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Research Project: Foreign Exploration And Preliminary Testing Of Potential Biological Control Agents For Azolla Pinnata Subspecies Pinnata

Location: Invasive Plant Research Laboratory

Project Number: 6032-22000-013-086-R
Project Type: Reimbursable Cooperative Agreement

Start Date: Jul 1, 2021
End Date: Aug 30, 2022

Objective 1: Survey infestations of A. pinnata subsp. pinnata in all states (except Western Australia) of Australia for prospective biological control agents. Objective 2: Continue field and laboratory host range evaluations of prospective agents like Bagous clarenciensis, Polypedilum sp., and Dysmicoccus sp., particularly acceptance of North American species of Azolla. Objective 3: Confirm identities of scale, midge, and moth insects found feeding on Azolla.

Foreign exploration and preliminary host range testing. Repeated surveys of known locations of A. pinnata subsp. pinnata will be conducted in all states (except Western Australia) in Australia to locate potential biocontrol agents. Plant samples from these locations will be collected by ABCL personnel and examined carefully for arthropods. Any eggs or larvae found will be reared to the adult stage to allow identification to taxonomic limits and to establish colonies. The most promising species will be evaluated for specificity in host range testing only against North American Azolla species, primarily A. filiculoides because this species has spread to Australia and is readily available. Colocation of both Azolla species at select field sites will also assist host specificity assessments under natural conditions if agents are present. Laboratory testing could also be done on A. caroliniana if available. No-choice, choice, and multigenerational tests will be conducted at ABCL in Brisbane, Australia on several species including a scale insect, some midges, and an unidentified moth. Abridged (reduced) testing is already underway with Bagous clarenciensis Blackburn (Coleoptera: Curculionidae) from S. E. Queensland and northern New South Wales where it feeds naturally on A. pinnata. If this or other identified insect species only attack A. pinnata, then a more extensive testing regime will be considered in the future, probably in the U.S. Morphometric and molecular methods will be used to identify other potential agents plus examine if B. clarenciensis has sibling species.