Preferential Parasitism of Ooencyrtus mirus (Hymenoptera: Encyrtidae) on Bagrada hilaris (Hemiptera: Pentatomidae) Regardless of Rearing Host

Abstract The invasive stink bug, Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae), is a serious pest of cole crops. Studies are underway to assess the potential of an exotic egg parasitoid from Pakistan, Ooencyrtus mirus Triapitsyn & Power (Hymenoptera: Encyrtidae), as a biological control agent for this pest. In the present study, the ovipositional preference of O. mirus reared for multiple generations on B. hilaris, Thyanta pallidovirens (Stal), or Nezara viridula (Linnaeus) (Hemiptera: Pentatomidae) for eggs of these three stink bug species was evaluated. The first host accepted for oviposition, the number of parasitoid eggs (as indicated by pedicels) laid on each host egg at different time intervals, and the number of wasps that emerged from parasitized eggs were recorded. Results show that O. mirus prefers eggs of its primary host, B. hilaris, for oviposition over the alternate hosts tested regardless of whether the parasitoids were reared on the primary or alternate hosts. The percent parasitism in the first 2 h of exposure also was higher on B. hilaris eggs although it was not significantly different from T. pallidovirens eggs for parasitoids reared on B. hilaris and N. viridula eggs. For all parasitoid populations, the mean number of emerged wasps per host egg ranged from 0.9 to 1.1 with no significant differences. Bagrada hilaris eggs were significantly smaller than T. pallidovirens and N. viridula eggs and female wasps that emerged from B. hilaris eggs had significantly shorter body length and head width than those that emerged from T. pallidovirens and N. viridula eggs. Graphical Abstract