Differential oviposition timing by seasonality and oviposition timing of parasitoids of the invasive roseau cane scale (Nipponaclerda biwakoensis) as revealed by multiplex PCR assays

Roseau cane scale, Nipponaclerda biwakoensis (Hemiptera: Aclerdidae) is an invasive species negatively impacting Phragmites australis (Cyperales: Poaceae) stands within the Mississippi River Delta. Previous research generated a PCR multiplex capable of identifying the three species of parasitoid wasps (Hymenoptera: Encyrtidae) that attack the scale in its invasive range. The appearance of a fourth species, Aprostocetus sp. (Hymenoptera: Eulophidae), within Louisiana in 2022 necessitated updating the multiplex with primers specific to the new species. The newly updated multiplex can identify the presence of all four parasitoid species within their host. DNA was extracted from the whole bodies of scales collected at different life stages and three different dates during the growing season and PCR performed with the new multiplex. Our findings show each species within the complex oviposits within a specific window of nymphal development which might help explain how successful multiparasitism frequently occurs in this system. The frequency of multiparasitism and relative abundance of each parasitoid species was consistent across the three sampling dates, except Astymachus lasallei (Hymenoptera: Encyrtidae), which was found in higher abundance during the end of the growing season.