Field evaluation of portable augmentorium cages for increasing parasitoid presence to manage Drosophila suzukii

Authors: MCDONALD, NICHOLAS - Oregon State University; Lee, Jana

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/10/2026
Publication Date: 6/17/2026
Citation: McDonald, N.S., Lee, J.C. 2026. Field evaluation of portable augmentorium cages for increasing parasitoid presence to manage Drosophila suzukii. Biological Control. 219. Article 106076. https://doi.org/10.1016/j.biocontrol.2026.106076.
DOI: https://doi.org/10.1016/j.biocontrol.2026.106076

Interpretive Summary: Since 2022, imported parasitic wasps have been approved and released on small fruit farms infested by the spotted-wing drosophila. Releasing high numbers of wasps has been a challenge, and growers expressed interest in adapting portable augmentoria to enhance wasp presence in the field. Augmentoria are used to rear beneficial wasps in the field by regularly placing infested fruit inside cages for the wasps to reproduce on while a selective mesh prevents pest flies from escaping but allows wasps entry/exit. During a two-year study, we confirmed that released wasps and wasps from the field could reproduce within augmentoria. However, portable augmentoria did not benefit parasitism of pests in the surrounding crop enough to warrant use.

Technical Abstract: Portable augmentoria are insect cages with a selective mesh entrance that contain pest-infested fruit while allowing parasitoid escape. Augmentoria may help strengthen biological control programs targeting the pest Drosophila suzukii Matsumura (Diptera: Drosophilidae) by encouraging parasitoid wasp reproduction without allowing pest escape. We evaluated whether portable augmentoria could increase local parasitoid presence and reduce D. suzukii-infestation in small-fruit farms in western Oregon, USA, during 2024–2025. The augmentoria were initially seeded with Ganaspis kimorum Buffington (Hymenoptera: Figitidae) and then resupplied periodically through the trials, along with weekly provisions of D. suzukii-infested blueberries. These treatment plots were compared with paired control plots that received no augmentorium in a randomized complete block design. Fruit was sampled at 0, 5, and 10 m from treatment points and then reared in the laboratory to assess insect emergence. Yellow sticky cards were also deployed and replaced weekly to measure insect populations. Across both years, augmentorium presence was not associated with any increase in overall parasitism, and no treatment × distance effects were detected. Yellow sticky card captures of D. suzukii and figitid parasitoid wasps were also similar between control and augmentorium plots. Fruit subsampled from inside the augmentoria confirmed intermittent oviposition by G. kimorum and adventive Leptopilina japonica. However, parasitoid mortality within the augmentoria was common, and internal temperatures exceeded 40 degrees Celsius despite measures to reduce heat. Portable augmentoria, as implemented here, supported some parasitoid reproduction but did not enhance nearby parasitism or suppress D. suzukii in surrounding fruit.