Biological Characteristics And Pollination Behaviors Of Two Gall Midges In Flowers Of Illicium Verum

The yellow Illicium blossom gall midge and the red Illicium blossom gall midge are two kinds of insects lived on the flower of Illicium verum. The paper studied their morphological characteristics、biological characteristics and pollination behaviors by indoor observation and field investigation. The yellow Illicium blossom gall midge belongs to Anabremia (Cecidomyiidae), the red Illicium blossom gall midge belongs to Clinodiplosis (Cecidomyiidae), their morphological characteristics were described; biological characteristics and population dynamics in flowering period of Ⅰ. verum about these gall midges were known; the flowering phenology of Ⅰ, verum、the flower-visiting insects of Ⅰ. verum were definite, two species gall midges are the pollinators of Ⅰ. verum. The results acted as a theoretical basis for planting、quality and high production of Ⅰ, verum and the protection of pollinators, and the new model was created for studying biological coevolution between insects and plants. The mainly results are as follows.1. The flowering period of Ⅰ, verumIt lasts from July to December, and usually get peak from August to September.Ⅰ. verum is typical of monoecious protogyny and cross-pollination plant. Anthers dehisce and pollen grains release at about24h after flowers opening. It takes about6-8days from blossom to withering for each flower.2. The flower-visiting insectsThe flower-visiting insects of Ⅰ. verum mainly include:The yellow Illicium blossom gall midge and the red Illicium blossom gall midge (Diptera:Cecidomyiidae), Frankliniella (Thysanoptera:Phlaeothripidae) and the ants of Hymenoptera.3. There are significant differences in the morphological characteristics of adult, egg, larva, pupa and cocoon between the two species of gall midges.4. Biological characteristics for two species of gall midges(1) A close relationship has been presented between occurrence amount of two species of gall midges in Guangxi and the flowering period of Ⅰ. verum. Last instar larvae usually build round cocoons in soil to overwinter. The cocoons are mainly distributed in the topsoil about0-5cm deep.(2) A generation of these gall midges usually lasts for11-14d, and their egg stage is1-2d, the larval stage is7-8d, the pupal stage is3-4d, the adult stage of yellow Illicium blossom gall midge is3-7d, the adult stage of red Illicium blossom gall midge is4-7d.(3) Adults of two species eat the mycelia of rhizopus sp.(Mucoraceae, Mucorales, Zygomycetes) infecting the flowers of Ⅰ. verum. Female midges lay abundant eggs inside the flowers and the larvae live inside the flower by eating the humus of the perianth.5. Population dynamics for two species of gall midges in flowering period of Ⅰ, verumIn the flowering period of Ⅰ. verum, the number of eggs and larvas increase persistently as the flower augment. The adults emerge out of the soil all through the year and reach the peak from July to October. However, a few of adults emerge in succession from November to June in the next year.6. Pollination behaviors on two kinds of gall midgesThe yellow Illicium blossom gall midge is mainly flower-visiting insects and can carry pollen. Therefore, they are the obligate pollinators of Ⅰ. verum. The red Illicium blossom gall midge seems to be secondary pollinator.