Distribution of Rhinolophopsylla, Rhopalopsyllus, and Rhynchopsyllus
Introduction
Siphonaptera, otherwise known as fleas, are an order of small external parasites that obtain nutrients by consuming blood from their host. With approximately 2,500 species, flea distribution extends to every continent, including Antarctica, and they can be found in habitats ranging from tropical rainforest to arctic tundra (Whiting 2008). This expansive range results from each species evolving a narrow range of tolerance for temperature and humidity. However, despite a narrow tolerance range, most adult fleas are not limited by microclimates. The seasonal and geographic distribution of fleas is primarily determined by larvae development's specific requirements (Hastriter 2009).
The second stage of the flea life cycle, larvae, are typically not parasitic and most often develop off-host (Krasnov 2007). During this stage, the larvae, which are worm-like, blind, and legless, are exceedingly susceptible to life-ending conditions. After three molts, the larvae become pupae and spin into cocoons, where their appendages will begin to develop. The emergence of adults from these cocoons requires specific stimuli dependent on the species, such as temperature, vibration, or pressure (Hastriter 2009). As adults, fleas become permeant satellites of their hosts, alternating their time between periods on the host and periods in the host’s burrow/nest (Krasnov 2007). As adults, a series of morphological adaptions allows fleas to attach and remain on their hosts. Laterally compressed bodies enable them to move through their host’s fur or feathers. Strong claws and setae enable them to anchor themselves to their host’s skin and prevent being dislodged. Their mouthparts have been modified for piercing skin and sucking. And despite not possessing wings, fleas have extremely strong hind legs adapted for jumping (Hastriter 2009). These strong legs allow individuals to jump from host to host or return to their original host after a period in the nest.
Much of fleas’ distribution and dispersal opportunities depend on what host species they reside on. Despite their strong hind legs, a flea’s small size makes traveling great distances difficult, if not impossible, under their own power. Thus, in order for fleas to colonize new locations or new hosts, they must be carried there by another species. As such, a flea’s habitat patch is their host, rather than their geographic location, with parasitic individuals distributed across host individuals who provide a place for living, foraging, and mating (Krasnov 2004). Thus, a flea’s distribution can be expected to be influenced by the host’s habitat and mode of transportation.
Based on this information, two hypotheses were investigated. The first hypothesis is that fleas found on flying hosts will have a greater distribution than fleas found on non-flying hosts. Many bird and bat species have yearly migratory patterns that result in them traveling great distances between their summer and winter locations. Meanwhile, non-flying organisms, like rodents and deer, do not migrate great distances and therefore occupy smaller ranges than their flying counterparts. The second hypothesis is that the genus Rhinolophopsylla will have greater overall distribution than the genera Rhopalopsyllus and Rhynchopsyllus because Rhinolophopsylla contains more species within its genus. Because fleas have narrow tolerance ranges where their larvae can survive, the increased number of species within Rhinolophopsylla will allow the genus to cover a larger range of temperature and humidity than the two genera with fewer species.