Determination of hazelnut storage pests and natural enemies in the eastern black sea region, and the bioecological characteristics of Plodia interpunctella (Lepidoptera: Pyralidae) on some hazelnut cultivars under laboratory conditions, its effects on quality, and the evaluation of modified atmosphere applications against phosphine resistance

Hazelnut holds a critical position in Turkey's agricultural production and export, contributing significantly to the economy both as a direct snack product and as a processed value-added commodity. The aim of this study was to determine the pests and natural enemies observed on hazelnuts during storage, to reveal the bioecological properties of Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) in some important hazelnut varieties under laboratory conditions, to evaluate the effects of this species on hazelnut quality and to investigate the effectiveness of modified atmosphere applications against phosphine resistance. In the first, the pest and beneficial faunal species in hazelnut storage facilities located in the Eastern Black Sea region (Ordu, Giresun, and Trabzon) were identified. The second section examines the life table parameters, consumption, and frass production rates of P. interpunctella, a significant stored-product pest, on Çakıldak, Mincane, Palaz, and Tombul hazelnut varieties which are extensively cultivated in the region. The third section investigates the chemical quality changes in hazelnuts caused by P. interpunctella infestation. The last section evaluates phosphine resistance in P. interpunctella populations collected from hazelnut stores in Eastern Black Sea region and the efficacy of nitrogen-based modified atmosphere applications as an alternative control method for phosphine-resistant populations. Effectiveness of modified atmosphere applications evaluated in egg and larval stages of the populations under various temperatures and exposure durations. According to the results, between June 2022 and November 2023, surveys were conducted in 174 facilities, including 94 industrial establishments, 69 trader warehouses, and 11 producer storage units. A total of 21 pest species belonging to 10 families within the Coleoptera and Lepidoptera orders were identified. Eleven of those species were pests of stored hazelnuts. The most incidence pests were Cadra cautella (Walker) (Lepidoptera: Pyralidae) (%55.8), P. interpunctella (%50.5), Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae) (%17.2), and Carpophilus dimidiatus (Fabricius) (Coleoptera: Nitidulidae) (%16.7). Natural enemies identified included Habrobracon hebetor (Say) (Hymenoptera: Braconidae), Venturia canescens (Gravenhorst) (Hymenoptera: Ichneumonidae), and the predatory mite Blattisocius tarsalis (Berlese) (Mesostigmata: Blattisociidae), with H. hebetor (%24.7) being the most commonly observed. Among the hazelnut varieties studied, the longest developmental period for P. interpunctella was observed on the Mincane variety (51.88 days). Life table parameters such as net reproductive rate (R0), intrinsic rate of increase (r), and finite rate of increase (λ) showed no significant variation across hazelnut varieties. The lowest R0 was recorded for Çakıldak (45.19), while the highest was for Tombul (55.09). Over a 120-day projection, the Tombul cultivar had the largest population growth, while the Mincane exhibited the highest consumption and frass production rates. Chemical quality assessments revealed that P. interpunctella infested hazelnuts, compared to non-infested control groups, experienced increased moisture levels and decreased protein and ash content. Unfavorable changes were noted, including elevated peroxide values and free fatty acid levels, along with reduced antioxidant activity. Although no significant differences were found in fatty acid composition, an increase in atherogenicity and thrombogenicity indices that both detrimental to human health was observed in infested samples. Free amino acid composition changes further indicated oxidative damage and protein degradation. Resistance to phosphine was detected in some P. interpunctella populations during the larval and egg stages. Resistance studies revealed that populations from Ordu (Or5) exhibited resistance in both stages, Giresun (Gir2) in the egg stage, and İstanbul (İst1) in the larval stage. Modified atmosphere treatments using 99% nitrogen achieved 100% control in eggs with 2.5 days of exposure at 30°C. Complete mortality of larvae required at least 3 days under similar conditions. This study highlights the pest-induced losses during hazelnut storage and offers valuable insights into developing effective pest management strategies for stored hazelnuts.