SIZE PREFERENCE AND SEX-RATIO FOR PTEROMALUS-CEREALELLAE (HYMENOPTERA, PTEROMALIDAE) PARASITIZING SITOTROGA-CEREALELLA (LEPIDOPTERA, GELECHIIDAE) IN STORED CORN

Hosts ranging from small larvae to pupae of tile Angoumois grain moth, Sitotroga cerealella (Olivier), were exposed to females of the pterom alid parasitoid, Pteromalus cerealellae (Ashmead), to determine the ef fects of host size on preference, parasitism success, adult size, and progeny sex ratio of the parasitoid. The parasitoid successfully paras itized larvae (>0.43 mm in maximum body width), prepupae (1.55 +/- 0.0 5 mm [mean +/- SEM] mm maximum average body width), and a single pupa (1.20 mm maximum body width). All female parasitoid progeny emerged fr om hosts that had a maximum body width >0.85 mm. Sixty-four percent of male parasitoid progeny emerged from hosts that had a maximum body wi dth between 0.43 and 0.85 mm. Size of P. cerealellae adults was correl ated with host size (larger parasitoids developed on larger hosts). Th e optimal host sizes for producing female parasitoid progeny were larv ae with a maximum body width between 1.69 and 2.05 mm and prepupae. Th e optimal host sizes for producing male parasitoid progeny were larvae with a maximum body width between 0.57 and 0.70 mm. These results are discussed in terms of maximizing potential biological control of the Angoumois grain moth by this parasitoid.