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One central tenet in sexual selection theory is that sexual traits are honest indicators of individual condition. This does not appear to be the case for Tenebrio molitor beetles whose males, when infected with the fungus Metarhizium robertsii , produce chemical signals (pheromones) that increase their attractiveness. Using this system, we have investigated the consequences of non-adaptive female choice with regard to: (a) survival of females in choosing fungus-infected males; and (b) whether the number and duration of copulations increases fungal infection in females. Females that mated with fungus-infected males lived half as long as females that mated with infection-free males. In addition, the greater the number and the longer the duration of copulation(s), the greater the fungal sporulation in females, suggesting that the fungus may be mainly transmitted during copulation. This study documents a conflict between the sexes: while the dishonesty of a sexual signal increases male fitness, it reduces female fitness. [ABSTRACT FROM AUTHOR]

Feeding behaviour is a dynamic process, especially if an individual is dealing with an infection. Here, we used Tenebrio molitor beetles to evaluate the effects of changes in diet macronutrients (protein:carbohydrate) on: (i) feeding behaviour before and after infection (using the entomopathogenic fungus Metarhizium robertsii) in males; and (ii) body condition, measured as the amount of proteins, carbohydrates, and lipids in the body, in males and females. Given that females also depend on the nutrients from the spermatophore, we also addressed the impact on female condition of using spermatophores from males whose diets differed in macronutrients whether they were confronting an infection. We found that males with different diets and regardless of their infection status, and females with different diets, all consumed less of the protein-rich diet but more of the carbohydrate-rich diet. In addition, infection in males produced anorexia. The infection resulted in males and the females they mated with, with fewer body proteins and lipids. This suggests that unlike studies in other insects, T. molitor does not consume large amounts of protein during the adult stage, even during an infection. Females' condition depended strongly on that of their mates, improving even when paired with infected males. This implies that females may be using the nutrients that the males transfer during mating for maintenance. [ABSTRACT FROM AUTHOR]

Postcopulatory sexual selection has shaped the ornaments used during copulatory courtship. However, we know relatively little about whether these courtship ornaments are costly to produce or whether they provide indirect benefits to females. We used the mealworm beetle, Tenebrio molitor, to explore this. We challenged males using an entomopathogenic fungus and compared their courtship (frequency of leg and antennal contacts to the female), copulation duration, number of eggs laid, and hatching rate against control males. Infected males copulated for longer yet they reduced their leg and antennal contacts compared to control males. However, there was no obvious relation between infection, copulation duration, and courtship with egg production and hatching success. In general, our results indicate that the ornaments used during postcopulatory courtship are condition-dependent. Moreover, such condition dependence cannot be linked to male fitness. [ABSTRACT FROM AUTHOR]