Mesh covers on sentinel parasitoid traps prevent Drosophila suzukii movement and impact parasitism by Ganaspis brasiliensis and Pachycrepoideus vindemiae

Abstract

ABSTRACT Parasitoids such as Ganaspis brasiliensis and Pachycrepoideus vindemiae are being researched for biological control of Drosophila suzukii, an important agricultural pest. Parasitoids can be monitored in the field by collecting infested fruit samples or using sentinel traps seeded with host larvae/pupae. Sentinel traps may be covered with a selective barrier to allow parasitoid movement, and prevent nontarget infestation and developing D. suzukii from exiting. In this study, two types of fabric mesh (‘square’ 1.1 × 1.1 mm2 and ‘oval’ 1.2 × 0.8 mm2) were assessed for restricting passage of D. suzukii, and enabling passage and parasitism by G. brasiliensis and P. vindemiae. Square wire meshes (1.04, 1.08, 1.11, 1.13, 1.18, and 1.53 mm2) were also tested as a durable alternative to the fabric mesh for G. brasiliensis sentinels. Both fabric meshes and the 1.08 and 1.13 mm2 square wire mesh prevented passage of D. suzukii. Passage was similar through fabric mesh for both parasitoids. For G. brasiliensis, parasitism was higher in open control sentinels than square mesh covered sentinels in one trial, but parasitism was similar at ∼40% in open and square mesh sentinels in another trial. The 1.04, 1.08 and 1.13 mm2 square wire mesh lowered G. brasiliensis parasitism. For P. vindemiae, parasitism was 2-fold higher in oval mesh than open sentinels which may be due to the mesh encouraging this wasp to forage longer. If a selective mesh must be used, the square fabric mesh prevented D. suzukii passage and resulted in the highest G. brasiliensis parasitism compared to wire meshes.