Papilio homerus

The family Papiliondae has the greatest diversity in the tropics, where P. homerus is found. Morphological analysis reveals that P. garamas (a smaller swallowtail endemic to Central America) and P. homerus share a recent common ancestor. The butterflies may have island-hopped between Honduras and Jamaica during the Last Glacial Maximum of the Late Pleistocene when sea levels were lowest, Jamaica closer to the mainland, and more islands existed between them. Within Papilio, P. homerus and P. garamas are sister species within the Neotropical Homerus species group of the mostly New World Pterourus subgenus. Other member of Pterourus are the mostly Nearctic North American Troilus and Glaucus clades, and the exclusively South American Zagreus and Scamander clades. Only Homerus contains species within Central America and the Greater Antilles, as well as being the only group with distribution in both North and South America. == Geographic range and habitat ==

P. homerus is endemic to Jamaica, which is located in the Neotropical realm. It previously occupied half of the 14 parishes of Jamaica but can only be found as two or three small populations today. While many researchers have previously claimed that there are only two remaining strongholds, This is also the least understood of the three populations. The region that they had inhabited consists of plateaus at an elevation of . The population was located centrally around Mt. Diablo, which is located 70 km from both of the other populations. Thus, this population likely served as a key means of allowing gene flow between the three populations to prevent genetic bottlenecking, the genetic isolation of a subset of any given population. The population has been lost to anthropogenic habitat disruption. With deforestation and the expansion of developments bordering much of the remaining forest land, the climate of the region is more arid. This less than 100% humidity results in developmental defects in pupae reared in the lab. The disappearance of this population poses an ecological threat to the stability of the remaining two populations. Western population Located in the mountainous and cave-filled Cockpit Country, this population is in less danger of human interference due to difficulty of the terrain. The geography, coupled with the privatization of land by marijuana farmers has made the population more difficult to access and thus study. There is known less precipitation here than compared to the geography occupied by the Eastern population. A small population can be found on Pitfour Boulevard, outside the Nyahbinghi Rastafarian Centre in Pitfour just outside Montego Bay. Eastern population This is the most well-studied of the three populations. This population occupies the region where the Blue Mountains and the John Crow Mountains meet. The area is ideal of Papilio homerus, with abundant host plants and high levels of rain, leading to a regular high humidity. == Life cycle ==

Eggs Upon oviposition, the eggs of P. homerus are smooth, spherical, and white measuring 1.5-2.0 mm in diameter. Larvae The first and second instar of the larvae resemble bird droppings, with a dark brown body and a white lower abdominal region. This is thought to provide a selective advantage as to avoid predation. Lasting five days, the first instar is 9mm in length and has bristles along the body. The second instar has diminished bristles and grows to 15mm in length. This second instar also develops an enlarged thoracic region. The second instar lasts five days. The third instar displays eyespots on the thoracic segment and reaches a length of 26mm. The third instar lasts 9 days. The larvae take on a green appearance in the fourth instar. In this stage, the thoracic segments are swollen and display colored eyespots. This instar grows to 40mm and lasts ten days. The fifth instar resembles the fourth but has more intense coloration. Pupae Pupae appear to be dark gray, brown and green, or brown. All forms of pupae also display several white spots. Pupae measure upwards of 40mm in length and 18.5mm in maximum width. Pupae have been observed on the branches of the Hernandia plant and on the branch of a fern in the field. The pupal stage lasts from 10 to 14 days. Adults The dorsal side of the adult wing is dark brown with a bright yellow band on both wings. The large broad, rounded hind wing also has powder-blue spots on it. The ventral surface is also dark brown and has a less intense band of yellow. Male and female adults generally have the same coloration and patterning, but differ in key aspects. Females are larger than males. Females also have brighter coloration of the blue and yellow features. Adults are estimated to only live a few weeks in the field and have been able to survive six days in the laboratory setting. == Host plants ==

Adults are known to feed on various nectar sources such as L. camara, H. rosasinensis, including endemic Jamaican species such as Hernandia catalpaefolia and H. jamaicensis. Both sexes have been observed feeding on nectar, suggesting that P. homerus are opportunistic flower feeders. There are no reports of the species feeding on other food sources. Larval food plant Although, H. catalpaefolia and H. jamaicensis have been known to be the host-plants, the access to these plants now seem to be restricted. Currently, there is no confirmed larval food plant species known. However, oviposition has been observed on Ocotea species plants that are found in all three geographies known to have recently been occupied by the populations of Jamaican swallowtail. == Larval behavior ==

New larvae hatch from the egg, consume the chorion, and feed on the leaf of oviposition. They are typically found alone, but can share the same leaf with upwards of five other larvae. When the larvae reach the fourth instar, they move onto other, younger leaves to feed. Larvae have also been observed drinking water droplets after heavy rains. == Adult behavior ==

The Jamaican swallowtail can be spotted during the daylight hours of nine in the morning to two in the afternoon. In the morning, the butterfly can be seen basking in the sunlight atop trees and shrubs. They can also be observed feeding on nectars of various flowers. == Mating ==

Only one observation of mating in the wild has been recorded to date. The instance, recorded by Garraway, involved a male and female pair rested in tandem to one another. They remained in the position for 25 minutes before taking off in flight, with the male following the female into the foliage of the rainforest. The pair was spotted resting on the leaf of a common bamboo tree. The duration of the actual mating activity remains unknown as no start time was observed or recorded for the mating. Further, no recorded observation of courtship behavior exists in the literature. == Parasitoids and predators ==

A parasitoid is an organism that spends a considerable period of its life history within a host organism. Parasitoid infection leads to host death due to the exploitation of the host body for the growth and development of the parasitoid. A study in 1992 found the parasitoid infection rate of eggs was 77%. This poses a major threat to the stability of the remaining populations. The two most common parasitoid species are an encyrtid (Ooencytrus sp.) and a eulophid (Chrysonotomyta sp.). However, other forms of egg mortality exist, including predation by ants and fungal infections. Bacterial pathogenesis, detrimental bacterial infection, is the leading cause of death of larvae. Predation from birds, insects, and lizards has also been observed among larvae and adults. Due to the size and beauty of the butterfly, poaching has also threatened the remaining populations of the Jamaican swallowtail. However, increased awareness and legal protection have significantly reduced the amount of illegal collection. == Conservation ==

Population estimates Lehnert estimated the size of the eastern population at less than 50 adult individuals. This estimation was done using a mark and recapture procedure. There has been no attempted size estimate of the other populations. A regressive analysis of historical data of the observation of P. homerus indicates that there is no decline in the number of adults found in the wild. However, population size is still facing the great threat of habitat loss, destruction, and climate change. The sex ratio developed from field observations indicate a male bias. However, laboratory reared P. homerus indicate that the sex ratio is most likely 1:1. The bias seen in the field is likely due to sample bias, as it is easier for males to be spotted and captured due to their behavior of soaring above and patrolling territories. Species status Given the small number of adults left and the dwindling habitat, the species is considered and protected as a threatened species in various ways. The species is listed in the IUCN Red Data Book. Further, it is legally protected under Appendix I of the Convention on International Trade in Endangered Species (CITES) and the Jamaican Wildlife Act of 1998. Conservation efforts Along with the legal protections by the regulatory entities mentioned previously, conservation efforts are being promoted by biologists to protect the remaining population of the species. Jamaica has expanded the National Park system to include the habitats of the two populations, further protecting the habitat from destruction by human developments. Lehnert outlines a substantial conservation plan. Components of the conservation efforts include further research to develop more comprehensive population size estimates and population dynamics. Lehnert advocates for further study of the habitat and ecological threats in order to understand how to provide adequate space and protection for the species. Finally, Lehnert advocates for the establishment of a refugium population of the butterfly that could be reared in a controlled environment and reintroduced into the field. This, paired with continued efforts to boost local awareness of the species and its status, may help in creating more stable and present population of P. homerus in its native land. Habitat loss and destruction Habitat loss is a major concern due to rapid changes that have occurred in the Jamaican landscape. While the deforestation rate is at 0.1%, presents as an imminent threat as the Jamaican government has planted monocrops of fast growing pines while uprooting native, pre-existing rainforests to meet the fuel demands of the region. Habitat destruction has occurred most dramatically among the central population of the Jamaican swallowtail. Human development leads to a change in the local atmosphere, including a decrease in humidity. Deforestation paired with construction and development bordering the rainforest has contributed to the eradication of the population. In the Eastern and Western populations, habitat destruction is not presenting as direct of a threat to the stability of the populations. The Eastern population has little human development and the few developments are not withstanding, with heavy rains destroying recently established farms. The Western population is protected by marijuana farmers illegally disallowing local traffic and the difficulty of the terrain in which it is located. ==References==