Morphological and colour differences between subspecies of Sphecophaga vesparum (Hymenoptera: Ichneumonidae)

Sphecophaga vesparum (Curtis), an ichneumonid parasitoid of vespid wasps, has been introduced into New Zealand for the biological control of Vespula species. S. vesparum is divided into two allopatric subspecies: S. v. vesparum (Curtis) from Europe, and S. v. burra (Cresson) from North America. S. v. vesparum has been released over most of New Zealand since 1987, and is established at two sites. S. v. burra was released in the field at one site in 1979 and failed to establish. It is now being held in quarantine pending re-release. Establishment success and distribution patterns of the two subspecies will be studied in future, so a morphological study was carried out to determine whether they could be reliably distinguished. We examined 164 specimens of S. v. vesparum and 87 specimens of S. v. hurra, and scored 13 characters. Results showed that the two subspecies could not be reliably discriminated on any morphological characters, but that three colour characters gave >98% separation for females (not including the character originally used to define the subspecies), and seven colour characters gave 100% separation for males. A key for separating the subspecies is presented. A further strain from Israel was examined, and appeared to differ morphologically from the European and North American subspecies, but too few specimens were available for definitive conclusions.