柿園に放飼されたフジコナカイガラムシ Allotropa sp. の分散

抄録

The dispersion of Allotropa sp. liberated in a persimmon grove was examined. 7, 500 mummies of Allotropa sp. were released as an attempt to control Planococcus kraunhiae Kuwana. The mummies were released on four trees in a grove of 20a, where the host population density was relatively low.
Distance of the dispersion was estimated from the number of individuals of this parasite which stuck to "Haetori Ribbon" a kind of sticky trap. The sticky traps were hung on 20 trees, five of which were inside of the grove and the others were outside. Each one was placed on three parts of the tree, upper, medium, lower, by tying it on a thread hung from the top branch.
Before releasing the parasite, these traps were left hanging for a day to know the number of individuals of the parasite originally living there. At the time of release other new traps were hung and collected seven days after.
Inside of the grove, the average number of the parasite increased by approximately three times after release, which was observed on the traps located at about 10m from the trees released. Outside of the grove, however, average number was reduced to about a half after release, although an increase was observed at No. 16 situated at 8.5m from the nearest tree released.
From this investigation; it may be concluded that this parasite dispersed to a distance of about 10m and the present result agrees approximately with the estimation by Tanaka & Ko-bayashi (1967) and it seems to disperse searching the host hovering about the height of 2m or higher, the medium and upper parts of the crown. From this result, it can be expected to use this parasite as a biotic insecticide.