Troides aesacus C. & R. Felder, 1860

CONSERVATION

IUCN Redlist category
Least Concern (IUCN 2020)

Rationale for redlist categorization
Troides aeacus is a widespread species ranging from northern India and Nepal into Southeast Asia, the Malayan peninsula and to Taiwan, and has been assessed as Least Concern. Although this species is threatened in parts of its range by habitat loss and degradation (e.g. subspecies kaguya on Taiwan), at the species-level it does not qualify for a higher extinction risk. Some conservation measures are recommended to aid the species in areas where declines have been observed, e.g. via propagation of food plants and retaining the most beneficial habitat for the species (e.g. closed- rather than open-canopy habitats in Taiwan). (IUCN 2020)

Threat category
Ecosystem conversion|Ecosystem degradation,Species mortality (IUCN 2020)

Cause of stress
Mining & quarrying,Intentional use (species is the target),Herbicides and pesticides,Unintentional effects: (subsistence/small scale) [harvest] (IUCN 2020)

Described Threats
This species is threatened, at least in parts of its range, by habitat loss and degradation, as well as collecting. Habitat loss is of particular importance since it has been shown, for example, that population numbers of this species increase with an increase in the number of larval host plants, but more importantly an increase in the number of adult nectar plants, while it decreases with denser forest canopy structure (Li et al. 2010). Subspecies kaguya has been described as declining due to the loss of host plant habitat and commercial collecting (Collins and Morris 1985, Wu et al. 2010). In China, population of the species was found to be primarily threatened by continued human activities such as destruction of forest for land and firewood, grazing and mining, but also herbicide application and unfavourable afforestation (Li et al., 2010). Habitat loss has reduced the population to presence in a number of limited patches, often with small local populations (e.g. southern Gansu; Li et al. 2010). Lien (2014) reports that the extent and quality of remaining mountain forests of the Dong Van Karst Plateau is declining as a result of logging activities, firewood collection and expansion of settlements. In Nepal, changes in the natural habitat have had a major negative impact on butterflies like Troides species, specifically in the Kathmandu mountain forests, where deforestation and habitat loss are particularly associated with the following factors (Khanal et al. 2013b; Khanal 2014): expansion of agricultural land and tourism development; pesticide use; and forest fires.

Trade in butterflies has risen in certain parts of the world, such as China (Li et al. 2010), putting pressures on natural populations which are harvested for specimens and craftwork. This species has been ranched in parts of China since the early 1990s (Parsons 1992). Collins and Morris (1985) note that the Entomological Suppliers Association banned trade in the rare endemic subspecies kaguya . The species is listed on CITES Appendix II together with the genera Ornithoptera and Trogonoptera , with the exception of O. alexandrae which is listed on Appendix I. Recently traded individuals appear to come mostly from captive or ranched populations (CITES 2015). Butterfly ranching is generally thought of as a sound, economically viable and sustainable rural industry (Wambi 1996, Hanscom 1993, Burrows 2003 in Small 2007). However, there are concerns that butterfly ranching may not be as sustainable in some countries as it is often perceived to be (e.g., Papua New Guinea; Small 2007). This is based on a lack of data and species monitoring to assess the status of butterfly populations, and for many species, such monitoring is fraught with difficulty due to inaccessibility of their habitat (Small 2007). New and Collins (1991) noted that trade is extremely difficult to monitor because transportation of unpinned specimens is easy, especially of comparatively low value species which may instead be traded at high volumes. It has been stated that overcollecting seldom becomes a threat to butterflies, due to the reproductive capacity of insects and the difficulty in capturing significant numbers of the population (Pyle and Hughes 1978, in Parsons 1992). However, where birdwing butterflies are highly specific to host plants and where density of these hosts plants limits population size, collection in conjunction with habitat loss could have significant impacts on the species or subpopulations. (IUCN 2020)

Commercial use
Butterflies are mostly traded dead for the curio market (Collins and Morris 1985, New and Collins 1991). Between 1998 to 2007, 306,000 butterflies were traded from southeast Asia, with 13,000 of these being wild-caught (Nijman 2010). There is a distinct shift towards ranched and captive-bred individuals in trade from 2003 onwards; in 1985, it was reported that globally less than 10% of trade was in ranched individuals (Collins and Morris 1985). Altogether at least 34 different species were recorded in trade, most of which belonged to the birdwing butterflies ( Troides and Ornithoptera ; Nijman 2010). It should be noted that trade in butterflies may be under-reported, because of difficulties monitoring. New and Collins (1991) noted that trade is extremely difficult to monitor because transportation of unpinned specimens is easy, especially of comparatively low value species which may instead be traded at high volumes.

Birdwings can fetch high prices on the market. For example, butterfly collectors have paid high prices for birdwing butterflies of this genus: a pair of Ornithoptera meridionalis was reported to have fetched USD 3,400 in Germany (Melisch and Schutz 2000). Reported prices for Troides are however much lower. For example, a more recent pricing was around $85 per pair of T. hypolitus , around $15 per individual of T. helena and between $43 and $85 per pair of T. haliphron (Putri 2016). Trade in butterflies of this species has risen in certain parts of the world, such as China (Li et al. 2010) putting pressures on natural populations which are harvested for specimens and craftwork. This species is listed on Appendix II of CITES. Recent data from the CITES Trade database show, that since 2000 and present around 830 individuals were exported from range states (China, Malaysia, Thailand and Viet Nam) as part of the wildlife trade; of these, just under 40% were reported to be wild-caught (CITES 2015). Previous data taken between 1987 and 2005 only shows trade from wild-caught individuals (UNEP-WCMC 2007). There were no exports recorded between 2000 and 2015 from Bangladesh, Bhutan, Cambodia, India, Laos, Myanmar, Nepal, and Taiwan (CITES 2015). Some entomological suppliers associations, e.g. the Entomological Suppliers Association of Great Britain, have banned trade in the rare Taiwan endemic subspecies (Collins and Morris 1985). (IUCN 2020)

Kind of conservation needed
Awareness & communications (IUCN 2020)

Applied conservation actions
This species was not considered threatened at the species level by Collins and Morris (1985); however, they suggested that the species may be locally at risk from habitat loss in Peninsular Malaysia and stated that the Taiwanese subspecies is rare. In Bangladesh, this species has been assessed as Endangered at the national level (Chowdhury 2015). In Nepal, a status assessment made in 1995 included the species as Susceptible (threat code 5) into the National Red Data Book of Nepal (NRDB 1995). In parts of its range where the species is in decline, such as Nepal, increased conservation education and awareness for students and in villages may help to effectively support conservation efforts for this species. In Hong Kong, the species and one of its host plants, Aristolochia tagala , are under legal protection (P. Lo, pers. comm. Feb. 2018). The wide species range overlaps with a number of protected areas, including areas where studies on the conservation and habitat needs of the species were carried out (e.g., Baishuijiang Natural Reserve, Gansu Province; Li et al. 2010). Other protected areas include Lawachara National Park (Chowdhury 2015), Kanching Forest Reserve, Selangor, Malaysia (Corbet and Pendlebury 1934), the Kameng Protected Area Complex in Arunachal Pradesh, India (Sodhi and Kunte 2016), Manas Biosphere Reserve, Assam, India (Saikia and Saikia . 2014), Kenting National Park, Taiwan (Hsieh et al. 2008), Phnom Samkos Wildlife Sanctuary (Monastyrskii et al. 2011) and Hong Kong Wetland Park, which has been re-vegetated specifically to aid with the protection of butterflies (Hong Kong Wetland Park 2011). The species also occurs at low population numbers in Nagarjun-Shivapuri National Park located in Kathmandu Valley, Nepal, at 1,400-2,000 m elevations (Khanal and Smith 1997). In Vietnam, the species was reported from 25 sites within protected areas: Hoang Lien National Park, Van Ban Proposed Nature Reserve, Tam Dao National Park, Ba Be National Park, Huu Lien Nature Reserve, Ba Vi National Park; Cat Ba National Park, Bai Tu Long National Park and Cuc Phuong National Park in Northern Vietnam; Pu Mat Nature Reserve, Huong Son State Forest Enterprise, Vu Quang National Park, Phong Nha Ke Bang National Park, Back Ma National Park, Song Thanh Nature Reserve, Kon Chu Rang Nature Reserve, Kon Ka Kinh National Park, Yok Don National Park, Hon Ba Nature Reserve, Bao Loc State Forest Enterprise, and Da Teh State Forest Enterprise in Central Vietnam; Cat Tien National Park, La Nga State Forest Enterprise in Southern Vietnam (Monastyrskii 2007). The species is protected in the following countries: Malaysia, Taiwan (subspecies kaguya ; Hsieh et al. 2010), Thailand (genus Troides is listed as protected insect species under the Ministerial Regulation No. 4, 1995, issued under the Wild Animal Preservation and Protection Act of 1992; Hutacharern and Tubtim 1995). The species is also listed in the Red Data Book of Vietnam (Ministry of Science and Technology and Vietnam Academy of Science and Technology 2007, Lien 2014). It is also listed on Appendix II of CITES, along with all other Troides, Trogonoptera and Ornithoptera (with the exception of O. alexandrae which is listed on Appendix I). Recent studies showed that while presence of larval host plants is a prerequisite for the presence of the species, conservation action targeting provision of nectaring plants for adults and a cutting management to maintain incomplete forest cover and encourage growth of food plants may have positive effects on species abundance (Li et al. 2010). In Taiwan, especially in the Kenting area where subspecies kaguya still has a stronghold, it is vital that food plants be propagated and maintained under closed- rather than open-canopy habitats to improve the population status of this butterfly (Hsieh et al. 2008, Hsieh et al. 2010). (IUCN 2020)

REFERENCES

• Chowdhury, S.H. 2015. Troides aeacus. IUCN Bangladesh. Red List of Bangladesh Volume 7: Butterflies, pp. 157. IUCN, International Union for Conservation of Nature, Bangladesh Country Office, Dhaka.
• CITES. 2015. CITES Trade Data Base. Available at: http://trade.cites.org/.
• Collins, N.M. and Morris, M.G. 1985. Threatened Swallowtail Butterflies of the World. The IUCN Red Data Book. IUCN, Gland and Cambridge.
• Corbet, A.S. and Pendlebury, H.M. 1934. The butterflies of the Malay Peninsula: including aids to identification, notes on their physiology and bionomics, and instructions for the collection and preservation of specimens under tropical conditions. Kyle, Palmer, Kuala Lumpur.
• Hanscom, T. 1993. Setting hearts aflutter: little butterflies take wing as big business. The Rotarian 163: 16-19.
• Hong Kong Wetland Park. 2011. Hong Kong Wetland Park Habitat Management Plan. Agriculture, Fisheries and Conservation Department, Hong Kong.
• Hsieh, K.J., Kuo, Y.L., Perng, J.J., Lai, P.Y. and Lee, T.C. 2008. Population Distribution of Aristolochia zollingeriana, an Endangered Vine Exploited by Three Papilionid Butterflies in Kenting National Park, Taiwan. Journal of Forest Science 23(3): 243-254.
• Hsieh, K.J., Kuo, Y.L., Perng, J.J., Lee, T.C. and Lee, H.L. 2010. Oviposition preference and larval survival of Troides aeacus formasanus (Lepidoptera: Papilionidae) on Aristolochia zollingeriana in different environments in the Kenting area. Taiwan Journal of Forest Science 25(4): 353-368.
• Hutacharern, C. and Tubtim, N. 1995. Checklist of forest insects of Thailand. Office of Environmental Policy and Planning, Bangkok.
• IUCN. 2020. The IUCN Red List of Threatened Species. Version 2020-3. Available at: www.iucnredlist.org. (Accessed: 10 December 2020).
• Khanal, B. 2014. Study on changes in butterfly fauna at different altitudinal levels in central Nepal. PhD Thesis. Department of Zoology, Mizoram University, India.
• Khanal, B. and Smith, C. 1997. Butterflies of Kathmandu Valley. TecPress Books, Thailand.
• Khanal, B., Chalise, M.K. and Solanki, G.S. 2013a. Threatened butterflies of central Nepal. Journal of Threatened Taxa 5(11): 4612-4615.
• Lien, V.V. 2014. Species list and conservation priority of butterflies (Lepidoptera, Rhopalocera) in Dong Van Karst Plateau, Ha Giang Province. Tap Chi Sinh Hoc 36(4): 444-450.
• Melisch, R. and Schutz, P. 2000. Butterflies and beetles in Germany. Traffic Bulletin 18: 91-93.
• Ministry of Science and Technology, and Vietnam Academy of Science and Technology. 2007. The Red Data Book of Vietnam, part 1. Animals (in Vietnamese). Science and Technology Publishing House, Hanoi.
• Monastyrskii, A. 2007. Butterflies of Vietnam. Papilionidae. Dolphin Media, London.
• Monastyrskii, A.L., Yago, M. and Odagiri, K. 2011. Butterfly assemblages (Lepidoptera, Papilionoidea) of the Cardamom Mountains, Southwest Cambodia. Cambodian Journal of Natural History 2011(2): 122-130.
• New, T.R. and Collins, N.M. 1991. Swallowtail butterflies: an action plan for their conservation. International Union for Conservation of Nature and Natural Resources/Species Survival Commission Lepidoptera Specialist Group, Gland, Switzerland.
• Nijman, V. 2010. An overview of international wildlife trade from Southeast Asia. Biodiversity and Conservation 19(1101-1114).
• NRDB. 1995. National Red Data Book of Fauna of Nepal. Department of National Parks and Wildlife Conservation, Kathmandu, Nepal.
• Parsons, M.J. 1992. The butterfly farming and trading industry in the Indo-Australian region and its role in tropical forest conservation. Tropical Lepidoptera 3(Suppl. 1): 1-31.
• Putri, I.A.S.L.P. 2016. Handicraft of butterflies and moths (Insecta: Lepidoptera) in Bantimurung Nature Recreation Park and its implications on conservation. Biodiversitas 17(2): 823-831.
• Pyle, R.M. and Hughes, S.A. 1978. Conservation and Utilization of the Insect Resources of Papua New Guinea. Wildlife Branch, Department of Natural Resources, Port Moresby.
• Small, R.D.S. 2007. Becoming unsustainable? Recent trends in the formal sector of insect trading in Papua New Guinea. Oryx 41(3): 386-389.
• Sodhi, S. and Kunte, K. 2016. Butterflies (Lepidoptera) of the Kameng Protected Area Complex, western Arunachal Pradesh, India. Journal of Threatened Taxa 8(8): 9053-9124.
• UNEP-WCMC. 2007. Review of trade in ranched birdwing butterflies. UNEP-WCMC, Cambridge.
• Wambi, D. 1996. Birds, bugs and butterflies. New Guinea Insight 6: 5-9.
• Wu, I.-H., Yang, P.-S., Liu, C.-Y. and Yeh, W.-B. 2010. Genetic differentiation of Troides aeacus formosanus (Lepidoptera: Papilionidae),based on cytochrome oxidase I sequences and amplified fragment length polymorphism. Annals of the Entomological Society of America 103(6): 1018-1024.