Root Weevil (Coleoptera: Curculionidae) and Ground Beetle (Coleoptera Carabidae) Immigration into Strawberry Plots Protected by Fence or Portable Trench Barriers.

Physical exclusion shows some potential as a novel root weevil control strategy, but barriers to root weevil immigration may also exclude beneficial insects, such as ground beetles. A field study was undertaken in 1997 to assess the impact of two physical barriers-portable plastic trenches and aluminum fences with Teflon tape- on root weevil and ground beetle immigration into plots of strawberry, Fragaria x ananassa (Duchesne). Banjpeithes pellucidus (Boheman) and Nemocestes incomptuc (Horn), each comprised 43% of the root weevils caught at the site. Most (86%) of the ground beetles caught in control plots were longer than 1 cm, the width of the gap in the portable trench top. Trenches excluded 75 and 63% of B. petlucidus and N. incoinptus, respectively, without significantly reducing immigration of large (<1 cm) ground beetles. Fences excluded 65, 84, and 99% of B. pellucidus, N. incomptus, and large ground beetles, respectively. Adding diatomaceous earth to trenches did not increase theft efficacy, and fences without Teflon tape excluded ground beefles but not root weevils The reduction in the population of root weevils and other strawberry pests caused by the use of barriers reduced damage to strawberry plant leaves and increased strawberry plant survival relative to unprotected control plots. Advantages and disadvantages of these physical control tools are discussed with a view to creating superior tools for root weevil exclusion, compatible with an integrated pest management approach. Portable trenches may offer a means of selectively excluding root weevils but not ground beetles. [ABSTRACT FROM AUTHOR]