The feeding impact of the spider mite pest, Oligonychus coffeae Nietner on the leaves of the European crab apple (Malus sylvestris (L.) Miller) was analysed through visual assessment of feeding symptoms and by estimating and comparing the quantitative changes in the photosynthetic pigments and photosynthetic efficiency of mite infested and uninfested leaves. The visible symptoms induced by the species comprised of the development of chlorotic spots or patches, necrotic spots, etc. and heavily infested leaves presented a bleached, sunken and crinkled appearance. Results of quantitative analysis of the photosynthetic pigments enabled to record significant loss in chlorophyll a, chlorophyll b, total chlorophyll and carotenoids in the tune of 61.69 ± 0.081%, 68.21 ± 0.073%, 63.52 ± 0.012% and 55.42 ± 0.064% respectively (p < 0.01 level). Analysis of photosynthetic efficiency by measuring the value of Fv/Fm ratio (a parameter to measure chlorophyll fluorescence for denoting the PSII system of leaves) using the Handy Photosynthetic Analyzer revealed a lowered value for infested leaves (0.587 ± 0.015) when compared to the uninfested leaves (0.823 ± 0.003). The result when statistically analyzed was found significant at p < 0.01 level, thereby clearly establishing that infestation by O. coffeae would drastically affect the photosynthetic efficiency and hence the vigor of M. sylvestris
