Melaleuca was first imported into the United States during 1886, and introduction records suggest that at least six sources have contributed to extant populations in Florida. Allozyme analyses found substantial genetic variation within and among populations, contributing to geographic structuring of melaleuca in southern Florida. The presence and distribution of two chemical phenotypes (chemotypes) contributed to this variation. Performance of the melaleuca snout beetle imported as a biological control agent differed dramatically in laboratory studies depending on which chemotype it was fed, with larval survivorship and growth substantially greater on an (E)-nerolidol chemotype. We are currently investigating whether these differences can be detected in the field.

Nomenclature: Melaleuca, Melaleuca quinquenervia (Cav.) Blake; melaleuca snout beetle, Oxyops vitiosa Pascoe.

Additional index words: Allozyme analysis, biological control, chemotype, herbivory, invasion history, insect–plant interactions.