Abai, MR

6th International Congress of DipterologyLight effect on the photosynthetic reflectance properties ofan oval-pointed cecidomyiid gall of Machilus thunbergiileavesHuang, W.-D. (1), M.-H. Hsu (2), Z.-W. Yang (2), M.-Y. Huang (3) & C.-M. Yang (1,2)*(1) Department of Agronomy, National Taiwan University, Daan, Taipei, Taiwan 101,ROC(2) Research Center for Biodiversity, Academia Sinica, Nankang, Taipei, Taiwan 115,ROC(3) Department of Life science, National Taiwan Normal University, Taipei, Taiwan 116,ROC*Corresponding author: cmyang@gate.sinic.edu.twAn oval-pointed cecidomyiid gall (Dephnephila sp.) residing on the lowerepidermis of Machilus thunbergii leaf has red side exposing to light andgreen side unexposing to light, i.e. while the latter attaches to the host leaf,the former not. Therefore, the aim of this study was to test the hypothesesthat the surface reflectance characteristics of red and green side aredifferent in the same gall, and that the spectral properties of both sides ofthe same gall are directly related to photosynthetic processes and pigmentcomposition. The galls were divided into four stages on the basis of size tostand for its various development stages. By using the reflectance spectrumranging from 400-900nm, seven indices such as photosynthetic reflectanceindex (PRI), red/green ratio (R/G), normalized difference vegetation index(NDVI), adjusted NDVI (aNDVI), cold hard band (CHB), the structureindependent pigment index (SIPI) and normalized pigment chlorophyllratio index (NPCI), were applied to investigate the surface reflectancecharacteristics of galls. While the PRI, NDVI, aNDVI and CHB of innergreen side gradually increased during the gall development, the R/G, SIPIand NPCI were reversed. Meanwhile, the PRI, R/G, NDVI, aNDVI andCHB of outer red side gradually decreased, the SIPI and NPCI wereinverted. It is concluded that exposure to light affect the surface reflectanceproperties and their corresponding photosynthetic, and nonphotosyntheticpigments of galls.119