Florida's Established Arthropod Weed Biological Control Agents and Their Targets1
Nonnative invasive weeds are considered to be one of the most important threats to biodiversity, second only to habitat destruction (Randall 1996; Pimm and Gilpin 1989). They interfere with crop and pasture production in agroecosystems or alter the composition, structure, and function of natural ecosystems and waterways (Pimentel et al. 2000; Pimentel 2005). The losses in productivity and associated costs of controlling invasive weeds are staggering. Pimentel et al. (2000, 2005) estimate the total cost of invasive weeds to the US economy is $34 billion annually.
Compared to the rest of the continental United States, Florida is more prone to the introduction, eventual establishment, and subsequent invasion of natural communities by invasive weeds because of its unique geographic and environmental characteristics (Simberloff 1997). South Florida's extensive tropical and aquatic habitats, for example, are conducive to the establishment of nonnative terrestrial and aquatic ornamental plants. The Florida peninsula, which is bounded on three sides by water and the fourth by a freeze line, is essentially a subtropical "island" habitat that predisposes this region to nonnative plant invasions. Florida also is dominated by novel habitats created by intense human disturbance because of its popularity as a vacation destination. In FY 2017–2018, government agencies in the state of Florida spent approximately $14 million to control invasive plants (FWC 2018).
Approximately 1,200 out of an estimated 25,000 plant species (~ 5%) deliberately introduced into Florida for crop production and horticultural uses have invaded sensitive aquatic and terrestrial natural areas as well as improved pastures (Pimentel et al. 2005; Rogers et al. 2011). One of the reasons these nonnative plants become invasive is they are introduced into an environment in which they did not evolve and, therefore, lack the natural enemies that limit their reproduction (Williams 1954). Biological control reunites these natural enemies (usually arthropods) with their host plants to selectively weaken and suppress the invasive weeds.
In Florida, arthropod biological control agents currently are established on ten invasive weeds: air potato (Dioscorea bulbifera L.: Dioscoreaceae), alligatorweed (Alternanthera philoxeroides (Mart.) Griseb.: Amaranthaceae), Brazilian peppertree (Schinus terebinthifolia Raddi: Anacardiaceae), hydrilla (Hydrilla verticillata (L. f.) Royle: Hydrocharitaceae), melaleuca (Melaleuca quinquenervia (Cav.) S.T. Blake: Myrtaceae), Old World climbing fern (Lygodium microphyllum (Cav.) R. Br.: Lygodiaceae), tropical soda apple (Solanum viarum Dunal: Solanaceae), waterhyacinth (Eichhornia crassipes (Mart.) Solms: Pontederiaceae), salvinia (Salvinia spp.: Salviniaceae) and waterlettuce (Pistia stratiotes L.: Araceae) (Table 1).
Various resources on Florida's weed biological control programs are available to county faculty. Extensive reviews have been published on the biological control programs of the aforementioned invasive weeds (Buckingham 1994, Center 1994, Van Driesche et al. 2002). Also, up-to-date information on Florida's weed biological control programs can be found on several websites: the aquatic weeds alligatorweed, hydrilla, waterhyacinth, waterlettuce (http://plants.ifas.ufl.edu/manage/control-methods/biological-control/), air potato (http://www.fleppc.org/Manage_Plans/AirpotatoManagementPlan_Final.pdf), Brazilian peppertree (http://ipm.ifas.ufl.edu/pdfs/BPmanagPlan.pdf, http://www.fleppc.org/Manage_Plans/2006BPmanagePlan5.pdf, Cuda et al. 2019), melaleuca (http://tame.ifas.ufl.edu), Old World climbing fern (http://www.fleppc.org/Manage_Plans/Lygo_micro_plan.pdf), and tropical soda apple (http://plants.ifas.ufl.edu/node/426, http://freshfromflorida.s3.amazonaws.com/tsa-management-plan-01-12.pdf).
References
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Buckingham, G. R. 1994. Biological control of aquatic weeds, pp. 413–480. In: D. Rosen, F. D. Bennett and J. L. Capinera (eds.). Pest management in the subtropics: biological control - a Florida perspective. Intercept, Andover, U.K.
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