Research
Ph.D. Research
Environmental symbiont acquisition and its effects on host insect fitness
I am researching the effects that different strains of environmentally acquired microbial symbionts can have on host insect development and survival under various environmental conditions using the bug-Caballeronia symbiosis as a model system. Through this work, I will analyze strain variability across symbiosis associated genomic regions and unique genes in the Caballeronia genome, investigate how the Caballeronia symbiont may mediate host thermal performance, and how variation in symbiont gene expression may relate to variation in host fitness.
Symbiosis associated genomic region
Microbial symbionts are important for the development of many Eukaryotes, and often the genes for these associations are contained with genomic islands. These islands are contiguous regions in the symbiont genome that encode pathways for microbial survival or host colonization, allowing the symbiosis to take place. Recently, a symbiotic island was detected in the Caballeronia symbiont of several pentatomomorphans (Hemiptera).
We determined that this genomic island is actually a symbiosis associated region, not an island, as it does not have any of the common features associated with genomic islands. This region is still associated with symbiosis, but the full function is unknown although many of the genes in this region are up regulated during symbiosis.
Publication: Stillson PT, Baltrus DA, Ravenscraft A. (2022). Prevalence of an insect associated genomic region in environmentally acquired Burkholderiaceae symbionts. Applied and Environmental Microbiology. doi:10.1128/aem.02502-21
M.S. Research
Aster Leafhopper Management
Managing insect vectors in agriculture is of great concern to farmers and developing effective tools to mitigate the spread of disease is essential. This work focused on developing a decision support tool to improve aster leafhopper (Macrosteles quadrilineatus) management in celery and carrots. These leafhoppers vector the bacterial plant pathogen aster yellows phytoplasma which can cause up to 10% crop loss when unmanaged, and greatly affect farmers with small profit margins.
This research can be used to inform farmers about disease infectivity levels, thus, providing greater insight into the harm the leafhoppers could cause to their crops. Additionally, this provides farmers with better idea of when it is necessary to apply insecticides to their fields to control the spread of disease.
Publication: Stillson PT, Bloom EH, Gutiérrez Illán J, Szendrei Z. (2020). A novel plant pathogen management tool for vector management. Pest Manag Sci. doi:10.1002/ps.5922
Identification of Novel Vectors
Identifying new vectors of plant pathogens is essential to minimize disease outbreaks. This work focused on identifying putative vectors of aster yellows phytoplasma in leafhopper species located in the field margins of celery and carrot farms.
During this project, I was able to confirm that the Aster leafhopper is the primary vector in Michigan, and that it is moving between the crop and the field margins. I also detected several other known vectors in these cropping systems.
Publication: Stillson PT, Szendrei Z. (2020). The quest for new vectors of aster yellows phytoplasma to improve management. Insects. doi:10.3390/insects11070411
