The Respiration of Tyroglyphus Farinae

This investigation into the reactions of Tyroglyphut farinae to varying concentrations of carbon dioxide and oxygen and to the presence of small quantities of hydrocyanic acid, was carried out in order to obtain some insight into the respiratory activities of the mite, very little being known of its physiological reactions. As a necessary preliminary, its reactions to humidity were determined. T. farinae belongs to the family Tyroglyphidae and respires by direct diffusion through the body surface, since no tracheae are present. These mites infest stored food material, being found on grain, flour and meal. They are associated with the micro-organisms of decay and it might be expected that the gaseous conditions under which they live differ considerably from those of ordinary air. It was decided, therefore, to isolate cultures and to investigate the gaseous changes produced by the organisms in the culture and the effect of such changes on the mites present. The respiratory quotient in normal air was also determined, together with the quotient obtained in the presence of an JVf/iooo solution of potassium cyanide. The reactions of the mite to varying concentrations of carbon dioxide, oxygen and water vapour in the atmosphere were also determined.