Seasonal and environmental variations in community structure of house dust mites (Acari) in subtropical southern Brazil

Abstract

ABSTRACTHouse dust mites (HDM) are globally distributed in human habitats. The most favourable locations for their development are carpets, curtains, couches, mattresses and pillows. This association with indoor environments makes HDM one of the most important sources of indoor allergens. Distribution and concentration may be influenced by food availability, temperature and, mostly, humidity. This study investigated seasonal and environmental patterns in HDM communities in order to understand the influence of housing type and climate conditions on their richness, abundance and concentration. We sampled four different types of housing (brick houses, wooden houses, carpeted apartments and tiled-floor apartments) and four habitats (double mattress, couch, curtain and carpet). We carried out four samplings in 2010, each one in a season of the year, and collected a total of 128 samples. We analysed richness, abundance and concentration of all sample units. We found a total of 1653 mites. Blomia tropicalis (van Bronswijk, Cock & Oshima, 1973), Dermatophagoides farinae Hughes, 1961 and Tarsonemus fusarii Cooreman, 1941 were the most abundant species. All variables tended to decrease from winter to summer. Wooden and carpeted houses had higher richness and abundance than brick houses and tiled-floor apartments. Curtain had the highest concentration, followed by double mattress, couch and carpet. We found seasonal and environmental variations in the community structure of HDM. Concluding, we demonstrated the prevalence of allergenic indoor mites in the coldest months, in more favourable conditions of wooden and carpeted houses. This study indicates that through careful regulation of climatic conditions, housekeeping policies and laundering procedures, dust mite and allergen levels can be controlled even in a climate suitable for the development of breeding mite populations.