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 representing 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 symptoms of paralysis commonly reported for venoms of the Hymenoptera. A natural host, the flesh fly Sarcophaga bullata, was highly sensitive in the pupal stage (LD50 = 5.4 and 5.5 VRE/g for nondiapausing and diapausing pupae, respectively), the stage that is normally parasitized, and larvae and adults were as susceptible to the venom as the pupae. Adults 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 interpunctella, Trichoplusia ni, Tenebrio molitor) were more susceptible to envenomation than larval or adult stages. In fact, the highest sensitivity observed in this study (LD50 = 0.58 VRE/g) was with pupae of the cabbage looper, T. ni, a species that is not a natural host. In contrast, the larvae (LD50 = 7.23 VRE/g) and adults (LD50 = 7.48) of T. ni were far less sensitive. Adults of Nasonia vitripennis were not sensitive to their own venom (LD50 = > 533 VRE/g), although adults of another hymenopteran, Apis mellifera, were suceptible (4.62 VRE/g). Adults of Lymantria dispar, Oncopeltus fasciatus, Aphis nerii, Euborellia annulipes, Diapheromera femorata, Blattella germanica, Periplaneta americana, and Reticulitermes flavipes demonstrated a high tolerance to Nasonia venom. When tested in vitro, the venom caused cultured Lepidoptera (TN-368) and Diptera (NIH SaPe4) cells to round up, swell, and eventually die. The LC50S were 0.0014 and 0.0010 VRE/microliters for TN-368 and SaPe4 cells, respectively. Cytotoxicity was observed within 10 min after exposure 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 venom component responsible for in vivo and in vitro activities may be different, but results from the cell culture work suggest that this method 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 considerable potential for development as a biopesticide.