Intraspecific competition between the larval instars of sexual and asexual strains of the parasitoid wasp, Lysiphlebus fabarum (Braconidae: Aphidiinae), in the simultaneous and successive ovipositions

In superparasitism, a host is parasitized by one or more conspecific females, a phenomenon resulting in immature competition within the host’s body. In the present study, the competition between sexual and asexual strains of the parasitoid wasp, Lysiphlebus fabarum (Marshall) (Braconidae: Aphidiinae), was studied in simultaneous and successive introductions. The biological traits by both strains were determined in surviving individuals of superparasitized aphids as well. For this purpose, eight wasp females of each strain were introduced into 40 second instar of black bean aphid, Aphis fabae Scopoli, simultaneously or by a 24-hour priority. Our results revealed that the early introduction of each strain had a significant effect on the number of emerging adults of that strain. However, in simultaneous introduction, a greater number of sexual progeny emerged than asexual ones. The development time of sexual progeny was significantly decreased when their females were introduced earlier into the host aphids. Other morphological and biological traits (hind tibia length, head width, ovary area, egg load and egg size) of surviving individuals of superparasitized aphids were not affected by the oviposition sequence of the strains. The findings showed that sexual L. fabarum females were successful in competition with asexual females, the superiority of which could be more important in a host limitation conditions.