Biocontrol introduction
Target pest: Cavariella aegopodii (Hemiptera: Aphididae), carrot-willow aphid
Agent introduced: Aphidius salicis (Hymenoptera: Braconidae)
Imported:
Teulon et al. (2008) - accidental introduction. Aphidius salicis has been recorded in New Zealand since at least 1962.
Released:
Teulon et al. (2008) - accidental introduction. Aphidius salicis has been recorded in New Zealand since at least 1962.
Impacts on target:
Teulon et al. (2008) - while carrot-willow aphid is a serious pest of carrots in New Zealand, there is little information on the impact of the A. salicis.
Impacts on non-targets:
Teulon et al. (2008) - DNA sequencing of parasitoids attacking New Zealand native aphids, from collections made since 1998, mostly in the South Island, found a range of braconid and aphelinid species. While some species have yet to be fully characterised and may be New Zealand native parasitoids new to science and other species need to be verified using morphological characters, one Aphidius sp. attacking Aphis healyi is a putative introduced species.
Bulman et al. (2021) - to identify Aphidiinae parasitoids [the subfamily of family Braconidae to which Aphidius belongs] of native New Zealand aphids, native aphids were collected throughout the South Island between 2006 and 2018. Aphidiinae parasitism was rare; in total, parasitism was observed from eight native aphid species at 16 locations. All cases of parasitism were by phylogenetically related native Aphidiinae, 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 Aphidiinae was found.
General comments:
Teulon et al. (2008) - Aphidius salicis was intentionally released as a biocontrol agent of C. aegopodi in Australia in 1962; its introduction and a change in the predominant carrot cultivar grown significantly reduced the pest status of carrot-willow aphid in that country.
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
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
