Abstract
The life history of a trematod fluck, Himasthla kusasigi was studied on the morphological characters of metacercariae, its infection rate in the clam and the contamination experiment to the herring gull, Larus crassiostris. The size of the metacercariae was $210{\sim}230{\times}220{\mu}m$, excysted metacercariae was $420{\times}160{\mu}m$ and it had 31 collar spines. The ventral sucker($112{\times}100{\mu}m$) was located just below the central part of the body. Esophagus was narrow and long, the intestine was branched in the upper part of the ventral sucker and extended to the hind part of the body. Excretory bladder without the infected part was located in the hind part of the body. The branched excretory tube was filled with the small granules and extended to the pharynx area. The infection rate of the metacercariae varied from place to place. In Naecho do and Puan the rates were $98.4\%$ and $95.9\%$ respectively. The infected number of Himasthla kusasigi per clam was positively proportional to the size of the clam. The adult fluckes developed from the metacercariae were obtained from the experimented herring gull. The metacercariae emerge from their cysts in the stomach of the herring gull, then they migrate it the intestine and 25 days after, most of them were found in the intestine. The size of the adult was $4.8{\sim}7.5{\times}0.22{\sim}0.24mm$, oral sucker; $68{\sim}120{\times}70{\sim}120{\mu}m$, pharynx: $80{\times}50{\mu}m$, ventral sucker: $630{\sim}680{\times}610{\sim}680{\mu}m$. The head collar $48{\sim}75{\times}10{\mu}m$ had 31 collar spines. The isolated trematod fluck from the samples was classified as a Himasthla kusasigi by the morphological characteristics of the adult flock and its metacercariae. We oberved that the second intermediate host of Himasthla kusasigi was hard clam, Meretrix lusoria, while its final host was herring gull, Larus crassiostris and Tringa ochropus.
서해안 내초도 및 부안돈지산 백합의 족부 근육내에서 Himasthla kusasigi의 피낭유충을 다량 검출하고, 충체의 형태와 기생률을 조사하였고, 검출된 피낭유충을 괭이갈매기에 먹여 10일, 25일후 충체를 분리함으로써 동흡충의 감염 경로를 규명하였다. 검출된 피낭유충의 크기는 $210{\sim}230{\times}220{\mu}m$, 탈낭된 유충은 $420{\times}160{\mu}m$이며, 두극은 좌우 우극을 포함하여 31본이다. 구흡반은 $52{\times}52{\mu}m$이고, 복흡반은 $112{\times}100{\mu}m$으로서 충체의 후방에 위치하며 식도는 가늘고 길며, 장은 복흡반 상단에서 좌우로 분지되어 중체 후단에 까지 달한다. 내초도산 백합 448개중 441개, 부안산 123개중 118개가 감염되어 각각 $98.43\%,\;95.93\%$의 감염률을 나타낸 반면에 서산산은 동흡충이 검출되지 않았다. 조개의 크기가 클수록 기생충수가 많았고, 최고 99개(각장 6.64cm), 최저 1개(각장 2.05cm)이었다. 조개에서 얻은 피낭유충 120개를 괭이갈매기에 먹여25일후 102개의 성충을 장에서 분리하였다. 이 성충은 크기가 $4.8{\sim}7.5{\times}0.22{\sim}0.24mm$이었고, 구흡반은 $68{\sim}120{\times}70{\sim}120{\mu}m$, 인두는 $80{\times}50{\mu}m$, 복흡반 $630{\sim}680{\times}610{\sim}680{\mu}m$, 두관부는 $48{\sim}75{\times}10{\mu}m$의 두극 31개가 배열되어 있다. 충난은 $92{\sim}95{\times}58{\sim}60{\mu}m$의 크기이다. H. kusasigi의 제이중간숙주는 백합이며 종숙주는 괭이갈매기 및 삑삑도요새이다.