Occurrence of pest species of the genus Oulema [Coleoptera: Chrysomelidae] in cereal fields in Northern Poland

The cereal leaf beetles Oulema melanopus L. and Oulema gallaeciana Heyden (Chrysomelidae) are common pests in European and North American cereal fields. Here we report infestation rates by Oulema spp. and yield loss of winter wheat and barley in Northern Poland (1995 to 1997) and show that both Oulema species might be of significant economic importance. Oulema melanopus was in all the three study years more abundant than Oulema gallaeciana. Larval densities ranged from 22 to 26 larvae per 100 stalks for winter wheat and 29 to 36 larvae per 100 stalks for barley. From these data we estimate yield losses of 0.5 to 4% for winter wheat and 3 to 8% for barley. The significant negative correlation between beetle abundances and the hydrothermic index indicates that higher precipitation and/or lower temperature had a negative effect on the activity of O. melanopus and O. gallaeciana.