Quarantine Testing to Develop Biological Control of Old World Climbing Fern Lygodium microphyllum in Florida

Authors: Lake, Ellen; Mattison, Elizabeth; PURCELL, MATTHEW - Commonwealth Scientific And Industrial Research Organisation (CSIRO)

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 1/30/2019
Publication Date: N/A
Citation: N/A

Interpretive Summary: Lygodium microphyllum, Old World climbing fern, is expanding its range in Florida and negatively impacting native plants and animals. Two biological control agents have established against the weed in Florida but additional agents are needed to achieve desired levels of control. Host-range testing is in progress with two moths and a sawfly at the USDA ARS Invasive Plant Research Laboratory quarantine facility in Fort Lauderdale, FL. No-choice host-range testing has been completed with the moth Lygomusotima stria (Lepidoptera: Crambidae). This moth can complete development on several lygodium species. Multigenerational tests to determine if the moth can form sustainable populations on non-target species are ongoing. Cold-tolerance testing for L. stria indicates that this moth is unlikely to fully colonize Florida or overlap in range with the southernmost populations of the native fern Lygodium palmatum. Herbaria records of L. palmatum are being compiled to delineate the range of this species for comparison to climate mapping of the projected range of L. stria. Although progress has been made with two species of stem boring moths, these insects remain extremely difficult to rear. Additional replicates of multigenerational testing with the sawfly Neostrombocerus albicomus (Hymenoptera: Tenthredinidae) were completed on L. volubile, further testing is needed with additional species. A foliage feeding moth collected in Hong Kong in 2016 and 2018 was identified by a taxonomic expert as Callopistria exotica (Lepidoptera: Noctuidae). This moth feeds very heavily on L. microphyllum foliage creating “fish-boning” damage. Callopistria exotica has been colonized and rearing methods have been developed for this moth. Host-range tests completed to date indicate that C. exotica is a lygodium specialist. Experiments are underway to learn more about the biology of L. stria, N. albicomus, and C. exotica to improve rearing and testing methods.

Technical Abstract: Lygodium microphyllum, Old World climbing fern, is expanding its range in Florida and negatively impacting native flora and fauna. Two biological control agents have established against the weed in Florida but additional agents are needed to achieve desired levels of control. Host-range testing is in progress on three additional insect species at the USDA ARS Invasive Plant Research Laboratory quarantine facility in Fort Lauderdale, FL. No-choice host-range testing has been completed with the moth Lygomusotima stria (Lepidoptera: Crambidae). This moth can complete development on several lygodium species and multigenerational tests are ongoing. Cold-tolerance testing for L. stria indicates that this species is unlikely to fully colonize Florida or overlap in range with the southernmost populations of the native species Lygodium palmatum. Herbaria records of L. palmatum are being compiled to delineate the range of this species for comparison to CLIMEX mapping of the projected range of L. stria. Although progress has been made with two species of stem boring moths, these insects remain extremely difficult to rear. Additional replicates of multigenerational testing with the sawfly Neostrombocerus albicomus (Hymenoptera: Tenthredinidae) were completed on L. volubile, further testing is needed with additional species. A foliage feeding moth collected in Hong Kong in 2016 and 2018 was identified by a taxonomic expert as Callopistria exotica (Lepidoptera: Noctuidae). This moth feeds very heavily on Lygodium microphyllum foliage creating “fish-boning” damage. Callopistria exotica has been colonized and rearing methods have been developed for this moth. Host-range tests completed to date indicate that C. exotica is a lygodium specialist. Experiments are underway to learn more about the biology of L. stria, N. albicomus, and C. exotica to improve rearing and testing methods.