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ARS Home » Southeast Area » Fort Lauderdale, Florida » Invasive Plant Research Laboratory » Research » Publications at this Location » Publication #161652
Title: NATURAL ENEMY ESCAPE AND THE EVOLUTION OF HERBIVORY RESISTANCE IN THE INVASIVE PLANT MELALEUCA QUINQUENERVIA

Author
item Franks, Steven
item Pratt, Paul
item Dray, F Allen
item SIMMS, ELLEN - UC BERKELEY

Submitted to: Gordon Research Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 2/1/2004
Publication Date: 2/29/2004
Citation: Franks, S.J., Pratt, P.D., Dray Jr, F.A., Simms, E.L. 2004. Natural enemy escape and the evolution of herbivory resistance in the invasive plant melaleuca quinquenervia. Gordon Research Conference Proceedings.

Interpretive Summary: We conducted a study to determine if the invasive tree Melaleuca quinquenervia may develop resistance to herbivory by biological control insects. We collected seeds from plants in Florida and Australia and kept tract of the maternal seed source tree. Seedlings were planted in a common garden, and half were sprayed with insecticide while insects were allowed to visit and feed on the other plants. Seeds from plants in Florida (the introduced range) had more insects and more damage than Australian plants, which supports the hypothesis that plants in their new range loose resistance to herbivory because their herbivores are absent. Plants from the introduced range also had a lower density of leaf hairs, and leaf hairs were correlated with the presence and damage of insects. The results of the study generally support the natural enemy release hypothesis, but do not indicate that the evolution of increased herbivore resistance will pose a substantial threat to biological control efforts.

Technical Abstract: To examine how an invasive plant may evolve resistance to herbivory by biological control insects, we conducted a quantitative genetics study of the invasive tree species Melaleuca quinquenervia. We planted seedlings of known maternity into a common garden, and seedlings were either subjected to herbivory or were sprayed with insecticide. Genotypes from the introduced range had a greater proportion of insects and suffered greater damage than genotypes from the native range, supporting the natural enemy escape hypothesis. Plants from the introduced range also had a lower density of leaf hairs, and leaf hairs were correlated with the presence and damage of insects. Leaf pubescence also appears to be heritable and under directional or possibly stabilizing selection. The results of the study generally support the natural enemy release hypothesis, but do not indicate that the evolution of increased herbivore resistance will pose a substantial threat to biological control efforts.