Submitted to: Biological Control
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/30/2006
Publication Date: 6/15/2006
Citation: Wheeler, G.S., Ordung, K.M. 2006. Lack of an induced response following fire and herbivory of two chemotypes of Melaleuca quinquenervia and its effect on two biological control agents. Biological Control. 39:154-161. Interpretive Summary: The invasive species Melaleuca quinquenervia is an invasive weed that threatens the Florida Everglades. We studied the compatibility of fire and biological control to manage this invasive species. Although many plant species respond to insect damage by increasing the levels of defensive chemicals, no such response was found in the leaves of Melaleuca. However, the leaves produced following fire were much softer and when fed to the biological control agents, the weevil Oxyops vitiosa and the psyllid Boreioglycaspis melaleucae, both had reduced survival. The integration of fire and biological control will result in decreased survival of both insects when fed the replacement leaves following treatments. However, previous damage by weevils appears compatible with continued feeding by the same species and feeding by the psyllid.
Technical Abstract: Induced responses following damage from herbivory or fire may reduce the nutritional quality of plants for subsequent herbivores. If compatible, the combination of fire and biological control has the potential of effectively controlling invasive weeds at reduced costs. Potentially plants subjected to previous herbivory from biological control agents or damage from fire will be less susceptible to biological control because of decreases in the nutritional quality of the plant from changes in physical defenses and/or accumulated secondary compounds. In the fire adapted species, Melaleuca quinquenervia, the impact of previous herbivory by the weevil biological control agent Oxyops vitiosa and fire was studied on the first leaves produced following damage. The plant quality factors foliar toughness, nitrogen, and volatile constituents were determined on these replacement leaves. Moreover the effect of these changes was determined on the survival, growth, and development of the immature stages of the biological control agents the weevil O. vitiosa and psyllid Boreioglycaspis melaleucae. Two chemical variants or chemotypes of M. quinquenervia were included and both responded similarly with decreased leaf toughness in leaves produced following burning. When fed these replacement leaves following burning, the survival of both the weevil and psyllid decreased significantly. Few additional changes were found in either plant quality or insect performance in response to these treatments. These results indicate that although burning will decrease survival in both species fed the replacement leaves, previous herbivory by weevils is compatible with subsequent damage by both biological control agents.