none Plodia interpunctella; HYMENOPTERAN-PARASITES; Bracon hebetor; Host brood mate avoidance mechanisms Bracon hebetor; AGE-; Mating receptivity relationships; MATING-; Age related receptivity, brood mate avoidance mechanism; PAIR-FORMATION; INBREEDING-; Brood mate avoidance mechanisms; SPECIES-RECOGNITION; Female discrimination of brood mates, inbreeding avoidance mechanism; LEPIDOPTERAN-HOSTS; Plodia interpunctella; Inbreeding avoidance mechanisms, evidence for use of environmental cues The parasitic wasp Bracon hebetor suffers severe inbreeding depression. This study examined two behavioural mechanisms that minimize mating between close relatives. First, the majority of males and females were unwilling to mate immediately upon emergence. Receptivity to mating slowly increased with age of the adult. By the time most individuals were willing to mate, the majority of wasps had dispersed from the natal site. Second, females tended to avoid mating with brood-mates when given a choice between a male that developed on the same host and one that developed on a different host. Experiments using eye-colour mutants and broods composed of relatives and non-relatives indicated that females discriminated against male brood-mates on the basis of environmental cues. Females consistently mated with brothers and non-brothers if they developed on another host, but tended to reject brothers and non-brothers from the same brood as themselves. Females maintained the ability to recognize brood-mates for at least 5 days after eclosion.