LIFE-HISTORY OF THE APHID HYPERPARASITOID ASAPHES VULGARIS WALKER (PTEROMALIDAE) - POSSIBLE CONSEQUENCES ON THE EFFICACY OF THE PRIMARY PARASITOID APHIDIUS NIGRIPES ASHMEAD (APHIDIIDAE)

Aspects of the life history of the aphid hyperparasitoid Asaphes vulga ris Walker, when reared on Aphidius nigripes Ashmead, were investigate d under laboratory conditions. Longevity was significantly related to temperature and to the sex of adults. Female life span was about 4 mon ths at 15 degrees C compared with 46 days at 25 degrees C; under the s ame conditions male longevity was 66 and 19 days, respectively. Female s started to oviposit in aphid mummies upon eclosion and lifetime fecu ndity was high, reaching 1433 offspring. The sex ratio (proportion of males) was low early in reproductive life but rose sharply after sever al weeks. The implications of these results on the efficacy of A. nigr ipes in the potato agrosystem are discussed. It is suggested that high hyperparasitoid fecundity and longevity might play a role in reducing the impact of the primary parasitoid.