Abstract
Variation in the condition of females can affect their mate preferences. This may explain variation in the expression of male ornaments. We tested these ideas in the mealworm beetle (Tenebrio molitor), a species in which females choose males based on their pheromones. We modified female condition using diets that differed in proteins and carbohydrates. We then allowed females to choose among males in which we had previously modified pheromone expression (either by varying diets as in females, or by fungal infection). Females were offered a choice between two males, both of which had been fed the same diet as the female, but which differed in whether they were infected or not. We repeated the same diet and infection treatments to determine whether poor (lower carbohydrate) diets decrease survival in both sexes. There was no effect of female diet on mate choice, but the infection state of the male did have an effect, with infected males being preferred. It is possible that infected males invest their resources in producing pheromones rather than attacking the pathogen. Both sexes, independent of infection, had higher survival when fed carbohydrate-rich diets. The results showed no effect of female condition on their preferences, at least not prior to copulation.
Dietary macronutrient balance and fungal infection as drivers of spermatophore quality in the mealworm beetle
