The use of copper-containing pesticides, such as Kocide, may affect non-target beneficial insects in Florida citrus and could limit the success of biological control management strategies. The transformation of beneficial insects with the yeast metallothionein gene, CUP1, could be used to produce populations that are resistant to copper. To determine if CUP1 confers increased tolerance to copper, the model insect Drosophila melanogaster was transformed with a P-element construct carrying the Drosophila metallothionein promoter, Mtn, and CUP1 open reading frame. Concentration-response data using Kocide were obtained for a base-line population of D. melanogaster and used to determine the concentration that causes 99% mortality in the control strain. The transgenic lines will be assessed for increased tolerance to determine whether this gene will be of potential value for genetic improvement projects.