1. A single construct comprising: (i) a promoter; (ii) a sequence encoding an RNAi molecule, operably linked to the promoter, wherein the RNAi molecule comprises a guide strand; (iii) a target sensor, operably linked to the promoter, the target sensor comprising: a sequence encoding a reporter and a target sequence that comprises from about 8 to about 29 contiguous nucleotides complementary to at least a portion of the guide strand of the RNAi molecule.