Abstract
To clarify the life cycle of Microcephalothrips abdominalis, the abundance of adults, the ovarian development of females, and the relative wing length of males captured both on flower heads of three species of Compositae in the field, and by water traps in Cosmos fields in Kyoto, were examined from 1991 to 1994. The effects of pollen-feeding and photoperiod on preoviposition period and fertility were investigated. Female adults were collected on flower heads throughout the year, but male adults were never found in winter. Most females had well developed ovaries from April to early October, but ovaries of almost all females were immature from late October to March. Females reared under short day length entered reproductive diapause. Macropterous, brachypterous, and intermediate forms were recognized in male adults. Macropterous females and males were collected by water traps, but brachypterous and intermediate males were never collected by the traps. Changes in male wing form composition showed no seasonal pattern. The wing form composition of males, the number of adults, and the adult sex ratio were different on different bloom stages. Female adults fed both leaf tissue and pollen had higher fertility and shorter preoviposition period than female adults reared without pollen.
