Tribolium castaneum: A Model for Investigating the Mode of Action of Insecticides and Mechanisms of Resistance

The red flour beetle, Tribolium castaneum, is a worldwide insect pest of stored products, particularly food grains, and a powerful model organism for developmental, physiological and applied entomological research on coleopteran species. Among coleopterans, T. castaneum has the most fully sequenced and annotated genome and consequently provides the most advanced genetic model of a coleopteran pest. The beetle is also easy to culture and has a short generation time. Research on this beetle is further assisted by the availability of expressed sequence tags and transcriptomic data. Most importantly, it exhibits a very robust response to systemic RNA interference (RNAi), and a database of RNAi phenotypes (iBeetle) is available. Finally, classical transposonbased techniques together with CRISPR/Cas-mediated gene knockout and genome editing allow the creation of transgenic lines. As T. castaneum develops resistance rapidly to many classes of insecticides including organophosphates, methyl carbamates, pyrethroids, neonicotinoids and insect growth regulators such as chitin synthesis inhibitors, it is further a suitable test system for studying resistance mechanisms. In this review, we will summarize recent advances in research focusing on the mode of action of insecticides and mechanisms of resistance identified using T. castaneum as a pest model.