• defence capacity;
  • mate choice;
  • offence capacity;
  • sperm competition;
  • Tribolium castaneum

Abstract Female mate choice, both before and after copulation, is pervasive among insect species. It is often hypothesized that females would preferentially mate with males that are genetically dissimilar to promote the genetic variability of the offspring. We used various strains of red flour beetle, Tribolium castaneum, and tested the effect of male and female genetic backgrounds on precopulatory and post-copulatory female mate choice. Simultaneous mate choice experiments using previously well established pheromone assays did not detect female preference for males of different strains. Post-copulatory female mate choice was examined through paternity analysis. Two parameters were used to measure post-copulatory female mate choice, including male defence capacity (P1, proportion of offspring sired by the first male when a female mated with two males consecutively) and offence capacity (P2, proportion of offspring sired by the second of two males to mate with a female). When female and male beetle strains were same, defence capacity was significantly higher than when female and male strains were different. However, such a pattern was not observed for offence capacity. The results suggest that female precopulatory mate choice is not affected by genetic background, but the outcome of post-copulatory processes depends on the genetic background of male and female beetles.