Biocontrol introduction
Target pest: Bactericera cockerelli (Hemiptera: Triozidae), Tomato/potato psyllid (TPP)
Agent introduced: Tamarixia triozae (Hymenoptera: Eulophidae)
Imported:
2017
Import source:
Mexico
Import notes:
Barnes (2017) - the first shipment of T. triozae received from Mexico (2017) was found to have fungal contamination, so could not be released. A second 'clean' batch was imported in July 2017. Those individuals were reared and the F1 progeny were those approved by the Ministry for Primary Industries (MPI) for the first releases. A condition of the current MPI import permit is that "imported parasitoids will be reared in quarantine through one generation, and once this is completed, all Tamarixia triozae adults from the original imported product will be destroyed." [See Davidson et al. (2023) entry below for more details.]
Davidson et al. (2023) - between June and September 2017, approximately 1,000 T. triozae adults from Biobest Mexico and another 1,000 adults from Koppert Mexico were imported into containment at Auckland. The imported parasitoids were confirmed free of any external fungal hyphae and the first generation of T. triozae was approved for release out of containment in August 2017. Samples of T. triozae used for the gene sequencing analysis (10 females and 10 males of those released out of containment) were shown to contain two haplotypes out of the six described in 2010 from a study in Texas, USA. Following release from quarantine, T. triozae was reared in temperature-controlled rooms at Lincoln, Canterbury from August 2017 to June 2018 for the first summer releases between November 2017 and February 2018, and in small greenhouses at Lincoln for the second summer releases from November 2018 to March 2019. A company that received T. triozae from the colony at Auckland was supplying the parasitoid to commercial growers and home gardeners by the third summer (November 2019 - March 2020).
Released:
2017
Release details:
Barnes (2017) - 400-500 T. triozae were released at three sites in Hawke's Bay in August 2017, and a further 150 were released at two sites in Canterbury in early September. They were released onto African boxthorn (Lycium ferocissimum) plants, where overwintering populations of TPP can be found, as there were no host crops such as potatoes or tomatoes in the ground at the time of release. Ways of establishing a supply of T. triozae for releases this summer (2017/18) are being investigated. One option is to use a local commercial biocontrol agent supplier to rear the parasitoid. [See Davidson Olaniyan et al. (2020) - the Bio-Protection Research Centre (BPRC) at Lincoln University, New Zealand, in partnership with industry stakeholders, is culturing this parasitoid in large numbers; approximately 8,000 wasps have been provided to commercial tomato growers in New Zealand to date for inundative releases.[NB: the inundative releases are independent of the 'classical biological control' releases intended to establish permanent populations detailed in the Davidson et al. (2023) entry below.] Davidson et al. (2023) - all releases were as adults, from vials (maximum of 250 adults per vial) attached to B. cockerelli host plants, within 48 hours of collection of T. triozae from colonies. In the first summer (November 2017 - February 2018), 800 T. triozae were released at one site in Auckland, North Island, 580 at three sites in Hawke’s Bay, North Island and 1,060 at two sites in Canterbury, South Island. The Auckland release was by a grower onto vegetation surrounding commercial tomato greenhouses, the Hawke’s Bay and Canterbury releases were carried out by Plant and Food Research onto African boxthorn, a perennial B. cockerelli host plant. At all release sites in subsequent summers (November 2018 - March 2019, November 2019 - mid-March 2020) the parasitoid was released by growers, primary industry personnel or home gardeners. The growers released T. triozae in organically grown Solanaceae crops (potatoes, tomatoes, or tamarillos) or in surrounding non-crop vegetation. In the 2018-19 summer there were releases at one site in Auckland (2,900), four sites (including the three 2017-18 release sites) in Hawke’s Bay (3,400) and four sites (including one of the 2017-18 release sites) in Canterbury (1,400); in the 2019-20 summer, 20,600 parasitoids were released at 34 sites throughout New Zealand.
Establishment: Davidson et al. (2023) - surveys in the 2018-19 and 2019-20 summers at the Auckland, Hawke’s Bay and Canterbury release sites and a survey in the 2019-20 summer of B. cockerelli host plants within a 30 km radius of the first summer release sites in Hawke’s Bay and Canterbury indicate T. triozae has successfully established in New Zealand. Tamarixia triozae was recovered in the second (January 2019) and third summer (January 2020) at the Canterbury release site where it had only been released in the first summer (2017-18), suggesting the parasitoid population had survived over two consecutive winters. It was recovered in the second (December 2018) and third summer (December 2019) from the three Hawke’s Bay sites and second Canterbury site where it had been released in the first summer. However, because of releases in subsequent years at or near these sites, survival of T. triozae over winter at these sites could not be confirmed. No T. triozae were recovered from the Auckland site. Of the 86 non-release sites surveyed in Hawke’s Bay, B. cockerelli were found at 38 sites, with T. triozae recorded at 24 of these sites, up to 24 km from the nearest known release site. In Canterbury, B. cockerelli parasitised by T. triozae were found at two of the 13 non-release sites surveyed, at a maximum of 0.6 km from the nearest release site. Field parasitism rates of 13.7 - 15.6% were estimated based on two post-release survey methods employed in this study.
Impacts on target: Olaniyan et al. (2020) - preliminary trials in New Zealand indicate that inundative releases of T. triozae in combination with the generalist predatory mite Amblydromalus limonicus may have potential for B. cockerelli control on tomatoes in glasshouses. Veronesi et al. (2022) - in a glasshouse study, a combined treatment of T. triozae and the mirid bug Engytatus nicotianae [exotic and established in New Zealand] showed a consistent and significant reduction of B. cockerelli (TPP)-infested leaves as well as TPP populations, suggesting a combination of the two species might deliver a biological control of TPP under glasshouse conditions. Further research is needed to determine the optimum ratio of T. triozae and E. nicotianae release-densities under different levels of TPP infestation and how this may translate from caged conditions to greenhouse performance.
Impacts on non-targets: Gardner-Gee (2012) - pre-release host range testing was conducted against seven New Zealand native psyllid species (including four species of Trioza) and the exotic psyllid Arytainilla spartiophila (introduced to New Zealand as a biological control of broom). In no-choice screening tests, T. triozae oviposited on two native psyllid species, Trioza curta and Trioza panacis. Oviposition rates on both were lower than on B. cockerelli. In addition, no adult parasitoids emerged from parasitised T. curta, and those emerging from T. panacis had reduced reproductive capability compared to those emerging from B. cockerelli. These tests indicate that T. triozae will attempt to use novel species as hosts, and can develop in at least some of these species. Consequently T. panacis, and possibly other native psyllid species, could act as hosts for T. triozae. The impacts of this non-target parasitism are unlikely to be severe for widespread and abundant psyllid species, but rare species may be vulnerable.
General comments: Olaniyan et al. (2020) - T. triozae was approved for importation and mass release in New Zealand mainly to suppress B. cockerelli populations on non-crop hosts and secondarily for inundative release trials in tomato glasshouses. Davidson et al. (2023) - sequencing results [see Davidson et al. (2023) entry in ‘Import notes’ section] indicated the T. triozae material imported into New Zealand contained two of the six haplotypes reported for T. triozae in 2010. The consequences of this with respect to the genetic diversity and effectiveness of the parasitoid in New Zealand are unclear since the T. triozae analysed in the 2010 study were collected from a single population at Weslaco, Texas, USA.
EPA Applications: EPA (2016c) - 27 Jan 2016: application by Horticulture New Zealand Inc. to release from containment the psyllid parasitoid Tamarixia triozae into New Zealand to assist with the biological control of the tomato potato psyllid (Bactericera cockerelli). EPA Application # APP201955, approved without controls 17 June 2016.
Barnes H. (2017). New biocontrol agent released. NZ Grower, 1 October 2017. Horticulture New Zealand magazine
Davidson M, Sachtleben T, MacDonald F, Watkins L, Barnes A-M, Drayton G, Walker M (2023). The establishment and spread of Tamarixia triozae, a parasitoid of the potato psyllid, in New Zealand. BioControl 68(4): 363-373 https://doi.org/10.1007/s10526-023-10194-6
EPA (2016c). EPA application APP201955: to release from containment the psyllid parasitoid Tamarixia triozae into New Zealand to assist with the biological control of the tomato potato psyllid (Bactericera cockerelli). Environmental Protection Authority website https://www.epa.govt.nz/database-search/hsno-application-register/view/APP201955
Gardner-Gee R. (2012). Risks to non-target species from the potential biological control agent Tamarixia triozae, proposed for use against Bactericera cockerelli in New Zealand: A summary of host-range testing. PFR SPTS No. 7296. A report prepared by Plant and Food Research for Horticulture New Zealand. https://www.epa.govt.nz/assets/FileAPI/hsno-ar/APP201955/c7f0f09eb6/APP201955-APP201955-Appendix-9.1-Robin-Gardner-Gee-Host-range-testing-26.01.2016.pdf
Olaniyan O, Rodríguez-Gasol N, Cayla N, Michaud E, Wratten SD (2020). Bactericera cockerelli (Sulc), a potential threat to China's potato industry. Journal of Integrative Agriculture 19(2): 338-349 https://www.sciencedirect.com/science/article/pii/S2095311919627541
Veronesi ER, Wratten SD, van Koten C, Goldson SL (2022). Potential of the mirid bug Engytatus nicotianae, and the parasitic wasp Tamarixia triozae for the biological control of the tomato-potato psyllid; a cage greenhouse assay. New Zealand Journal of Crop and Horticultural Science, 6 Dec 2022: 1-8 https://doi.org/10.1080/01140671.2022.2152843
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