THE EFFECTS OF TEMPERATURE AND HUMIDITY ON THE RATE OF DEVELOPMENT AND THE MORTALITY OF TRIBOLIUM CONFUSUM DUVAL (COLEOPTERA, TENEBRIONIDAE)

The speed of development and the developmental mortality of Tribolium confusum were studied over a series of constant temperatures between 15 degrees and 40 degrees C. at 10, 30, 70 and 90 % R. H. using wheatfeed as food. Eggs did not hatch at 15 degrees or 40 degrees C. at any humidity. At 37.5 degrees C. about 60 % of eggs hatched and at all other conditions about 90% hatched. The effect of temperature on the duration of the egg period is shown graphically, the shortest period being at 35 degrees C. Humidity does not affect the egg period. Larvae failed to develop to pupae at 17.5 degrees C., at 10 % R.H. at 20 degrees C., and at 10 and 90 % R. H. at 37.5 degrees C. The rate of larval development was affected by both temperature and humidity being quickest at the higher humidities and at about 32.5 degrees C. Larval mortality was less than 16 % except at 37.5 degrees C., at 10 % R. H. or less, and at zoo C., 90 % R.H. The duration of the pupal period was not affected by humidity and was shortest at 37.5 degrees C. The total developmental period is compared with that of T. castaneum over the range of temperature and humidity conditions in which both species can grow. The optimum for developmental speed and the maximum and the minimum temperatures at which development is possible were all about 2.5 degrees C. lower for T. confusum than for T. castaneum. The developmental periods for the two species were equal at temperatures between 23 and 27 degrees C., depending on humidity. At lower temperatures, T. confusum developed the more quickly and at higher temperatures the more slowly.