Adventive Gryon aetherium Talamas (Hymenoptera, Scelionidae) associated with eggs of Bagrada hilaris (Burmeister) (Hemiptera, Pentatomidae) in the USA

Abstract

Bagrada bug, Bagrada hilaris (Burmeister) (Hemiptera, Pentatomidae), has become a major pest of cole crops (cabbage, broccoli, cauliflower, kale) in California since its arrival in 2008. In this study we documented parasitism of B. hilaris eggs at a highly infested site in northern California by deploying sentinel B. hilaris eggs and collecting naturally-laid B. hilaris eggs in the soil. Two parasitoids, Gryon aetherium Talamas (Hymenoptera, Scelionidae) and Ooencyrtus californicus Girault (Hymenoptera, Encyrtidae), emerged from sentinel eggs, but only G. aetherium was documented attacking eggs in the soil. Gryon aetherium is currently being assessed as a classical biological control agent for B. hilaris in California, and mating experiments showed that crosses between G. aetherium from Pakistan and California yielded viable female offspring. This report marks the first known record of G. aetherium in the USA, and further work should be conducted to assess the potential of this parasitoid for biological control of B. hilaris.

A maximalist approach to the systematics of a biological control agent: Gryon aetherium Talamas, sp. nov. (Hymenoptera, Scelionidae)

“…Despite the setbacks of these misidentifications, the taxonomy of Gryon and Hadronotus has advanced, and we here provide a sounder foundation for continued research. Our eventual identification of G. aetherium and determination of the quarantine and adventive populations of G. aetherium as conspecific are supported by multiple lines of evidence: molecular analysis, morphological comparison, and the interbreeding studies performed by Hogg et al (2021). In the United States and Mexico, the arrival of G. aetherium provides new prospects for the management of bagrada bug and an opportunity to compare its biology under laboratory and field conditions.…”

“…We here reevaluate and correct the identifications of the Gryon species under consideration as a biological control agent and the specimens reared from bagrada eggs in Mexico. This is done considering multiple sources of evidence that include molecular and morphological analyses of specimens from a broad geographical area, comparison to primary types, evaluation of host-related variability, and crossbreeding experiments conducted by Hogg et al (2021).…”

Psix striaticeps (Dodd) (Hymenoptera, Scelionidae): an Old World parasitoid of stink bug eggs arrives in Florida, USA

“…halys, and then by parasitoids of B. hilaris eggs, Tr. hyalinipennis Rajmohana & Narendran, 2007 and Gryon aetherium (Ganjisaffar et al 2018Hogg et al 2021. Before this recent spate of introductions, Johnson and Masner (1985) reported Ps.…”

Parasitism by Gryon aetherium (Hymenoptera: Scelionidae) on Bagrada hilaris (Hemiptera: Pentatomidae) eggs in northcentral California

“…Gryon aetherium and T. hyalinipennis have since appeared in the invasive range of B. hilaris in the New World, where they are likely to be adventive. Gryon aetherium was found attacking B. hilaris eggs in California (Hogg et al 2021, 2022), Mexico (Felipe-Victoriano et al 2019, reported as G. myrmecophilum ) and Chile (Rojas-Gálvez et al 2021), and T. hypalinpennis emerged from sentinel B. hilaris eggs in southern California (Ganjisaffar et al 2018). Previous studies in California documented the presence of G. aetherium at individual sites, either using previously frozen sentinel eggs (Hogg et al 2022) or a combination of sentinel and naturally laid eggs (Hogg et al 2021), but the distribution and impact of G. aetherium in California remain unclear.…”