Difference in response of egg parasitoid, Ooencyrtus nezarae Ishii (Hymenoptera : Encyrtidae) to eggs of two major host bug species

The response of the egg parasitoid wasp, Ooencyrtus nezarae Ishii to eggs o f the two host bugs, Riptortus clavatus and Piezodorus hybneri, was investi gated in laboratory experiments. In a test tube, 80% to 100% of O. nezarae female wasps parasitized eggs of R. clavatus, On the other hand, less than 60% of females parasitized egg masses of P. hybneri. The female wasps tende d to attack R. clavatus first when provided with eggs of both R. clavatus a nd P. hybneri in a test tube, and took more time to start oviposition behav ior on P. hybneri eggs than on R. clavatus eggs. These results indicate tha t O. nezarae females prefer R, clavatus eggs to P. hybneri eggs. The female s' acceptance ratio for R. clavatus did not change after several generation s reared on P. hybneri, suggesting that the preference for R. clavatus is p artly determined genetically. Significantly higher survivorship was recorde d in O. nezarae developed in eggs of R. clavatus than in eggs of P, hybneri . In addition, female wasps emerging from R. clavatus showed greater fecund ity and longevity. These findings suggest that the preference for R. clavat us is correlated with the reproductive success of O. nezarae on R. clavatus .