Studies on intermediate hosts of bovine thelazia : II. Investigation on Miyake Island, Tokyo

Abstract

An investigation of bovine thelaziasis and its vectors was conducted on Miyake Island, Tokyo, during the period of September 16th-23rd, 1963. The results are as follows : 1. Adults of Thelazia species collected from the eyes of the cows were mostly T. rhodesi, and a few specimens of T. skrjabini was also captured. 2. Twelve cows were examined and they were all infected with Thelazia. Some of them were infected with both T. rhodesi and T. skrjabini. 3. The flies found on the cows were mainly Musca convexifrons and Morellia simplicissima. 4. Seventy one males and 1, 310 females of Musca convexifrons were dissected, and 7 females were infected with thelazian larvae. These thelazian larvae were identified as Thelazia rhodesi. Twenty five males and 179 females of Morellia simplicissima were dissected, but no thelazian larvae were found from them. 5. Infection rate showed a direct correlation with ovarial development in M. convexifrons. The highest infection rate was found among the flies with fully developed ovaries. 6. The vectors of Thelazia rhodesi were females of M. convexifrons. The vectors of Thelazia skrjabini were not found in this survey, but females of M. convexifrons were estimated to be the vectors.