Don’t tell the people behind Axe body spray, but entomologists have shown that the fertility of male Nasonia vitripennis wasps is predicted by how much sex pheromone they produce [$-a].

How many sperm a male wasp can produce turns out to be a big deal for female Nasonia wasps, because the species is haplodiploid — fertilized eggs become females, and unfertilized eggs become males. Because females are the only sex that can fly off to lay more eggs, the number of female offspring a wasp produces strongly determines her reproductive fitness. She wants, therefore, to mate with a male who can fertilize a lot of eggs, and determines who that is by smelling prospective mates.

Reference

Ruther, J., Matschke, M., Garbe, L., & Steiner, S. (2009). Quantity matters: male sex pheromone signals mate quality in the parasitic wasp Nasonia vitripennis. Proc. R. Soc. B DOI: 10.1098/rspb.2009.0738