Immature Stages of Development in the Parasitic Wasp, Trissolcus japonicus (Hymenoptera: Scelionidae), on its host, Halyomorpha halys (Hemiptera: Pentatomidae)

The morphological changes experienced during the immature stages of the solitary endoparasitic wasp, Trissolcus japonicus Ashmead (Hymenoptera: Platygastridae: Scelionidae), were studied.  This wasp attacks eggs of the Brown Marmorated Stink Bug (BMSB), Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), a generalist agricultural invasive pest in the U.S.  Six phases of development were identified, along with several other distinctive characteristics of parasitism.  Time to emergence and percent parasitism were also monitored.  Males emerged on average 4 days faster than females at 20 °C, 60% RH, and 16:8 L:D (Day 20 vs. Day 24).  Development rates between males and females did not differ until eye sclerotization began on Day 14.  Percent parasitism in this study was 94%.  In general, immature stages of endoparasitoids are poorly documented.  This work contributes to a more thorough understanding of growth and maturation in this wasp.  Knowing how to recognize the development phases of the wasp will enable us to evaluate the success of parasitism of BMSB in the field.  This information will impact the implementation of T. japonicus as a classical biological control agent for the BMSB.