Abai, MR

6th International Congress of DipterologyPositive indirect effects of deer browsing on dwarf bamboofor the abundance of gall midgeTabuchi, K. (1), A. Ueda (2), K. Ozaki (3) & T. Hino (4)(1) JSPS Research Fellow, Hokkaido Research Center, Forestry and Forest ProductsResearch Institute (FFPRI), 7 Hitsujigaoka, Toyohira, Sapporo 062-8516, Japan(2) Hokkaido Research Center, FFPRI, 7 Hitsujigaoka, Toyohira, Sapporo 062-8516,Japan(3) FFPRI, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan(4) Kansai Research Center, FFPRI, 68 Nagaikyutaro, Fushimi, Kyoto 612-0855, JapanTo examine the indirect effects of deer browsing for the abundance of gallmidge, we investigated density of the bamboo culm gall midge(unidentified, tribe Oligotrophini) in- and outside of the deer exclosures.The gall midge studied here forms bean-shaped galls on culm of the dwarfbamboo (Sasa nipponica Makino et Shibata), the major forage for Sikadeer (Cervus nippon Temminck). Field study was conducted at Mt.Ôdaigahara, in west-central Japan from 1997 to 2004. Gall and larvaldensity was ordinary low (both area and plant level) at inside of deerexclosures where the bamboo culms were longer and the density ofbamboo shoot were low due to their escape from browsing. On the otherhand, at outside of deer exclosures, bamboo culms were shorter but denseby compensation growth of bamboo against deer browsing. Although galland larval density was low inside of deer exclosures, midge femalesselected large one as oviposition site in the choice experiment of large andsmall bamboo sprout. This result suggests that large bamboo sprouts havesome resistance for the gall formation because large bamboo sprouts wouldbe oviposited more eggs in the field. In summary, deer browsing producesmall and galling-susceptible bamboo and causes positive indirect effectfor the abundance of gall midge.Key Words: community ecology, indirect effect, Cecidomyiidae,Gramineae, Cervidae255