抄録
The susceptibility of five common species of mosquitoes in Japan to the infective stage of mermithid nematode Romanomermis culicivorax was examined. The incidence of parasitism was highest in Culex pipiens molestus, followed by Cx. p. pallens, Aedes albopictus, Ae. togoi, Armigeres subalbatus. Effect of type of nematode introduction and host arrangement was studied. 2400 nematodes in infective stage were released in a 6.5×120cm stagnant water path, comparing two types of introduction. In the 1st type nematodes mixed well in overall water and in the 2nd type nematodes were introduced at an end of the path. Eight screened containers 30 larvae of Cx. p. molestus each were variously located. Parasitism was highest when nematodes were mixed in overall water and the larvae were held in 8 locations. No parasites were recovered when nematodes were introduced at an end and the larvae located 120cm away. When nematodes introduced at an end and the larvae were placed every 15cm from the point of introduction, the parasitism was highest at the nearest place from the released spot. Number of parasites recovered (N) is given as N=-48.4 log D+96,where D is distance from the released point. These findings indicate that the nematodes in infective stage may not disperse more than 100cm in stagnant water.
