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Biocontrol introduction

Target pest: Sirex noctilio (Hymenoptera: Siricidae), sirex wood wasp

Agent introduced: Ibalia leucospoides ensiger (Hymenoptera: Ibaliidae)


1963, 1966-1968

Import source:

1963 California, 1966-1968 USA via Tasmania

Import notes:

Cameron et al. (1989) - in 1963, 19 male and 24 female adults were received from CIBC station in California. Many were carrying mites which were removed with a fine brush dipped in alcohol. The wasps were sluggish, oviposition was not observed and no progeny were obtained. In 1966 (110 males, 100 females), 1967 (188 males, 186 females) and 1968 (99 males, 98 females) were received from CSIRO, Tasmania, from cultures sent there from USA in 1963. All 1966 specimens were used for insectary culture, although 33 females were released after oviposition. Fifty of each sex received in 1967, and 23 males and 24 females received in 1968, were retained for insectary culture and the rest released. Culturing ceased in 1970.



Release details:

Cameron et al. (1989) - not released in 1963. In 1966, 33 imported females (after oviposition in insectary) were released at Berwick (Otago). In 1967, releases were made in Kaingaroa (Bay of Plenty), Omihi (North Canterbury) and Tahorakuri (near Taupo), and in 1968 in the Otago Coast Forest (south of Dunedin) and at Ashley (North Canterbury). The 1967 and 1968 releases comprised a mix of imported adults and insectary emergents. Liberation of reared specimens continued to 1971 when the last release was made at Motueka (Nelson). In total 1,883 males and 1,729 females were released in 14 forests.


Cameron et al. (1989) - first recovered in 1968. Recoveries have been made from 6 of the 14 forests it was released in but because of inbreeding with Ibalia leucospoides leucospoides it has not been recognised in collections since 1976.

Hurley et al. (2020) - an investigation of I. leucospoides in its native and introduced ranges found no evidence that the subspecies I. leucospoides ensiger has established (or hybridised with I. l. leucospoides) outside its native range. [Note though, that specimens from the introduced range used in the study did not include insects from New Zealand; only South Africa, Chile, Argentina and Australia.]

General comments:

Hurley et al. (2020) - two sub-species of the parasitoid I. leucospoides (I. l. leucospoides and I. l. ensiger) have been introduced to the southern hemisphere as a biological control agent for Sirex noctilio and are reported to have hybridised. However, an investigation of the genetic variation of I. leucospoides in its native and introduced ranges using mitochondrial (COI) and nuclear (ITS) markers found no evidence of hybridisation between the two sub-species of the parasitoid in its introduced range. [Note though, that specimens from the introduced range used in the study did not include insects from New Zealand, only South Africa, Chile, Argentina and Australia.]


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.

Hurley BP, Fitza KNE, Wingfield MJ, Slippers B. (2020). Sequence data reflect the introduction pathways of the Sirex woodwasp parasitoid, Ibalia leucospoides (Ibaliidae, Hymenoptera). Agricultural and Forest Entomology 22(2): 129-135 https://doi.org/10.1111/afe.12367