K (2013) Dynamics of macronutrient self-medication and illness-induced anorexia in virally infected insects

1. Some animals change their feeding behaviour when infected with parasites, seeking out substances that enhance their ability to overcome infection. This ‘self-medication ’ is typically considered to involve the consumption of toxins, minerals or secondary compounds. However, recent studies have shown that macronutrients can influence the immune response and that pathogen-challenged individuals can self-medicate by choosing a diet rich in protein and low in carbohydrates. Infected individuals might also reduce food intake when infected (i.e. illness-induced anorexia). 2. Here, we examine macronutrient self-medication and illness-induced anorexia in caterpil-lars of the African armyworm (Spodoptera exempta) by asking how individuals change their feeding decisions over the time course of infection with a baculovirus. We measured self-medication behaviour across several full-sib families to evaluate the plasticity of diet choice and underlying genetic variation. 3. Larvae restricted to diets high in protein (P) and low in carbohydrate (C) were more likely to survive a virus challenge than those restricted to diets with a low P: C ratio. When allowed free choice, virus-challenged individuals chose a higher protein diet than controls