Abstract:

In order to provide the essential biomaterials and logical proofs for cultivating new good breeds, the directed selection of two representative color varieties of T. molitor was done for several generations based on the color of the cuticular at 60-day-old of larvae and the reproductive traits of them were compared with each other. The yellow-and black-color varieties of T. molitor, with good genetic stability, were obtained successfully through directed selection of 12 continual generations for more than 4 years. The cuticular color of the two varieties differed greatly, for both larvae and adults at same day age. Cuticular color of larvae and adults of the yellow-color variety was golden-yellow and dim-yellow, respectively, while that of the black ones was blackish-brown and black. Further research on reproductive traits of the adults showed that sex ratio, longevity and oviposition duration showed no significant difference between the two varieties. Sex ratio of the females to males of both varieties was about 1.0:1.0, and average longevity of both male and female adults was longer than 100 d, and average oviposition duration of the female of both varieties was about 3-4 months. But under different test conditions, pre-egg period, oviposition peak and fecundity of females of both varieties showed significant difference. The pre-egg period of partheno-adults of both varieties was 10 d, and they had no visible oviposition peak, and the average fecundity of them was very low (yellow variety: 40 eggs/female, black variety: 28 eggs/female). Pre-egg period of the females matched with males shorten to only 4 d, and they had two marked oviposition peaks, and the average fecundity of them was greatly enhanced compared with the partheno-adults. Average fecundity of females of the yellow- and black-color variety in the single-pair-mating groups which were made up of one male and one female was 438 eggs/female and 406 eggs/female, while that of the yellow and black ones in the flock-mating groups which were made up of 50 males and 50 females was 653 eggs/female and 530 eggs/female. It was thus clear that mating could improve the fecundity of females of yellow mealworm greatly, and the flock-mating females had an average fecundity much higher than the single-pair-mating ones. So flock-breeding and flock-mating should be applied into the mealworm beetles’ culture. In addition, the yellow variety females under the flock-mating conditions had an average fecundity significantly higher than that of the black ones. The above results not only built up the essential data and biomaterials of value for selecting new good varieties of T. molitor, but also provide some useful reference for breeding of adults of the mealworm beetles.