Insect-flower Relationship in the Campus of Kyoto University, Kyoto : An Overview of the Flowering Phenology and the Seasonal Pattern of Insect Visits

Abstract

In 1985-1987 insect visitors to flowers were weekly or biweekly surveyed on a total of 113 plant species or 48 families in the campus of Kyoto University in Kyo-to city, Japan. Although the total number of plant species was nearly equal to those in Ashu and Kibune, native species were only 25, due to urbanization and disturbance. Flowering started from cultivated plants, e.g. Prunus spachina, in early April and ended also in cultivated plants, e.g. Camellia sazanqua in late November. The total number of plant species at flowering peaked in May. The flowering period of a single species was 17 days on average. A total of 2109 individuals of 320 species in nine orders of Insecta and two or-ders in Arachnoidea were collected in our samples. The total number of arthropod species was estimated to be 790 by the Preston's octave method and thus 40.5 % were in our samples. The most abundant order was Hymenoptera (50 % of in dividuals), followed by Coleoptera (26 %) and Diptera (16 %). The number of species was highest in Diptera (34%), followed by Hymenoptera (33 %) and Coleoptera (14 %). Compared with the undisturbed areas, Ashu and Kibune, two dominant Coleopteran families, Cerambycidae and Nitidulidae were quite rare here. In Hymenoptera, Megachilidae were quite abundant on exotic cultivated plants. The estimated total number of bee species (170 sp.) was more than those in the undisturbed areas. The number of insect species peaked twice in June and September, whilet he total number of individuals peaked in May and September. Coleoptera peakedi n May and June, Diptera peaked in June and October, while Hymenoptera appeared rather constantly throughout the flowering season. Cluster analysis separated 48 plant families into four groups: 30 families mainly visited by Hymenoptera, 6 families by Diptera, 9 families by Coleoptera and the others (3 families) by Lepidoptera.