Contribution of Pollinators to Seed Production as Revealed by Differential Pollinator Exclusion in <em>Clerodendrum trichotomum</em> (Lamiaceae)

<div><p>A diverse assemblage of pollinators, such as bees, beetles, flies, and butterflies, will often visit a single plant species. However, evaluating the effect of several insects on fruit and seed production is difficult in plants visited by a variety of insects. Here, we analyzed the effect of three types of pollinators, <em>Papilio</em> spp., <em>Macroglossum pyrrhosticta</em>, and <em>Xylocopa appendiculata</em> on fruit and seed production in <em>Clerodendrum trichotomum</em> by using a flower visitor barrier experiment with nets of specific mesh sizes. As a result, fruit/flower and seed/ovule ratios were significantly lower under <em>Papilio</em> exclusion than under natural conditions. On the other hand, ratios were not significantly different between <em>Papilio</em> excluded and both <em>Papilio</em> and <em>M. pyrrhosticta</em> excluded treatments. Therefore, <em>Papilio</em> and <em>X. appendiculata</em> are effective pollinators, whereas <em>M. pyrrhosticta</em>, which was the most frequent visitor, of <em>C. trichotomum</em>, is not. From our observations of visiting behaviors, we believe that because <em>M. pyrrhosticta</em> probably promotes self- pollination, this species is a non-effective pollinator. This is the first study to separate and compare the contribution of various visitors to the reproductive success of a plant.</p>