Egg parasitoids of green shield bug, Palomena prasina L. (Hemiptera: Pentatomidae) in hazelnut orchards of Turkey

Abstract

Green shield bug (GSB), Palomena prasina L. (Hemiptera: Pentatomidae), is an important pest of hazelnut orchards causing significant yield and quality losses in Turkey. The application of insecticides is the only option to manage GSB in Turkey; however, effective and alternative eco-friendly control practices are needed to manage the pest in the country. Surveys of egg parasitoids using frozen sentinel egg masses were conducted in the main hazelnut-growing regions of Turkey. Furthermore, the composition of native species parasitising GSB eggs and their parasitism rates were determined under field conditions. A total of 11,570 eggs were exposed to field conditions, of which 10,386 eggs were recovered from the surveyed area after 7 days in 2018 and 2019. Trissolcus cultratus, Tr. belenus, Tr. sp1, Telenomus turesis, and Te. sp1 were morphologically identified as egg parasitoids, which was molecularly confirmed based on the cytochrome c oxidase subunit I gene (CO1). The parasitism rate was 9.3% for all eggs exposed to field conditions. Trissolcus cultratus was the predominant species and responsible for 70.06% of the parasitism rate, followed by Tr. belenus (15.75%), Te. turesis (10.26%), Te. sp1 (3.83%), and Tr. sp1 (0.01%). The existence of Tr. cultratus is reported for the first time in Turkey. The egg parasitoid species of GSB determined in this study witnessed the presence of natural parasitism in the natural habitat of the pest. Furthermore, it must be considered that Tr. cultratus can act as a facultative hyperparasitoid.