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ARS Home » Southeast Area » Fort Lauderdale, Florida » Invasive Plant Research Laboratory » Research » Publications at this Location » Publication #253120

Title: Prospects for biological control of Old World climbing fern, Lygodium microphyllum - Encouraging results with the brown lygodium moth and update on other agents

Author
item Boughton, Anthony
item Center, Ted

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/26/2010
Publication Date: 5/5/2010
Citation: Boughton, A.J., Center, T.D. 2010. Prospects for biological control of Old World climbing fern, Lygodium microphyllum - Encouraging results with the brown lygodium moth and update on other agents . Meeting Abstract.

Interpretive Summary: Old World climbing fern, Lygodium microphyllum is one of the most problematic invasive weeds affecting natural areas in southern and central Florida. Management of this weed using fire or mechanical methods is ineffective, because the weed rapidly regrows from rhizomes, while herbicidal management is expensive, because of the need for follow-up treatments. These challenges have prompted interest in developing biological control options for this damaging weed. The brown lygodium moth, Neomusotima conspurcatalis was the first biological control agent to successfully establish field populations on lygodium in Florida. This insect was first released in Jonathan Dickinson State Park in Martin County, Florida in early 2008 and quickly developed large populations that caused substantial defoliation damage to lygodium at release sites. During the first 8 months after the insect was released, defoliation by caterpillars reduced lygodium at release sites by about 50% from an average of 49% present at the time releases were initiated, down to a mean of 20% at the end of 2008. Over this same period, lygodium levels at control sites, where the moth was not present, remained relatively static at about 43% lygodium cover. A combination of low winter temperatures and parasitism of caterpillars by native parasitoid wasps appeared to cause a marked reduction in moth populations in early 2009, although moth populations seemed to partially recover during spring and summer as the weather warmed up. When vegetation was next measured in early 2010, lower feeding pressure by caterpillars of the moth had allowed some regrowth of the weed to occur and lygodium ground cover at release sites had recovered to 27%, although this was still only about half that present before the moth was released. Control plots were colonized by the moth during 2009 and suffered heavy defoliation, reducing lygodium cover by about 50% from the previously observed average of 43% seen in early 2009 down to 22% in early 2010. The extent to which parasitism of moth caterpillars increases above rates observed during 2009, together with the ability of moth populations to recover from episodes of cold winter weather, will be key factors affecting the long-term efficacy of the brown lygodium for lygodium biocontrol. New releases of a second biocontrol agent, the lygodium moth, Austromusotima camptozonale, are planned for 2010. A third biocontrol agent, the lygodium sawfly, is currently undergoing regulatory evaluation. Meanwhile research continues in Australia on several species of moth whose stem-boring caterpillars appear to have great potential for lygodium biocontrol.

Technical Abstract: Old World climbing fern, Lygodium microphyllum is one of the most problematic invasive weeds affecting natural areas in southern and central Florida. Management of this weed using fire or mechanical methods is ineffective, because the weed rapidly regrows from rhizomes, while herbicidal management is expensive, because of the need for follow-up treatments. These challenges have prompted interest in developing biological control options for this damaging weed. The brown lygodium moth, Neomusotima conspurcatalis was the first biological control agent to successfully establish field populations on lygodium in Florida. This insect was first released in Jonathan Dickinson State Park in Martin County, Florida in early 2008 and quickly developed large populations that caused substantial defoliation damage to lygodium at release sites. During the first 8 months after the insect was released, defoliation by caterpillars reduced lygodium at release sites by about 50% from an average of 49% present at the time releases were initiated, down to a mean of 20% at the end of 2008. Over this same period, lygodium levels at control sites, where the moth was not present, remained relatively static at about 43% lygodium cover. A combination of low winter temperatures and parasitism of caterpillars by native parasitoid wasps appeared to cause a marked reduction in moth populations in early 2009, although moth populations seemed to partially recover during spring and summer as the weather warmed up. When vegetation was next measured in early 2010, lower feeding pressure by caterpillars of the moth had allowed some regrowth of the weed to occur and lygodium ground cover at release sites had recovered to 27%, although this was still only about half that present before the moth was released. Control plots were colonized by the moth during 2009 and suffered heavy defoliation, reducing lygodium cover by about 50% from the previously observed average of 43% seen in early 2009 down to 22% in early 2010. The extent to which parasitism of moth caterpillars increases above rates observed during 2009, together with the ability of moth populations to recover from episodes of cold winter weather, will be key factors affecting the long-term efficacy of the brown lygodium for lygodium biocontrol. New releases of a second biocontrol agent, the lygodium moth, Austromusotima camptozonale, are planned for 2010. A third biocontrol agent, the lygodium sawfly, is currently undergoing regulatory evaluation. Meanwhile research continues in Australia on several species of moth whose stem-boring caterpillars appear to have great potential for lygodium biocontrol.