This study was carried out from June 22 to October 31 to examine the number and species of leaf- and planthoppers and their natural enemies collected by light trap which was set at the Shimane Agricultural Experiment Station Orchard in Izumo City in Japan.
The leaf- and planthoppers collected by the trap was 32,012, consisting of more than 60 species. A number of leaf- and planthoppers injurious to rice plants were also included. The number of Sogatella furcefera, which was a major species, was 23,791 and 19,648 samples of them were collected on September 9. Also, a number of Nilaparvata lugens and Nephotettix cincticeps were collected on the same day. Parasitization of Dryinid wasps was observed in 7 species of Delphacidae, 2 species of Deltocephalidae and Empoasca spp. of Cicadellidae. Stylops were found to infect 3 species of Delphacidae. A number of S. furcifera and Laodelphax striatellus were infected by Dryinid wasps and a number of S. furcifera were infected by Elenchus japonicus. The percentage of parasitism by Dryinid wasps found in light trap was conspicuously higher than that by E. japonicus. A number of Dryinid wasps and E. japonicus were solitary, producing only one adult per host and attacked on female hosts. Modification of genital segments was observed in S. furcifera attacked by E. japonicus at a high percentage. The percentage of parasitism of Dryinid wasps on the rice planthoppers which moved from the mainland China to Japan was about 10 % in S. furcifera and less than 1-2 % in N. lugens.