A beneficial species becomes a pest - the common earwigForficula auricularia (Linnaeus 1758)

Abstract: The common earwig Forficula auricularia has been classified as a beneficial predatorin vineyards. Amongst others the insect feeds on grape pests like different tortricids. In recentyears within many regions of the viticultural area of the Palatinate the individual densitiesincreased to an extremely high level. Earwigs may cause direct damages such as contaminationof the grapes with faeces, eroded berries and transfer of pathogens. The chemical agent 2-methyl-1,4-benzoquinone, released from the abdominal glands while earwigs are menaced and likewisecontained in faeces, may have a negative influence on the wine quality. All these facts constitutea deterioration of grape quality for wine-growers. The high number of earwigs in the grapes aftervintage causes a negative image by consumers. This study was carried out to investigate possiblerelations between the population dynamics of earwigs and specific environmental conditions invineyards. The main focus of the research project was focussed on chemical, ecological andbiological strategies to reduce the population densities. Another important point of survey was tostudy the life cycle of earwigs especially in vineyards. For sampling purposes in the cluster zonea special life trap made of bamboo tubes has been developed. This type of trap showed thehighest catch rate of the four trapping types tested. For monitoring the ground dwelling earwigspitfall traps were used.