Mysterious airborne pollutants in central Taiwan determined to be feces dropped from bees.
Lee Y. H., Shyu T. H., Chiang M. Y.
Author Affiliation: Taiwan Agricultural Chemicals and Toxic Substances Research Institute, Council of Agriculture, Taichung 413, Taiwan.
Plant Protection Bulletin (Taipei) 45 : 365-371
Abstract : For the past several years, we have been involved in investigating a puzzle of mysterious airborne pollutants in central Taiwan. These incidences periodically occurred in the cool season from December through April. Around polluted sites, small airborne droplets were found on cars, clothes, buildings, and plants that were exposed to the open air. Residents in the neighbourhood areas were disturbed, and speculations that these airborne substances were harmful pollutants from airplanes or industrial emissions raised serious concerns. We conducted field surveys and follow-up investigations by comparing samples as well as interviewing related personnel. At the polluted sites, droplets appeared to be yellow or light brown, but differed in size, shape, and density. These droplets were not soluble in a non-polar solvent, but dispersed readily in water, producing suspended particles. Upon microscopic examination, we found that most particles were composed of pollen grains with various morphologic features. Pollen of inspected samples were mainly from Acacia confusa, Bidens pilosa var. radiata, Brassica campestris, Euphoria longana [Dimocarpus longan], Litchi chinensis, Macaranga tanarius and Mangifera indica which flower during this season. We expanded our investigation at several sites where migratory bee farmers regularly place their hives. Airborne droplets similar in shape and components to those of polluted sites also appeared around beehives but at higher densities. This confirmed our suspicion that the airborne droplets were faeces dropped from flying bees.