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United States Department of Agriculture

Agricultural Research Service

Title: Post-Release Evaluation of the Biological Control of Melaleuca Quinquenervia in South Florida.

Authors
item Rayamajhi, Min
item Van, Thai
item Pratt, Paul
item Center, Ted

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: December 20, 2003
Publication Date: April 20, 2004
Citation: Rayamajhi, M.B., Van, T.K., Pratt, P.D., Center, T.D. 2004. Post-release evaluation of the biological control of melaleuca quinquenervia in south florida.. Meeting Abstract. Vol. 44, p 64.

Interpretive Summary: Melaleuca trees from Australian origin are spreading in the Everglades and other natural areas in South Florida. After rigorous feeding tests on several economically and environmentally important plants in Florida, two Australian insects (a leaf-feeding weevil and a sap-sucking psyllid)were found to feed and reproduce on melaleuca only. We released the weevil (in 1996) and psyllid (in 2002) in Florida's melaleuca forests. In addition, we also discovered a leaf-rust fungus on Florida's melaleuca in 1996. These three biocontrol agents attack healthy new growth of melaleuca, and cause substantial damage to trees of all ages. Preliminary results showed that these biocontrol agents are capable of disrupting tree health and reducing mature trees' ability of producing flowers, fruits, and new seedlings. Recently, we evaluated one of the sites in Broward County where all three biocontrol agents are present. In this site, we estimated over 83% mortality of young melaleuca seedlings and saplings, and the remaining 17% trees had over 70% defoliation. This high mortality rate combined with defoliation stress will reduce melaleuca's regeneration potential and survival as an invasive plant.

Technical Abstract: Melaleuca (Melaleuca quinquenervia), of Australian origin, is spreading rapidly in the Everglades and other natural ecosystems in South Florida. Presently, the melaleuca biocontrol program consists of two agents, the melaleuca weevil (Oxyops vitiosa) released in 1997, and the melaleuca psyllid (Boreioglycaspis melaleucae)in 2002. Additionally, a rust fungus, Puccinia psidii, was discovered on melaleuca in 1996. These biocontrol agents attack healthy new growth of melaleuca, and cause substantial damage to trees of all ages. Herein, we report preliminary results that show the impacts of these biocontrol agents on stand structure, tree health, and reproductive potential. For example, comparing data at one release site in Broward County before (1996) and after (2003) insect release indicated over 70% defoliation, and 83% mortality of young melaleuca seedlings and saplings. This high mortality of juvenile trees directly interferes with natural regeneration of melaleuca stands at the release sites.

Last Modified: 10/22/2014
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