The effect of root weevils (Coleoptera: Curculionidae) on yield of five strawberry cultivars in British Columbia

Abstract

To determine the effect of root weevils on strawberry yield, 5 strawberry cultivars: Totem, Shuksan, Northwest, Cheam and BC-25 were infested in the field with 2 or 8 adults per plant of 1 of 4 species of root weevils: the black vine weevil, <i>Otiorhynchus sulcatus</i> (F.); the strawberry root weevil, <i>O. ovatus</i> L.; the obscure strawberry root weevil, <i>Sciopithes obscurus</i> Horn; and the woods weevil <i>Nemocestes incomptus</i> (Horn). There were no significant differences in yield between weevil infestations in the first cropping season. In the second year plants in the plot infested with 8 <i>O. sulcatus</i> per plant produced significantly less fruit than those in all other infestations. Within this plot Totem and Cheam produced significantly more fruit than the other cultivars. In the third year most of the other weevil-infested plots produced significantly less fruit than the uninfested plot. The plot with 2 <i>N. incomptus</i> per plant was the most severely damaged in the third season. The cultivars Totem and Cheam were usually the most tolerant to all weevils. Northwest and BC-25 were the most susceptible to all weevils. The tolerance of Totem to attack by the main root weevil species, <i>O. sulcatus</i>, is probably related to the ability of the plant to produce and regenerate a large supply of roots.