Mesh covers on sentinel parasitoid traps can restrict Drosophila suzukii movement and allow parasitism by Ganaspis brasiliensis and Pachycrepoideus vindemiae

Authors: GREENHALGH, ABIGAIL - Oregon State University; VOYVOT, SALIHA - Ege Forestry Research Institute; JOHNSON, BENJAMIN - University Of Maine; CHOWDHURY, SHEHNAZ MUNNAF - University Of Maine; FANNING, PHILLIP - University Of Maine; Lee, Jana

Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/6/2023
Publication Date: 11/8/2023
Citation: Greenhalgh, A., Voyvot, S., Johnson, B., Chowdhury, S., Fanning, P., Lee, J.C. 2023. Mesh covers on sentinel parasitoid traps can restrict Drosophila suzukii movement and allow parasitism by Ganaspis brasiliensis and Pachycrepoideus vindemiae. Biocontrol Science and Technology. https://doi.org/10.1080/09583157.2023.2272227.
DOI: https://doi.org/10.1080/09583157.2023.2272227

Interpretive Summary: Parasitic wasps such as the Samba wasp are being released for biological control of spotted-wing drosophila (SWD), a costly pest of blueberries, raspberries, and blackberries. Oftentimes, we check for these wasps by collecting fruit infested with SWD from the field and check if any wasps are in SWD. Fruit collection may not always be possible or the field is well-managed and few fruit are infested. In these cases, we use sentinel traps consisting of fruit purposely infested with SWD and check if they are parasitized by these wasps. With sentinel traps, researchers may be concerned if SWD can exit or other fly species in the field can also infest the fruit, and thereby affect our measurements. Various fabric and wire meshes were tested as covers for sentinel traps for restricting SWD movement and allowing wasp passage and parasitism. One fabric mesh with ~1.1 x 1.1 mm square openings worked well to prevent SWD from exiting but allowed wasp passage, and was the best option for a selective barrier in sentinel traps.

Technical Abstract: Parasitoids such as Ganaspis brasiliensis and Pachycrepoideus vindemiae are currently researched for biological control of Drosophila suzukii, an important agricultural pest of small fruits. Parasitoids can be monitored in the field by collecting infested fruit samples. When this is not possible, sentinel traps can assess parasitoid presence. Sentinel traps may be covered with a selective barrier to allow movement of parasitoids and prevent nontarget infestation and developing D. suzukii from exiting. In this study, two types of fabric mesh (square 1.1 x 1.1 and oval 1.2 x 0.8 mm openings) were assessed for passage of D. suzukii, G. brasiliensis, and P. vindemiae, and parasitism rates. In addition, wire meshes (1.04, 1.08, 1.11, 1.13, 1.18, and 1.53 mm2) were tested as a more durable alternative to the fabric mesh for G. brasiliensis sentinel traps. Both fabric meshes and the 1.08 and 1.3 mm2 wire mesh prevented passage of D. suzukii. Passage was similar through fabric oval and square mesh for both parasitoids. For G. brasiliensis, parasitism was 3-fold higher in open control sentinel 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 wire mm2 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.