Effects of Gall Formation by Neothoracaphis yanonis (Hemiptera : Aphididae) on Shoot,Fruit,and Seed Production of Its Host Plant,Distylium racemsum (Hamamelidaceae)

Abstract

Effects of leaf gall formation by Neothoracaphis yanonis (Hemiptera: Aphididae) on the growth and reproduction of its host plant, Distylium recamosum (Hamamelidaceae), were studied in a viewpoint of sink-source relationship. Gall formation on the leaves of current-year spring shoots did not affect the production of lammas shoots in later seasons of the current year and of spring shoots in the following year. Many galled leaves abscised in late May and early June after the gall dehisced and alates left the galls, but the abscission of galled leaves appeard unrelated to the production in lammas and spring shoots. The leaf gall formation reduced significantly the production of fruit and seeds. in particular, the abscission of galled leaves affected the seed production more severely than the fruit production.