The first national monitoring survey of the blue gum chalcid wasp, Leptocybe invasa, in the eucalypt plantations of the summer rainfall region of South Africa was conducted between November 2016 and February 2017. One hundred and eighteen sites were surveyed for the presence of L. invasa-induced damage, damage intensity and presence of other insect pests and pathogens. Leptocybe invasa was present in 27% of sites sampled. When present, damage was predominantly of low intensity and uniformly spread, affecting most trees in the stand. The higher susceptibility of Eucalyptus grandis and its hybrids was evident. However, an in-depth analysis of L. invasa occurrence by species and genotype was not possible due to the limited sample size and the lack of available information regarding clone identity.
It is recommended that the monitoring protocol is adjusted to address the issue of optimal timing, by geographic region, to ensure that monitoring occurs at peak infestation times. Additionally, the site selection process should be adjusted to ensure adequate sample sizes across species/genotypes and climatic regions.