TOXICITY OF THE VENOM FROM NASONIA-VITRIPENNIS (HYMENOPTERA, PTEROMALIDAE) TOWARD FLY HOSTS, NONTARGET INSECTS, DIFFERENT DEVELOPMENTAL STAGES, AND CULTURED INSECT CELLS

A venom preparation from Nasonia vitripennis, a wasp ectoparasitoid of fly pupae, was assayed for lethality in different stages of insects r epresenting ten different orders and in cultured insect cells. In most cases, the motor activity of the injected insects remained completely normal for 1-2 days after the injection and displayed none of the sym ptoms of paralysis commonly reported for venoms of the Hymenoptera. A natural host, the flesh fly Sarcophaga bullata, was highly sensitive i n the pupal stage (LD50 = 5.4 and 5.5 VRE/g for nondiapausing and diap ausing pupae, respectively), the stage that is normally parasitized, a nd larvae and adults were as susceptible to the venom as the pupae. Ad ults of another fly host, Phaenicia sericata, were nearly as sensitive (LD50 = 6.5 VRE/g), but nonhost adult flies were more tolerant. Among the other orders tested, pupae of several species (Plodia interpuncte lla, Trichoplusia ni, Tenebrio molitor) were more susceptible to enven omation than larval or adult stages. In fact, the highest sensitivity observed in this study (LD50 = 0.58 VRE/g) was with pupae of the cabba ge looper, T. ni, a species that is not a natural host. In contrast, t he larvae (LD50 = 7.23 VRE/g) and adults (LD50 = 7.48) of T. ni were f ar less sensitive. Adults of Nasonia vitripennis were not sensitive to their own venom (LD50 = > 533 VRE/g), although adults of another hyme nopteran, Apis mellifera, were susceptible (4.62 VRE/g). Adults of Lym antria dispar, Oncopeltus fasciatus, Aphis nerii, Euborellia annulipes , Diapheromera femorata, Blattella germanica, Periplaneta americana, a nd Reticulitermes flavipes demonstrated a high tolerance to Nasonia ve nom. When tested in vitro, the venom caused cultured Lepidoptera (TN-3 68) and Diptera (NIH SaPe4) cells to round up, swell, and eventually d ie. The LC50S were 0.0014 and 0.0010 VRE/mul for TN-368 and SaPe4 cell s, respectively. Cytotoxicity was observed within 10 min after exposur e to LC99 levels of venom, with 100% cell mortality at 100 min for the NIH SaPe4 cells and 24 hr for TN-368 cells. It is possible that the v enom component responsible for in vivo and in vitro activities may be different, but results from the cell culture work suggest that this me thod offers a promising assay for quickly screening venom samples. The high susceptibility of flies and pupae of other insects to the venom, as well as its novel (nonparalytic) action suggest that it may have c onsiderable potential for development as a biopesticide.