Ecology of eggs of Gynacantha japonica Bartenef in paddy fields
2004
Nakagawa, M. (Ryokusei Kenkyusho Inc., Chofu, Tokyo (Japan)) | Motobayashi, T. | Arai, Y. | Nishimura, T.
Abstract A dragonfly, Gynacantha japonica often inhabits paddy fields and passes the winter at the egg stage in soil of paddy fields. It had been seen often, but a marked decrease in density has been reported. In this paper, dormancy and hatching conditions were studied in eggs of G. japonica. Diapause eggs showed relatively high tolerance against drying condition, while post-diapause eggs in spring were sensitive to drying history. Hatching of the post-diapause eggs was promoted by receiving light stimulus under ponding condition. It was considered that changes in physical conditions, especially moisture condition, of paddy fields by farm land consolidation and increase in number of fallow paddy fields may result in decrease of number in G. japonica.
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