GENETIC-ANALYSIS OF EMBRYONIC PATTERNING MECHANISMS IN THE BEETLE TRIBOLIUM-CASTANEUM

Genetic analysis has been a powerful tool for dissecting the patternin g mechanisms that define the embryonic axes of Drosophila melanogaster . Mutants that alter embryonic patterning in a more primitive insect w ill provide insights into patterning mechanisms that do not occur in D rosophila. Tribolium castaneum, the red flour beetle generates body se gments after the blastoderm stage, like primitive insects, and is amen able to genetic analysis. We review the tools of Tribolium genetics an d describe the kinds of mutant screens that have been carried out in T ribolium Allele screens and reversion screens of spontaneous homeotic mutations have isolated embryonic lethal alleles of homeotic genes. Th e phenotypes of these mutations reveal changes in homeotic gene functi on between Drosophila and Tribolium. We have screened directly for Tri bolium patterning mutants by looking for changes in the first instar l arval cuticle pattern. The phenotypes of these mutants shed light on s egmentation mechanisms that may be characteristic of primitive insects .