BioControl 46: 511–528, 2001. © 2001 Kluwer Academic Publishers. Printed in the Netherlands. Whether to release Oxyops vitiosa from a second Australian site onto Florida’s melaleuca? A molecular approach P.T. MADEIRA 1∗ , R.E. HALE 2 , T.D. CENTER 1 , G.R. BUCKINGHAM 3 , S.A. WINERITER 4 and M. PURCELL 5 1 USDA, ARS, Invasive Plant Research Lab, Fort Lauderdale, Florida, USA; 2 University of Florida, Department of Zoology, Gainesville, Florida, USA; 3 USDA, ARS, Florida Biological Control Lab, Gainesville, Florida, USA; 4 University of Florida, IFAS, Department of Entomology and Nematology, Gainesville, Florida, USA; 5 Long Pocket Laboratories, Division of Entomology, Commonwealth Scientific and Industrial Research Organization, Indooroopilly, Queensland, Australia ∗ author for correspondence; e-mail: ptmadeira@ars.usda.gov Received 31 January 2000; accepted in revised 19 December 2000 Abstract. Quarantine colonies of the melaleuca snout beetle Oxyops vitiosa, the first melaleuca-feeding insect released in Florida, consisted of individuals collected from the Burpengary region (near Brisbane) of Queensland and their descendants. Constraints on the number of weevils available at this site motivated us to import weevils from a second site (Bundaberg). While individuals from the two sites could not be differentiated using taxonomic characters, the weevils from Bundaberg were consistently larger. This prompted concern that Bundaberg individuals might differ genetically from the quarantine population thus confounding the original host specificity studies. In a worse case scenario, the Bundaberg population might represent a separate sub-species or even a separate (cryptic) species. RAPD analysis was conducted on individuals from the two sites and on an outlier species, Gonipterus scutellatus. Neighbor Joining analysis clearly delineated the two species and also indicated some differentiation of individuals from the two O. vitiosa sites. Bootstrap analysis, however, indicated little statistical support for this intraspecific differentiation. Principal Coordinate analysis distinguished individuals from the two populations, and even distinguished two sub- populations from Bundaberg. AMOVA analysis indicated most of the variation occurred within populations but that the between population variance was significant. We conclude that further limited specificity testing and field host range observations should be conducted on the Bundaberg population before release into Florida. Key words: biological control, Melaleuca quinquenervia, RAPD