Abstract

Tribolium castaneum which is utilized in quantitative genetical studies is the insect commonly known as the rust-red flour beetle. The adult is about 3.5 mm in length and 1.0 mm in width. The egg size is about 0.6 mm in length and 0.4 mm in diameter and weight per 100 is about 4.0 mg. Larva hatches 31/2 days after oviposition. Larvae continue their growth until 15-16 days of age. Maximum larval weight is attained in 1-1V2 days before pupation. There is no fixed number of larval instars, the number being variable with environments and populations ranging from 5 to 10. Pupation takes place under most laboratory conditions in 17-18 days after hatch. Pupae are white but darken as they approach to the time of emergence. The average duration of pupal stage is about 5 days. Sexes are easily distinguished by the appearance of the ventral surface of the terminal abdominal segment in pupal stage. The dark spot on the forelegs of the male is sometimes used for sexing. The newly emerged adult reaches its minimum live weight on the third day and restores a stable weight within a week after emergence. Then, the female starts egg production. The peak egg production appears at 10-15 days after emergence and the number of eggs per day runs from 10-20. It is easy to run a selection experiment with 4-week generation cycles.

Y. Yamada

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume 1, Madrid, Spain, 439–450, 1974