Franziska Brunner worked with me on a semester project exploring how the bumblebee Bombus terrestris responds to infection with a common trypanosome parasite Crithidia bombi. She liked it so much that she decided to return to do her masters project. Franziska’s new work explores how gene expression changes with exposure to this parasite and will attempt to understand the variation in responses that are seen in the lab and field.

Robert Dünner is working on a project with me and Gabriel Leventhal to explore the costs of fecundity compensation. Many organisms respond to cues of risk by increasing reproduction. Robert is using models to predict the costs that prevent this higher rate of reproducing from being constantly expressed.

Eric Seiger recently finished a semester project exploring the influence of mating on immunity in B. terrestris. Mating in many cases initiates a strong physiological response which can be costly and divert resources away from other costly endeavors, like fighting infection.

Ben Parker and I have been working on a project to assess the costs of immunity in pea aphids. Developing, maintaining and using an immune system is takes lots of resources that could go into other important things like reproduction or growth. So immunity must be traded off against other traits. We’re looking at whether we can detect costs in aphid fitness when aphids are given a variety of different pathogens.

Jill Spragg* has been exploring the relationship between host genotypic variation in disease susceptibility and protection against a fungal pathogen conferred by bacterial symbionts.  She has been focussing on the interaction between pea aphids, beneficial bacteria that protect them against pathogens, and aphid-specific fungal pathogens.  We predict that at least some aphid clones will be less susceptible to fungal infection when carrying the symbiont Regiella insecticola, but the difference in resistance conferred between host genotypes should reflect the complexity of symbiont-host interactions.  We are interested to see whether differences in resistance are due to intrinsic susceptibilities in particular aphid clones, the strain of symbiont the aphid carries, or some interaction between particular hosts and symbionts. Jill has also been examining the expression of antimicrobial peptides in pea aphids in response to fungal infection.

1. *Jill is now a grad student at the University of Washington.
   

Dan Sok worked with me in a series of experiments that looked into how pea aphids respond to a number of challenges. We found that giving pea aphids cues of death or stress determines their investment in reproduction. The results of this work can be found in our paper (which is available on the papers page).