Abstract
Successive rearing of the tachinid fly, Exorista japonica TOWNSEND, a natural enemy of many lepidopterous larvae, was conducted using two different breeding techniques in order to provide insects for small and medium-scale laboratory experiments. Ten pairs of parasitoids collected in the field were used as the parent generation to begin the inbreeding and rotational breeding experiments. The rates of adult emergence and host motrality decreased even at F2, and lines derived from all pairs became extinct by F6, under the inbreeding conditions, However these rates did not differ significantly from F1 to F9 during rotational breeding. When a sister and a non-sister female fly were simultaneously provided as potential mates, male flies did not avoid sib-mating. Therefore, rotational breeding is necessary to prevent inbreeding depression when rearing these parasitoids in a laboratory on a relatively small scale.
