Performance of adult psyllids in no‐choice experiments on juvenile and adult leaves of Eucalyptus globulus

Abstract

The presence of glaucous juvenile leaves and glossy adult leaves in the canopy of the heteroblastic plant Eucalyptus globulus Labill., is a source of within-tree variation that affects herbivory by three psyllid species (Ctenarytaina eucalypti Maskell, C. spatulata Taylor and Glycaspis brimblecombei Moore) (Homoptera, Psyllidae). In no-choice field experiments with adult female psyllids in clip-on cages, we compared (1) leaf-settling, honeydew production, and survival of the Ctenarytaina species on juvenile and adult leaves of E. globulus, (2) leaf-settling and survival of G. brimblecombei on juvenile and adult leaves, (3) leaf-settling and survival of the three species on waxy (untreated) juvenile leaves and de-waxed (rubbed) juvenile leaves, and (4) leaf-settling and survival of C. spatulata on juvenile leaves from which wax was repeatedly removed. Leaf-settling by C. eucalypti was significantly greater on juvenile than adult leaves, however, honeydew production and survival were equal on both leaf types. In contrast, leaf-settling, honeydew production, and survival by C. spatulata were significantly greater on adult than juvenile leaves. Similarly, leaf-settling and survival by G. brimblecombei were significantly greater on adult than juvenile leaves. Wax removal from juvenile leaves significantly increased leaf-settling and survival of C. spatulata and G. brimblecombei. Although wax removal decreased leaf-settling by C. eucalypti, it did not affect survival. Repeated removal of regenerating wax from juvenile leaves did not affect leaf-settling or survival of C. spatulata. These results suggest that the epicuticular wax of juvenile leaves plays a role in resistance to C. spatulata and G. brimblecombei, however other unknown factors are probably also involved.

Impact of defoliation in temperate eucalypt plantations: Physiological perspectives and management implications

“…Constitutive defences in eucalypts comprise physical leaf traits such as toughness (Steinbauer and Matsuki, 2004) and texture (e.g. glaucousness, Brennan and Weinbaum, 2001), variation in leaf structure (e.g. mesophyll density, Smith et al, 2007) as well as chemical leaf traits that are dominated by high concentrations of plant secondary metabolites (PSMs) (Table 3).…”

Intra‐plant host selection, oviposition preference and larval survival of Chrysophtharta agricola (Chapuis) (Coleoptera: Chrysomelidae: Paropsini) between foliage types of a heterophyllous host

“…The oil yield and composition of each foliage type differ markedly (Li, 1993;Li et al, 1994), with juvenile leaf oils containing higher levels of 1,8 cineole, limonene, Y-terpinene, a-terpineol, sesquiterpenoids, monoterpenoids and a-phellandrene than adult leaf oils (Li, 1993). However, the evolution of distribution of insect species between the foliage types of heterophyllous eucalypt species has received little attention (Brennan & Weinbaum, 2001a;Steinbauer, 2002), despite leaf production phenology having a substantial impact on insect population dynamics (Mopper & Simberloff, 1995).…”

Biologia de Ctenarytaina spatulata (Hemiptera, Psyllidae) em Eucalyptus grandis

“…São encontrados normalmente nas brotações jovens e mais apicais, raramente em folhas adultas de E. grandis ao contrário das observações de BRENAN & WEINBAUM (2001) onde os adultos sobrevivem mais tempo nas folhas adultas do que nas folhas jovens de E. globulus. Isto pode ser explicado pela ausência de heteroblastia em E. grandis e ausência de ceras nas suas folhas novas, enquanto que E. globulus apresentam nas folhas jovens uma grande quantidade de ceras.…”