How does ontogeny in a Eucalyptus species affect patterns of herbivory by Brushtail Possums?

Abstract

Summary 1.Comparisons of adult and juvenile plant stages are often confounded by other factors such as differences in height between plants. However, these factors can be teased apart using common garden experiments and appropriate sampling designs. 2. Using paired sampling of upper and lower canopies of Eucalyptus nitens trees, which were growing in a common environment trial and only one of which had undergone the transition to adult foliage, this study assessed the effects of ontogeny and canopy position on the feeding preferences of Common Brushtail Possums ( Trichosurus vulpecula ) in captive feeding trials under choice conditions. 3. Possums preferred juvenile foliage over adult foliage. In contrast, canopy position did not influence preferences. 4 Adult foliage contained significantly less sideroxylonals (a compound known to deter herbivory by Brushtail Possums), but was significantly tougher (with thicker cuticle, more fibre, more lignin and a higher percentage dry mass) than juvenile foliage, suggesting that leaf toughness was more significant than defensive chemistry in influencing intake by possums. Adult foliage did not differ significantly from juvenile foliage in nitrogen, total phenolics or essential oil concentration. 5. Greater resistance to herbivory of adult foliage compared with juvenile foliage by a significant browser of eucalypt tree foliage could contribute to selection for an earlier change from juvenile to adult foliage in areas that are heavily browsed by possums.

Development of an Insect Herbivore and its Pupal Parasitoid Reflect Differences in Direct Plant Defense

“…In addition to the wild B. oleracea populations, genetic variation in the expression of allelochemicals has been studied extensively in only a few species of wild plants, including both forbs and trees (Fritz et al 2003;Lawrence et al 2003;Ode et al 2004;Zangerl and Berenbaum 2005;Loney et al 2006). Interpopulation differences in the expression of allelochemicals may be driven by the intensity of selection from herbivores, particularly if natural enemies are scarce or absent (Ode et al 2004;Zangerl and Berenbaum 2005).…”

“…Interpopulation differences in the expression of allelochemicals may be driven by the intensity of selection from herbivores, particularly if natural enemies are scarce or absent (Ode et al 2004;Zangerl and Berenbaum 2005). Reciprocally, this can have profound effects on plant selection and performance in generalist herbivores, although studies have focused mainly on mammals, such as brush-possums in Australia (O'Reilly-Wapstra et al 2005;Loney et al 2006). However, population-related differences in secondary plant chemistry have also been shown to affect the performance of arthropod natural enemies such as parasitoids and predators ; this study).…”

Ontogenetic differentiation between Mediterranean and Eurasian pines (sect. Pinus) at the seedling stage

“…Of course, besides the possible adaptation to the abiotic environment, the inclusion of biotic interactions in a broader phylogenetic study would enlarge our interpretation of the evolution of ontogeny in pines. Particularly, herbivory has been postulated to be strongly influenced by plant phase change in different genera (Karban and Thaler 1999;Lawrence et al 2003;Loney et al 2006). The inclusion of abiotic and biotic factors would probably help us understanding why almost every pine species considered represents such an original combination of developmental features at a particular timing along the developmental programme.…”

Changes in plant chemical defenses and nutritional quality as a function of ontogeny in Plantago lanceolata (Plantaginaceae)

“…For example, variation in herbivore damage from the seedling stage to senescence can change by several orders of magnitude for the same plant-herbivore interaction (e.g., Pires and Price 2000;Fonseca et al 2006;Loney et al 2006), and may even involve considerable changes in the composition of the herbivore community inXicting damage throughout plant ontogeny (e.g., Waltz and Whitham 1997;Boege 2005;Thomas et al 2010). Similarly, the impact of herbivore damage on plant Wtness also depends on the ontogenetic stage being attacked, ranging from complete compensation by the host plant to long-lasting reductions in Xower production and fruit set (Warner and Cushman 2002;Boege et al 2007;Hanley and Fegan 2007).…”