The Box Bug Gonocerus acuteangulatus (Hemiptera: Coreidae) and Its Egg Parasitoids: Updates on Biocontrol in a Hazelnut Producing Area in Southern Italy

Among hazelnut phytophagous insects, the box bug Gonocerus acuteangulatus is a key pest in Southern Italy that severely compromise the production of healthy hazelnut fruits with severe economic losses. Currently, the box bug is controlled by many chemical control methods, but biological control could represent a promising tool. An intensive monitoring program of G. acuteangulatus egg parasitoids in five Sicilian organic hazelnut orchards was carried out. Adults, nymphs, and eggs (parasitized and non-parasitized) of G. acuteangulatus were collected. Moreover, hazelnut fruit samples were observed to assess fruit damage. Five parasitoid species emerged from G. acuteangulatus eggs: Anastatus bifasciatus, Hadronotus bosellii, H. muscaeformis, Trissolcus belenus, and Ooencyrtus sp. Anastatus bifasciatus was the most widespread species, followed by H. bosellii. The highest parasitoid diversity occurred at mid-elevation sites. Fruit damage remained substantial, indicating that natural parasitism may not provide satisfactory pest control. Here, field emergence of T. belenus from G. acuteangulatus eggs demonstrates a host association historically reported as T. grandis. Therefore, this study updates and expands the parasitoid assemblage associated with G. acuteangulatus by revisiting historical records with contemporary field evidence for future augmentative or conservation biocontrol program against the box bug.