Coreus marginatus (Heteroptera: Coreidae) as a natural enemy of Rumex obtusifolius (Polygonaceae)

Rumex obtusifolius is the preferred host plant of Coreus marginatus. The survival of nymphal C. marginatus, its development on a diet of R. obtusifolius and the effects of herbivory on Rumex seed were investigated. Although the diet consisting solely of seed did not allow complete development, growth rates and survival of nymphs were proportionate to the quantity of provided seed. Nymphal feeding did not noticeably decrease seed mass but significantly decreased the proportion of germinating seed. In this way C. marginatus affects Rumex reproduction. Germination ability decreased with decreasing seed availability and increasing duration of seed predation. Nymphs confined to Rumex inflorescences in the field-completed development and significantly reduced both seed mass and germination ability. The mortality of seed overwintering on standing dry shoots of dock plants was moderately affected by feeding of C. marginatus.