Biocontrol introduction
Target pest: Helicoverpa armigera (Lepidoptera: Noctuidae), tomato fruitworm
Agent introduced: Microplitis croceipes (Hymenoptera: Braconidae) = Glabromicroplitis croceipes
Imported:
1986
Import source:
Mississippi, USA
Import notes:
Cameron et al. (1989) - Microplitis croceipes [as Glabromicroplitis croceipes - see Taxonomic note (28 July 2024) in 'General comments' section below] was first imported from the United States Department of Agriculture at Stoneville, Mississippi in 1986. It is the most successful and wide-ranging parasitoid of Helicoverpa and Heliothis species in the USA and has been successfully reared on Helicoverpa armigera in New Zealand.
Walker & Cameron (1989) - Microplitis croceipes [as Glabromicroplitis croceipes - see Taxonomic note (28 July 2024) in 'General comments' section below] was received from the United States Department of Agriculture, Stoneville, Mississippi in eight shipments from March 1986 to February 1988, totalling 1,075 cocoons. It accepted H. armigera as a new host and cultures were established in this species.
Released:
1987
Release details:
Cameron et al. (1989) - releases of M. croceipes commenced in January 1987 in Auckland, Gisborne (Poverty Bay) and Hastings (Hawke’s Bay) in the North Island.
Walker & Cameron (1989) - over 18,000 M. croceipes cocoons and parasitised H. armigera larvae were released in 1987 and 1988 in the Auckland, Gisborne and Hawke’s Bay regions of the North Island, mainly into lucerne crops.
Herman & Davidson (2000) - surveys in 1994-95 at the onset of a H. armigera outbreak in pine forests across the North Island volcanic plateau showed that M. croceipes was not present in these forests, leading to releases in this environment. Releases were made across three seasons (Jan-Apr 1996, Dec-Apr 1996-97, Dec-Apr 1997-98). A total of 4,400 M. croceipes pupae were released at 11 sites in four forests over the first two seasons, and 4,800 released at 10 sites in the same forests in the third season.
Establishment:
Cameron et al. (1989) - minor recoveries have been made in each of the release areas (Auckland, Gisborne, Hawke’s Bay).
Walker & Cameron (1989) - Microplitis croceipes was recovered at the Auckland, Gisborne and Hawke’s Bay release sites in April 1987, and recoveries in the Gisborne and Hawke’s Bay regions in 1988 and 1989 indicate the parasitoid has overwintered twice in these regions and suggest it has established there. It was not recovered from the Auckland site in 1989. The locations of the 1989 recoveries shows M. croceipes had dispersed 3-5 km from the original Gisborne and Hawke’s Bay release sites.
Herman & Davidson (2000) - Microplitis croceipes had spread at least 20 km by the 1990-91 in Gisborne and Hawke’s Bay, four years after its release. However, surveys in 1994-95 showed that it was not present in pine forests across the North Island volcanic plateau, leading to releases in this environment between January 1996 and April 1998 [see Herman & Davidson (2000) entry in ‘Release details’ section above]. Surveys of H. armigera over this period showed M. croceipes establishing in all four forests in which it was released and spreading 2-3 km from the release sites. Mean monthly parasitism (of larvae not parasitised by the biocontrol agent Cotesia kazak) by M. croceipes increased in all four forests over the three seasons, from 2.6% in 1995-96 to 10.7% in 1997-98.
Walker et al. (2005) - a survey of H. armigera parasitoids in a process tomato crop at Pukekohe [in the Auckland region of the North Island] from February to April 2004 showed that M. croceipes was relatively common (accounting for 13% of parasitism), whereas previous surveys have indicated that this species was only established on the East Coast of the North Island and the North Island volcanic plateau and rarely found in other regions.
Impacts on target:
Walker & Cameron (1989) - laboratory trials indicate that M. croceipes should complement Cotesia kazak [also released as a biocontrol agent against H. armigera], with C. kazak dominant in smaller host larvae and M. croceipes attacking larger larvae that have escaped C. kazak. This is supported by preliminary field results in which M. croceipes has been recovered mainly from larger H. armigera larvae. Mean levels of parasitism (of H. armigera larvae not parasitised by C. kazak) by M. croceipes in the Gisborne and Hawke’s Bay regions between January and April 1989 in lucerne, tomato and corn crops were 0-67%, though in one large lucerne area near Hastings [Hawke’s Bay] parasitism rates were 58-100%.
Cameron et al. (1993) - Microplitis croceipes, in conjunction with Cotesia kazak [see the C. kazak 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 M. croceipes, parasitism of H. armigera larvae by Cotesia kazak [previously introduced against H. armigera] 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. Monthly parasitism of H. armigera larvae (not parasitised by C. kazak) by M. croceipes in Gisborne and Hawke’s Bay increased over the first few seasons after its release and then generally fluctuated between 15 and 60%, although it was less than 10% in some months. Microplitis croceipes was released in North Island volcanic plateau pine forests between January 1996 and April 1998 [see Herman & Davidson (2000) entry in ‘Release details’ section above] and by the end of this period was parasitising 10.7% of H. armigera larvae (not parasitised by C. kazak) each month and was becoming an important mortality factor for collected H. armigera larvae.
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, Cotesia kazak and M. croceipes. Surveys in process tomatoes in Hawke’s Bay have shown that while C. kazak has remained the dominant parasitoid of H. armigera (although this will not necessarily be the case in other cropping systems where a wider range of alternative hosts are available as a reservoir for M. pulchricornis) [see the C. kazak introduction entry] levels of M. croceipes parasitism have dropped since the arrival of M. pulchricornis. From 1990 to 1996 M. croceipes parasitised 9.6-26.9% of H. armigera larvae, and from 1997 to 2003, after the arrival of M. pulchricornis, just 2.3-7.0%.
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 Cotesia kazak and M. 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 and in the 'Impacts on target' section of the C. kazak introduction record]. 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 survey of H. armigera parasitoids in a process tomato crop at Pukekohe [in the Auckland region of the North Island] from February to April 2004 showed M. croceipes accounting for 13% of parasitised larvae (the accidentally introduced Meteorus pulchricornis 54% and deliberately introduced Cotesia kazak 33%).
Impacts on non-targets:
Walker & Cameron (1989) - specificity of M. croceipes in New Zealand was tested in no-choice oviposition trials against six noctuid species common in New Zealand: H. armigera, Thysanoplusia orichalcea (soybean looper), Mythimna separata (cosmopolitan armyworm), Agrotis ipsilon (greasy cutworm), Chrysodeixis eriosoma (green looper) and Diarsia intermixta [orange peel moth]. Microplitis croceipes made no attempt to oviposit in larvae other than H. armigera, confirming it is specific to this host in New Zealand. Laboratory trials indicate that M. croceipes is unlikely to competitively displace Cotesia kazak [also released as a biocontrol agent against H. armigera]. Results show that C. kazak is dominant in smaller H. armigera larvae (4-10 mm), with successful parasitism of larger hosts uncommon, while M. croceipes preferred larger hosts (>10 mm) and only competed successfully with C. kazak in these hosts. Microplitis croceipes should therefore complement C. kazak by attacking larvae which have escaped this parasitoid.
General comments:
Taxonomic note (28 July 2024) - Papp (1986) transferred Microplitis croceipes to the genus Glabomicroplitis. However, Austin & Dangerfield (1993) placed the genus Glabromicroplitis into synonymy with Microplitis.
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
