CORRELATION BETWEEN FLORAL TRAITS OF CHRYSANTHEMUM (DENDRANTHEMA MORIFOLIUM) AND INSECT VISITORS
WANG Wei, DAI Hua-Guo, CHEN Fa-Di, GUO Wei-Ming
Chin J Plan Ecolo. 2008, 32 (4):
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Aims Chrysanthemum (Dendranthema morifolium) is a self-incompatible allogamous plant. Its main pollination vectors are bees and butterflies. Our aim is to investigate and evaluate the effects of flower color, corolla density, corolla diameter, tubular flower diameter, plant height and essential oil components on attracting insect visitors.
Methods We investigated the floral traits of 19 chrysanthemum cultivars. Five cultivars with different floral traits were selected for identification of essential oil components using a Thermo Finnigan TRACE GC/DSQ spectrometer, and data on essential oil components were analyzed by SPSS (Analysis of Variance, stepwise and correlation).
Important findings Bees (Apis mellifera) preferred yellow color flower to others including orange yellow, red, mauve, orange and pink. The number of visiting bees was significantly correlated with corolla density (r=0.715, p<0.01), indicating that the effect of a colony was more significant than the size of a single flower head. For all tested traits of a single flower head, tubular flower diameter had the most significant influence on attracting bees (r=0.622, p<0.01), followed by corolla diameter (r = –0.502, p<0.05). Butterflies (Vanessa indica) preferred red color flowers, and tubular flower diameter significantly influenced the number of pollinating butterflies (r=0.635, p<0.01). Results suggested that rewards from the flowers were the dominating attractive factors to visitors. The effect of single flower head on number of visiting butterflies was more significant than corolla density (r=0.487, p<0.05). In all tested traits of a single flower head, flower color and tubular flower diameter were the main influencing factors on numbers of visiting butterflies. The main essential oil components, such as camphor (rbees= –0.191, p>0.05; rbutterflies=0.507, p>0.05) and borneol (rbees=0.354, p>0.05; rbutterflies= –0.387, p>0.05) had little correlation with number of visiting insects, whereas some specific essential oil components, such as camphene (r= –0.909, p<0.05), 2-pentadecanone,6,10,14-trimethyl- (r=0.882, p<0.05) showed significant correlations with number of visiting bees, and α-terpineol (r=0.979, p<0.01), cis-limonene oxide (r=0.979, p<0.01), E-farnesene epoxide (r=0.979, p<0.01), p-mentha-6,8-dien-2-ol, cis- (r=0.973, p<0.01), p-menth-1-en-8-ol (r=0.962, p<0.01) and p-menth-1-en-4-ol, [R]-[–]-(r=0.957, p<0.05) showed significant correlations with number of visiting butterflies. Therefore, some specific essential oil components were important in attracting visitors.