Identifying an optimal screen mesh to enable augmentorium-based enhanced biological control of the olive fruit fly Bactrocera oleae(Diptera: Tephritidae) and the Mediterranean fruit fly Ceratitis capitata (Diptera: Tephritida

Authors: DESURMONT, G - European Biological Control Laboratory (EBCL); TANNIERES, M - European Biological Control Laboratory (EBCL); ROCHE, M - European Biological Control Laboratory (EBCL); BLANCHET, A - European Biological Control Laboratory (EBCL); Manoukis, Nicholas

Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2022
Publication Date: 5/31/2022
Citation: Desurmont, G.A., Tannieres, M., Roche, M., Blanchet, A., Manoukis, N. 2022. Identifying an optimal screen mesh to enable augmentorium-based enhanced biological control of the olive fruit fly Bactrocera oleae (Diptera: Tephritidae) and the Mediterranean fruit fly Ceratitis capitata (Diptera: Tephritida. Journal of Insect Science. 22(3):1-7. Article 11. https://doi.org/10.1093/jisesa/ieac027.
DOI: https://doi.org/10.1093/jisesa/ieac027

Interpretive Summary: An augmentorium is a screened enclosure that holds fruit culls and ground fruit to exclude emergence of fruit fly pests while allowing their parasitoids to escape. This enhances biological control of fruit flies. The system only works if the augmentorium is constructed of a screen with mesh small enough to keep the fruit flies in the augmentorium but also large enough to let the parasitoids out. Here we tested various screens using a simple method of "mini augmentoria" in the laboratory to find a mesh that could be used for olive fly and medfly and a few of their parasitoids. Results indicate that one mesh type was effective and can be used to construct viable augmentoria against these two species.

Technical Abstract: The augmentorium is a cost effective screened enclosure designed to receive fruits infested with insect pests, retain the pests inside but let their natural enemies (parasitoids) escape to enhance biological control of pest populations in the field. Mesh selection is critical to ensure that an augmentorium is functional and effective for a particular system: the mesh size and shape must be optimized to prevent the pests from exiting and let parasitoids escape freely. Here we tested five types of mesh with a mini-augmentorium design and measured the escape rate of four insect species under laboratory conditions: the pests olive fruit fly Bactocera oleae (Diptera: Tephritidae) and medfly Ceratitis capitata (Diptera: Tephritidae), and two parasitoids of B. oleae, Psyttalia lounsburyi (Hymenoptera: Braconidae) and P. ponerophaga. The sex ratio of insects that escaped the meshes was compared to the sex ratio of insects that could not escape. Results showed that one mesh type (“Crystal”) was the best for the purpose of designing a functional augmentorium: it retained 90% of B. oleae adults and 100% of C. capitata adults while letting 72% of P. lounsburyi adults and 94% of P. ponerophaga adults escape. The other mesh types tested were suboptimal, either because they let too many flies freely escape or because they retained too many parasitoids. Sex ratio was almost always similar for insects that managed to escape the meshes and insects that were retained by the meshes, with the exception of P. ponerophaga and the mesh type “Clear”. For this mesh, the sex ratio of adults that managed to escape the mesh was significantly male-biased. These results are promising for the development of a functional augmentorium against the olive fruit fly and the medfly.