Pre-dispersal seed predation in Central AmericanAcacia farnesiana: factors affecting the abundance of co-occurring bruchid beetles.

摘要: Pre-dispersal seed predation of the leguminousAcacia farnesiana byMimosestes nubigens andM. mimosae (Coleoptera: Bruchidae) was investigated in Santa Rosa National Park, northwestern Costa Rica. The purpose study to determine patterns resource utilization by predators and mechanisms causing such patterns. Immature, mature, fallen fruits were monitored during dry seasons 1987 1988 from different shrubs areas. Parameters describing plant size, fecundity, relative isolation measured on each shrub. No evidence spatial or temporal segregation found between two species intensity independent variables plant.M. scarcer always occurred withM. nubigens. Both present areas with low high densities host plant, frequency distributions their emergences overlapped through fruiting season.urosigalphus sp., a hymenopteran parasitoid, represented ca. 40% all insect 30% 1988. This wasp attacked greater proportion bruchid eggs pods shrub than beneath it, more green mature fruits. Parasitism thus appears select against females that oviposit at an early stage pod maturation. harsh conditions season, namely heat desiccation, also accounted for level pre-emergence mortality, especially fruits, where survival egg adult only about 18%. Beneath shrubs, exhibited selectivity, ovipositing shade those exposed direct sunlight. In contrast parasitoids, abiotic factors probably impose selective force late maturation already dropped. can have one generation period. did not, however, change season. data obtained this suggest like natural enemies severe weather are likely limit population intra- interspecific competition.