Biological Control as Part of Integrated Weed Management of Old World Climbing Fern (Lygodium microphyllum)

Authors: David, Aaron; RODGERS, LEROY - South Florida Water Management District; EASTWICK IV, ANDREW - Us Fish And Wildlife Service; Lake, Ellen

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/4/2019
Publication Date: N/A
Citation: N/A

Interpretive Summary: Lygodium microphyllum (Lygodiaceae), Old World climbing fern, is an invasive non-native vine found throughout much of south and central Florida and is expanding northward. The plant forms dense mats that smother native vegetation and alters fire behavior. The fern can be difficult to control using conventional management techniques. Two approved biological control agents, the defoliating moth Neomusotima conspurcatalis (Crambidae) and a leaf-galling mite Floracarus perrepae (Eriophyidae), were introduced from the native range and have established in Florida. Our recent studies demonstrate that these agents can reduce L. microphyllum biomass and, in the case of F. perrepae, substantially reduce the growth rate of individual climbing rachises. Over the past five years, we have mass-reared and released both agents to establish viable populations across the invaded landscape in Florida. These efforts include release of >1 million agents in two regions of the Loxahatchee National Wildlife Refuge—tree islands within Water Conservation Area 1 and cypress swamps of the adjacent Strazzulla Tract. Surveys indicate that the agents have successfully established in many of these sites. The N. conspurcatalis population generally is highest in the cooler winter months and lowest in the summer. Monitoring of F. perrepae in an outdoor, shade house colony indicates similar seasonal dynamics, with populations highest in months with low rainfall. Importantly, establishment of the agents must work in conjunction with other control efforts. Collaboration and coordination between US Fish and Wildlife Service, South Florida Water Management District, and the USDA Agricultural Research Service has led to a strategy of releasing agents in areas not slated for immediate herbicide treatment and the demarcation of no-spray zones within active treatment areas. This strategy will allow agents to locally establish and persist during herbicide treatments and colonize L. microphyllum regrowth post-treatment. Further research is underway to better integrate biological control with mechanical controls, herbicide applications, and prescribed fire. An integrated management approach in the Loxahatchee National Wildlife Refuge is expected to achieve the most effective long-term control of L. microphyllum.

Technical Abstract: Lygodium microphyllum (Lygodiaceae), Old World climbing fern, is an invasive non-native vine found throughout much of south and central Florida and is expanding northward. The plant forms dense mats that smother native vegetation and alters fire behavior. The fern can be difficult to control using conventional management techniques. Two approved biological control agents, the defoliating moth Neomusotima conspurcatalis (Crambidae) and a leaf-galling mite Floracarus perrepae (Eriophyidae), were introduced from the native range and have established in Florida. Our recent studies demonstrate that these agents can reduce L. microphyllum biomass and, in the case of F. perrepae, substantially reduce the growth rate of individual climbing rachises. Over the past five years, we have mass-reared and released both agents to establish viable populations across the invaded landscape in Florida. These efforts include release of >1 million agents in two regions of the Loxahatchee National Wildlife Refuge—tree islands within Water Conservation Area 1 and cypress swamps of the adjacent Strazzulla Tract. Surveys indicate that the agents have successfully established in many of these sites. The N. conspurcatalis population generally is highest in the cooler winter months and lowest in the summer. Monitoring of F. perrepae in an outdoor, shade house colony indicates similar seasonal dynamics, with populations highest in months with low rainfall. Importantly, establishment of the agents must work in conjunction with other control efforts. Collaboration and coordination between US Fish and Wildlife Service, South Florida Water Management District, and the USDA Agricultural Research Service has led to a strategy of releasing agents in areas not slated for immediate herbicide treatment and the demarcation of no-spray zones within active treatment areas. This strategy will allow agents to locally establish and persist during herbicide treatments and colonize L. microphyllum regrowth post-treatment. Further research is underway to better integrate biological control with mechanical controls, herbicide applications, and prescribed fire. An integrated management approach in the Loxahatchee National Wildlife Refuge is expected to achieve the most effective long-term control of L. microphyllum.