Temperature Adaptation in the Postembryonic Development of Acanthocephalus tenuirostris (Palaeacanthocephala: Echinorhynchidae)

Under experimental conditions, the larval development of a fish parasite, Acanthocephalus tenuirostris was studied. This species is common in the eastern regions of Russia from Primorye Territory to the upper reaches of the Kolyma River. The material for the experiments was collected in different areas of the Magadan region which is located mainly in the subarctic climate zone. In several series of experiments, the infection and maintenance of intermediate hosts, the isopod Asellus hilgendorfii, took place at a constant temperature 15°C. In all cases, no more than 45 days were required for the formation of the final cystacanth stage. At the same time, in the hemocoel of isopods a large number of other larval stages were present simultaneously with cystacants. An additional experiment was conducted for the first 45 days at 15°C and the next 207 days at 4–6°C, showed the possibility of further development of larvae at low temperatures. Based on the comparison with the data available in the literature on the development times of European Acanthocephalus species living in temperate climates, it is concluded that the A. tenuirostris has anadaptation to a cold climate, whichprovides a twofold acceleration of the rate ofits development relative to larval A. lucii in Europe.