The role of variable weather for the dynamics of a seed-seed predator system.

A simple model is presented describing the interaction between weather conditions, seed production of a longlived herb, Vincetoxicum hirundinaria (Asclepiadaceae), and abundance of a predispersal seed predator, Euphranta connexa (Diptera, Tephritidae). The model is used to investigate the role of weather-induced fluctuations in seed set on the interaction between plant and seed predator and the resulting longterm production of seeds escaping predispersal seed predation.As weather variability increases Euphranta populations become less effective in tracking their food resources, leading to increased longterm production of dispersing seeds. Occasional years of crop failure due to drought stress may thus in the long run be of benefit to the plant.