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ARS Home » Southeast Area » Fort Lauderdale, Florida » Invasive Plant Research Laboratory » Research » Publications at this Location » Publication #138076
Title: Modeling the influence of resource availability on population densities of Oxyops vitiosa (Coleoptera: Curculionidae), a biological control agent of the invasive tree Melaleuca quinquenervia

Author
item Pratt, Paul
item RAYAMAJHI, MIN - UNIVERSITY OF FLORIDA
item Van, Thai
item Center, Ted

Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/11/2003
Publication Date: 2/1/2004
Citation: Pratt, P.D., Rayamajhi, M., Van, T.K., Center, T.D. 2004. Modeling the influence of resource availability on population densities of Oxyops vitiosa (Coleoptera: Curculionidae), a biological control agent of the invasive tree Melaleuca quinquenervia. Biocontrol Science and Technology. 14(1):51-61.2004.

Interpretive Summary: Melaleuca quinquenervia, the broad-leaved paperbark tree, has invaded approximately 400,000 acres in south Florida, including portions of the Everglades National Park. The Australian melaleuca snout beetle, Oxyops vitiosa, was introduced to south Florida U.S.A. as a biological control agent of the invasive tree during the spring of 1997. As part of ongoing post-release evaluations of this weevil, we questioned what is the sustainable population density that can be maintained by the insect when fully exploiting the melaleuca foliage, or what is the carrying capacity for larvae. Seasonal carrying capacity was modeled according to tree size distribution and density, plant phenology, quantity of acceptable foliage (suitable for larval development) and larval consumption values. Larval carrying capacity varied dramatically due to fluctuating resource availability and ranged from 723 004 larvae/ha in July-August to >4 million larvae/ha in January-February. Annual carrying capacity for a generalized (mixed sized) tree distribution was estimated to be 11.7 million larvae/ha. Carrying capacity increased to 18.1 million larvae/ha/yr when large trees (>20 cm diameter at breast height) represented the dominant size class, whereas habitats dominated by medium (10-19 cm) and small (1.3-9 cm) trees were predicted to have larval carrying capacities of 8.9 and 1.3 million/yr, respectively. Validation data obtained from smaller, more accessible plants suggested that the model overestimated realized yearly larval densities by 9% or 15 416 larvae/ha/yr.

Technical Abstract: The Australian melaleuca snout beetle, Oxyops vitiosa, was introduced to south Florida U.S.A. as a biological control agent of the invasive tree Melaleuca quinquenervia during the spring of 1997. As part of ongoing post-release evaluations of this weevil, we sought to quantify the carrying capacity (i.e., the sustainable population density that can be maintained by the herbivore when fully exploiting the resource) of melaleuca stands for O. vitiosa larvae. Seasonal carrying capacity was modeled as a function of tree size distribution and density, plant phenology, quantity of acceptable foliage (suitable for larval development) and larval consumption values. Larval carrying capacity varied dramatically due to fluctuating resource availability and ranged from 723 004 larvae/ha in July-August to >4 million larvae/ha in January-February. Annual carrying capacity for a generalized (mixed sized) tree distribution was estimated to be 11.7 million larvae/ha. Carrying capacity increased to 18.1 million larvae/ha/yr when large trees (>20 cm diameter at breast height) represented the dominant size class, whereas habitats dominated by medium (10-19 cm) and small (1.3-9 cm) trees were predicted to have larval carrying capacities of 8.9 and 1.3 million/yr, respectively. Validation data obtained from smaller, more accessible plants suggested that the model overestimated realized yearly larval densities by 9% or 15 416 larvae/ha/yr.