First study of the diversity and relative importance of parasitoids of nymphs and adults of the hazelnut pest Palomena prasina (L.) (Hemiptera, Pentatomidae)

Abstract

Palomena prasina (L.) (Hemiptera: Pentatomidae), the Green Shield Bug, is an important pest of hazelnut crops in southern Europe. While biological control strategies against this pest have focused on using egg parasitoids, those targeting nymphs and adults have been neglected. In this study, we investigated the community of parasitoids of P. prasina nymphs and adults present in France by identifying the species and comparing the rates of overwintering and spring-summer parasitism. Palomena prasina individuals were sampled in overwintering sites, emergence traps during early spring, and hazelnut orchards and natural habitats during the active period. Parasitoids were collected by dissecting collected adults, and from cages where adults and nymphs were reared. The parasitoids were identified based on both morphology or the COI gene. Of the adults collected during the wintering and the active periods, 32.8% and 15.2%, respectively, were parasitised. The parasitoids belonged to the Braconidae and Tachinidae families. Braconidae were exclusively represented by Aridelus rufotestaceus Tobias, accounting for 100% of the parasitoids identified in the winter period and the vast majority of those present during the P. prasina active period. Tachinidae were represented by, based on molecular and morphological approaches, Ectophasia sp., Gymnosoma sp., Phasia aurigera (Egger) and, based on morphology only, Trichopoda pictipennis Bigot. Aridelus rufotestaceus and T. pictipennis are reported for the first time as parasitoids of P. prasina . Given A. rufotestaceus abundance and its impact on species of Pentatomidae closely related to P. prasina , we consider that this parasitoid shows great promise as a biological control agent.