Predation on Appasus japonicus (Heteroptera: Belostomatidae) egg mass by the larva of Cybister tripunctatus lateralis (Coleoptera: Dytiscidae) in the field

Abstract

Appasus japonicus (Heteroptera: Belostomatidae) inhabits paddy fields and ponds. Females lay eggs on the dorsal surface of the male’s body; males then care for the egg mass. The predation risk for Belostomatinae males may increase because their swimming ability is compromised while caring for the egg masses. However, there are currently no records of predators of these males and the eggs in their care. In this study, we observed the capture of the egg mass of A. japonicus by Cybister tripunctatus lateralis (Coleoptera: Dytiscidae) larva in the field. This may be the first record of Dytiscidae larvae feeding on A. japonicus egg masses, suggesting that these larvae may exert predation pressure on A. japonicus individuals that care for the egg mass.