Female mate preference for egg-caring males in the giant water bug <i>Diplonychus rusticus</i> (Heteroptera Belostomatidae)

Paternal care can be maintained under sexual selection in case that it helps caring males to attract more mates. Females of two back-brooding water bug species, the belostomatids <i>Appasus major</i> and <i>A. japonicus</i>, prefer egg-caring males over non-caring males. Here, we tested under laboratory and field conditions whether females of another belostomatid species, <i>Diplonychus rusticus</i>, prefer egg-caring males as mating partners. Caring males received more eggs from females than non-caring males under the both conditions. Our results suggest that sexual selection plays an important role in maintaining paternal care not only in species of the genus <i>Appasus</i>, but also in the genus <i>Diplonychus</i>.