It is further noteworthy that IMD genes that were up-regulated upon infection without priming (Control-Btt and Bt407--Btt) did not show differential regulation when there was previous priming with Btt. Finally, in the Bt407--Naive treatment groups, the ROS, AMP and Toll pathways were significantly down-regulated compared with control-primed beetles. Here, TLR4 is linked to infection.