Development of new biological control agents for Old World climbing fern, Lygodium microphyllum

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

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/12/2019
Publication Date: N/A
Citation: N/A

Interpretive Summary: Lygodium microphyllum, Old World climbing fern, is an invasive vine that 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. Exploration is ongoing in the native range of Old World climbing fern, particularly in Australia and southeast Asia, to collect herbivores feeding on this plant for development as biological control agents. 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, Florida. No-choice testing has been completed with the moth Lygomusotima stria (Lepidoptera: Crambidae). This moth can complete development on several lygodium species and multigeneration tests are ongoing. Testing indicates that L. stria is not very cold tolerant and would be unlikely to fully colonize Florida or overlap in range with the southernmost populations of the U.S. native 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. Progress has been made with two species of stem boring moths, but these insects are extremely difficult to rear. The sawfly Neostrombocerus albicomus (Hymenoptera: Tenthredinidae) can reach outbreak densities on Old World climbing fern in the native range. Multigeneration testing is ongoing with this insect and three lygodium species. The moth Callopistria exotica (Lepidoptera: Noctuidae) feeds very heavily on the foliage of Old World climbing fern, 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. Petitions for field release of these insects will be submitted pending successful completion of host-range testing.

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. Exploration is ongoing in the native range of L. microphyllum, particularly in Australia and southeast Asia, to collect arthropods feeding on L. microphyllum for development as biological control agents. 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 testing has been completed with the moth Lygomusotima stria (Lepidoptera: Crambidae). This moth can complete development on several lygodium species and multigeneration 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 are extremely difficult to rear. A sawfly, Neostrombocerus albicomus (Hymenoptera: Tenthredinidae), can reach outbreak densities on L. microphyllum in the native range. Multigeneration testing is ongoing with this insect and three lygodium species. The moth Callopistria exotica (Lepidoptera: Noctuidae) 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. Petitions for field release of these insects will be submitted pending successful completion of host-range testing.