Working with the PEAR group for many years now, I have both witnessed and participated in its incredible evolution. My work debut involved the miniscule but “mighty in damage” grapevine pest phylloxera and its plant hosts and I quickly learnt to adapt to large scale and often complicated (damaged insects and fibrous roots) genotyping. I also managed the Molecular lab for a short time and was instrumental in the development and implementation of training (equipment and procedural) and EHS practises.
It is fitting that after I became a mother. I returned to the group to work on “the Mother of all dengue vectors”, Aedes aegypti. Here I worked closely with an incredible and inspiring mentor, Nancy Endersby-Harshman, to develop and test genetic markers in Aedes aegypti but also Aedes notoscriptus and Aedes albopictus. Research applications for these markers included population genetics, phylogeography, phenotypic trait association and conversion to new technology platforms (for example, from the P33 radioisotope to the fluorescence based system for microsatellite markers).
Then an endosymbiotic bacterium called Wolbachia exploded into my working life and it was both incredibly promising in terms of its ability to block the dengue virus (and later zika virus) and complex because it was a “novel” vector control strategy with the option of multiple Wolbachia strains whose dengue blocking and host effects (negative and positive) varied. PEARG first focused on the Wolbachia strain wMel and a dedicated period of colony experiments, field releases, molecular testing and post-release monitoring followed providing us with a good understanding of its role in disease suppression. The PEARG captaincy by Professor Ary Hoffmann however soon added other mosquito hosts and Wolbachia strains into the mix and fine-tuned our research goals and approaches to better understand the genetic mechanisms both driving and confounding the spread of Wolbachia in natural populations.
My contributions to this “Wolbachia era” include screening of thousands of Aedes samples for Wolbachia infection status with established “high throughput” light cycler assays but also developing and optimising new light cycler assays including those that can detect very low level and multiple Wolbachia infections in mosquitoes and fruit flies. But by far the most rewarding experiences have been sharing these methodologies with visiting collaborators from China, Indonesia and Sri Lanka and my visit to the wonderful Institute of Medical Research (IMR) in Kuala Lumpur, Malaysia, where I helped adapt our procedures to their working environment. The importance of this IMR collaboration was further highlighted by colleagues who had been infected by dengue three and four times. A job that has the potential to help the lives of many people is something rare and special as is working for Ary, who believes in sharing and advancing the technology and resources that he and his team have developed to fight dengue where it is truly needed.
Recently I hopped over to grasshoppers: So far I have tested mitochondrial and nuclear markers on the parthenogenetic species Warramaba virgo (comprised of two distinct phylads, Standard and Boulder-Xanthus) and maintained a colony of and performed physiological trait measurements on Vandiemenella (another genus of Australian grasshoppers that is made up of different chromosome races). I am now learning about the fascinating Keyacris scurra grasshopper and its conservation plight that restricts it to a handful of regional graveyards. And I am also exploring potential next generation sequencing technologies that can be used to characterise the genetic diversity and evolutionary histories of matchstick grasshoppers (family Morabidae, comprised of over 300 species that do not occur outside Australia) and help identify threats to their future (for example, climate change) and practises that can reduce those threats (for example, translocations of individuals to threatened populations).
Keyacris scurra walks into a Melbourne Uni lab and the scientist says “Why the long face?” and she answers “Because I am at grave risk of extinction”.
*Photo credit: Michael Kearney.
*Molecular training of overseas visitors from Iran and China (mosquito project).
*Development of nuclear SNP markers to detect clonal variation in the parthenogenetic grasshopper Warramaba virgo.
*Ongoing colony maintenance and physiological trait measurements (such as feeding rate) in Vandiemenella grasshoppers.
*Exploring suitable next generation sequencing technologies for understanding the evolutionary histories of and current threats to Morabidae grasshoppers.
Umina, P. A., Corrie, A. M., Herbert, K. S., White, V. L., Powell, K. S. and Hoffmann, A. A. (2007) The use of DNA markers for pest management -clonal lineages and population biology of grape phylloxera. Acta. Hortic.,733, 183-189.
Endersby, N. M., Hoffmann, A. A., White, V. L., Lowenstein, S., Ritchie, S., Johnson, P. H., Rapley, L. P., Ryan, P. A., Nam, V. S., Yen, N. T., Kittiyapong, P. and Weeks, A. R. (2009) Genetic structure of Aedes aegypti in Australia and Vietnam revealed by microsatellite and Exon-Primed Intron-Crossing markers suggests feasibility of local control options. Journal of Medical Entomology, 46, 1074-1083.
Endersby, N. M., Hoffmann, A. A., White, V. L., Ritchie, S. A., Johnson, P. H. and Weeks, A. R. (2011) Changes in the genetic structure of Aedes aegypti (Diptera: Culicidae) populations in Queensland, Australia, across two seasons: Implications for potential mosquito releases. Journal of Medical Entomology, 48, 999-1007.
Lee, S. F., White, V. L., Weeks, A. R., Hoffmann, A. A. and Endersby, N. M. (2012) High-throughput PCR assays to monitor Wolbachia infection in the dengue mosquito (Aedes aegypti) and Drosophila simulans. Appl. Environ. Microbiol. 78(13), 4740-4743.
Endersby, N. M., White, V. L., Chan, J., Hurst, T., Rašić, G., Miller, A. and Hoffmann, A. A. (2013) Evidence of cryptic genetic lineages within Aedes notoscriptus (Skuse). Infection, Genetics and Evolution, 18, 191-201.
Rakimov, A., Ben-Dov, Y., White, V. and Hoffmann, A. A. (2013) Soft scale insects (Hemiptera: Coccoidea: Coccidae) on grapevines in Australia. Australian Journal of Entomology, 52, 371-378.
White, V. L., Endersby, N. M., Chan, J., Hoffmann, A. A and Weeks, A. R. (2014) Developing Exon-primed intron-crossing (EPIC) markers for population genetic studies in three Aedes disease vectors. Insect Science, 22(3), 409-423.
Wuliandari, J. R., Lee, S. F., White, V. L., Tantowijoyo, W., Hoffmann, A. A. and Endersby-Harshman, N. M. (2015) Association between Three Mutations, F1565C, V1023G and S996P, in the Voltage-Sensitive Sodium Channel Gene and Knockdown Resistance in Aedes aegypti from Yogyakarta, Indonesia. Insects, 6, 658-685.
Rasic, G., Endersby-Harshman, N., Tantowijoyo, W., Goundar, A., White, V., Qiong, Y., Filipovic, I., Johnson, P., Hoffmann, A. and Arguni, E. (2015) Aedes aegypti has spatially structured and seasonally stable populations in Yogyakarta, Indonesia. Parasites & Vectors, 8, 610.
Hancock, P. A., White, V. L., Callahan, A. G., Godfray, C. H. J., Hoffmann, A. A. and Ritchie, S. A. (2016) Density-dependent population dynamics in Aedes aegypti slow the spread of wMel Wolbachia. Journal of Applied Ecology, 53(3): 785-793.
Hancock, P. A., White, V. L., Ritchie, S. A., Hoffmann, A. A. and Godfrey, H. C. J. (2016) Predicting Wolbachia invasion dynamics in Aedes aegypti populations using models of density-dependent demographic traits. BMC Biology, 14, 96.
Ross, P. A., Wiwatanaratanabutr, I., Axford, J. K., White, V. L., Endersby-Harshman, N. M. and Hoffmann, A. A. (2016) Wolbachia Infections in Aedes aegypti differ markedly in their response to cyclical heat stress. PLOS Pathogens, 13(1): e1006006.