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United States Department of Agriculture

Agricultural Research Service

Research Project: DEVELOPMENT & EVALUATION OF BIOLOGICAL CONTROL AGENTS FOR INVASIVE SPECIES THREATENING THE EVERGLADES & OTHER NATURAL AND MANANGED SYSTEMS

Location: Invasive Plant Research Laboratory

Title: Acquired natural enemies of the weed biological control agent Oxyops vitiosa (Coleoptera: Curculionidae)

Authors
item Christensen, Robin -
item PRATT, PAUL
item Costello, Sheryl -
item RAYAMAJHI, MIN
item Center, Ted

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 16, 2010
Publication Date: March 15, 2011
Repository URL: http://www.bioone.org/doi/full/10.1653/024.094.0101
Citation: Christensen, R.M., Pratt, P.D., Costello, S.L., Rayamajhi, M.B., Center, T.D. Acquired natural enemies of the weed biological control agent Oxyops vitiosa (Coleptera: Curculionidae). Florida Entomologist. 94(1):1-8. 2011.

Interpretive Summary: The Australian curculionid Oxyops vitiosa Pascoe was introduced into Florida during 1997 as a biological control agent of the invasive tree Melaleuca quinquenervia (Cav.) S.T. Blake. Populations of the weevil increased rapidly and became widely distributed throughout much of the invasive tree’s adventive distribution. In this study we ask if O. vitiosa has acquired natural enemies in Florida, how these enemies circumvent the larvae’s protective terpenoid laden exudate, and what influence one of the most common natural enemies has on O. vitiosa population densities? Surveys of O. vitiosa populations and rearing of field-collected individuals resulted in no instances of parasitoids or pathogens exploiting weevil eggs or larvae. In contrast, 44 species of predatory arthropods were commonly associated (>5 individuals when pooled across all sites and sample dates) with O. vitiosa. Eleven predatory species were observed feeding on O. vitiosa during timed surveys, including six pentatomid species, two formicids and three arachnids. Species with mandibulate or chelicerate mouthparts fed on adult stages while pentatomids, with haustellate beaks, pierced larval exoskeletons thereby by-passing the protective larval coating. Observations of predation were rare, with only 8% of timed surveys resulting in one or more instances of attack. Feeding by the pentatomid Podisus mucronatus Uhler accounted for 76% of all recorded predation events. P. mucronatus numerically responded to fourth instar larvae but no response was observed for other life stages. Damage to M. quinquenervia plants from feeding by O. vitiosa, however, was not influenced by P. mucronatus densities, indicating that predation does not alter plant suppression. Key Words: Biological control, biotic resistance, predation, Oxyops vitiosa, Melaleuca quinquenervia, Podisus mucronatus.

Technical Abstract: The Australian curculionid Oxyops vitiosa Pascoe was introduced into Florida during 1997 as a biological control agent of the invasive tree Melaleuca quinquenervia (Cav.) S.T. Blake. Populations of the weevil increased rapidly and became widely distributed throughout much of the invasive tree’s adventive distribution. In this study we ask if O. vitiosa has acquired natural enemies in Florida, how these enemies circumvent the larvae’s protective terpenoid laden exudate, and what influence one of the most common natural enemies has on O. vitiosa population densities? Surveys of O. vitiosa populations and rearing of field-collected individuals resulted in no instances of parasitoids or pathogens exploiting weevil eggs or larvae. In contrast, 44 species of predatory arthropods were commonly associated (>5 individuals when pooled across all sites and sample dates) with O. vitiosa. Eleven predatory species were observed feeding on O. vitiosa during timed surveys, including six pentatomid species, two formicids and three arachnids. Species with mandibulate or chelicerate mouthparts fed on adult stages while pentatomids, with haustellate beaks, pierced larval exoskeletons thereby by-passing the protective larval coating. Observations of predation were rare, with only 8% of timed surveys resulting in one or more instances of attack. Feeding by the pentatomid Podisus mucronatus Uhler accounted for 76% of all recorded predation events. P. mucronatus numerically responded to fourth instar larvae but no response was observed for other life stages. Damage to M. quinquenervia plants from feeding by O. vitiosa, however, was not influenced by P. mucronatus densities, indicating that predation does not alter plant suppression. Key Words: Biological control, biotic resistance, predation, Oxyops vitiosa, Melaleuca quinquenervia, Podisus mucronatus.

Last Modified: 9/10/2014
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