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United States Department of Agriculture

Agricultural Research Service

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ABCL, Biological control of the old world climbing fern
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Biological control of the old world climbing fern

 

Old world climbing fern, Lygodium microphyllum (Lygodiaceae) is native to the Old World tropics and subtropics from Africa to India, Southeast Asia, Australia, and some Pacific Islands.  It is common near permanent water, freshwater creeks, depressions and coastal wetlands.   Throughout its range in Australia and Asia, this fern doesn’t dominate its plant community and rarely reaches the canopy.

Lygodium microphyllum has rapidly invaded southern Florida after being introduced as an ornamental in 1965, climbing over other plants, including tall trees, forming massive curtains or walls.  It also forms thick mats on the ground that can smother all native vegetation. Because of dead and drying material beneath the curtains, wildfires can spread rapidly to the tops of trees and on to other stands by wind-borne burning fern material.  Infestations are still expanding and now cover more than 40,000 ha.  It is also rapidly invading the Florida Everglades as fine spores colonize undisturbed areas.

 

 

Old world climbing fern in Australia, photo courtesy of ABCL

In 1997, ABCL began searching for potential biological control agents of L. microphyllum.  Three have undergone host specificity testing and have been released in the U.S.  The defoliating pyralid moth, Austromusotima camptozonale, was released in Florida in 2005 but hasn’t established. A gall-forming eriophyid mite, Floracarus perrepae, which deforms the growth of L. microphyllum and causes leaf necrosis and premature leaf drop, was released in 2007.  A second defoliating moth, Neomusotima conspurcatalis, was released in 2008 and has established at a small number of sites where it is causing substantial defoliation. Testing and evaluation of a defoliating sawfly, Neostrombocerus albicomus, has been completed and a petition for its release in Florida will be submitted in 2009.  Research at ABCL is now concentrating on stem-boring pyralid moths whose larvae can kill large plants by infiltrating the stems near the ground.  Three species have been identified: one from Singapore, a second from northern Thailand and a third from Hong Kong.  ABCL is focusing on the latter species given that it develops in thin stems of L. microphyllum allowing laboratory rearing within quarantine.

 

 

Old world climbing fern in Florida, photo courtesy of ABCL

 

 

Lygodium Ambia Larva, photo courtesy of ABCL

 

 

 

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Last Modified: 8/13/2009
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