Jill Spragg

Jill 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.

Dan Sok

Despite his smiley appearance, Dan is preoccupied with stress; not human stress, mind you, but aphid stress. He has been studying how exposure to the aphid alarm pheromone EBF alters aphids’ reproductive investment and resistance to diseases. Aphids exposed to stressful conditions can produce winged dispersing offspring. Dan is examining whether these winged offspring are also loaded with secondary symbionts to provision them in their new environment.

Carmen Linares

Carmen and I just finished a project that tested the lifetime fitness consequences of immune activation in pea aphids. In order to elicit an immune response, we challenged aphids with either a sterile needle or a septic needle dipped in a suspension of heat-killed bacteria and monitored their lifetime reproduction, the onset of reproduction, age at final reproduction and survival.

Our results indicated no significant change in aphids’ reproduction or survival, regardless of whether they were stabbed with a sterile or septic needle or the number of times they were stabbed. This would suggest that aphids may not be mounting a costly immune response, which is consistent with recent genomic analyses suggesting that aphids have a weakened immune system compared to other insects.