Tribolium flour beetles are strongly attracted to decomposing wood, their putative historical habitat, over flour

Tribolium castaneum and T. confusum are important stored grain pests and model organisms, yet little is known about the life history of these beetles outside the stored grain environment. While the historical habitat is thought to be rotting logs, current affinity and use of such habitat is unknown despite its potential role in mediating dynamics between natural landscape and stored product facilities. Here we assessed attraction to three different species of decomposing wood, sex-mediated differences in attraction, and survival and reproduction on wood versus flour substrates. We found that both Tribolium species demonstrated significantly higher attraction to decomposing wood than to wheat flour (2.5-7.25x), and reproduction studies with T. castaneum showed reduced survivorship and no reproduction on a decomposing wood substrate. Evidently, attraction to decomposing wood is conserved across these two prominent stored product pests, yet wood alone may not fulfill dietary or reproductive requirements. Wheat flour also elicits a significant olfactory response but also provides high reproductive capacity, which may contribute to Tribiolium's utilization of this novel anthropogenic resource. This study contributes to an important yet understudied area of inquiry into the role natural microhabitats play in supporting these economically important species and the origin of stored grain associations.