Carabid beetles as pests of germinating gherkins

摘要

In May 1999 damage to field-grown gherkins occurred in Lower Austria in that many plants failed to germinate. Many seeds showed traces of biting and had often been carried away for a short distance. It was presumed that this might be the result of feeding by ground beetles. Where gherkin failed to establish, carabid beetles of the species Anisodactylus signatus. Poecilus cupreus and Pseudophonus rufipes were found frequently. A laboratory feeding experiment showed that A. signatus and P. rufipes would feed on germinating gherkin seeds, whereas P. cupreus refused them. Feeding activity lasted as long as the cotyledons had not yet turned green. In a choice experiment the two ground beetle species A. signatus and P. rufipes preferred pieces of wheat and millet compared to whole gherkin seeds. Therefore it seems very promising to avoid damage to germinating gherkins by baiting the beetles with wheat bran applied to the ground at the time of sowing.