Biocontrol introduction
Target pest: Sirex noctilio (Hymenoptera: Siricidae), sirex wood wasp
Agent introduced: Megarhyssa nortoni nortoni (Hymenoptera: Ichneumonidae)
Imported:
1962, 1963, 1964
Import source:
California, USA
Import notes:
Cameron et al. (1989) - adult M. n. nortoni were received from the California Station of the Commonwealth Institute of Biological Control in 1962 (two females), 1963 (one male, two females) and 1964 (144 males, 233 females). Oviposition in an insectary onto S. noctilio larvae occurred and the first progeny emerged in 1963. The last two consignments in 1964 were not used for colony rearing but released directly into the field. Insectary culturing for releases continued for the next six years.
Released:
1964
Release details:
Cameron et al. (1989) - two consignments of adults received in 1964 were directly released; for the following six years releases were of insectary-reared individuals, after which specimens for liberation were obtained from established populations in the field. The 1964 releases of imported individuals were at Waitangi (Northland, North Island); the first reared individuals were released at Tairua (Waikato, North Island) and the parasitoid was eventually released in 33 forests and plantations.
Establishment:
Cameron et al. (1989) - by 1988 M. n. nortoni had been recovered from 17 of the 33 forests and plantations in which it had been released and was known to have spread naturally to 23 other localities.
Impacts on target:
Cameron et al. (1989) - the presence of successfully introduced parasitoids [including M. n. nortoni], together with the accidentally introduced nematode Deladenus siricidicola [subsequently reclassified as Beddingia siricidicola] and good forest management has been effective in keeping losses caused by S. noctilio at a low level. The combined effect of the introduced parasitoids may kill over 70% of S. noctilio larvae in a particular forest.
Cameron et al. (1993) - Megarhyssa nortoni nortoni, in conjunction with Ibalia leucospoides leucospoides, Ibalia leucospoides ensiger and Rhyssa persuasoria persuasoria [see the I. l. leucospoides, I. l. ensiger and R. p. persuasoria introduction entries], is categorised as exerting “partial” control (defined as “additional control remains commonly necessary but…pest outbreaks occur less frequently”) over Sirex noctilio. The partial control of S. noctilio exerted by these biocontrol agents is augmented by a naturally occurring nematode [Beddingia siricidicola - see Cameron et al. (1989) entry above in this section] (the prime factor in control of this pest) to provide overall substantial control of S. noctilio.
Bain et al. (2012) - Sirex noctilio is now considered only a minor pest in New Zealand. Control has been achieved by a combination of forest management practices and the presence of natural enemies, including the parasitoids Rhyssa persuasoria persuasoria, Megarhyssa nortoni nortoni (in some localities M. n. nortoni has achieved parasitism rates of about 90%), Ibalia leucospoides leucospoides and the nematode Beddingia siricidicola. Over the entire 1980-2010 period, in over 98,000 forest health inspections in Pinus radiata forests, only 974 records of S. noctilio were found. Only 0.5% of inspections from 2000 to 2009 mention S. noctilio. The total number of records has declined over the past three decades, and the number of reports of high to severe damage has declined markedly. In the 1980s there were 248 records of high to severe damage, from 2000 to 2009 only 34. Since 2000, well over half the records made were of secondary attack, insects found in forest debris such as thinning slash or stumps, or of negligible damage, compared with one third of the records made in the 1980s.
References
Bain J, Sopow SL, Bulman LS (2012). The Sirex woodwasp in New Zealand: history and current status. In: Slippers B, de Groot P, Wingfield M (eds) The Sirex Woodwasp and its Fungal Symbiont. Springer, Dordrecht. https://doi.org/10.1007/978-94-007-1960-6_13
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.
Cameron PJ, Hill RL, Bain J, Thomas WP (1993). Analysis of importations for biological control of insect pests and weeds in New Zealand. Biocontrol Science and Technology 3(4): 387-404 https://doi.org/10.1080/09583159309355294
