Spindle shaped leaf galls on Cyclobalanopsis glauca (Fagaceae)-the biology and taxonomy of gall midge

• Main Authors: Chang-Ti Tang, 唐昌廸
• Other Authors: 楊曼妙
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/98230544949837370044

碩士 === 國立中興大學 === 昆蟲學系所 === 96 === Cyclobalanopsis glauca is an extensively distributed species of Fagaceae in Taiwan. Spindle-shaped galls on the lateral veins or midribs induced by a species of Cecidomyiidae are of common occurrence in Taiwan. The taxonomy and biology of the spindle-gall inducing gall-midge species (tentatively named CGM – Cyclobalanopsis-glauca midge) have not been described. To establish the biology and taxonomy of CGM, populations of C. glauca bearing galls induced by CGM from Baoshan Township of Hsin-Chu County and on Mt. Tung-Mau in Heping Township of Taichung County were sampled. Populations of C. glauca in Wulai Township of Taipei County and Wanda Reservoir of Nantou County were used as secondary sampling sites. Life history data measured from January 2007 to May 2008 revealed that the gall midge take one year from eggs, larvae, pupae, and adults, with a single generation in a year. Adults emerged and laid eggs in March 2007, when C. glauca shot new leaves. The female laid eggs on young shoots or young leaves of the host. After emergence, the neonate larvae crawled to the upper surface of young leaves and settled on lateral veins or midribs to stimulate the leaf veins and peripheral tissues to induce galls. Each gall is one chambered with housing one CGM larva. The larvae turn into second instars in April, prolonged for about eight months, and turn into third instars in November--December. Pupation occurs in February--March of the following year, and then the emergence and oviposition of adults occurs in March coiciding with the shooting of young leaves of C. glauca. The parasitic wasps of larval stages include both endoparasites and ectoparasites. Four species of endoparasitic wasps belonging to Torymidae, Eulophidae, and Platygastridae parasitize CGM. However, adults of ectoparasitoids could not be located and their identification remains unknown for the present. The rate of parasitism maximizes March (2008) and the percentage of endoparasitic wasps was higher. Time-related development of galls and larvae is different. Morphometric data of galls indicate that the galls reach the maximal size in six days, within which the first instar larvae trun into second instars till their adult stage. Comparisons of the width of sternal spatulae of second and third instar larvae and gall volume from populations of Baoshan, Mt. Tung-Mau, Wanda Reservoir, and Wulai sites indicate that the widest sternal spatulae of second instar larvae occur in Baoshan, the intermediate widths in Mt. Tung-Mau and Wanda sites, and the narrowest occur in Wulai while the widest sternal spatulae of third isntar larvae occur in Baoshan and Mt. Tung-Mau, the intermediate width occur in Wulai, and the narrowest occur in Wanda sites. Comparisons of gall volume revealed the largest galls occur in Baoshan, the intermediate galls occur in Wuali, while the smallest galls occur in Mt. Tung-Mau and Wanda Reservoir. Further analyze whether the preference of galling position on the leaves will result in larger gall volume and revealed the larvae had preference of galling position but did not correlate with gall volume. To determine the meaning of the pre-cut exit holes third instar larvae, the emergence ratio of galls with and without exit holes in the same time were compared. The emergence ratio of galls with exit holes was 87.5% while without exit holes was 0%. The results revealed the pre-cut exit hole behavior is a sign of successful emergence of adults. Morphological examination of the third instar larvae, pupae, and adults by slide mounting specimens and SEM. The adults’ characters fit to the descriptions of the genus Dasineura. Since there are no records of gall midges induce spindle-shaped galls on the leaves of C. glauca, this species treat as a new species and named Dasineura glaucae sp. nov.