Rapid identification of cryptic biological control agents using near‐infrared spectroscopy

The ability to rapidly differentiate morphologically similar species would facilitate the implementation of biological programs. Compared with molecular tools, Near-infrared spectroscopy (NIRS) is non-destructive and requires minimal sample preparation. This study aimed to investigate the efficacy of NIRS for identifying the larval parasitoid community associated with the spotted wing drosophila (SWD), Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), a worldwide pest of berries and soft-skinned stone fruit. Ganaspis kimorum Buffington (Hymenoptera: Figitidae) has been identified as highly specialized on SWD and is currently being released in Europe and the USA. Ganaspis kimorum is one of two cryptic species that coexist as natural enemies of SWD in the fly’s native range. Its cryptic counterpart, G. lupini Buffington (Hymenoptera: Figitidae) is morphologically indistinguishable but has a broader host range and has not been approved for release. In the invaded regions, G. kimorum is also associated with similar-looking figitid species [e.g., Leptopilina japonica Novković & Kimura and L. heterotoma (Thomson)]. Our results showed that these four species can be differentiated by applying canonical discriminant analysis to their spectral signatures, with total classification rates varying between 94 and 99%. This technique could be used to (1) differentiate the two cryptic species when processing foreign collection materials in quarantine and skip the lengthy process of creating isolines followed by molecular work and to (2) facilitate the sorting of wasps captured in regions where G. kimorum is currently being released allowing to assess the impact of these releases more accurately and efficiently.