Population structure and dynamics of the house dust mite Dermatophagoides farinae (Acarina: Pyroglyphidae) in Czechoslovakia.

The relationship between the room microclimate and population dynamics of the house dust mite Dermatophagoides farinae Hughes, 1961 was studied. A distinct increase of the mite population density in mattresses was observed only in the period, when the monthly means of relative air humidity in rooms were higher than 47-50%, denominated by the author as critical air humidity. This is a considerably lower value than that relevant to Dermatophagoides pteronyssinus (Trouessart, 1897) from the paper by Bronswijk et al. (1971) (critical air humidity 60-65%). The climatic humidity affecting the room microclimate is consequently the main reason why one species or another is predominant under different geographical conditions. From October till May the D. farinae population is primarily composed of protonymphs, in the period of maximum population density (May-October) the presence of adults is predominant. Protonymphs are considered to be least resistant to the humidity decrease in their environment.