Impact of Cydia pomonella Infestation on the Quality Parameters of 'Jonagold' Apples

Abstract

The codling moth (Cydia pomonella L.) is a major pest in pome fruit and walnut orchards worldwide, causing significant economic losses due to fruit damage and quality deterioration. This study evaluates the impact of C. pomonella infestation on major commercial and physiological parameters of `Jonagold´ apples, with emphasis on the applicability of the Whiteness Index (WI) and Tissue Water Content Index (Tw) as indicators of biotic stress. Fruits from the first and second generations were classified as infested or non-infested and analyzed for weight, firmness, soluble solids (°Brix), colour coordinates (L, a, b*), WI, and Tw. Infested fruits exhibited significantly reduced weight and increased °Brix, WI, and Tw, particularly in the first generation (p <0.05). ANOVA revealed significant effects of both generation and infestation status on weight, °Brix, and WI, including notable interactions. Tw showed strong sensitivity to infestation, reflecting alterations in tissue water balance, while firmness remained unaffected. The positive correlation between WI and Tw (r = 0.65) and their negative association with °Brix highlight their diagnostic potential. The results demonstrate that WI and Tw can serve as reliable, non-destructive indicators of physiological stress caused by C. pomonella, supporting early damage detection, postharvest quality assessment, and breeding programmes aimed at improving resistance.