Parasite mind control
Parasites routinely manipulate their hosts for their own survival and transmission. This is known as extended phenotype where the genes of one animal impact another. Using transcriptomics we are investigating how terrestrial insects are manipulated to drown themselves in water. This fascinating host manipulation is induced by two types of parasites, nematodes and hairworms. We are currently working with collaborators at the University of British Columbia, University of New Mexico and University of Bath to understand how this manipulation is induced in a cricket/hairworm system.
Fig. Example of a host manipulation in Weta by a Nematomorpha parasite.
Expanding upon this work we are also investigating how parasites interact with each other inside their hosts. Hosts are routinely infected with multiple conspecific parasites and we are developing a co-infection model to understand how development stage and relatedness of the worms impact the manipulation in co-infected hosts. As part of this work we showed that eDNA can be used to detect endoparasitic infections from live insect hosts (Doherty et al Mol Eco Res 2023).
A weta with hairworm emerging, image: D Jean-François Doherty (University of British Columbia)
Diapause regulation in Rhagoletis
Diapause is a hormonally controlled seasonal response to environmental cues that results in developmental arrest, enabling arthropods to avoid unfavorable environmental conditions. The timing of diapause or dormancy is critical for organisms to synchronize themselves to changes in seasonal food sources. During diapause, development and cell proliferation are halted until termination is triggered via environmental cues.
Using a large scale comparative transcriptomic dataset through winter pupal diapause we compare physiological changes between populations that terminate diapause earlier (apple hosts R. pomonella, low altitude R. cerasi) to populations that terminate diapause later (haw hosts R. pomonella, high altitude R. cerasi). The combination of gene expression differences through winter (from diapause initiation to near diapause termination) and whole genome resequencing of early/late/average eclosers have enabled us to build a clearer understanding of how diapause termination timing is controlled in early and late diapausing populations (Dowle et al 2020). Insect overwintering physiology can be disrupted by climate change and research in this area is critical to understand how species will respond to changing environmental conditions.
Doherty JG, Bhattarai UR, Ferreira S, Poulin R, Gemmell NJ, Dowle EJ. The proof is in the poo: non-invasive method to detect endoparasitic infection. Molecular Ecology Resources 2023
Bhattarai UR, Poulin R, Gemmell NG, Dowle E. Genome assembly and annotation of the mermithid nematode Mermis nigrescens. bioRxiv, 2022.11. 05.515230
Bhattarai UR, Katuwal M, Poulin R, Gemmell NJ, Dowle E. A high-quality genome assembly and annotation of the European earwig Forficula auricularia. G3 2022
Dowle, EJ., Powell, THQ., Doellman, MM., Meyers, PJ., Calvert, MB., Walden, KKO., Robertson, HM., Berlocher, SH., Feder, JL., Hahn, DA., Ragland, GJ. Genome-wide variation and transcriptional changes in diverse developmental processes underlie the rapid evolution of seasonal adaptation. PNAS 2020 117 (38): 23960-23969