Studies on the biology of Ixodes tasmani Neumann, 1899, and its potential as a vector of haematozoa to small mammals

Weilgama, Danister Jayampathy (1979). Studies on the biology of Ixodes tasmani Neumann, 1899, and its potential as a vector of haematozoa to small mammals PhD Thesis, School of Molecular and Microbial Sciences, The University of Queensland. doi:10.14264/uql.2014.504

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Author Weilgama, Danister Jayampathy
Thesis Title Studies on the biology of Ixodes tasmani Neumann, 1899, and its potential as a vector of haematozoa to small mammals
Formatted title
Studies on the biology of Ixodes tasmani Neumann, 1899, and its potential as a vector of haematozoa to small mammals
School, Centre or Institute School of Molecular and Microbial Sciences
Institution The University of Queensland
DOI 10.14264/uql.2014.504
Publication date 1979
Thesis type PhD Thesis
Supervisor D. E. Moorhouse
Total pages 258
Language eng
Subjects 060808 Invertebrate Biology
070708 Veterinary Parasitology
Formatted abstract
This study was made to determine the biology of Ixodes tasmani, the seasonal incidence on animals and its potential as a vector of haematozoa to vertebrates. Two hundred and seventy small mammals belonging to 11 species were examined for ticks. The animals were trapped in Brisbane and in the suburbs over a period of 24 months, from March 1976 to February 1978.

One argasid and eight ixodid species were collected, of which I. holocyclus and I. tasmani were the most numerous and appeared commonly on the Phalangeridae and Peramelidae. The I. holocyclus larvae were more numerous from January to May; the nymphs from May to September and adults from September to December. I. tasmani larvae were mostly present in the cooler months of the year; the nymphs in winter but the adults were seen throughout the year. Populations of these two species appeared to be related to the rainfall.

The biological studies of I. tasmani were made under laboratory conditions with most emphasis on the non-parasitic stages. These stages are most vulnerable to changes in the environment and thus knowledge on the limits of their tolerance to temperature and humidity would help to understand their distribution and seasonal incidence.

The eggs of I. tasmani were highly susceptible to desiccation. Egg development occurred at 15°-31°C but only at low saturation deficits. The incubation period was influenced both by temperature and saturation deficit. Exposure to dry air even for one day curtailed hatching.

The engorged larvae showed increased tolerance to desiccation than the eggs. Heavy mortality was experienced among larvae exposed to saturation deficits higher than 5 mm Hg. The minimum pre-moult period was influenced by temperature and saturation deficit but the duration of moult was not influenced by saturation deficit.

The engorged nymphs were not affected by high saturation deficit which moulted even in dry air, Temperature influenced the pre-moult period and the duration of moult. Males emerged earlier than the females.

Engorged females failed to oviposit at 5°C and at 34°C, but were tolerant of desiccation. Temperature influenced the pre-oviposition period, the duration of oviposition and the longevity of females. The number of eggs laid was influenced only by saturation deficit. The number of eggs laid was influenced by the engorged weight of the female and was also related to the duration of oviposition.

The unfed stages were less tolerant of desiccation than the engorged stages. However these exhibited long survival periods at 20°C and 1.8 mm Hg. s.d. The larvae lived for 295 days while the nymphs and adults lived for over 300 days.

I. tasmani had short parasitic periods. On short-nosed bandicoots, I. macrourus, larvae and nymphs engorged in 48 to 72 hours The majority of females engorged in 5 to 6 days. Larvae and nymphs fed well on laboratory-bred rats but the females failed to attach to these animals.

I. tasmani transmitted Theileria peramelis and Trypanosoma thylacis of the bandicoot, I. macrourus. Transmission was trans-stadial and not trans-ovarial. T. peramelis was a common protozoan being detected in nearly fifty percent of the bandicoots trapped.

Under experimental conditions, T. peramelis appeared in the peripheral blood of bandicoots in 13 to 28 days following tick application. T. thylacis had a shorter incubation period that varied from 4 to 12 days.

The development of T. thylacis was studied in the metamorphosing larvae. Amastigotes, sphaeromastigotes, epimastigotes and trypomastigotes were encountered but at no stage were promastigotes found. The principal multiplication stage was the amastigote. Development was seen to occur mostly in the lumen of the gut diverticula. However, intracellular development was also observed in the cells shed into gut lumen and in the epithelial cells of the gut. The metacyclic trypanosomes, appeared about two days prior to moulting, into nymphs. The ticks had an infection rate of 77.4 percent. Transmission was thought to be inoculative due to regurgitation.
Keyword Ticks
Arthropod vectors
Ticks as carriers of disease
Additional Notes Other Title: Biology of Ixodes Tasmani and transmission of haematozoa.

Document type: Thesis
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