Release and recovery of the introduced wasp parasitoid,Sphecophaga vesparum vesparum(Curtis) (Hymenoptera: Ichneumonidae) in New Zealand

Abstract

The introduced European wasp parasitoid, Sphecophaga vesparum vesparum (Curtis) was reared in the laboratory at DSIR Lincoln then distributed in the South Island and at one location in the North Island, from 1985 to 1987. In early November 1986, one yellow parasitoid cocoon was recovered from an overwintered nest of the German wasp, Vespula germanica (F.), in suburban Christchurch. Before that recovery about 197 female parasitoids had emerged from release boxes in the area, and 41 wasp nests had been collected. There have been no other recoveries in this area, despite the emergence of about 1585 parasitoids from released cocoons and the collection of a further 385 wasp nests. Systematic searches for and examination of wasp nests from 17 sites in the north and west of the South Island recovered rapidly multiplying parasitoid populations from 2 out of 42 nests of the common wasp, Vespula vulgaris (L.) at Pelorus Bridge, 42 km east of Nelson. The nests were 33 m and 625 m away in separate directions from different parasitoid release boxes. From the three parasitoid release boxes in the area, 266 adult parasitoids had emerged. When poisoned on 5 May 1988, the two parasitised wasp nests contained 471 and 1034 parasitoid stages, respectively. At least 1491 wasps had been killed by the parasitoid. The completion of all propagation stages of the parasitoid life cycle at Pelorus Bridge suggests that the environment of the area is favourable for the parasitoid. Because parasitoids had multiplied in and dispersed from the two common wasp nests, and the likelihood of the existence of other attacked nests in the area seems high, it is considered that the parasitoid has probably established at Pelorus Bridge. The potential for a rapid increase in parasitoid numbers appears to be very good.