Laboratory host range testing of Neomusotima conspurcatalis (Lepidoptera: Crambidae) - a potential biological control agent of the invasive weed, Old World climbing fern, Lygodium microphyllum (Lygodiaceae)

Authors: Boughton, Anthony; Bennett, Christine; Goolsby, John; Pemberton, Robert

Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/22/2009
Publication Date: 4/29/2009
Citation: Boughton, A.J., Bennett, C., Goolsby, J., Pemberton, R.W. 2009. Laboratory host range testing of Neomusotima conspurcatalis (Lepidoptera: Crambidae) - a potential biological control agent of the invasive weed, Old World climbing fern, Lygodium microphyllum (Lygodiaceae). Biocontrol Science and Technology, 19, 369-390.

Interpretive Summary: Old World climbing fern, Lygodium microphyllum is a serious invasive weed in southern Florida. Biological control is an approach that uses insect and mite herbivores from the native range of an invasive weed, and introduces them into areas that have been colonized by the invasive weed. These herbivores feed upon the invasive weed and reduce its capacity for growth and reproduction. Unfortunately, relatively few insects and mites feed upon L. microphyllum, which makes developing biological control options more difficult. Neomusotima conspurcatalis is a species of moth native to Southeast Asia, whose caterpillars feed on L. microphyllum. Neomusotima conspurcatalis was first discovered feeding on L. microphyllum in Hong Kong in 1997 and was subsequently found causing feeding damage on the plant throughout much of Southeast Asia. Testing was undertaken in a quarantine facility to determine the host range of N. conspurcatalis to determine whether it might have potential for use as a herbivore against L. microphyllum. Testing was designed to determine which plant species the moth would lay eggs on, and which plant species the caterpillars would feed and develop on. Thirty-seven species of ferns outside the genus Lygodium, 1 coniferous tree species, 3 crop species, 6 other species of ferns in the genus Lygodium, as well as the primary host plant L. microphyllum were tested. No significant egg laying by moths or feeding by caterpillars was observed on any of the 41 non-Lygodium species evaluated. Egg laying and feeding occurred on all Lygodium species, but amounts were low and usually significantly less than observed on L. microphyllum. The exception was L. japonicum, on which female moths showed a preference for laying large numbers of eggs. Caterpillars of Neomusotima conspurcatalis were only able to complete development to moths on L. japonicum and L. palmatum, but survival of caterpillars on these plant species was only half that occurring on L. microphyllum. These results suggest that N. conspurcatalis is specialized to feed on ferns in the genus Lygodium. Lygodium japonicum is an invasive weed in the United States. The geographic range of Lygodium palmatum is restricted to areas of the United States where freezing winter temperatures would be lethal to N. conspurcatalis. It was concluded that N. conspurcatalis wouldn’t pose a threat to native or cultivated plants in North America or the Caribbean and should be considered for biocontrol of L. microphyllum. This insect may also have utility as a herbivore against L. japonicum in warmer areas of Florida. An application summarizing these experimental findings was submitted in 2005, seeking permission to release N. conspurcatalis against the weed L. microphyllum. A release permit granting permission to release this insect against L. microphyllum was issued by USDA-APHIS in 2007.

Technical Abstract: Old World climbing fern, Lygodium microphyllum, is a serious invasive weed in south Florida. Development of biological control is vital for sustainable management of L. microphyllum. Neomusotima conspurcatalis was discovered in Hong Kong in 1997 and was subsequently found causing feeding damage on L. microphyllum in much of its native range in Asia. Quarantine testing of N. conspurcatalis used 37 Non-Lygodium fern species representative of New World genera of cultivated ferns and fern allies, 1 gymnosperm, 3 crop species, 6 Lygodium species, and the primary host L. microphyllum. No significant oviposition or feeding was observed on any of the 41 non-Lygodium species evaluated. Oviposition and feeding occurred on all Lygodium species, but amounts were low and usually significantly less than observed on L. microphyllum. The exception was L. japonicum, which was preferred as an oviposition host. Neomusotima conspurcatalis was only able to complete development on L. japonicum and L. palmatum, but survival on these species was only half that occurring on L. microphyllum. Neomusotima conspurcatalis is a Lygodium specialist. Lygodium japonicum is an invasive weed in the United States. Lygodium palmatum is restricted to areas of the United States where freezing winter temperatures would be lethal to N. conspurcatalis. It was concluded that N. conspurcatalis wouldn’t pose a threat to native or cultivated plants in North America or the Caribbean and should be considered for biocontrol of L. microphyllum. This insect may also have utility against L. japonicum in warmer areas of Florida. A release petition was submitted in 2005. An USDA-APHIS release permit for N. conspurcatalis was issued in 2007.