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United States Department of Agriculture

Agricultural Research Service

Title: Impacts of Biological Control Agents on Melaleuca Quinquenervia Seedlings: Controlling Recruitment

Authors
item Johnson, Robin - SCA
item Franks, Steven
item Kral, Andrea - MI STATE UNIVERSITY
item Pratt, Paul

Submitted to: Florida Weed Science Society Proceedings
Publication Type: Proceedings
Publication Acceptance Date: February 1, 2004
Publication Date: February 24, 2004
Citation: Johnson, R., Franks, S.J., Kral, A., Pratt, P.D. 2004. Impacts of biological control agents on melaleuca quinquenervia seedlings: controlling recruitment. Florida Weed Science Society Proceedings.

Interpretive Summary: We investigated the influence of herbivory by two introduced biocontrol insects on survival and performance of Melaleuca quinquenervia (Myrtaceae) seedlings, an invasive tree native to eastern Australia. In November 2002, Boreioglycaspis melaleucae (Psyllidae) nymphs and Oxyops vitiosa (Curculionidae) larvae were transferred onto Melaleuca seedlings within replicated 1/4 m2 caged plots in Palm Beach County, Florida. The treatments included three densities of 1st and 2nd Boreioglycaspis instars at 1, 15, and 50 nymphs per seedling, one treatment of a single Oxyops larva per seedling, another treatment of both one Oxyops larva and one Boreioglycaspis per seedling, a caged plot without insects, and an uncaged control. Yellow sticky cards were placed within each cage to trap out adult Boreioglycaspis as they emerged, thereby maintaining uniform herbivore densities among replicates. Leaf number and plant height were evaluated monthly for four months. Herbivory by Oxyops did not affect seedling height, leaf number, or survival. Boreioglycaspis herbivory significantly decreased leaf number, and orthogonal contrasts showed significant differences among Boreioglycaspis density treatments. After completion of one generation, Boreioglycaspis herbivory at the highest density caused mortality in 16 of 25 Melaleuca seedlings. The results indicate that Boreioglycaspis herbivory may be effective in reducing growth and survival of Melaleuca seedlings, with the impacts on the plants related directly to insect density. There was no evidence that Oxyops would be effective in controlling Melaleuca seedlings, or that there were any interactions among the biocontrol insects.

Technical Abstract: We investigated the influence of herbivory by two introduced biocontrol insects on survival and performance of Melaleuca quinquenervia (Myrtaceae) seedlings, an invasive tree native to eastern Australia. In November 2002, Boreioglycaspis melaleucae (Psyllidae) nymphs and Oxyops vitiosa (Curculionidae) larvae were transferred onto Melaleuca seedlings within replicated 1/4 m2 caged plots in Palm Beach County, Florida. The treatments included three densities of 1st and 2nd Boreioglycaspis instars at 1, 15, and 50 nymphs per seedling, one treatment of a single Oxyops larva per seedling, another treatment of both one Oxyops larva and one Boreioglycaspis per seedling, a caged plot without insects, and an uncaged control. Yellow sticky cards were placed within each cage to trap out adult Boreioglycaspis as they emerged, thereby maintaining uniform herbivore densities among replicates. Leaf number and plant height were evaluated monthly for four months. Herbivory by Oxyops did not affect seedling height, leaf number, or survival. Boreioglycaspis herbivory significantly decreased leaf number, and orthogonal contrasts showed significant differences among Boreioglycaspis density treatments. After completion of one generation, Boreioglycaspis herbivory at the highest density caused mortality in 16 of 25 Melaleuca seedlings. The results indicate that Boreioglycaspis herbivory may be effective in reducing growth and survival of Melaleuca seedlings, with the impacts on the plants related directly to insect density. There was no evidence that Oxyops would be effective in controlling Melaleuca seedlings, or that there were any interactions among the biocontrol insects.

Last Modified: 9/10/2014
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