Population status and detriments of Halyomorpha halys'in hazelnut gardens in the province of Artvin

Surrounded by three seas and neighboring eight countries, our country as a transition zone is a habitat for an extended variety of plantation and animal species. The indigenous climate of Türkiye renders the country a prominent figure in hazelnut farming through increasing diversity of agricultural produce. Halyomorpha halys (Stâl) has become a significant pest of hazelnut in recent years. Intended as a comprehensive study on Halyomorpha halys (Stâl) which is an invasive species in Türkiye, this study aims to identify the dissemination, density of the pests and the status of damage to hazelnut. Adhesive pheromone traps were utilized in three different locations across four different districts to determine the population status in the study areas in Kemalpaşa, Hopa, Borcka and Arhavi districts where H.halys has spread across. The biology of the insect and the host species on which it feeds were determined through observations conducted in the territory. Moreover, hazelnuts collected from hazelnut orchards were examined and the damage to the kernel was determined. According to the results obtained; it has been observed that the period of egg-laying by insects is mostly in July-August, and nymphs emerge in a week. The highest number of catches by the pheromone traps was identified to be achieved in August and the population density was observed to be high in Arhavi, Borcka, Kemalpasa and Hopa districts. Upon examination of the hazelnut samples, the highest ratio of damage to hazelnut fruit was observed in Arhavi district (30%) whereas the lowest was in Hopa district in consideration of the deformation of the kernel cavitation, browning of the kernel color along with the intense bitterness in the kernel flavor in connection with the degree of damage to the kernel. A number of crop plants, particularly hazelnut, kiwi, corn, orange, blueberry, bean and tomato were identified to host H.halys throughout the territory where the study was conducted. The increase in the level of population and the detriment of the pest is expectative in the following years. Thus, efforts to control H.halys should be initiated promptly in the districts of increased population of such pest. Measures of collection and destruction of overwintering mature insects should be carried out in warehouses, vacant houses, attics, woodsheds, and if necessitated, disinfestation should be implemented in such areas with organic insecticides. The pest management should be pursued by increasing the number and use of pheromone traps in the dissemination areas of the insect.