Heterocyclic compound and resistant harmful arthropod-controlling method for composition containing same

The present invention provides a compound that has an excellent efficacy for controlling resistant harmful arthropods, a composition comprising the compound, and a method using the compound or the composition. A compound represented by formula (1) [wherein R1 represents a C1-C6 chain hydrocarbon group, etc., R3 and R7 each represents a hydrogen atom, etc., R4 and R6 each represents a hydrogen atom, etc., R5 represent a hydrogen atom, etc., Q represents a group represented by Q1, etc. (where # represents a binding site to a pyridine ring, and * represents a binding site to a benzene ring), A1 represents a nitrogen atom, etc., A2 represents a nitrogen atom, etc., and A3 represents a nitrogen atom, etc.]or its N-oxide, or salts thereof has an excellent efficacy on controlling resistant harmful arthropods.