Evolution of resistance and counter-resistance
A braconid wasp parasitizing an aphid
Pea aphid are attacked by a variety of natural enemies including specialised parasitoids (e.g. the braconid Aphidius eadyi) and species with a broader host range, as well as generalist predators and fungal pathogens. We have found considerable clonal variation in resistance to parasitoids and fungal pathogens, which begs the question of why such traits have not become fixed in the population. We are interested in identifying trade-offs between resistance and other components of fitness, and in understanding the genetic basis of resistance. We also interested in how selection acts on the natural enemy to overcome host resistance, and whether this leads to coevolutionary interactions. Much of this work is linked to our studies of aphid symbionts, as it is now well-established that symbiotic bacteria form an important element of the aphid immune defence. However, even when resistance is conferred by a symbiont, the aphid genotype may continue to play an important role in the level of resistance observed. Understanding how aphid and symbiont interact to produce a resistant phenotype is therefore now an aspect of our work on the evolution of resistance.
- Ferrari, J. & Godfray, H.C.J. 2003 Resistance to a fungal pathogen and host plant specialisation in the pea aphid. Ecology Letters 6, 111-118.
- Ferrari, J., Müller, C.B., Kraaijeveld, A.R. & Godfray, H.C.J. 2001 Clonal variation and covariation in aphid resistance to parasitoids and a pathogen. Evolution 55, 1805-1814.