Viruses as Costs to Gregarious Feeding Behaviour in the Lepidoptera

I present evidence that gregariously feeding species of Lepidoptera have evolved resistance to infection by their viral parasites, in terms of the larger amounts of virus needed to cause an infection as larvae age. First, I show a significant positive association between age-related resistance to infection by viruses and gregarious feeding behaviour in 13 case studies involving temperate Lepidoptera. Since pronounced levels of resistance to viral infection are not found in solitary species it can be inferred that this resistance has evolved in gregarious species at a cost