Location: Invasive Plant Research Laboratory
Project Number: 6032-22000-013-136-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Jul 1, 2024
End Date: Jun 30, 2025
Objective:
Objective 1: Continue to 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 and Dysmicoccus sp., particularly acceptance of North American species of Azolla.
Objective 3: Confirm identities of pseudo scale, moth and midge insects found feeding on Azolla.
Approach:
Foreign exploration, identification of herbivores 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 is native 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 pseudo scale insects, some midges, and an unidentified moth. Preliminary testing is already completed with Bagous clarenciensis Blackburn (Coleoptera: Curculionidae) from S. E. Queensland and northern New South Wales where it feeds naturally on A. pinnata. Field populations of B. clarenciensis from pure stands of A. pinnata subsp. pinnata will be sourced and adults from both populations will be crossed tested on both Azolla species for specificity and performance. Dysmicoccus sp. has been colonized in Brisbane, after careful and detailed elimination of all field parasites which appear to heavily regulate this Pseudococcidae mealybug in the natural environment, and host range testing will be completed on Azolla species. Moth specimens reared to adult from multiple Australia wide locations indicate variation and cryptic species will be determined and evaluated. Identified insect species that only attack A. pinnata, could be subjected to a more extensive testing regime in U.S. quarantine. Morphometric and molecular methods will be used to identify other potential agents plus examine if B. clarenciensis has sibling species.
