Red Flour Beetle

Tribolium castaneum — the red flour beetle — is the most cosmopolitan stored-product insect pest in the world and one of the most important model organisms in modern developmental and evolutionary biology. The species is 3-4 mm long, dark reddish-brown, and infests virtually every flour, meal, cereal, dried fruit, spice, dried-pet-food, and stored-grain product on Earth. Tribolium has been a global mill pest for at least the last 5,000 years (specimens have been found in Egyptian Old Kingdom granaries) and currently destroys an estimated 10-30% of global stored-grain production at various points along the supply chain. The species reproduces year-round in heated warehouses, has a 4-6 week life cycle, and contaminates products with not only direct feeding damage but also defensive secretions (benzoquinones from prothoracic glands) that produce a pink discoloration and acrid taste in heavily-infested flour. The species' second great significance is as a model organism. Tribolium became the second insect ever to have its complete genome sequenced (Tribolium Genome Sequencing Consortium, Nature, 2008), after Drosophila melanogaster. The genome revealed that beetles — the most species-rich animal order — contain ancestral insect genes that flies have lost. As a result, Tribolium is now a more representative insect model than Drosophila for many traits, including segmentation, appendage development, immunity, and metabolic genes. The species is the basis of dozens of evolutionary developmental biology research programs worldwide.