Pollen and spores in yellow rain from Lucknow, northern India

Abstract

ABSTRACTThis paper presents the results of pollen and spore concentration of yellow drops in the Lucknow environs during the summer of 2014. The yellow spots were procured from the surface of a number of leaves and other objects from three different localities of Lucknow District of Uttar Pradesh. The size and shapes of these spots vary, ranging from linear to circular. Pollen grains recovered in good frequencies chiefly belong to angiosperms, whereas some gymnosperm pollen was also observed in trace frequencies. Other microbiota include fern spores, fungal remains and insect body parts in lower values. The study broadly suggests that palynomorphs recovered from yellow droppings are not fully airborne; rather, they are the types that honey bees gather from crop fields to feed their young. Brassica campestris and Asteroideae are the dominant plant taxa recorded in yellow rain samples. On investigation, it was noticed that yellow drop falling occurred for a few minutes on limited days during the summer of 2014, when the atmosphere experienced optimal temperature conditions with relatively humid environs. The observation also confirms that the yellow spots are nothing but faecal droppings, as suggested by the bee faeces theory which proposed that the origin of yellow rain is a phenomenon of nature. The study, in addition to aiding in understanding yellow rain occurrence, could also be helpful in aerobiological research, especially in examining the allergenicity of various pollen grains/spores in the area of investigation, causing bronchial asthma, hay fever (allergic rhinitis/pollinosis), nasobronchial allergy and other respiratory disorders along with conjunctivitis, contact dermatitis, eczema, food allergies and other health ailments. A multivariate principal component analysis (PCA) was applied to quantified data obtained from pollen frequency analyses of different areas of Lucknow, which clearly revealed a significant group variation in vegetation type on the basis of dispersal and deposition of pollen in yellow spots.