Coinfections, when hosts are infected with more than one parasite, are common. Despite a
large body of literature about the consequences of competition in coinfected hosts for
parasite life-history and virulence evolution, there is surprisingly little work about
facilitation. We are currently investigating the consequences of facilitation by Tomato
spotted wilt virus (TSWV) on the spider mites Tetranychus urticae and T. evansi. I will present
results showing how TSWV positively affects both species of spider mites, increasing
fecundity and the number of offspring becoming adult. I will show the results of further
experiments exploring transgenerational effects; whether being on a TSWV infected plant
impacts offspring fitness when placed on an uninfected plant. I will also talk about some
experiments we are doing at the moment investigating virulence and virulence evolution.