外国産マツ属の虫害に関する研究 : 第9報 マツモグリカイガラムシの寄生による樹体湾曲

Abstract

本報告には, マツモグリカイガラムシ (Matsucoccus matsumurae (KUWANA)) の寄生によりおこるマツ属樹体の湾曲被害を, 上賀茂, 徳山および白浜の各試験地において調査した結果がまとめられている。1. 樹体湾曲被害はCritchfield & Littleにより, Sylvesllres亜節に分類されているマツ属5種とP. thunbergiiを雌性親として種間交雑された4F_1雑種で観察された。2. 樹体の湾曲は, 樹齢とともに被害が増大し, 植栽後10年以後で急激に被害が増加する傾向がみられた。3. P. thunbergii×P. khasya F_1, P. massoniana, P. thunbergii×P. massoniana F_1, P. thunbergii×P. luchuensis F_1で湾曲被害が激しく, P. thunbergii, P. densiflora, P. tabulaeformis, P. thunbergii×P. tabulaeformis F_1で被害がすくなかった。雄性親のもつマツモグリカイガラムシとの親和性, 樹体湾曲の傾向がF_1雑種にうけ継がれるようである。4. マツモグリカイガラムシの寄生は, 樹体湾曲をひきおこすとともに, 激しい生長減退を生じ, 被害木は最後には枯れる。5. 樹体湾曲を示すマツの針葉は, 早期の黄変, 落葉により, 健全木と比較して相対的にすくなかった。

The margarodid scale, Matsucoccus matsumurae (KUWANA), is a native of Japan. The flagging by the attacks of this scale upon the exotic pines had been investigated at the three Experiment Stations of Kyoto University Forest, Kamigamo in Kyoto prefecture, Tokuyama in Yamaguchi prefecture and Shirahama in Wakayama prefecture from 1985 to 1988. The flagging were observed in two native pure pines, P. densiflora and P. thunbergii, three exotic pure pines, P. massoniana, P. tabulaeformis and P. khasya, and four F1 hybrids, P. thunb. x P. masso., P. thunb. x P. tabulae., P. thunb. x P. khasya and P. thunb. x P. luchu.. These pines have been classified into subsection Sylvestres by Critchifield & Little. The flagging damages of stem and branches increased with age of these pines, furthermore, increased rapidly after ten years from planting. Two native pines, P. densiflora and P. thunbergii, were most resistant and a pure and three hybrids pines, P. massoniana, P. thunb. x P. khasya, P. thunb. x P. masso. and P. thunb. x P. luchu., were respectively susceptible. The damages of P. tabulaeformis and P. thunb. x P. tabulae. were a little. It seems that the susceptibility of paternal parents to the scale have been conferred upon the F1 progeny resulted from crosses with P. thunbergii. The foliage discolors, the stem and branches become bent and distorted, and the growth of the flagging tree is less than that of the healthy tree. The flagging tree dies within five to ten years.