Fitness consequences of female preference for male pheromones in Tenebrio molitor

Hypothesis: Sexual selection is maintained by ‘good genes’ effects of mate choice on females, and by mating with males with preferable pheromones females increase their fitness. Organism: Cultured mealworm beetles (Tenebrio molitor). Methods: Male mealworm beetles were paired by mass and age, their pheromones were collected by confining them on filter paper, and the two halves of the filter paper disks were presented to two mass-matched females. Females and males were then allowed to mate in three ways: (1) Among females preferring pheromones of the same male, one female mated with the male who had the preferred pheromones and the other female with the male who had the non-preferred pheromones. Among females preferring separate disks, both females mated either with (2) the male with the preferred pheromones or (3) the male with the non-preferred pheromones. Results: Females made a clear choice between the pheromone disks, but preference for male pheromones did not translate into the number of live or dead offspring. However, females who preferred the disk of the same male and mated with the male with the preferred pheromones lived longer than the females who mated with the male with the non-preferred pheromones.