Bionomics and feeding impact of Ctenarytaina eucalypti (Hemiptera: Psylloidea: Aphalaridae) on Eucalyptus globulus (Myrtaceae) in the central tablelands of New South Wales

Ctenarytaina eucalypti is considered a key pest of Eucalyptus plantations, especially E. globulus, in different parts of the world. In this study different levels of response of E. globulus to oviposition and feeding by C. eucalypti are reported. The responses in the juvenile E. globulus leaf tissues to oviposition include subcellular damage with the accumulation of callosic material superimposed by lignin-like polymers in cells proximal to the oviposition site, indicating the earliest response of stress signals in E. globulus to wounding. The feeding action of the first- and second-nymphal instars on the mesophyll cells inflicts both mechanical and chemical damage and manifests newly developed apoplastic spaces between cell walls and plasma membranes, poorly differentiated primordial-palisade cells, and autolysed protoplast. The phloem-feeding third-, fourth-, and fifth-nymphal instars induce changes in phloem parenchyma, which occur as actively dividing cells and including autophagic vacuoles. Leaf cells fed by adults also include hypertrophied mitochondria, degenerating cytoplasm and secondary metabolic compounds. The arrangement of antennal sensilla of C. eucalypti varies among nymphs and adults. The adults and nymphs of C. eucalypti appear to prefer specific leaf parts, suggesting that the levels and quality of nutrients vary in the same leaf. Growth in C. eucalypti is allometric, and the total body and antennal lengths show similar patterns in growth rates when compared with other sclerotised parts.