Featured Researcher

Dr. Barbara van Asch

PhD in Genetics – Faculty of Science, University of Porto, Portugal - 2010

Senior lecturer at the Genetics Department, Faculty of Agrisciences, Stellenbosch University, South Africa - 2015 to present

Research interests

Insect genetic diversity, phylogenetics and phylogeography, with focus on agricultural pests and edible species of Southern Africa.

My academic and scientific journey has been somewhat unconventional as I only started my undergraduate studies when I was 30 years old. The undergraduate years were not particularly interesting, but I was determined to endure that phase and become a researcher because it seemed to me that the naturalist profession that produced the likes of Darwin and Wallace had regrettably gone extinct. Also, sailing the world for collecting and cataloguing exotic species was not a viable life option at that point. Eventually, I was offered a PhD project in population genetics of autochthonous dog and pig breeds and their wild ancestors, but it was my side hustle on the genetic diversity of olive entomofauna that really sparked my curiosity. When I relocated to Stellenbosch University, South Africa in 2015, I was free to explore the wonderful world of sub-Saharan insect diversity that was as foreign to me as the constellations in Southern Hemisphere sky.

Insects associated with Olea europaea are fascinating because they are a small group of highly specialized insects – olives and olive trees are generally not attacked by polyphagous species. South Africa is the most important producer of olives and olive products in sub-Saharan Africa and, although the region is rich in species associated with O. europaea, local producers are relatively free from the burden of insect pests compared to other world regions. In contrast, the Mediterranean and California are severely affected by the olive fruit fly Bactrocera oleae (Tephritidae), which has two close relatives (B. biguttula and B. munroi) in sub-Saharan Africa that are only found in the African Wild Olive (O. e. subsp. cuspidata). This suggests that B. oleae has evolved specific adaptations that allow it to feed on cultivated olives, and that understanding this “toolbox” may lead to innovative biocontrol strategies. Among other projects, I have been cataloguing the entomofauna associated with the Wild African Olive and cultivated olive using DNA sequences and phylogenetic analyses, including olive fruit flies and their parasitoids, hyperparasitoids and olive seed wasps (Braconidae and Chalcidoidea), olive lace bugs (Tingidae), olive flea beetles (Chrysomelidae), and olive psyllids (Liviidae). This endeavour has led me to Anchonocranus oleae (Curculioninae), a seed-feeding weevil that was brought to my attention by collaborators with shared interests in olive-associated insects. As is usually the case of insects associated with olives, Anchonocranus oleae feeds on both Wild African Olive and cultivated olives. Presently, little is known about the life cycle, biology and natural enemies of A. oleae, but it is clear that it may spend a few years in the larval stage within the olive seed before it emerges as an adult. The species has remained in relative obscurity because it is not held responsible for significant economic losses in commercial olive groves. We have found A. oleae mostly in the Western Cape of South Africa, but its distribution likely accompanies that of the Wild African Olive. As part of the effort to describe the olive-associated entomofauna in South Africa, we are finalizing a report on the mitogenomics and phylogenetics of A. oleae that contributes with novel genetic data for assisting future work on DNA-based species identification, genetic diversity and phylogenetic position of the genus Anchonocranus and related taxa. I owe everything I know about weevils and their phylogenetic relationships to Rolf Oberprieler, who has been sharing his expertise with extraordinary patience and generosity and cannot be blamed for my ignorance. In the near future, I plan to analyse the large amount of DNA barcoding data publicly available for Curculionidae and contribute to assess the utility of this marker for species identification in the family. My preliminary results suggest that a large proportion of the DNA barcode dataset available for Curculionidae is affected by taxonomic inconsistency, non-monophyly, cryptic diversity, clerical mistakes and misidentifications.

My wide range of interests allowed me to co-author over 50 papers in peer-reviewed journals, and I invite you to check out my ORCID (https://orcid.org/0000-0002-0171-879X) and my Research Gate (https://www.researchgate.net/profile/Barbara-Van-Asch) profiles hoping that you may find something of interest, and feel free to get in touch by email to bva@sun.ac.za!

Last updated October 19, 2021