We analyzed factors that affect Ipomoea pes-caprae (L.) R. Br. (Convolvulaceae) seed production within the vegetation of 10 beaches on Santa Catarina Island, state of Santa Catarina, Brazil. Ipomoea pes-caprae is a self-incompatible reptant psamophyte, with long stolons. Thus, genets are difficult to distinguish in the field. We therefore monitored patches of Ipomoea pes-caprae, defined as discontinuous areas, colonized by the plant. Abortion occurred in 9.4% to 76.0% of the inflorescences of all sites. Abortion after flowering was the major cause of these losses, probably due to ineffective pollination. Sand burrowing had damaged buds and fruits. Seed predation by larvae of the bruchids Megacerus baeri and M. reticulatus and by caterpillars of the moth Ephestia kuhniella was expressive. The bruchids had laid their eggs on fruits near maturation and had damaged as much as 65.7% of the seeds. Ephestia kuhniella damaged up to 57.4% of seeds in 1996, but only 5.4% in 1997, a year with lower fruit abundance. Fruits damaged by the moth did not open in order to disperse their seeds and remained attached to the plant for about three and a half months. The seeds not attacked by the moth were viable, and their seedling survival was similar to that of uninfested fruits. The types of damage observed were capable of reducing the viable seeds of Ipomoea pes-caprae to 9.0% of the total production. Densities from 0.5 to 30.6 viable seeds m-2 were estimated, with the highest densities in patches with a greater abundance of fruit. We therefore concluded that a strategy of high fruit production might prove to be advantageous. The low density of viable seeds in some locations could represent a limitation on local regeneration.
coastal dunes; seed predation; seed production; pre-dispersal hazards
