Longevity, fertility, sex ratio, and host preference of Diaeretiella Rapae (McIntosh) (Hymenoptera : Aphidiidae)

Suitability of the green peach aphid, Myzus persicae (Sulzer), and the cabbage aphid, Brevicoryne brassicae (L.), as hosts for the parasite Diaeretiella rapae (Mclntosh) was determined by comparing longevity and fertility of the adult female prasite and the sex ratio of the progeny on each of the host species. Preference was determined and its impact assessed.

Both aphid species were found to be suitable hosts with no significant differences in developmental or performance criteria. When given a choice, D. rapae oviposited more frequently in the cabbage aphid and a significantly greater percentage of female progeny was produced with that host.