Aspects of the biology of Uropsylla tasmanica Rothschild (Siphonaptera)

The flea Uropsylla tasmanica Rothschild is the only known flea with a parasitic larval stage (Dunnet 1970). In Tasmania the most commonly found host of U. tasmanica is the native cat Dasyurus viverrinus (Dasyuridae Marsupialia). The life cycle of U. tasmanica in relation to the annual cycle of D. viverrinus is described. It was found that U. tasmanica adults and parasitic larvae only occur on the hosts from March to September (Autumn and Winter). Other species of fleas found on native cats decline in numbers during this period. Reproduction in U. tasmanica coincides with the reproductive period of its host. Experimental work indicated that adult U. tasmanica emerge from their cocoons in response to mechanical stimulation. \Readiness\" to emerge depends upon the amount of time spent in the cocoon as well as the stage of desiccation of the fleas in the cocoons. (Fleas kept at 80% RH took 10)4 -1-0.2 (n=10) days to emerge whilst those kept at 20% RH took 73-1- .19 (n=10) days to emerge from the beginning of the experiment.) After emergence and in the absence of a host fleas kept at high relative humidities survived for longer periods than those kept at low relative humidities (32±1.8 n=10 days at 80% RH compared with 13±3.25 n=10 days at 20% RH). On emergence from the cocoons U. tasmanica are not sexually mature and require a blood meal to complete sexual maturation. Newly emerged fleas prefer to feed from sub-adult rather than mature native cats during the host's non-reproductive phase. Experiments in which prolactin and hydrocortisone were administered to some of the fleas indicated that these mammalian hormones facilitated sexual maturation and reproduction in. U. tasmanica. The parasitic larvae of U. tasmanica undergo four larval stages and are morphologically different from non-parasitic flea larvae. There are some taxonomic features of U. tasmanica larvae which appear to converge with the myiasis-producing Dipteran larvae. Fully developed U. tasmanica larvae leave the host and build a cocoon in the litter of the hosts den. The larvae do not always pupate immediately but may enter a diapause the induction and duration of which appears to depend upon the daily cycle of warmth and cold to which they are subject on emergence from the host. The phylogeny of U. tasmanica was investigated by comparing the chromosomes of this species with those of Fygiopsylla hopZia and Lycopsylla nova. U. tasmanica appears to have 2n = 14 chromosomes while the other two species have 2n = 20 chromosomes."