The Humidity Responses of Tribolium Confusum Jacquelin Duval in Wheat Flour, Sand, and Air

Abstract

Larval and adult Tribolium confusum were tested in flour and sand substrates at various relative humidities, ranging from 10% to 90%. Both life stages preferred a flour environment of from 10% to 50% relative humidity. In sand, however, the insects selected more humid environments.

Investigations of survival in sand, flour, and air environments indicated that two factors may be operating in the preference for a wet-sand environment: (1) desiccation, and (2) loss of nutrition and source of metabolic water. Insects presented with two air streams, each of 35% relative humidity or greater, selected the drier air stream. In a humidity gradient in air, both life stages indicated a preference for relative humidities of 10% to 25%. Data from an exploratory experiment indicated that adult beetles were not responding to humidity through a kinetic mechanism, though larvae may have been responding kinetically.

The three major conclusions were that: (1) both larval and adult Tribolium confusum preferred a dry-flour environment, (2) this preference was reversed if the nature and nutritional content of the medium were altered, and (3) the insects selected an air environment with relative humidities between 10% to 25%.