Relative performance of Tribolium castaneum Herbst across resource types and in relation to resource structure

1. The evolution of phosphine resistance in Tribolium castaneum (Herbst) in stored grain systems is a concern worldwide. An understanding of the spatial spread of the resistance gene and its frequency in populations requires quantitative information on performance of the insects across the different resources available in the field, through the whole lifecycle. 2. Cotton seed is common in some grain production areas (e.g. the Darling Downs, Queensland) and is reputedly a good food resource for T. castaneum. The suitability of wheat, sorghum and cotton was quantified in terms of T. castaneum life time production, and each resource was tested in their in whole, kibbled and flour forms. 3. Wheat was the most productive resource for T. castaneum in terms of the number of larvae that survived, pupated and eclosed as adults and also with respect to fecundity. The performance of beetles on sorghum was comparable to that on wheat, and on both of these was significantly higher than on cotton. Even the proportion of larvae hatching and mature larvae pupating was significantly lowest on cotton. 4. Kibbled grains, of each grain type, and their respective flours were not significantly different from each other in terms production of individuals through the life cycle, but the productivity was significantly better than that from whole grains. 5. Wild caught beetles responded similarly to laboratory cultured beetles with respect to all the food resources tested, but the overall production of laboratory cultured beetles was better than that of wild caught beetles. Nevertheless wild caught beetles had significantly higher fecundity as compared to laboratory reared beetles.