Target pest: Vespula germanica (Hymenoptera: Vespidae), German wasp
Agent introduced: Sphecophaga vesparum vesparum (Hymenoptera: Ichneumonidae)
1980, 1981, 2016, 2017
1980 Switzerland, Germany and Austria; 1981 Switzerland and Austria; 2016, 2017 south-western UK
Cameron et al. (1989) - three shipments of S. v. vesparum totalling 7,524 cocoons in combs of Vespula vulgaris collected in Switzerland, Germany and Austria were received at Lincoln, Canterbury during September and October 1980. Three further shipments totalling 7,524 cocoons (781 from nests of Dolichovespula saxonica, the rest from nests of V. vulgaris) were received during October and November 1981 from Switzerland and Austria. From 33 female parasitoids that emerged shortly after the 1980 importation, three generations were reared on German wasps (V. germanica). In December 1984 the last of the imported parasitoid cocoons produced 14 females, from which a continuous breeding population was established on common wasps (V. vulgaris).
Landcare Research (2016m) - common wasp (Vespula vulgaris) nests were collected in the UK (from the same geographic range New Zealand's common wasps come from [south-western UK - see Brown and Groenteman (2017), Bob Brown (Landcare Research) (2018 - pers. comm.) entry in 'General comments' section]) in September and October 2016 and imported into containment at Lincoln, Canterbury. A good proportion of cells appear to be parasitised with S. v. vesparum.
Landcare Research (2017h) - for some yet unknown reason the first lot of S. v. vesparum cocoons from the material collected in the UK in September and October 2016 all turned out to be overwintering pupae. There is no way to know what proportion of them will emerge this coming spring, which will affect planned releases.
Landcare Research (2017i) - thirteen Vespula nests collected in southern UK in late-summer 2017 were imported into quarantine at Lincoln, Canterbury. Parasitoids present included well over 1,000 S. v. vesparum pupae, which, added to the material imported in 2016, will boost the genetic variance of the quarantine population.
Cameron et al. (1989), Donovan et al. (1989) - parasitoids raised in quarantine were released into seven Vespula vulgaris (common wasp) and six Vespula germanicus (German wasp) nests in Canterbury at Southbridge, Lincoln, Christchurch and Mt Thomas (North Canterbury) from early-March to mid-May 1985. By October 1985, a further 858 cocoons were released into nests at Christchurch and Mt Thomas. In 1987 more than 30,000 overwintering cocoons were distributed over the South Island as follows: Buller (420), North Canterbury (945), Mid-Canterbury (5,145), South Canterbury (945), Central Otago (1,155), Dunedin (1,050), Marlborough and Marlborough Sounds (7,980), Nelson (7,350), Otago lakes (1,155), Southland (1,050), Waikato (1,050) and Westland (2,835). A further 1,050 overwintering cocoons were released near Hamilton in the North Island.
Read et al. (1990) - public and private organisations contributed financially to the project to rear and release S. v. vesparum and were provided with parasitoids to release at sites of their choice. As a result of this funding, 108,400 parasitoids were released (as overwintering pupae in protective release boxes) throughout New Zealand (including Stewart Island) between 1987 and 1989.
Landcare Research (2016m) - pending disease freedom, releases of the S. v. vesparum collected in the UK in September and October 2016 [see Brown & Groenteman (2017), Bob Brown (Landcare Research) (2018 - pers. comm.) entry in 'General comments' section for rationale for new releases] will begin in January 2017, as adult parasitoids emerge from the imported wasp comb.
Brown and Groenteman (2017) - the new genetic stock of S. v. vesparum imported from UK in 2016 has passed through one generation in containment and is expected to be released into the wild in early-2018.
Landcare Research (2017h) - as all S. v. vesparum cocoons from the material collected in the UK in September and October 2016 all turned out to be overwintering pupae an autumn 2017 release was not possible. There is no way to know what proportion of them will emerge this coming spring (2018), but field releases at that time will probably not be as numerous as had been hoped.
Cameron et al. (1989) - evidence of establishment was seen in Canterbury following 1985 releases: post-release examination of the nests into which S. v. vesparum was released in March-May 1985 showed six V. vulgaris and three V. germanica nests had been attacked with at least one generation of parasitoid adults having emerged in four V. vulgaris nests and one V. germanica nest, and in November 1986 one parasitoid overwintering cocoon was recovered from an overwintered V germanica nest in Christchurch. In 1988, the parasitoid was recovered from two V. vulgaris nests at Pelorus Bridge, Marlborough.
Donovan et al. (1989) - one S. v. vesparum cocoon was recovered from a German wasp nest in Christchurch in November 1986 [see Cameron et al. (1989) entry above]; however, the lack of recovery of parasitoids from 385 nests collected in this area since November 1986 suggests that establishment of the parasitoid in Christchurch is unlikely. The parasitoid was recovered from two V. vulgaris nests at Pelorus Bridge, Marlborough in 1988 [see Cameron et al. (1989) entry above]; because parasitoids had multiplied in the nests (all propagation stages of the life cycle had been completed) and dispersed from them, it is likely S. v. vesparum has established at Pelorus Bridge.
Read et al. (1990) - Vespula nests were examined at 22 sites in the South Island and one at Ruakura, Waikato, North Island in the summer and autumn of 1988/89, and one at Pelorus Bridge, Marlborough, South Island in January 1990. Sphecophaga vesparum vesparum was only found at the Pelorus Bridge site; as these must have been field-developed individuals, this parasitoid is now considered established in New Zealand.
Barlow et al. (1998) - measurement of S. v. vesparum parasitism rates at Pelorus Bridge, Marlborough from the time of release (1987 and 1988) until 1993 indicates a rate of spread of 1 - 1.5 km per year. However, there is a very low rate of local increase (in the area it is already present), suggesting an approximate 3-fold increase in the total parasitoid population each year.
Donovan et al. (2002) - recovered from one German wasp (V. germanicus) nest in Christchurch (Mid-Canterbury) in 1986, and considered to have established at Pelorus Bridge (Marlborough) by 1988. By 1995 it was being recovered from 10% of common wasp (V. vulgaris) nests in foothills west of Christchurch and in 1998 was found in one common wasp nest in Christchurch.
Landcare Research (2016l) - the distribution of S. v. vesparum is limited to one site in Marlborough and one in Canterbury (both in the South Island). The poor establishment was probably the result of a genetic bottleneck due to rearing difficulties (one, or at best two, founder females) and a geographic mismatch between the target (originating from the UK) and agent (sourced from Switzerland, Germany and Austria) populations.
Landcare Research (2018l) - surveys for S. v. vesparum were carried out in 2018 in the View Hill area near Oxford, Canterbury and the Pelorus River area upstream of the Pelorus River Bridge in Marlborough; areas still known to have S. v. vesparum populations as recently as 2016. No S. v. vesparum were found in Vespula nests from View Hill, despite a highly-infested nest being found there in 2016. Of 42 nests surveyed in the Pelorus area, two nests had low level infestations of the parasitoid. This site has had intensive poison baiting over the past several years; it was reassuring there were any Sphecophaga recovered there at all.
Impacts on target:
Barlow et al. (1998) - while S. v. vesparum appears to be spreading relatively quickly at Pelorus Bridge, Marlborough, with an overall high rate of population growth [see Barlow et al. (1998) entry in the â€˜Establishmentâ€™ section], the carrying capacity, or local equilibrium level for the parasitoid appears to be low, in the sense that only about 10% of available Vespula nests are actually parasitised. It is the apparent low local equilibrium level and/or slow rate of local increase, rather than poor dispersive ability, which is likely to limit its future impact as a biological control agent of wasps.
Donovan et al. (2002) - during 1999 and much more so 2000-2002 the numbers of wasp nests were unusually low over wide areas. The cause of the collapse of wasp populations is unknown; however, the establishment of S. v . vesparum is the only new factor known to be killing wasps. If this parasitoid has established widely and is attacking small early-season nests, then it could be contributing to the reduced numbers of wasps observed later in summer.
Beggs et al. (2008) - assessing the impact of S. v. vesparum: the maximum proportion of Vespula nests parasitised was 17%, but there was no significant increase with time. However, there was an exponential reduction in the number of parasitoids produced per parasitised nest from a peak of 570 per nest in 1990 to only 15 in 2004. There was no evidence that the wasp population density at the parasitised site (Pelorus Bridge, Marlborough) had declined relative to the five sites where the parasitoid had not established. The parasitoid is unlikely to have had any significant effect on wasp populations hitherto, nor is it likely to impact host populations in the future.
Brown & Groenteman (2017), Bob Brown (Landcare Research) (2018 - pers. comm.) - in 2016 permission was granted to re-introduce new genetic stock of Sphecophaga vesparum vesparum. This involved an Environmental Protection Authority (EPA) ruling that S. v. vesparum was present in New Zealand prior to 29 July 1998 and therefore not a "new organism", so that EPA approval to import this species was not required, and Ministry for Primary Industries (MPI) import permits were issued in 2016 and 2017. The rationale in revisiting S. v. vesparum as a control agent was that insects collected for the original introductions came from a geographic range that poorly matched the geographic origin of Vespula in New Zealand, and that better-matched parasitoids may have a better capacity to evade nest hygiene and have an impact on Vespula populations. Recent DNA analysis has determined that the origin of New Zealand's common wasp is probably south-western UK.
Barlow ND, Beggs JR, Moller H (1998). Spread of the wasp parasitoid Sphecophaga vesparum vesparum following its release in New Zealand. New Zealand Journal of Ecology 22(2): 205-208 https://www.jstor.org/stable/24054693
Beggs JR, Rees JS, Toft RJ, Dennis TE and Barlow ND (2008). Evaluating the impact of a biological control parasitoid on invasive Vespula wasps in a natural forest ecosystem Biological Control 44 (3): 399-407
Brown B, Groenteman R. (2017). Vespula biocontrol in New Zealand revisited. Proceedings of the 5th International Symposium on Biological Control of Arthropods, Langkawi, Malaysia, September 11-15, 2017: 306-308 https://www.cabi.org/cabebooks/FullTextPDF/2017/20173267531.pdf
Cameron PJ, Hill RL, Bain J, Thomas WP (1989). A Review of Biological Control of Invertebrate Pests and Weeds in New Zealand 1874-1987. Technical Communication No 10. CAB International Institute of Biological Control. DSIR Entomology Division. 424p.
Donovan BJ, Havron A, Leathwick DM and JS. (2002). Release of Sphecophaga orientalis (Hymenoptera: Ichneumonidae: Cryptinae) in New Zealand as a possible 'new association' biocontrol agent for the adventive social wasps Vespula germanica (F.) and Vespula vulgaris (L.) (Hymenoptera: Vespidae: Vespinae). New Zealand Entomologist 25: 17-25 https://doi.org/10.1080/00779962.2002.9722090
Donovan BJ, Moller H, Plunkett GM, Read PEC, Tilley JAV (1989). Release and recovery of the introduced wasp parasitoid, Sphecophaga vesparum vesparum (Curtis) (Hymenoptera: Ichneumonidae) in New Zealand. New Zealand Journal of Zoology 16(3): 355-364 https://www.tandfonline.com/doi/pdf/10.1080/03014223.1989.10422900
Landcare Research (2016l). Wasp biocontrol update 7. Wasp biocontrol update: 7, July 2016. https://www.landcareresearch.co.nz/discover-our-research/biosecurity/invasive-invertebrates/vespula-wasps/wasp-biocontrol-updates/update-7/
Landcare Research (2016m). Wasp biocontrol update 9. Wasp biocontrol update: 9, November 2016 https://www.landcareresearch.co.nz/discover-our-research/biosecurity/invasive-invertebrates/vespula-wasps/wasp-biocontrol-updates/update-9/
Landcare Research (2017h). Wasp biocontrol update 11. Wasp biocontrol update: 11, August 2017 https://www.landcareresearch.co.nz/discover-our-research/biosecurity/invasive-invertebrates/vespula-wasps/wasp-biocontrol-updates/update-11/
Landcare Research (2017i). Wasp biocontrol update 12. Wasp biocontrol update: 12, 2017 https://www.landcareresearch.co.nz/discover-our-research/biosecurity/invasive-invertebrates/vespula-wasps/wasp-biocontrol-updates/update-12/
Landcare Research (2018l). Wasp biocontrol update 13. Wasp biocontrol update: 13, 2018 https://www.landcareresearch.co.nz/discover-our-research/biosecurity/invasive-invertebrates/vespula-wasps/wasp-biocontrol-updates/update-13/
Read PEC, Donovan BJ, Schroeder NC (1990). Rearing and distribution of the introduced wasp parasitoid Sphecophaga vesparum throughout New Zealand. Proceedings of the New Zealand Weed and Pest Control Conference 43: 191-194 https://journal.nzpps.org/index.php/pnzwpcc/article/view/10899/10731