Phenology of the strawberry blossom weevil and damage instrawberries

摘要

The strawberry blossom weevil, Anthonomus rubi Herbst (Col., Curculionidae) is a key pest in strawberries. Depending on the strawberry cultivar and the temperature profile in spring, it can reduce yield up to 60 %. The primary damage is caused by thefemales of the overwintering generation, cutting the petiole of the flower buds after oviposition into them. These buds usually wither after a short period of time and are eventually dropped off. Hatched larvae feed for ca. 3 weeks on the buds until pupation inside the buds. Emerging adults leave the buds and feed on the petals of abundant strawberry flowers without causing further damage and migrate to their hibernation sites. Thus, A. rubi is an univoltine species directly reducing strawberry yield and necessary to control. However, little is known about the phenology and damage caused by A. rubi to different strawberry cultivars and plant age. Since the hibernation sites are not clearly identified yet, soil and litter samples were taken from the survey areas and the nearby forests in a time series at different distances from the field border to assess the phenology and abundance in the field. Furthermore, intact and damaged flower buds, flowers in different developmental stages (BBCH-stages), and fruits were collected to determine damage level. The results showed that the infestation in plants was highest near the field borders adjacent to forests, and decreasing in intensity with increasing distance to the forests. Damage was higher in older thanin younger plantations. Between cultivars, the early flowering cv. "Daroyal" showed a higher loss of flowers than the later flowering and ripening cv. "Salsa" or "Malwina". From our results, we recommend to start infestation monitoring particularly on fields near to forests and on early flowering cultivars. Rich flowering cultivars, such as cv. "Salsa" can possibly compensate yield loss.