Life-cycle characteristics of Tetrastichus turionum, a parasitoid of the European pine shoot moth, Rhyacionia buoliana

The life cycle of Tetrastichus turionum, a pupal endoparasitoid of the European pine shoot moth Rhyacionia buoliana, was studied in Spain in the field, prior to its use as a potential biological control agent of this pest in Chile. T. turionum showed two generations acting on the same host generation. Adults from the overwintering generation emerged and dispersed from mid- to late spring and gave rise to a fast developing, current year generation. Adults of this generation emerged and oviposited in early to mid-summer, producing progeny that overwintered as fourth instar larvae inside their host. Both generations appeared highly synchronized to the presence of pupae in the host population. The role of decreasing day length in the induction of diapause is also discussed. Laboratory bioassays showed that T. turionum did not oviposit on R. buoliana larvae already parasitized by Orgilus obscurator, a major larval parasitoid, already introduced in Chile. The results reinforce the suitability of T. turionum as a promising parasitoid that would complement O. obscurator in the biological control of European pine shoot moth.