Pre‐emptive host‐specificity testing of Trissolcus japonicus (Ashmead) (Hymenoptera: Scelionidae) reveals high parasitism levels against the endemic New Zealand alpine shield bug in laboratory no‐choice tests

Abstract

Brown marmorated stink bug (BMSB), Halyomorpha halys (Hemiptera: Pentatomidae), is a serious horticultural pest causing considerable damage to local production and international supply chains as it spreads around the world. The samurai wasp, Trissolcus japonicus (Hymenoptera: Scelionidae), is well recognised as the most promising classical biological control against BMSB. The wasp has been conditionally approved for release in New Zealand in the event the stink bug establishes here. Previous host range testing showed that all available non-target New Zealand pentatomids except a single exotic species were accepted for oviposition and that the parasitoid was capable of parasitising the eggs of two native pentatomids at proportions similar to BMSB. Only one New Zealand species of pentatomid, the endemic alpine shield bug Hypsithocus hudsonae, was not previously tested owing to the difficulty of collecting it from the field. Here we report the results of no-choice oviposition tests between H. hudsonae and T. japonicus, conducted in containment, to complement previous physiological host range testing of this parasitoid in New Zealand. Parasitoids emerged from 14 out of 15 egg masses, and in total, from 78 out of 83 eggs (94%). The mean sex ratio was 89% female, and no males emerged from six egg masses. H. hudsonae is confirmed as a physiological host for T. japonicus, and this finding is discussed in relation to the strengths and limitations of physiological host range studies.

Preempting the Arrival of the Brown Marmorated Stink Bug, Halyomorpha halys: Biological Control Options for Australia

“…Except for the three endemic New Zealand species, all these pentatomids are present in Australia and most also have congeneric species [ 23 ]. All species tested were attacked by T. japonicus in no-choice tests, except the green vegetable stinkbug, Nezara viridula , which is a pest in both countries [ 23 , 99 ]. Parasitism rates were highest for Cermatulus nasalis and Glaucias amyoti with 95% parasitism, followed by Monteithiella humeralis (78%) and Dictyotus caenosus (73%) [ 23 ].…”

Partial refuges from biological control due to intraspecific variation in protective host traits

“…The T. japonicus laboratory colony was established from individuals originally collected in Beijing, China, in 2009 by the United States Department of Agriculture, Agricultural Research Service (USDA‐ARS). This is the same T. japonicus colony used in host range testing studies in North America, New Zealand, and Europe (Boyle et al, 2020; Charles et al, 2019; Hedstrom et al, 2017; Lara et al, 2019; Sabbatini‐Peverieri et al, 2021; Saunders et al, 2021; Table 1). Parasitoids were maintained on newly laid (<48 h) eggs of H. halys in ventilated plastic containers (width: 9.2 cm; height: 11.7 cm) and reared at 23 ± 1°C, 25%–50% RH, and a 16:8 h L:D photoperiod.…”

Partial refuges from biological control due to intraspecific variation in protective host traits: a case study with the egg parasitoidTrissolcus japonicus

“…The T. japonicus laboratory colony was established from individuals originally collected in Beijing, China in 2009 by the United States Department of Agriculture, Agricultural Research Service (USDA-ARS). This is the same T. japonicus colony used in host range testing studies in North America, New Zealand, and Europe (Hedstrom et al 2017; Charles et al 2019; Lara et al 2019; Boyle et al 2020; Saunders et al 2021; Sabbatini-Peverieri et al 2021; Table 1). Parasitoids were maintained on newly laid (< 48h) eggs of H. halys in ventilated plastic containers (width: 9.2 cm; height: 11.7 cm) and reared at 23 ± 1ºC, 25-50% RH, and a 16:8 h L:D photoperiod.…”