Biocontrol introduction
Target pest: Helicoverpa armigera (Lepidoptera: Noctuidae), tomato fruitworm
Agent introduced: Cotesia kazak (Hymenoptera: Braconidae) = Apanteles kazak
Imported:
1977
Import source:
Bulgaria and Greece
Import notes:
Cameron et al. (1989) - Cotesia kazak was collected from Helicoverpa amigera in Bulgaria and Greece by the Commonwealth Institute of Biological Control and reared on Heliothis virescens for shipment to New Zealand in 1977.
Released:
1978
Release details:
Cameron et al. (1989) - approximately 3,500 adults or parasitised larvae were released over two seasons from 1978 to 1980 at 30 sites in Northland, Auckland, Bay of Plenty and Gisborne in the North Island. It was redistributed to Marlborough in the South Island in 1985 through the release of 85 cocoons at one lucerne site.
Establishment:
Cameron et al. (1989) - widely established in vicinity of all North Island release sites by 1982. Natural dispersal of approximately 100 km per year has spread the C. kazak to Waikato and Hawke’s Bay but not to Manawatu. Recoveries from four sites in Marlborough in 1987 indicate the parasitoid has established there.
Impacts on target:
Cameron et al. (1989) - by 1986 parasitism rates frequently exceeded 60%, resulting in fewer H. armigera larvae reaching damaging size and a reduction in crop damage. However, this parasitoid is not sufficient on its own to eliminate economic damage by H. armigera in unsprayed crops and the introduction of further biocontrol agents is warranted.
Walker & Cameron (1989) - in unsprayed tomato crops in the Gisborne and Hawke’s Bay regions between January and April 1989, levels of parasitism (of H. armigera larvae <15 mm) by C. kazak were consistently high (36-99%).
Cameron et al. (1993) - Cotesia kazak, in conjunction with Microplitis croceipes [see the M. croceipes introduction entry], is categorised as exerting “partial” control (defined as “additional control remains commonly necessary but…pest outbreaks occur less frequently”) over Helicoverpa armigera. In tomato crops the establishment of these parasitoids of H. armigera has allowed the development of IPM [integrated pest management] programmes that have decreased the need for insecticide spraying.
Herman & Davidson (2000) - prior to the introduction of Microplitis croceipes in 1987 as a biocontrol agent for H. armigera, parasitism of H. armigera larvae by C. kazak averaged 42-52% in tomato and soybean crops in Pukekohe [South Auckland]. After M. croceipes established in Gisborne and Hawke's Bay, total parasitism of H. armigera, by both parasitoids, increased to 60-80% in these regions.
Berry & Walker (2004) - the accidentally introduced generalist parasitoid Meteorus pulchricornis was first reared from H. armigera from process tomatoes in Hawke’s Bay in 1997. In 1998 it parasitised up to 30% of H. armigera in this crop, indicating it might be competing with both of the deliberately introduced biocontrol agents of this pest, C. kazak and Microplitis croceipes. Surveys in process tomatoes in Hawke’s Bay have shown that while levels of M. croceipes parasitism have dropped since the arrival of M. pulchricornis [see the M. croceipes introduction entry], C. kazak has remained the dominant parasitoid of H. armigera. From 1990 to 1996 C. kazak parasitised 39-73.5% of H. armigera larvae, and from 1997 to 2003, after the arrival of M. pulchricornis, 39-66%. The ability of C. kazak to attack smaller larvae and develop more quickly than M. pulchricornis, advantages of being a specialist and the restricted number of alternative hosts available as a reservoir for M. pulchricornis may explain why C. kazak has not been disrupted by M. pulchricornis in Hawke’s Bay tomato crops. However, the impact that M. pulchricornis may have on C. kazak in other cropping systems where a wide range of alternative hosts will be available is cause for concern. For example, 53% of H. armigera larvae collected from various crops and weeds in Pukekohe (South Auckland) in 2003 were parasitised; M. pulchricornis was the predominant parasitoid (89% of parasitised larvae), while C. kazak and M. croceipes were reared from 7% and 4% respectively [see Walker et al. (2004) entry below in this section, and note that it reports 49% total H. armigera parasitism rather than 53%]. The equivalent figures in the same season in Hawke’s Bay tomatoes were 65% total parasitism, of which 2% were M. pulchricornis, 90% C. kazak and 8% M. croceipes.
Walker et al. (2004) - a survey of lepidopteran larvae on vegetable crops and associated weeds at Pukekohe [South Auckland] from December 2002 to June 2003 showed 49% of H. armigera larvae parasitised (a relatively low rate probably due to the application of broad-spectrum insecticides to some crops). The accidentally introduced parasitoid Meteorus pulchricornis accounted for 89% of parasitised larvae while the deliberately introduced parasitoids C. kazak and Microplitis croceipes only 7% and 4% respectively. This is in contrast to a 2003 survey in tomatoes in Hawke’s Bay, where C. kazak remained the dominant parasitoid [see Berry & Walker (2004) entry above in this section]. Therefore, it appears that M. pulchricornis may be competitively displacing C. kazak and perhaps M. croceipes at Pukekohe, where the availability of alternative hosts for the generalist M. pulchricornis (compared to Hawke’s Bay tomato crops, where there are few alternative hosts) may lead to the build-up of large populations of this parasitoid.
Walker et al. (2005) - a study in a process tomato crop was undertaken at Pukekohe [in the Auckland region of the North Island] from February to April 2004 to investigate the interactions between H. armigera and its larval parasitoids, the accidentally introduced generalist, Meteorus pulchricornis, and the deliberately introduced specialists, Cotesia kazak and Microplitis croceipes. Total mortality from parasitism was 74.6%, with M. pulchricornis the dominant parasitoid, being reared from 54% of parasitised H. armigera larvae, while 33% produced C. kazak and 13% M. croceipes. Meteorus pulchricornis appears to be competitively displacing C. kazak as the dominant parasitiod of H. armigera at Pukekohe, in contrast to the situation in process tomatoes in Hawke’s Bay, where in 2003 90% of parasitised larvae were parasitised by C. kazak, 8% by M. croceipes and just 2% by M. pulchricornis, with similar patterns observed in 2002 and 2004. This may be due to the ready availability of alternative hosts as a reservoir for the generalist M. pulchricornis at Pukekohe, while a restricted number of alternative hosts are available near tomato crops in Hawke’s Bay. While the displacement of C. kazak as the dominant parasitoid of H. armigera at Pukekohe is ostensibly having little impact on the biocontrol of this pest in tomatoes, there may be an economic impact, as C. kazak kills its host at a smaller size than M. pulchricornis, before they damage fruit.
References
Berry JA, Walker GP (2004). Meteorus pulchricornis (Wesmael) (Hymenoptera: Braconidae: Euphorinae): An exotic polyphagous parasitoid in New Zealand. New Zealand Journal of Zoology 31(1): 33-44 https://doi.org/10.1080/03014223.2004.9518357
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
Herman TJB, Davidson MM (2000). Introduction and establishment of Microplitis croceipes, a larval parasitoid of heliothis in North Island pine forests. New Zealand Plant Protection 53: 328-33 https://doi.org/10.30843/nzpp.2000.53.3624
Walker GP, Cameron PJ (1989). Status of introduced larval parasitoids of tomato fruitworm. Proceedings of the New Zealand Weed and Pest Control Conference 42: 229-232 https://doi.org/10.30843/nzpp.1989.42
Walker GP, Herman TJB, Qureshi MS, Winkler S, Wallace AR (2005). Parasitism of tomato fruitworm larvae in process tomatoes at Pukekohe. New Zealand Plant Protection 58: 224-28 https://doi.org/10.30843/nzpp.2005.58.4277
Walker GP, Qureshi MS, Wallace AR (2004). Parasitism of lepidopteran larvae collected from vegetables and associated weeds at Pukekohe. New Zealand Plant Protection 57: 1-7 https://doi.org/10.30843/nzpp.2004.57.6932
