Pigeon Fly

Pseudolynchia canariensis (Macquart, 1839)

Figure 1: Dorsal(Top) and Ventral(Bottom) images of the Pigeon fly. Image Credit: Leshon Lee

Distribution

Pigeon fliesare found in most parts 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 4: Known occurances of Pigeon Fly. Photo credits: Wikimedia Commons

Identification

Figures 5-9: 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. 7(A): Dorsal and ventral thorax, basal area of left wing. Fig. 7(ALU): Alula. Fig. 7(AN+): Combined anal, 3rd posterior and axillary cells of the wing. Fig. 7(AXV): Axillary vein. Fig. 7(2B+): Combined 2nd basal and 2nd posterior cells of the wing. Fig. 7(CO): Costa. Fig. 7(DCL): Upper Calypter. Image Credit: Smithsonian National Museum of Natural History, Department of Entomology.

Life cycle

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 secretions of its mother’s “milk glands”. After the 3rd larval instar stage and when the larvae has reached its maximum size, it forms a prepupa or a puparium. The mother will then “give birth” to it. Shortly after leaving the mother’s body, the prepupa will harden to form a brown pupa. The pupa are generally found around bird's roosting sites or even on the birds themselves. Finally, it will undergo complete metamorphosis and emerge as a young adult

.

Figure 10:White prepupa (Mature 3rd larval instar which has stopped feeding and immediately begins to form a puparium when it is delivered by the mother), brown pupa and an adult pigeon fly. Image Credits: Karen Wheeler, University of Florida.(Pending Permission)

Parasitism

As the name suggests, its main host is the pigeons and doves from the Order Columbiformes. It has piercing mouthparts that punctures 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.

Disease Vector

Pigeon flies have been known to be a carrier of Haemoproteus columbae, the protozoan that causes pigeon malaria.

Figure 14: General life cycle of Haemoproteus. Image credit: Pinterest

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.

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.

Do pigeon flies feed on humans?

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.

Is it also a vector for human diseases?

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.

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.

Type Information

It does not have a holotype. However, it has a syntype stored at the Muséum National d'Histoire Naturelle in Paris.

Figure 15-17 (Left to right): Image of Pseudolynchia canariensis syntype. Image credits: Muséum National d'Histoire Naturelle (Creative Commons).

Original Description

The pigeon fly was first described by Justin Pierre Marie Macquart, a french entomologist specialising in Diptera, in 1839 as Olfersia canariensis.

Figure 18: The original description of the pigeon fly.

 Image credits: Bibliothèque nationale de France

Name

Binomial name: Pseudolynchia canariensis Macquart, 1839

Vernacular name: Pigeon fly

Synonyms: Lynchia simillima Speiser, 1904  

Olfersia canariensis Macquart, 1839

Olfersia capensis Bigot, 1885      

Olfersia exornata Speiser, 1900

Olfersia falcinelli Rondani, 1879

Olfersia lividicolor Bigot, 1885   

Olfersia maura Bigot, 1885         

Olfersia rufipes Macquart, 1847

Olfersia testacea Macquart, 1843

Nomenclature History 

The pigeon fly was first described by Macquart as Olfersia canariensis in 1839. Since then, many other entomologists such as Bigot, Speiser, and even Macquart himself have redescribed the pigeon fly still under the genus Olfersia. In 1926, the genus Pseudolynchia was described by Bequaert, and the pigeon fly was eventually placed under the genus Pseudolynchia

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Why is the genus called Pseudolynchia?

Pseudolynchia literally means "fake Lynchia".According to Maa(1966), the genus Psuedolynchia is closely related to Lynchia sensu Bequaert 1926 and particularly to Microlynchia Lutz 1915 and its only unique character is the presence of finger-like processes on scutellum

. The sexual dimorphism, vibrissal and metabasisternal processes, facial and prescutal pilosity and posterior scutellar truncation are shared by some of the Lynchia species-groups; whereas the venation and abdominal features are similar to those in Microlynchia

. Therefore, Pseudolynchia stands most probably intermediate of Lynchia and Microlynchia and may be considered primarily an Old World counterpart of the latter

. 

Phylogeny

Figure 19: Phylogenetic tree of Hippoboscoidea showing bootstrap values and posterior probability.

Top line shows bootstrap values and posterior probability respectively.

This tree was built by Petersen et al. (2007) using maximum parsimony. Bootstrap values as shown in fig. 19 are generally high, thus showing high support for the nodes. However, the bootstrap values within the clade Ornithomya are less than 50. Additionally, the posterior probability values using bayesian inference are generally high. However, those values should be taken with a pinch of salt as they are generally more optimistic about the support at the nodes than it actually is. 

Figure 19: Phylogenetic trees showing bootstrap values and posterior probability(Top) and key evolution events(Bottom) of Hippoboscoidea.

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. 

ANSWERS

The answer is 3 pigeon flies as shown in the picture!

Figure 20: Answer time! Image credits: Chiu Sein Chiong

References

This page was authored by Leshon Lee (A0166748M)
Last curated on 10 November 2018