Figure 1-2: Dorsal and Ventral images of the Pigeon fly (Pseudolynchia canariensis) Image Credit: Leshon Lee
Pigeon Fly or Pseudolynchia canariensis (Macquart, 1840) is a biting fly in the family Hippoboscidae. Like most flies from the family Hippoboscidae, the Pigeon Fly specifically parasitizes on birds from the family Columbidae, such as pigeons and doves, thus its common name.
Figure 4: Video of Pigeon flies on a male Pink Necked Green Pigeon (Treron vernans). Video Credits: Chiu Sein Chiong
Pigeon flies are found is most part of the world (mainly subtropical and tropical) where pigeons can be found. Areas include Africa, Mediterranean Sub-region, Afghanistan, India, Bangladesh, Nepal, Taiwan, and across Southeast Asia.
Figure 5: Known occurances of Pigeon Fly. Photo credits: Wikimedia Commons
Figures 6-10: Illustrations of a Pigeon fly and its morphology. Fig. 6(A): Wing. Fig. 6(B): Head. Fig. 6(C): Puparium (Top view). Fig. 6(D): Puparium (Side view). Fig. 6(E): Puparium respiratory lobes. Fig. 6(F): Male terminalia. Fig. 6(G-H): Dorsal basal area of abdomen. Fig. 8(A): Dorsal and ventral thorax, basal area of left wing. Fig. 8(ALU): Alula. Fig. 8(AN+): Combined anal, 3rd posterior and axillary cells of the wing. Fig. 8(AXV): Axillary vein. Fig. 8(2B+): Combined 2nd basal and 2nd posterior cells of the wing. Fig. 8(CO): Costa. Fig. 8(DCL): Upper Calypter. Image Credit: Smithsonian National Museum of Natural History, Department of Entomology.
Figure 6-10. Illustrations of Pseudolynchia canariensis. From Illustration Archive, by Smithsonian National Museum of Natural History, Department of Entomology. http://n2t.net/ark:/65665/34020751f-6dca-492f-8a49-8bd11d652a06. Reprinted with permission.
Pigeon flies are brown and dorsoventrally flattened. This allows the fly to hide in between the feathers of its hosts to avoid detection. Additionally, it has a hard exoskeleton which makes it more difficult for the birds to crush the flies using their beaks when preening. It has a body length (tip of head to tip of wing) of around 10mm. Its wing length is 4.5-7.5mm long.
Pigeon flies have a very unique life cycle. Unlike most flies, they “gives birth” to its offspring instead of laying eggs. A single egg will hatch inside the fly’s uterus and feed on the mother’s “milk glands”. After the larva forms a prepupa or a puparium, the mother will “give birth” to it. Shortly after leaving the mother’s body, it will harden to form a pupa. Finally, it will undergo complete metamorphosis and emerge as a young adult.
As the name suggests, its main host is the pigeons and doves from the Order Columbiformes. It has biting mouthparts that pierces into the skin of the bird and sucks the blood of its host. With its ability to fly from one bird host to another, the Pigeon fly has been found on many other bird hosts from the Orders Ciconiiformes, Falconiformes, Cuculiformes, Strigiformes, Coraciiformes, and Passeriformes.
Bequaert, J. C. (1954). The Hippoboscidae or louseflies (Diptera) of mammals and birds. Part II. Taxonomy, evolution and revision of American genera and species(Vol. 34, New). Entomologica Americana.
Figure 11: Photo of Pseudolynchia canariensis from a captive rock pigeon (Columba livia) with 2 amblyceran lice attached to it. Inset: Scanning election microscope (SEM) image. Image credits: Bartlow et al.
Figure 12: Image of Myialges spp. egg cluster on the abdomen of a fly from the family Hippoboscidae. Image credits: Leshon Lee
Bartlow, Andrew W Villa, Scott M Thompson, Michael W Bush, Sarah E. (2016). Walk or ride? Phoretic behaviour of amblyceran and ischnoceran lice. International Journal for Parasitology, 46(4), 221-227. http://dx.doi.org/10.1016/j.ijpara.2016.01.003
Phoresy is a type of commensalism where one species hitches a ride on another species to ensure its dispersal. Pigeon flies have a phoretic association with mite species, such as Myialges spp. and Ornitocheyletia hallae volgin, and amblyceran and ischnoceran lice. This allows the mites and lice to be dispersed throughout a wide range of pigeons. This is especially important for these parasites as the hosts will eventually die, thus the Pigeon fly is an escape route for them to travel to another host to propagate and survive to pass on its genes to the next generation.
Pigeon flies have been known to be a carrier of Haemoproteus columbae, the protozoan that causes pigeon malaria.
Figure 13: General life cycle of Haemoproteus. Image credit: Pinterest
[Avian Malaria Cycle]. (n.d.). Retrieved October 7, 2018, from https://www.pinterest.com/pin/109071622210278203/?lp=true
Pigeons will be infected when bitten by a Pigeon fly that carries Haemoproteus columbae. The sporozoites from the saliva of the fly enters the blood stream and invade the endothelial cells of the blood vessels of the lungs, liver and spleen. They then congregate to form schizonts. Each schizont will multiply to form 15 or more small, unpigmented bodies known as cytomeres, each with a single nucleus. Each cytomere grows still further, and its nucleus undergoes multiple fission. Eventually, the host cell becomes considerably hypertrophied (enlarged) and is filled with a number of multinucleate cytomeres. The endothelial cells break down, releasing the cytomeres, which accumulate in the capillaries, ocassionally resulting in complete blockage. They are irregularly shaped and tortuous, and may send out branches along the capillaries, becoming bifurcate, trifurcate or even multiradiate. Each cytomere produces an enormous number of merozoites, which infects the ethyrocytes (Red blood cells) of the pigeon and develop into gametocytes.
Huff, C. (1942). Schizogony and Gametocyte Development in Leucocytozoon simondi, and Comparisons with Plasmodium and Haemoproteus. The Journal of Infectious Diseases, 71(1), 18-32. Retrieved from http://www.jstor.org/stable/30093867
Another Pigeon fly may feed of the infected bird's blood, resulting in the Pigeon fly being a vector. The gametocytes will then continue its life cycle in the midgut of the fly by maturing and sexually reproducing to form an encapsuled zygote known as an oocyst. The oocyst will rupture and infect the salivary glands of the pigeon fly, ready to infect its next pigeon host.
The pigeon fly is under the Superfamily Hippoboscoidea together with the infamous tsetse fly. The tsetse fly is a vector for the African trypanosomiasis, also known as the sleeping sickness. It is caused by the parasite,Trypanosoma brucei, which is dispersed by the tsetse fly to humans living in Central Africa. If not treated, the sleeping sickness can be lethal.
World Health Organisation. (2018, February 16). Trypanosomiasis, human African (sleeping sickness). Retrieved October 17, 2018, from http://www.who.int/news-room/fact-sheets/detail/trypanosomiasis-human-african-(sleeping-sickness)
Thankfully, the tsetse fly's geographical distribution is only within Central Africa. However, since the pigeon fly is a close relative to the tsetse fly, some scientists are conducting researcgh to find out if the pigeon flies also carry trypanosomes since it may also result in a disease outbreak all over the world! Till then, it is still not known if the pigeon fly is a vector for human diseases.
It may seem like an obvious answer but a daring study in 1931 done by G. Robert Coatney found that the Pigeon fly is able to feed on humans! Coatney recruited 2 friends to carry this experiment out by forcing the flies to bite them and suck their blood, effectively becoming the host for the flies. However, they only feed on humans blood when there is a lack of choice, on in this case, when being forced to. A red and itchy bite mark appeared which persisted for 6 days, 9 days, and 20 days for Coatney and his friends respectively.
By having a diet of only human blood, the flies could not survive for long or reproduce. The male Pigeon fly lived for 12 days while the female Pigeon flies lived for 7 days and never produced a larvae. This effectively shows that the Pigeon flies are very host specific and only by feeding on pigeons will they be able to survive and reproduce. Therefore fret not! Unless pigeons have been wiped out throughout the world, we, humans, do not have to worry about these little critters sucking our blood and potentially transmitting deadly diseases to us.
It does not have a holotype. However, it has a syntype stored at the Muséum National d'Histoire Naturelle in Paris.
Figure 14-16: Image of Pseudolynchia canariensis syntype. Image credits: Muséum National d'Histoire Naturelle (Creative Commons).
Muséum national d’Histoire naturelle, Paris (France). (n.d.). MNHN-ED-ED6023 [Digital image]. Retrieved October 16, 2018, from http://coldb.mnhn.fr/catalognumber/mnhn/ed/ed6023
Figure 17: Image of the original description of the pigeon fly.
Macquart J., 1839 - Animaux articulés recueillis aux Îles Canaries par MM. Webb et Berthelot. Diptères. Histoire Naturelle des Îles Canaries. II (2ème partie), 13 : 97-119.
Image credits: Bibliothèque nationale de France
The pigeon fly was first described by Justin Pierre Marie Macquart, a french entomologist specialising in Diptera, in 1839 as Olfersia canariensis.
Figure 17: Phylogenetic tree of Hippoboscoidea.
Petersen, F. T., Meier, R., Kutty, S. N., & Wiegmann, B. M. (2007). The phylogeny and evolution of host choice in the Hippoboscoidea (Diptera) as reconstructed using four molecular markers. Molecular Phylogenetics and Evolution, 45(1), 111–122. https://doi.org/10.1016/j.ympev.2007.04.023
As seen in fig. 10, viviparity, which is the retention and growth of the fertilized egg within the maternal body until the young animal, as a larva or newborn, is capable of independent existence, has evolved very early on in the phylogenetic tree, resulting in presence of viviparity in all organisms within Hippoboscidea. However, at that time, the larvae were still able to move. It was only when "true" ectoparasitism evolved, then the larvae had reduced movement, resulting in the change from the larvae burrowing into the soil to pupate like the flies in the Glossinidae family to becoming incapable of burrowing and in some cases pupate within the mother's body. The host shift to bird evolved independently in the tree, thus showing convergent evolution.
Figure 18: Answer time! Image credits: Chiu Sein Chiong
This page was authored by Leshon Lee (A0166748M)
Last curated on 16 October 2018