A system to efficiently maintain embryonic lethal mutations in the flour beetle Tribolium castaneum

 Due to its small size, short life cycle, and easy maintenance, the flour beetle Tribolium castaneum is well suited for the genetic analysis of development. One drawback of Tribolium as a genetic system is, however, the difficulty of keeping embryonic lethal lines. Presently, only few lethal mutations can be kept as balanced stocks. Therefore, heterozygous carriers must be identified anew in every generation in order to maintain a recessive embryonic mutation. To alleviate this problem we have devised a block system that allows the simultaneous processing of many mutant lines or test crosses for visual inspection of larval cuticle phenotypes. Using this technique, one person can maintain about 100 embryonic lethal stocks, which makes feasible the thorough genetic analysis of embryogenesis in this species. Received: 4 November 1998 / Accepted: 7 February 1999     

Polymorphism observed in mitochondrial genes of red flour beetle,Tribolium castaneum (Coleoptera: Tenebrionidae) of different origin in laboratory cultures

Tribolium castaneum, a pest of stored grain, has a uniform morphology, preventing the visual identification of strains from different areas. Polymorphisms in the nucleotide sequences of the mitochondrial genes of this species were examined, and combined into seven haplotypes among the test insect specimens originating from Japan, Thailand, and Canada. These results suggested the potential for geographical differentiation.     

Experimental evolution of external immune defences in the red flour beetle

The red flour beetle, Tribolium castaneum, secretes quinones that control the microbial flora in the surrounding environment. These secretions act as an external immune defence that provides protection against pathogens. At high concentrations, however, these secretions are harmful to the host itself, and selection may thus have optimized the level of expression under natural conditions. Here, we show that the expression of external immunity responded to selection during experimental evolution within a few generations. At the same time, one component of internal immune defence (phenoloxidase activity) was compromised in beetles selected for either high or low external defences. Intriguingly, offspring protection against a natural pathogen was reduced in flour obtained from beetle lines selected for low amounts of secretions. Altogether, this suggests that external and internal immune defences work together efficiently under natural conditions, whereas every manipulation on the side of external immune defence comes with costs to the internal immune defence.