The impact and production of the Old World climbing fern (Lygodium microphyllum) biological control agent Lygomusotima stria, is affected by the level of host plant fertilization

Authors: Wheeler, Gregory; Ripsom, Stephanie

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/17/2025
Publication Date: 9/17/2025
Citation: Wheeler, G.S., Ripsom, S.I. 2025. The impact and production of the Old World climbing fern (Lygodium microphyllum) biological control agent Lygomusotima stria, is affected by the level of host plant fertilization. Environmental Entomology. 1-8. https://doi.org/10.1093/ee/nvaf084.
DOI: https://doi.org/10.1093/ee/nvaf084

Interpretive Summary: Old World climbing fern, is one of the worst environmental weeds of southern and central Florida, USA. The weed climbs over other plants, forming thick mats that block sunlight to native shrubs and trees. In the introduced range, Old World climbing fern invades much of the southern peninsula of Florida where cost-effective, sustainable control methods are needed. A potential biological control agent, the defoliating moth Lygomusotima stria was collected in Thailand and Singapore and was shown to be safe for release in the invaded range. Here, we report the results of greenhouse studies that examined the performance of the Lygomusotima stria larvae and their impact on the target weed when grown at a range of fertilizer and insect damage levels. The results indicate that larvae had greater survival when fed plants at the highest fertilizer level. Further, two generations of feeding by larvae decreased stem weights at the lowest fertilizer level and new shoot numbers. At higher fertilizer conditions, the plants were able to tolerate larva damage resulting in no significant changes in plant tissue allocations. By impacting stems and new shoots, these results suggest this insect will impede the ability of this weed to climb substrates especially in lower resource conditions.

Technical Abstract: Old World climbing fern, Lygodium microphyllum (Cav.) R. Br., is one of the worst environmental weeds of southern and central Florida, USA. The weed climbs over other plants, forming thick mats that block sunlight to native shrubs and trees. In the introduced range, Old World climbing fern invades much of the southern peninsula of Florida where cost-effective, sustainable control methods are needed. A potential biological control agent, the defoliating moth Lygomusotima stria was collected in Thailand and Singapore and was shown to be safe for release in the invaded range. Here, we report the results of greenhouse studies that examined the performance of L. stria larvae and their impact on the target weed when grown at a range of fertilizer and herbivore levels. The results indicate that larvae had greater survival when fed plants at the highest fertilizer level. Further, two generations of feeding by L. stria larvae decreased rachis weights at the lowest fertilizer level and fiddlehead numbers. At higher fertilizer conditions, the plants were able to tolerate L. stria herbivory resulting in no significant changes in plant tissue allocations. By impacting rachises and fiddle heads, these results suggest this insect will impede the ability of this weed to climb substrates especially in lower resource conditions.