Influence of Humidity on Mortality and Rate of Development of Immature Stages of the Grain-Infesting Mite Tyrophagus castellanii (Hirst) (Acarina: Acaridae) Reared on Mould Cultures

Abstract

It was observed that populations of Tyrophagus castellanii (Hirst) reared on cereal flakes and yeast for studies of predator-prey interactions were feeding on moulds rather than on the food material, and that an increase in humidity increased their rates of development. To discover whether this was caused by the direct effect of humidity on the mites or by a greater supply of fresh food brought about by an increase in humidity, rearings were made with a technique developed by Rivard (1958). The mites were reared exclusively on mould cultures under controlled temperature and humidity conditions. It was also possible with this technique to regdate modd growth to some extent, so that a supply of fresh food was always available to the mites. This is a report on the influence of various humidities on mortality and rate of development of the immature stages of T. castellanii at a constant temperature.