Abstract: AIM:To identify the species of two isolates of Trichinella in China.METHODSAND RESULTS:Comparative studies of biological characteristics between Heilongjiang dog isolate of Trichinella (NL.45°35 and EA.1 2 6°35 ) and Henan pig isolate of Trichinella (NL .32° 40 and EA.1 1 2°1 0 ) were done.In single pair interbreeding experiments,mating between Henan pig isolate and the Heilongjiang dog isolate did not occur. Intrabreeding trials of Henan pig isolate and Heilongjiang dog isolate showed 30% and 20% mating, respectively. In temperature to lerance trials, the Heilongjiang dog isolate could to lerate a temperature of -15±1℃ for 12 months or - 25±1℃ for 16 days, the Henan pig isolate died with in 9 days at the temperature of -15±1℃ or -25±1℃. The Heilongjiang dog isolate had a relatively lower reproductive capacity index (RCI) in rat (14. 4) and in mice (6. 2) , while the Henan pig isolate had a higher RCI in rat (191. 3) and in mice (195. 7). The Heilongjiang dog isolate was weakly infective in domestic pigs, while the Henan isolate showed a higher degree of infectivity in the same host. The results of random amplified polymorphic DNA fingerprint trials showed that the RAPD pattern of the Heilongjiang dog isolate was the same as that of T. nativa whereas the RAPD pattern of Henan pig isolate was the same as that of T. spiralis. CONCLUSION: The Henan isolate of Trichinella is T. spiralis and the Heilongjiang isolate of Trich inellais T. nativa. Thus, there are at least two species of Trichinella in China.

Key words: Trichinella spiralis, Trichinella nativa, random amplified polymorphic DNA, RAPD, reproductive capacity, tem perature tolerance, taxonomy