First report of Cheiloneurus exitiosus (Perkins, 1906) and Helegonatopus dimorphus (Hoffer, 1954) (Hymenoptera: Encyrtidae) from Japan, with remarks on their abundance in rice paddies

Background Encyrtid secondary parasitoids of Delphacidae have not been recorded in Japan. However, they may play an important role in the rice ecosystem because they can reduce the number of Dryinidae, the natural enemies of rice planthoppers. New information We found two encyrtid species, Cheiloneurus exitiosus (Perkins, 1906) and Helegonatopus dimorphus (Hoffer, 1954), from rice paddies and the surrounding environment. Haplogonatopus oratorius (Westwood, 1833) and Anteon sp. were newly recognized as hosts of He. dimorphus. Parasitism of C. exitiosus was rare, but He. dimorphus was common in Kumamoto Prefecture. The sex ratio (male proportion) and clutch size of He. dimorphus was estimated as 0.19 and 4.95, respectively.