Incidence and severity of stink bugs damage on kernels in Turkish hazelnut orchards

Abstract

Some stink bugs (Hemiptera: Pentatomidae, Coreidae and Acanthosomatidae) are serious economic pests in hazelnut orchards. More than 15 species of them have been determined in Turkish hazelnut orchards and Palomena prasina (Pentatomidae) is by far the most common species among them. Their feeding damage on hazelnut fruits results in nut abortion, shriveled kernels and the occurrence of necrotic tissue in kernels. Especially necrotic tissue in kernels is a major problem for the industrial process. In this study, the nut samples from 15 hazelnut growing provinces of Turkey were evaluated to determine damage ratios on kernels by stink bugs during 2014-2016. The nut samples (1 kg) collected randomly from 3 orchards each of 118 different towns in 15 provinces at harvest time for each study year. Mature kernels were removed from their shells in a laboratory and 100 kernels from each location were checked for feeding damage. Kernels were sliced into 2 equal pieces individually with a kernel cutter and assessed for internal damage. The number of necrotic tissue in kernels, each of them evidence of bug feeding, was classified as one, two and more than 3 feeding spots on each kernel. The average damage ratio on the kernels of 3 years in all provinces was 7.44% (ranged 3.0-10.88% in provinces). Average damage ratios of all provinces were 7.38 (3.66-11.07), 3.79 (1.12-6.75) and 11.53% (2.66-20.0) for 2014, 2015 and 2016 respectively. Distribution of the number of necrotic tissue in the same kernels was 5.05, 1.74 and 1.11% respectively for one, two and more than three feeding spots, as average of all years. When only 5 main provinces (Ordu, Giresun, Samsun, Sakarya and Düzce) are considered, these are responsible for more than 85% of the yearly production in Turkey, the damage ratios in the kernel were 6.50, 3.16 and 9.82% respectively for 2014, 2015 and 2016. In this case, the damage ratio was 6.49% on average for the 3 years. Damage ratio of stink bugs in the western hazelnut growing area of the country (Düzce and Sakarya provinces) was higher than that of the eastern part of the region (Ordu, Giresun and Samsun), with 8.23 and 5.34% respectively. © 2018 International Society for Horticultural Science. All Rights Reserved.