Degree
Doctor of Philosophy (PhD)
Department
Entomology
Document Type
Dissertation
Abstract
Roseau cane scale, Nipponaclerda biwakoensis (Hemiptera: Aclerdidae) is an invasive species of scale insect negatively impacting Phragmites australis (Cyperales: Poaceae) stands within the Mississippi River Delta. The scales were first detected in 2017 from reports of Phragmites die-back within the MRD by landowners. Initial range surveys located RCS infested Phragmites stands were primarily limited to southeastern Louisiana with a single population near Port Arthur, Texas. Follow-up field surveys conducted annually from 2021 to 2023 monitoring further range expansion by the scale show the current range extends nearly 600 km between High Island, Texas and Bayou la Batre, Alabama. Climate matching model, MaxEnt, determined the climate along the Gulf Coast to be suitable for further westward and eastward range expansion. Field surveys performed in the native (Taiwan) and adventive (Louisiana) ranges of the scale in 2021 and 2022 found the native range to have higher peak scale densities than in Louisiana, but much lower parasitism rates. Natural enemy exclusion experiments performed concurrently between Taiwan and Louisiana in 2021 and 2022 determined that the parasitoid wasps present in Louisiana were more effective at reducing RCS populations than they were in their native range of Taiwan. Conversely, larger predators were more effective at population reduction in Taiwan than in Louisiana. A PCR multiplex was produced that can identify the larvae of four species of RCS parasitoids present in Louisiana: Boucekiella depressa, Neastymachus japonicus, Astymachus lasallei (Hymenoptera: Encyrtidae), and Aprostocetus sp. (Hymenoptera: Eulophidae) while inside the host. The multiplex was used to identify which host life stage each species first oviposits within and determined temporal niche partitioning to occur between the four species. Data from rearing parasitoids found host size and multiparasitism to not influence the sex ratio of emerging wasps. Larger hosts were found to have more individuals emerge from them across all species, while multiparasitism only significantly decreased the number of emerging individuals for B. depressa and no other species. Finally, rankings of competitive superiority were generated for the four parasitoid species based off survival frequency during multiparasitism and determined B. depressa to be the most superior competitor. These findings provide insights into the ecology and management of Roseau cane scale, offering information for developing potential control strategies in its invasive range.
Date
12-6-2024
Recommended Citation
Sparks, Tanner C., "Biological control of roseau cane scale with parasitoid wasps in Louisiana" (2024). LSU Doctoral Dissertations. 6645.
https://repository.lsu.edu/gradschool_dissertations/6645
Committee Chair
Diaz, Rodrigo