Seed rot of post-dispersal Prunus verecunda seeds induced by sucking of Macroscytus japonensis

Abstract

We examined pre- and post-dispersal seed predation in Prunus verecunda in a deciduous broad-leaved forest, northern Japan. Few seeds died before dispersal, but most seeds were preyed upon by small rodents on the forest floor after dispersal. Although the seeds on the forest floor died of rot at a high rate when vertebrates were excluded, most seeds survived when vertebrates and invertebrates were excluded. Many burrower bugs (Macroscytus japonensis) were observed around seeds in experiment plots. As soon as we fed the burrower bugs on P. verecunda seeds in the laboratory, they stuck their proboscises into the side of seeds and sucked the seeds. We inoculated intact seeds and the seeds sucked by the bugs with fungi isolated from rotten seeds. Most sucked seeds then rotted, although few intact seeds rotted. Therefore, the sucking by the burrower bugs probably induced seed-rot by fungi in P. verecunda seeds even if the seeds escaped predation by small rodents on the forest floor after dispersal.