Biocontrol introduction
Target pest: Tuberculatus annulatus (Hemiptera: Aphididae), oak aphid
Agent introduced: Aphelinus subflavescens (Hymenoptera: Aphelinidae)
Imported:
Cameron et al. (1989) - imported in 1939, but was already present in New Zealand. The programme to introduce A. subflavescens as a biocontrol agent in Australia in 1936 created interest in New Zealand, although it was advised that this parasitoid was already common on oak aphid in Nelson (upper South Island).
Import source:
Europe via Australia
Import notes:
Cameron et al. (1989) - all the importations into New Zealand appear to have originated from the Australian biocontrol programme. There was some doubt about the origin because of Department of Scientific and Industrial Research files indicating Europe as the source, but presumably these refer to the original source.
Valentine & Walker (1991) - Aphelinus subflavescens was introduced into New Zealand in 1939 under the name Aphelinus flavus, a misidentification.
Released:
1939
Establishment:
Cameron et al. (1989) - A. subflavescens has been reared out of oak aphid from Christchurch, Nelson and Auckland, but it is uncertain if the imported A. subflavescens established.
Impacts on target:
Cameron et al. (1989) - as there are no reported field studies of oak aphid and few records of A. subflavescens the importance of the parasitoid is unclear. It was reported in Department of Scientific and Industrial Research files that before the introduction A. subflavescens became extremely abundant each year towards autumn. Oak aphid is presently not considered to be a problem in New Zealand except on occasional ornamental trees.
Teulon et al. (2008) - oak aphid is no longer considered a significant problem, suggesting that A. subflavescens was a successful biocontrol agent.
Impacts on non-targets:
Bulman et al. (2021) - to identify parasitoids of native New Zealand aphids, native aphids were collected throughout the South Island between 2006 and 2018. Parasitism was rare; in total only observed from eight native aphid species at 16 locations. All cases of parasitism were by phylogenetically related native Aphidiinae [a subfamily of family Braconidae that use aphids as hosts], and it seems reasonable to conclude that this is the predominant parasitoid threat that these aphids experience. The total number of parasitoids located was low due to the rarity of the aphid hosts themselves, so the possibility of infrequent interactions between biocontrol agents and endemic aphids cannot be eliminated. However, over the 14-year collection period of this study, no examples of native aphid parasitism by introduced parasitoids was found.
References
Bulman S, Drayton GM, Cameron PJ, Teulon DAJ, Walker GP (2021). Endemic New Zealand aphids (Hemiptera: Aphididae) parasitised by native Aphidiinae (Hymenoptera: Braconidae), not biological control parasitoids. Austral Entomology 60(4): 713-721 https://doi.org/10.1111/aen.12564
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.
Teulon DAJ, Drayton GM, Scott IAW (2008). Exotic introductions of primary parasitoids of aphids in New Zealand: the good and the bad. In: Proceedings of the Third International Symposium on Biological Control of Arthropods (eds PG Mason, DR Gillespie & C Vincent), pp. 421–430. USDA, Forest Service, Morgantown, WV. https://www.cabi.org/ISC/FullTextPDF/2009/20093074320.pdf
Valentine EW, Walker AK (1991). Annotated catalogue of New Zealand Hymenoptera. New Zealand Dept. of Scientific and Industrial Research, Plant Protection Report No. 4
