Pollination of Leuhea (Tiliaceae) In Costa Rican Deciduous Forest

Abstract

Studies of the reproductive biology of three species of Luehae (Tiliaceae) conducted in Costa Rican deciduous forest demonstrated that all species produce hermaphroditic flowers exhibiting nocturnal anthesis, anther dehiscence, nectar secretion, and fragrances consistent with adaptation for nocturnal moth pollination. Luehea candida, flowering during the wet season, has self—incompatible flowers pollinated primarily by sphingid moths. Generalist diurnal visitors, including stingless bees, flies, and butterflies, were also common flower visitors, but experiments showed that they were ineffective pollinators. Luehea candida apparently rejects pollen from nearby conspecifics as a means of limiting inbreeding resulting from pollination by poor outcrossers such as stingless bees. The principal pollinators of L. seemannii, which flowers during the dry season, were determined to be the same types of diurnal visitors that contributed nothing to pollination success of L. candida. Nocturnal moths were low in abundance during the dry season and pollinated few flowers. Individuals of the deciduous forest population of L. seemannii ranged from partially to fully self—compatible, though an evergreen forest population was self—incompatible. The partial breakdown of incompatibility, diurnal pollinators, and nectar analysis of L. seemannii suggest an ongoing evolutionary shift to diurnal pollination resulting from the scarcity of nocturnal pollinators and selection by diurnal insects, especially stingless bees, in the deciduous forest. Luehea speciosa, with floral morphology and behavior nearly identical to L. candida, rarely attracted sphingids during its blooming period in the early dry season even though these moths were present in the habitat. Chemical analysis showed that nectar of L. speciosa is of a type preferred by bats rather than sphingids, but no evidence for bat pollination could be found. This species may also be pollinated largely by opportinistic diurnal visitors.

Preferential nectar robbing of flowers with long corollas: experimental studies of two hummingbird species visiting three plant species

“…Insofar as birds preferentially rob flowers with longer corollas, from which they cannot efficiently extract nectar through the corolla mouth, they may have played a role as a selective force countering corolla elongation. Other floral traits such as chemical deterrents (Guerrant and Fiedler 1981), dilute nectar (Bolten and Feinsinger 1978), protective floral bracts (Inouye 1983;Ornelas 1996), thickening of floral tissue (Inouye 1983;McDade 1984;Ornelas 1998), shifts from diurnal to nocturnal nectar production (Haber and Frankie 1982), and alliances with protective ants (Becerra and Venable 1989;Oliveira et al 1999) may also be the result of selection by nectarrobbing species.…”

Seasonality and Abundance Of Sphingids in a Garden on the Lower Slopes of the Uluguru Mountains in Morogoro Township in Tanzania

“…Moonlight is known to affect the occurrence of East African moths including the hawk moths Agrius convolvuli, Basiothia (Taylor, 1986) as well as the neotropical hawk moth Erinnyis ello (Abreu, 1974). Haber & Frankie (1982) report that sphingids pollinating trees are more abundant during rainy than dry season in Costa Rica. Moreover sphingid larvae are reported to have their peak occurrence during the early rainy season in Costa Rica (Janzen & Waterman, 1984).…”

Esfingídeos (Lepidoptera, Sphingidae) no Tabuleiro Paraibano, nordeste do Brasil: abundância, riqueza e relação com plantas esfingófilas

“…Os adultos alimentam-se de nectar e sao polinizadores efetivos, sobretudo em comunidades tropicais (SILBERBAUER-GOTISBERGER & GOTISBERGER 1975;HABER & FRANKIE 1989;BAWA 1990), onde sao adaptados as flores de especies arb6reas, arbustivas e trepadeiras (HABER & FRANKIE 1982). Sao forrageadores predominantemente noturnos e polinizam tipicamente plantas esfing6filas, com flores brancas, tubulares, hipocrateriformes ou em pincel e com urn forte aroma a noite (VOGEL 1954;FAEGRI & VAN DER PUL 1979, HABER & FRANKIE 1989.…”