Temporal fluctuations and geographic distributions of Leptopilina (Hymenoptera: Figitidae) species in North Carolina: Implications for biological control of Drosophila suzukii (Diptera: Drosophilidae)

To better understand populations of spotted wing drosophila (Drosophila suzukii) parasitoids, especially the newly established Leptopilina japonica, we compare detection methods and report on temporal fluctuations and geographic distributions in North Carolina blackberry fields. Data were collected from October 2022 to November 2023.

Methods
Comparison of detection methods

In October 2022 and November 2022, we compared three sampling methods: liquid traps, incubated fruit, and sentinel traps. Sentinel traps were prepared at the Beneficial Insects Lab of the North Carolina Department of Agriculture and Consumer Services’ Biological Control Program prior to being placed in the field. All samples, after being collected from the field, were brought back to the Specialty Crops Integrated Pest and Pollinator Management Laboratory at North Carolina State University for processing.

Additional detection method testing

Based on our experience with the above methods, we collected additional samples in 2023 during peak blackberry harvest. We only used liquid traps and fruit incubation to collect samples, but collected samples of both crop fruit and wild fruit. After being collected from the field, samples were processed as detailed above.

Temporal fluctuations of Leptopilina Species

To understand temporal fluctuations of Leptopilina species, we collected samples via liquid traps at one site for one calendar year from October 2022 to November 2023. After being collected from the field, samples were processed as detailed above.

Geographic Distribution of Leptopilina Species in Southeastern Blackberry Fields

To understand the geographical distribution of Leptopilina species across North Carolina blackberry fields, we collected samples via liquid traps from four sites and processed samples as detailed above.