Further Studies on the Relationship between Parental Age and the Life Cycle of the Mealworm, Tenebrio Molitor1

Eggs were collected at intervals of 2 weeks throughout the egg-laying period from beetles maintained at 30°, 25° and 20°C Eggs and larvae were maintained at the same temperature as was used for the parent beetles. Parental age had no effect on the duration of the egg stage or on the weights of the eggs or newly hatched larvae. At each temperature the percentage of eggs which hatched decreased with an increase in parental age, from approximately 90 for those laid during the first 2 months to about 50 for those laid 4 months after emergence. At each temperature, larvae from young parents grew at a slower rate than those from the same parents after they had aged 9 weeks. At 30° there were no other effects of parental age, but at 25° and 20° larvae from young parents required a significantly longer time to complete development and had more molts than those from the same parents after they had aged 1 month or longer. At these temperatures, an increase in parental age resulted in a decrease in the duration of adult life. This effect was not evident until the parents had aged 9 weeks in Series A (water was added to the food after 6 weeks of larval life) and 6 weeks in Series B at 25°C. (water was added to the food throughout the larval period). In every case larvae from Series B grew at a faster rate and required less time for development than those of Series A.