predators
through mechanisms like odour, camouflaged colorations,
and excretion of poisons. Advocacy programs on its conservation importance and
formation of community conservation support groups to protect its habitats is
seen as one of the priority activities in the identified range of Bhutanitis ludlowi.
Keywords: Chrysalis, eggs,
host plants, instars, life history, metamorphosis, molts.
Introduction
Discovery of Bhutanitis ludlowi
(Lepidoptera: Papilionidae) was first made in 1933–34
by Frank Ludlow (1885–1972) and George Sheriff (1898–1967) during their
botanical expedition at Tobrang Makang,
upper part of Trashiyangtse valley. Bhutanitis ludlowi
was sporadically distributed between altitude ranges of 2,200–2,500 m (Harada
et al. 2012). Bhutanitis ludlowi was named after the foreign botanist Frank
Ludlow and it was only after eight years of discovery that it was described as
new species in 1942 (Gabriel 1942). Except species description (Gabriel 1942),
there has been no reports which described complete life cycle of Bhutanitis ludlowi. The
only reference to life cycle of the concern species was made by a joint
research team from Ministry of Agriculture and Forests (MoAF),
Bhutan and a group of Japanese lepidopterists (Harada et al. 2012). In their
paper they compared Bhutanitis ludlowi morphological characteristics with Bhutanitis lidderdalii
Atkinson (Bhutan Glory) till second instar (Harada et al. 2012).
Bhutanitis
ludlowi was accorded increased protection status
in the provisions of Forest and Nature Conservation Act 1995 and Forest and
Nature Conservation Rules and Regulation (FNCRR) 2017. Listed in CITES appendix
II, it was also the first butterfly species to be included under Schedule I of
FNCRR making it a totally protected species (Singh & Chib
2015). Endorsed during 123rd sitting of Cabinet, Bhutanitis
ludlowi was officially declared as Bhutan’s
National Butterfly in 2012 (Singh & Chib 2015).
The paper was written after nine years of rediscovery of the concern species,
adding invaluable memorandum of complete life history report to other existing
three congeneric species: Bhutanitis lidderdalii Atkinson 1873, Bhutanitis
thaidina Blanchard 1871, and Bhutanitis
mansfieldi Riley 1939. The present study, which
is the first of such kind in Bhutan & the world, demystifies and elucidates
the complete life cycle of Bhutanitis ludlowi on its only novel larval host plant Aristolochia griffithii.
Materials and Methods
Study site
The study was carried
out at Bumdeling Wildlife Sanctuary (BWS) during
2017. The study site is located at an elevation of 1,752 m (27.614247° N
91.492268° E) in Trashiyangtse (Figure 1). The
experimental site experiences a warm temperate climate with an average annual
precipitation between 1,000–3,000 mm from June to September and the mean
temperatures of 20°C in summer and 10°C in winter. Lighting condition was
normal indirect sunlight through high density polyethylene (HDPE) green-agro shade net with mesh size 10 mm. An average hours of sun light received by
greenhouse varied from short duration of about seven hours during winter months
(November–March: 0800–1500 h) to long duration of about nine hours during
summer months (April–October: 0800–1700 h).
Methods
Before eggs were
introduced into an ex-situ environment, a green-agro
shade net house with dimensions of 12 X 5 X 3 m was constructed (Image 1A,B). A
single 2 X 2 m door was opened from one end of the green-agro
shade house. Thriving habitat was created artificially through establishment of
Aristolochia griffithii
nursery inside the agro shade house (Image 2AC).
The main purpose of agro net is to provide shade to
growing host plants and to maintain thriving habitat for Bhutanitis
ludlowi.
The first cluster of freshly laid Bhutanitis ludlowi
eggs were collected in mid-August and introduced into ex situ environment of
green-agro shade house at the study site with
established host plants. Eggs were allowed to hatch in greenhouse in ex situ
conditions. Rearing eggs were examined at every eight-hour intervals daily
(twice a day: 0900 h and 1700 h) to record eggs physical changes such as colours. The eggs were enumerated as hatched when the
larvae came out of them. Fresh young leaves of Aristolochia
griffithii (Image 2C) were used as food by
growing larvae. Molting stages were noted, thus the number of instars and their
metamorphosis.
Result
Butterflies go
through a life cycle known as complete metamorphosis. The stages of their life
cycle include egg, larva, pupa, and adult. Female butterflies were very
selective about their host plant and laying their eggs. Female Bhutanitis ludlowi laid
its eggs in clusters on underside of mature host plant leaves in pyramidal
mound, covered with very thin and hardly seen shiny sticky substance, which
attached them to the leaf surface (Image 3A). Each cluster composed of 60–160
number of eggs. The butterfly eggs underwent colour
change (Image 3B) as young larvae developed inside them and the whole
observation are recorded (Table 1).
Discussion
Aristolochia species is used by most of the Swallowtail
butterflies as host plants to lay their eggs to complete life cycle. Bhutanitis ludlowi Atkinson
laid its eggs on Aristolochia griffithii. Similarly, Young (1973) found that food
plants acceptance study of swallowtail butterfly Paridesarcas
mylotes (Papilionidae)
on Aristolochia constricta
Grisebach and Aristolochia
labiata was readily accepted. Concomitant to the
number of eggs per cluster (65–180) of Harada et al. (2012), eggs of the Bhutanitis ludlowi were
also laid in clusters or batch of 60–160 individuals in pyramidal dome mound,
generally in dorsal side of the leaves of Aristolochia
griffithii. Young (1973) wrote that eggs of Paridesarcas mylotes
were found on ventral side (occasionally on the crotches of small stems and
petioles) of the mature leaves of Aristolochia
constricta as opposed to Bhutanitis
ludlowi and B. lidderdalii
that laid eggs on dorsal side of leaves.
As reported by
Igarashi (1989), its closest kin Bhutanitis
lidderdalii laid 20–40 eggs at a time in flat
clusters (not mound) on Aristolochia griffithii (Bhutan), Aristolochia
kaempferi Willdenow
(Japan), Aristolochia mandshuriensis
(Korea), and Aristolochia shimadai Hayata (Taiwan). Bhutanitis Mansfield Riley and Bhutanitis thaidina Blanchard
were also found laying eggs in flat cluster of 7–42 eggs (Igarashi 1989; Harada
et al. 2012). Paridesarcas mylotes lay single but usually in loose clusters of 2–5
eggs on a single mature leaf of Aristolochia
constricta (Young 1973). The ovi-positioning
habit of Bhutanitis ludlowi
conformed to those of Bhutanitis lidderdalii, preferring underside of mature Aristolochia griffithii
leaves (Suzuki 1987; Igarashi 1989). Ovi-positioning
took place between August–September for Bhutanitis
ludlowi and they do not prefer highly exposed and
disturbed areas whereas, Bhutanitis lidderdalii took place between late September and early
October (Igarashi 1989).
Larval Stage of Bhutanitis ludlowi
The eggs of Parnassius overwintered and spent approximately 10
months to hatch (Igarashi 1989). A Monarch was an egg for 3–8 days (Howard
2006) Bhutanitis lidderdalii
took about 30 days in egg stage (Igarashi 1989) and hatched out between
mid-October and mid-November while Bhutanitis
ludlowi took 14–18 days to enter the first instar
between first-second weeks of September. The larvae proved to be very hardy and
passed through winter months of November, December, and January before they
pupated in mid-February. Larvae were
gregarious throughout their life. Similar to Bhutanitis
liddarlii larvae (Igarashi 1989), Bhutanitis ludlowi
larvae had tendency to disperse into smaller groups as they grow older to the
extent that the last mature instar larva lived in solitary. As opposed to the
feeding habit of Bhutanitis liddarlii that fed on leaves, mature larvae of Bhutanitis ludlowi
fed on leafstalks and tender shoots agreeing to feeding habit of Pachliopta (Swallowtail butterflies) and Atrophaneura (Red-bodied Swallowtails) of Papilionidae family. Bhutanitis
ludlowi underwent eight larval instars as opposed
to other swallowtails like Bhutanitis lidderdalii (Igarashi 1989) and Paridesarcas
mylotes (Young 1973) of five instars. It remained
in caterpillar stage for 161 days while monarch butterfly caterpillar stage was
for only 7–17 days (Howard 2006).
Pupa of Bhutanitis ludlowi
Bhutanitis ludlowi pre-pupated into “C”
shape for seven–nine days and monarch butterfly 8–15 days (Howard 2006).
Pupation took normal girdle position like most of the swallowtails. Unlike Bhutanitis thaidina that
pupated among the leaves (Igarashi 1989); Bhutanitis ludlowi restlessly roamed around in search of healthy
substrata. They pupated in mid-February on strong stems of the host plant and
iron rod pillars of greenhouse. Young (1973) reported that Paridesarcas
mylotes larva stopped feeding at maturation and moved
vigorously in search of pupation sites. The monarch butterfly stayed in pupal
stage for 8–15 days (Howard 2006) while Bhutanitis
ludlowi remained in pupal stage for 188 days, one
of the longest of such case for swallowtail butterflies.
Adult of Bhutanitis ludlowi
The basic life cycle
of a butterfly from egg to adult varied from three weeks to two years (Opler
& Krizek 1984). Young (1973) reported a developmental
time for Paridesarcas mylotes
on Aristolochia species of about 42
days under similar ex-situ condition. Developmental time of Bhutanitis
ludlowi on Aristolochia
griffithii in ex situ greenhouse was 365–367 days
which is incredibly lengthier. This long developmental time could be attributed
to the aestivating period during over-wintering of chrysalis in diapauses. Straatman (1970) found
out that egg-adult time of Ornithopteraa lexandrae Rothschild to be 131 days on Aristolochia schlechteri
Lauterb and 107 days on Aristolochia
tagala Cham.
Enemies of Bhutanitis ludlowi and its conservation measures
Predators varied in each life stages of Bhutanitis ludlowi. Owing to the
high mortality rate, very huge majority of them were not able to make it to become
a butterfly out of few hundred eggs. There were many predators in all stages of
lifecycle, but little information is available about the extent to which each
of those predators influenced the population. Invertebrate predators such as
snails (terrestrial gastropod mollusks), ants (Formicidae),
spiders (Arachnids), wasps (Vespidae), and praying
mantis (Mantidae) were among those that was found to
prey on immature Bhutanitis ludlowi
(eggs, larvae, pupae) on Aristolochia plants (Image
5A–D, 6A–E). This may be because of porous agro net
used for captive breeding. Similar results were found by Zhang et al. (2019)
while studying lifecycle of Bhutanitis lidderdalii in both natural and captive habitat, where the
larva and egg were attacked by parasites and insects (Zhang et al. 2019). Bhutanitis ludlowi has mechanism
to protect themselves and avoid from predations such as odour,
camouflaged colorations and poisons which might have gain after feeding on host
plant. A study carried out in Chile (2020) on larva and egg of pipevine Swallowtial found that larvae feed exclusively on highly
toxic plants of the genus Aristolochia from which
they sequester toxins and later used as defense mechanism to protect from
predators (Palma-Onetto et al. 2020).
Conclusion
Ever since the
discovery and rediscovery of Bhutanitis ludlowi by plant explorer Frank Ludlow and George
Sheriff and Bhutanese researchers respectively, such comprehensive study on its
life cycle was not carried out. For the first time, a complete life cycle
stages of Bhutanitis ludlowi
was recorded at Bumdeling Wildlife Sanctuary on
the host plant Aristolochia griffithii in ex-situ environment. Bhutanitis ludlowi is univoltine brood where the life cycle completes in 365–367
days with egg hatching (14–18 days), larva (five months and eight days), pupa
(six months and seven days), and adults emerged after eight instars. Predators
of Bhutanitis ludlowi
include spider, wasps, praying mantis, snails, and ants.
There is need to
carry out a comprehensive study of its life history in in-situ habitats. Though
Aristolochia griffithii
is not palatable to cattle disturbances due to presence of ‘Tsethar’
(lifelong freely released) bulls in Bhutanitis
ludlowi score habitats greatly contributed to
reduction of natural regeneration of host plant through foot trampling of young
shoots. In future it is important to carry out enrichment plantation of host
plants in its prime habitats. The current study recommends in-depth studies
like its distribution patterns, behaviors, population trends, and conservation
threats in future. Advocacy programs on its conservation importance and
formation of community conservation support groups to protect its habitats is
seen as one of the priority activities in the identified range of Bhutanitis ludlowi.
Table 1. Observation on life
cycle stages of Bhutanitis ludlowi.
|
|
Stages |
Observation |
|
1 |
Egg: The Beginning Stage |
Golden yellow colour of the eggs turned darkish pale after 14–15 days
and apical region of the eggs got darkened considerably before hatching
(Image 3C). Freshly laid egg hatched after 14–18 days (Image 3CD) in an ex
situ environment inside the greenhouse. Soon after emergence from the egg,
larva consumed its eggshell before it spread to feed on young tender leaves.
A complete life cycle of Bhutanitis ludlowi passed through eight larval instar stages
including a pupal stage to emerge as an adult butterfly over an incredible
period of 367 days. |
|
2 |
Larval: The Feeding Stage |
A young caterpillar that first hatches from its egg is referred to as
instar caterpillar (Image 3CE) and the caterpillar’s first molt is referred to as second instar. First cluster of
eggs were hatched in early September and the young caterpillar or larva that
emerged from eggs began their first feast by eating their eggshell along with
tender parts of host plant. During the feeding stage all individuals
generally fed on individual vine at the same time of the day. Larvae of all
instars were generally inactive in nights. Instars caterpillars continued to
eat and grow until it became too big for the exoskeleton to support. The
caterpillar molts transform into next instar until
they pupated to adults which is a dramatic change in ground colour occurred
with the molt (sixth, seventh and eighth (final)
instars). The dark yellow ground color of the body
became ashy grey and processes into darker shades thus appearing more
pronounced (Image 4A). The wart-like reddish orange processes on sub-dorsal
part became more prominent making body segments more distinct and clearer.
During these stages, instars intervals became longer with fewer activities.
It could be in response to unfavorable and
inhibiting conditions of cold winter months of November, December, January,
and February. The remarkable differences in appearance of the instar stages
were increased body size and length and more prominent setae on the body (Image
4A). The pattern of tubercle arrangement of the body remains same throughout
the rest of larval life, however, change in coloration pattern of chalazae
becomes more conspicuous. Ludlow’s Bhutan Glory Bhutanitis
ludlowi butterfly underwent eight larval instars
to emerge as an adult. |
|
3 |
Molting:
The exuviating stage
|
Caterpillar stopped eating and stayed still in one place in group
(during early instars) or single (later instars) for around seven–eight days
as it prepared to molt. When molted,
old head capsule slid forward and dropped off. Old exoskeleton then split
just behind the head allowing the caterpillar to walk forward out of its
former skin. The larva took one–two hours to inflate its body by drawing in
surrounding air to sufficiently toughen to continue normal feeding without
injuring itself. At this point, larva often ate its exuviae
of ecdysis. Bhutanitis ludlowi caterpillar underwent seventh molt to pupate. During this stage, feeding potentiality
was found to be very high in contrast to previous stages. At maturation,
larva stopped feeding and vigorously moved in search of pupation site. |
|
4 |
Adult (Imago): The reproductive stage |
It is the fourth stage of a butterfly. An adult butterfly (Image 4D)
is ready to emerge from a chrysalis after 188 days (six months and seven
days). The adult emerged in morning hours after the sun had come up at around
10–12 pm. As the adult butterfly emerged from its chrysalis, its wings were
weak, folded against its body and wet. It was not able to take flight
instantly. Adult butterfly emerged from pupa in third week of August after
365–367 days from the eggs. The adult butterfly pumped fluids from its
abdomen through the veins in its wings, which causes wings to expand to their
full size. It dries its wings in the sun by keeping it flat (Image 4F),
occasionally flaps to exercise flight muscles before it could fly. It took
several hours depending on the weather before it is ready to flutter away. In
this reproductive stage, adult butterfly mates to reproduce, searches for the
proper host plant to lay her eggs and the cycle continues. Duration of life
cycle ranged between 365–367 days (egg-18 days, larva- five months &
eight days), pupa- six months & seven days). |
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