Abstract
The response of the egg parasitoid wasp, Ooencyrtus nezarae Ishii to eggs of the two host bugs, Riptortus clavatus and Piezodorus hybneri, was investigated 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 tended to attack R. clavatus first when provided with eggs of both R. clavatus and P. hybneri in a test tube, and took more time to start oviposition behavior on P. hybneri eggs than on R. clavatus eggs. These results indicate that O. nezarae females prefer R. clavatus eggs to P. hybneri eggs. The females' acceptance ratio for R. clavatus did not change after several generations reared on P. hybneri, suggesting that the preference for R. clavatus is partly determined genetically. Significantly higher survivorship was recorded 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 fecundity and longevity. These findings suggest that the preference for R. clavatus is correlated with the reproductive success of O. nezarae on R. clavatus.
