Submitted to: Environmental Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/1/2006
Publication Date: 10/15/2006
Citation: Pratt, P.D., Morath, S., Silvers, C.S., Center, T.D. 2006. Herbivory by Boreioglycaspis melaleucae (Hemiptera: Psyllidae) accelerates foliar degradation and abscission in the invasive tree Melaleuca quinquenervia. Environmental Entomology. 35(5):1372-1378. Interpretive Summary: Melaleuca quinquenervia is a native of eastern Australia and was been introduced to various locations around the world. One hundred years after its introduction into Florida, melaleuca grows spontaneously and displaces native plants as well as animals in the wetlands that comprise the Florida Everglades. In an effort to curb the invasion of this weed, scientists have identified natural enemies or biological control agents that help in the suppression of melaleuca. This article provides details on the introduced biological control agent Boreioglycaspis melaleucae, with emphasis on its life history and impact on the invasive plant M. quinquenervia.
Technical Abstract: We quantified the density-dependent effects of herbivory by the psyllid Boreioglycaspis melaleucae Moore on the degradation of expanding and fully expanded leaves from two chemical variants (chemotypes) of the invasive tree Melaleuca quinquenervia (Cav.) S.T. Blake. Foliar chlorophyll content (OD) and percent nitrogen were not influenced by leaf age classes and chemotypes. In contrast, increases in the level of herbivory resulted in concomitant decreases in chlorophyll compared to undamaged leaves, with medium and high levels of herbivory reducing chlorophyll content by 64 and 72%, respectively. Likewise, low, medium, and high levels of herbivory resulted in 20, 53, and 60% reductions in percent nitrogen, respectively. Color analysis showed that increased herbivory also increased the amount of damaged tissue per leaf across both age classes but younger leaves demonstrated less susceptibility to herbivory than their older counterparts. Leaves sustaining moderate to high levels of herbivory progressed from dark green to yellow and finally to light tan as they deteriorated. These changes in color, particularly the yellowing aspect, were often more pronounced along the main leaf veins and vascular tissues. Feeding by B. melaleucae increased the likelihood of leaf abscission by 4.7-fold compared to leaves not subjected to herbivory and was not influenced by leaf age or chemotype. Implications for biological control of M. quinquenervia are discussed.