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Field plots containing broccoli, mustard, and rape were sampled weekly between June and October in 1994 and 1995 to determine parasitism and phenology of the harlequin bug, Murgantia histrionica (Hahn) (Hemiptera: Pentatomidae). Naturally-occurring wild turnips also were sampled in early spring 1995 for harlequin bugs before cultivated crops were planted. Weekly samples of harlequin bug adults, egg masses, and nymphs were field collected and returned to the laboratory. They were maintained in the laboratory until emergence to recover parasitoids and to determine the parasitization rates. No adult or nymphal parasitoids were recovered. Two species, Trissolcus murgantiae Ashmead (Hymenoptera: Scelionidae) and Ooencyrtus johnsoni Howard (Hymenoptera: Encyrtidae), were identified as egg parasitoids. The overall parasitization rates for 1994 and 1995 were 8% and 37%, respectively. Trissolcus murgantiae was more common than O. johnsoni and accounted for 87% and 96% of the parasitization, respectively. This is the first record of T. murgantiae in Virginia. The harlequin bugs had two and a partial third generation a year. Overwintered adults oviposited on wild turnips, where the first generation completed development. The subsequent generation migrated to cultivated plants in June and July. The second generation completed development on cultivated crops producing the adults which overwinter. |
