Mrs Gudrun Dittrich-Schröder

PhD Student
Tree Protection Co-operative Programme

Research Interests

Background   I completed a BSc (Agriculture) at the University of KwaZulu-Natal, Pietermaritzburg. Thereafter I conducted research in collaboration with the South African Sugarcane Research Institute (SASRI), Mount Edgecombe, Durban on Scarabaeids as well as a potential biocontrol agent of the stalk borer, Eldana saccharina. My MSc focused on identifying Scarabaeid larvae, problematic in sugarcane, by using molecular techniques to link unidentified larvae to identified beetles. Subsequently a field key and electronic key, using Lucid 3.4 software, were developed to allow identification of larvae in sugarcane fields.

Current Research My PhD is focussing on the Eulophid, Leptocybe invasa (Hymenoptera: Eulophidae). Leptocybe invasa, also known as the Eucalyptus gall wasp, causes serious damage to the young growing shoots of various Eucalyptus spp. grown in plantations. The pest is thought to have originated in Queensland, Australia, but it was described from Israel where it was first encountered in 2000. Since then it has spread rapidly in Africa and other parts of the world including South America, South East Asia and China. In Africa, L. invasa moved southwards rapidly to appear in Ethiopia in 2002, Kenya and Tanzania in 2005 and Zimbabwe in 2007. Leptocybe invasa was first found in South Africa in August 2007 in a Eucalyptus stand in Pretoria. Populations have, however, now been identified hundreds of kilometers away from its original site of interception. To date L. invasa has been recorded from five localities in South Africa, namely Brits, Johannesburg, Pretoria, Tzaneen and Upington. It, therefore, seems to be well established and spreading fast. Leptocybe invasa affects Eucalyptus spp. by oviposition on the midribs, petioles and branches of trees. This results in gall formation and in severe cases tree growth is seriously stunted. Eucalyptus camaldulensis (and other members of the Exertaria section of the genus) appear to be the most susceptible, but there are a number of other species which are also affected. These include E. grandis x E. camaldulensis and pure E. grandis clones that are commonly planted in South Africa. Leptocybe invasa attacks trees of all ages, from nursery stock to mature trees, but the damage is most severe on younger plants. No control measures are currently available, although biological control using parasitoids is well underway in Israel. Currently, molecular genetic studies using mitochondrial DNA are being conducted to determine the diversity in South African and other introduced populations.

 

Conference presentations

• Dittrich, G., Conlong, D. E. & Mitchell, A. 2005. Genetic diversity of Sturmiopsis parasitica Curran (Diptera: Tachinidae). South African Sugar Technologists’ Association. 19-22 July 2005, Mt. Edgecombe, Durban, South Africa.
• Dittrich, G., Conlong, D. E. & Mitchell, A. 2005. Genetic diversity of Sturmiopsis parasitica Curran (Diptera: Tachinidae). Entomological Society of Southern Africa. 10-13 July 2005, Grahamstown, South Africa.
• Dittrich, G., Conlong, D. E. & Mitchell, A. 2006. Molecular Identification of South African Sugarcane White Grubs (Coleoptera: Scarabaeidae). South African Sugar Technologists’ Association. 18-20 July 2006, Durban, South Africa.
• Dittrich-Schröder, G., Conlong, D. E. & Mitchell, A. 2008. Molecular identification of scarabaeid beetle pest species in South African sugarcane. 20th Biennial Congress of the South African Genetics Society. 27-29 March 2008, Pretoria, South Africa.
• Dittrich-Schröder, G., Slippers, B., Neser, S., Mendel, Z. & Wingfield, M. J. 2008. Leptocybe invasa (Hymenoptera: Eulophidae) spreading rapidly in Southern Africa. International Union of Forest Research Organizations Working Group 7.3.00. Recent Advances in Forest Entomology. 1-6 July 2008. Pretoria, South Africa.

 

Posters

• Dittrich-Schröder, G., Slippers, B., Neser, S., Mendel, Z. & Wingfield, M. J. 2008. Leptocybe invasa (Hymenoptera: Eulophidae) now in South Africa. XXIII International Congress of Entomology. 6-12 July 2008 International Convention Centre, Durban, South Africa.
• Dittrich-Schröder, G., Wingfield, M. J., Hurley, B., Neser, S., Mendel, Z. & Slippers, B. 2009. The invasive gall-forming wasp Leptocybe invasa (Hymenoptera: Eulophidae) in South Africa. Entomological Society of Southern Africa. 5-7 July 2009, Stellenbosch, South Africa.