Suitability of new and old association hosts for the development of selected microgastrine parasitoids of gramineous stemborers

The present study examined the acceptability and suitability of Old World s temborers (Chilo partellus and C. orichalcociliellus) for the development o f New World parasitoids (Apanteles deplanatus and A. minator) and New World stemborers (Diatraea saccharalis and D. grandiosella) for the development of Old World parasitoids (Cotesia sesamiae, C. flavipes and C. chilonis). R esults revealed that acceptance and suitability were high in old associatio ns. In new associations, parasitoids accepted about 60% of the new associat ion hosts. In addition, 10 out of 17 new associations were successful. Apan teles species appeared to be more physiologically host specific than Cotesi a species. For example, two of four new association hosts were accepted by A. deplanatus and only one (D. saccharalis) was partially suitable for prog eny development. Among the Cotesia species, Cotesia flavipes appeared to ha ve a wider host range than the two other species. It attacked all hosts off ered and successfully parasitized all but one (D. grandiosella). Diatraea s accharalis was accepted and was a suitable host for the development of all parasitoid species tested, whereas D. grandiosella was unsuitable for the d evelopment of four out of five parasitoid species tested. No clear pattern was observed as behavioral acceptance did not always agree with the pattern of physiological suitability. Implications of these findings for importati on biological control of stemborers are discussed.