Effects of defoliation by Eucalyptus weevil, Gonipterus scutellatus, and chrysomelid beetles on growth of Eucalyptus globulus in southwestern Australia

Efficiency of biological control of Gonipterus platensis (Coleoptera: Curculionidae) by Anaphes nitens (Hymenoptera: Mymaridae) in cold areas of the Iberian Peninsula: Implications for defoliation and wood production in Eucalyptus globulus

“…The high wood loss observed may be due, in part, to the continuous feeding of the weevils during the spring and autumn, as well as to the continuous growth of the trees, and it further suggests that fast-growing trees may be at higher risk of decreased wood production due to severe defoliation. Our results apparently contradicts previous findings that defoliation by Gonipterus weevils has a limited impact on growth of E. globulus (Loch and Matsuki, 2010). In this study however, defoliation estimates of 18-33% were calculated for the growing tip of the trees affected, whereas mean defoliation of the control group remained at 5-16%.…”

“…Reliable estimates of tree growth reduction due to a specific agent, face a major difficulty since they require the control of other factors influencing tree susceptibility and tolerance, such as soil, climate as well as other biotic interactions. Chemically treated control trees have been used by some researchers to estimate defoliation impact on tree growth (e.g., Salleo et al, 2003;Loch and Matsuki, 2010). However, in Gonipterus a preference of the adults to oviposit on leaves of chemically treated plants in the weeks following treatment and the combined damage done by both larvae and adults, mask the true defoliation impact when compared with non-chemically treated plants (Palma and Valente, 2008).…”

Identification and molecular phylogenetics of the cryptic species of the Gonipterus scutellatus complex (Coleoptera: Curculionidae: Gonipterini)

“…All studies of G. ‘scutellatus’ in WA (Loch & Floyd 2001; Cunningham et al . 2005; Loch 2005, 2006, 2008; Loch & Matsuki 2010) refer to G. platensis , while in TAS the main species in the oviposition studies of Clarke et al . (1998) is G. notographus (based on voucher specimens in the ANIC and on host preference), and also G. ‘scutellatus’ in the study of Dungey and Potts (2003) appears to be G. notographus .…”

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

“…Multiple defoliations are more common than single events, and typically have more impact on stem growth than single events, particularly if frequent (Pinkard et al, 2006a). Continuous defoliation at low to moderate levels in E. globulus had little effect in the long-term (Loch and Matsuki, 2010), while 100% defoliation continuing beyond three annual events caused short-term cessation of growth in E. marginata (Wills et al, 2004). Defoliation by a biotic pest is likely to have a greater impact if it coincides with silvicultural practices such as pruning (Elek and Wardlaw, 2010), as it is essentially the same as a scenario of repeated defoliation.…”

“…While potential productivity is high, maximum rates are rarely achieved because of limitations due to drought, nutrient availability and biotic disturbances. Outbreaks of herbivorous insects or foliar pathogens are common in eucalypt plantations (Loch and Matsuki, 2010) and a recent review has described the main damaging pests of eucalypts including both native and introduced insect herbivores and pathogens (Paine et al, 2011). Current methods of pest management in plantations vary greatly depending on the pest type and resources available (Elek and Wardlaw, 2010).…”