Galls are abnormal growths on a plant that can have various causes, including viruses, nematodes, bacteria, fungi, mites and insects. Aphids, flies and wasps are some of the insects known to cause galls. Generally plants can tolerate galls with no obvious injury. However, a very high incidence of galls can damage and even kills plants.

Gall formers on eucalypts

The Eucalyptus gall wasp (Leptocybe invasa) is currently the only gall forming insect in South Africa which is considered a serious pest of plantation forest trees. This insect, which infests Eucalyptus, was accidentally introduced from Australia. It was first detected in South Africa in 2007 (and only in 2009 in forestry areas). The Eucalyptus gall wasp causes galls on the stems, petioles and midrib of leaves. Damage by this insect is particularly severe on younger trees, where the majority of leaves can have galls, resulting in severe leaf drop. In such cases, stunting of growth and possibly tree death can occur. The adult wasp is minute (about 1.4 mm), but the galls, which often contain multiple eggs of the Eucalyptus gall wasp, are easily visible. Severely infested trees have a gnarled appearance.

New Publications

Clasen FJ, Pierneef RE, Slippers B, Reva O. (2018) EuGI: a novel resource for studying genomic islands to facilitate horizontal gene transfer detection in eukaryotes. BMC Genomics 19:323. 10.1186/s12864-018-4724-8
De Beer ZW, Marincowitz S, Duong TA, Wingfield MJ. (2018) (2592) Proposal to conserve Endoconidiophora fagacearum (Bretziella fagacearum, Ceratocystis fagacearum) against Chalara quercina (Thielaviopsis quercina) (Ascomycota: Sordariomycetes: Microascales). Taxon 67:440-440. 10.12705/672.14
Kanzaki N, Tanaka SE, Ito M, Tanaka K, Slippers B, Tabata M. (2018) Some additional bionomic characters of Deladenus nitobei. Nematology 10.1163/15685411-00003168
Barnes I, Fourie A, Wingfield MJ, Harrington TC, McNew DL, Sugiyama LS, Luiz BC, Heller WP, Keith LM. (2018) New Ceratocystis species associated with rapid death of Metrosideros polymorpha in Hawai`i. Persoonia 40:154–181. 10.3767/persoonia.2018.40.07
Dittrich-Schröder G, Hoareau TB, Hurley BP, Wingfield MJ, Lawson S, Nahrung HF, Slippers B. (2018) Population genetic analyses of complex global insect invasions in managed landscapes: a Leptocybe invasa (Hymenoptera) case study. Biological Invasions 10.1007/s10530-018-1709-0