Abstract:

Host-mediated effects on hemiparasitic mistletoes were hypothesized to contribute to mistletoes reproductive phenological asynchrony, thus providing a longer period of food supply to its mutualistic pollinators and dispersers. However, studies with empirical data interrogating this hypothesis are lacking. Weekly monitoring of flowering and fruiting patterns on a generalist mistletoe Dendrophthoe pentandra (Loranthaceae) was conducted for two consecutive years in tropical Xishuangbanna, Southwest China. We examined whether flowering and fruiting patterns were seasonal, quantified the degree of stagger within D. pentandra populations and determined the factors influencing the first flowering date (FFD) of D. pentandra. Furthermore, the effect of change in the number of host species on reproductive phenological asynchrony of mistletoe was examined. We found that (i) both flowering and fruiting exhibited unimodal peaks in the two consecutive years of the study; (ii) the FFD was significantly influenced by crown area of mistletoe and light, such that clump with larger crown and more light exposure had an earlier FFD and longer flowering and fruiting durations; (iii) different host species had a significant impact on the phenology of mistletoes. However, contrary to our hypothesis, the number of host species did not significantly change the asynchrony of reproductive phenology of mistletoe. Therefore, these results suggest that alternative hypotheses are needed to interpret the ecological significance of the number of host species and phenological asynchrony of generalist mistletoes.

Key words: asynchrony, Dendrophthoe pentandra, first flowering date, host effect, mutualism