Parental genetic traits in offspring from inter-specific crosses between introduced and indigenous Diadegma Foerster (Hymenoptera: Ichneumonidae): Possible effects on conservation genetics

Abstract

The effects of natural enemy releases on conservation genetics within ecosystems are rarely considered. Diadegma semiclausum (Hellen) (Hymenoptera: Ichneumonidae) was introduced and continues to be released for biological control of diamondback moth in Japan. Diadegma semiclausum and indigenous Diadegma fenestrale (Holmgren) (Hymenoptera: Ichneumonidae) share geographic ranges and hosts, and produce offspring when mated under laboratory conditions. We used DNA to examine whether offspring from inter-specific one-way parental crosses (D. semiclausum ♂ and D. fenestrale ♀) were hybrid, as some Hymenoptera (e.g. Aphidius colemani Viereck (Hymenoptera: Braconidae)) exhibit thelytokous reproduction by gynogenesis. Molecular analyses revealed offspring mtDNA (COI) is maternally inherited, as expected, but rRNA (ITS-2) originates from both parents. Should similar hybridization occur in the field beyond the F1 generation, genetic mixing is a possible consequence that may influence biological control efficacy or pollute native population genetics.