Nectar Robbing and Pollination of Lantana camara (Verbenaceae)

Abstract

Floral robbers are categorized as nectar-foraging, nectar-foraging-perforating, and pollen-foraging. Trigona fulviventris is a nectar-foraging-perforating robber of yellow flowers of Lantana camara. Flower head maturation of L. camara is centripetal and flowers turn from yellow to reddish-orange, resulting in inflorescences of central yellow flowers with peripheral orange and reddish-orange ones. In the laboratory, seed set occurs only after cross-pollination; in the field, the presence of orange and reddish-orange flowers is related to decreased nectar robbery of yellow flowers. Co-evolution of L. camara, its butterfly pollinators, and T. falviventris has presumably involved increased nectar production of this plant to feed both its pollinators and robber. THIS STUDY WAS MADE because of our limited knowledge of the pollination ecology of Latana camara; furthermore, it is the first record of nectar robbery by the stingless bee, Trigona (Trigona) fulviventris, or any other meliponine apid. T. fulviventris is a nectar-foraging-perforating robber of L. csmara which bites holes below the bases of the stamens (fig. 1) and probably effects little if any cross-pollination. Possible effects of its robbing behavior on butterfly pollinators and the general pollination ecology of this plant in Costa Rica were investigated. L. camara is a woody shrub distributed throughout tropical Central America; it has also become naturalized in other tropical and subtropical areas. Flowers gradually turn from yellow to reddish-orange in three days in the plants studied. Dronamraju (1958, 1960) reported that butterflies preferentially visit yellow flowers of Lantana and Muller (1877) hypothesized that having varicolored flowers makes inflorescences more visually attractive in potential pollinators. In Costa Rica, in addition to Lawtana, Trigona spp. rob nectar by perforation from Hamelia patens, Clerodendrum paniculatum, Rondeletia, and Malvaviscus. In other parts of the world, other genera of bees (e.g. Bombus, Apis, Xyloco pa, and Megachile) are or are likely to be nectar-foraging-perforating robbers of various genera of plants having flowers with tubular corollas (see for examples, Sprengel 1793, Darwin 1876, Kerner 1895, Porch 1924, Meidell 1944, Schremmer 1955, Meeuse 1961, Hurd and Linsley 1963, Macior 1966, 1970, 1971, Faegri and van der Pijl 1971).