[1] Univ South Bohemia Ceske Budejovice, Fac Agr, Ceske Budejovice, Czech Republic
[2] Acad Sci Czech Republ, Biol Ctr, Inst Parasitol, Ceske Budejovice, Czech Republic
[3] Slovak Acad Sci, Kosice, Slovakia
[4] North Dakota State Univ, Microbiol Sci Dept, Fargo, ND 58105 USA