Improving Mass-Rearing Techniques for Releases of Floracarus perrepae, a Biological Control Agent for OldWorld Climbing Fern (Lygodium microphyllum)

Authors: Aquino-Thomas, Jessene; Crees, Logan; Smith, Melissa; LAKE, ELLEN - Mt Cuba Center; Dray Jr, Forrest

Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2025
Publication Date: 1/31/2025
Citation: Aquino-Thomas, J.M., Crees, L.D., Smith, M., Lake, E.C., Dray Jr, F.A. 2025. Improving Mass-Rearing Techniques for Releases of Floracarus perrepae, a Biological Control Agent for OldWorld Climbing Fern (Lygodium microphyllum). Biocontrol Science and Technology. https://doi.org/10.3390/insects16020135.
DOI: https://doi.org/10.3390/insects16020135

Interpretive Summary: The United States Department of Agriculture – Invasive Plant Research Laboratory started limited production of a biological control mite, Floracarus perrepae, in 2008 for release against the invasive fern, Old World climbing fer, Lygodium microphyllum. Mass rearing of the mite was started in 2014 as part of a mass rearing and broader release effort associated with the Comprehensive Everglades Restoration Plan. The mite was released because it only targets Old World climbing fern and very closely related ferns. The objective is to curb the abundance of the invasive plant utilizing the mite which produces galls, damages the fern, and slows growth. In late 2021, relatively simple adjustments made to plant and agent mass rearing protocols produced large increases in the number of mites in the colony. Additionally, we monitored the of mite numbers within galls at different ages and used it to select plants for release that maximized mite numbers. Since implementing these changes to the mass rearing protocols there has been a substantially improvement in number of galls (265.3%), mites per gall (86.0%), and estimated mites per plant (453.2%). The increased mites have been released throughout the landscape and may improve rates of establishment, abundance, and impact of the mites on Old World climbing fern throughout Florida.

Technical Abstract: The United States Department of Agriculture – Invasive Plant Research Laboratory started limited production of a biological control mite, Floracarus perrepae, in 2008 for release against the invasive fern Lygodium microphyllum. Mass rearing of the biological control agent was initiated in 2014 as part of a mass rearing and broader release effort associated with the Comprehensive Everglades Restoration Plan. Releasing of this host-specific agent was done with the aim of curbing the abundance of the invasive plant utilizing the dynamics of their herbivore-prey relationship. In late 2021, relatively simple adjustments made to plant and agent mass rearing protocols produced exponential increases (factor of 46.5) in the F. perrepae colony productivity. Additionally, monitoring of mite numbers within galls was utilized to help create a systematic method for selecting plants for release that maximized mite numbers. Since implementing these changes to the mass rearing protocols there has been a substantially improvement in gall abundance (265.3%), F. perrepae density per gall (86.0%), and estimated mites per plant (453.2%). The increased F. perrepae have been released throughout the landscape and may improve rates of establishment, abundance, and impact of the agent throughout the invaded range of L. microphyllum in Florida.