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INVESTIGATIONS ON THE BIOLOGY OF A FEW DICROCOELIUM SPECIES FROM SHEEP ON QINGHAI PLATEAU

1985; Linguagem: Inglês

0001-7302

Ang L, Ai Q, Uo Y,

Mollusks and Parasites Studies

The present paper reports the results of our investigation on the biology of several species of Dicrocoelium on the highland of Qinghai. Adult specimens were collected from sheep in 29 endemic areas belonging to 14 counties. Pour species of Dicrocoelium were identified flrom these species collected. They are D. chinensis Tang et Tang, 1978, D. lanceatum (Rud., 1803) Stiles et Hassal, 1898, D. hospes Looss, 1907 and D. dendriticum (Rudolphi, 1819).Land snails and ante were collected from 3 endemic pastures in Yaocaotai of Ledu County, Xiaoyin of Minhe County and Garang of Guide County. These intermediaries were dissected and searched for dicrocoelid larval stages. There were 4 species of mature cercariae found from these land molluscs which bear the names Helicella candacharica and Cathaica przewalskii. These cercariae were found to belong to Di-crocoelium chinensis, D. lanceatum end two other types of cercariae, designated as B type and D type dicrocoelid eercariae. These cercariae can be distinguished from each other by size and by their morphological characters. To which species of Dicrocoelium belongs the adult stage of both the B type and D type of cercariae still remains to be elucidated.Pasture in Yaocaotai is situated on a high mountainous area about 4000 m above the sea level, where the incidence of infection in land snail Helicella candacharica is 1.32-4.97% (3.09%) (130/4206). Of these 130 positive snaile there were found 71 snails containing fully mature cercariae. Among these 59 snails harboured cercariae of D. chinensis and 12 harboured B type of dicrocoelid cercaria.Xiaoyin Pasture is situated on a lower level of mountainous region about 1200 m above the sea level on the Qinghai Plateau- In this area the. infection rate of larval D. lanceatum in Cathaica przewalskii is 19.6% (96/495). Of these 96 positive snails there were 46 harbouring mature cercariac.The pasture of Garang is situated on a higher plateau about 3000-3500 m above the sea level. In this later area the infection rate is 0.83% (10/1205) in Helicella candacharica. Of these positives there were 7 containing mature cercariae. Four snails harboured cercariae of D. lanceatum, one harboured B type, and two ha- rboured D type of dicroeoelid cereariae.More than 48,770 ants collected from the above-mentioned pastures were examined. Of these ants 7 species belong to the genus Formica. The metacercariae of Dicro-coelium were only found from Formica gagates collected from Yaocaotai pasture in hese metacercariae close resemble those of September. With respect to morphology, t D. chinensis.