Biocontrol introduction
Target pest: Lythrum salicaria (Myrtales: Lythraceae), purple loosestrife
Agent introduced: Nanophyes marmoratus (Coleoptera: Brentidae)
Release details:
Landcare Research (2025g) - no releases of N. marmoratus are planned until the impact of the other agents [approved for release against L. salicaria, namely Neogalerucella calmariensis, N. pusilla and Hylobius transversovittatus] have been fully assessed.
Impacts on non-targets:
Landcare Research (2023k) - host range testing for N. marmoratus was carried out prior to its introduction as a biocontrol agent into USA and Canada in the early-1990s. The 48 plant species tested were either taxonomically associated with L. salicaria, associated wetland plants of wildlife importance or important agricultural plants. The results indicated that N. marmoratus is highly host-specific to L. salicaria. In no-choice feeding tests a moderate amount of adult feeding was recorded on Lythrum hyssopifolia (present and fully naturalised in New Zealand) but oviposition and larval development were restricted to L. salicaria. In multichoice cage tests, new generation N. marmoratus adults were observed feeding on L. hyssopifolia at the end of the season after L. salicaria had died back but there was no oviposition. In New Zealand, there are no native plants and 12 exotic species (other than L. salicaria) in the family Lythraceae. Three exotic species are cultivated as ornamentals (Lythrum virgatum, Lagerstroemia indica, Lagerstroemia limii) and one, Punica granatum (pomegranate) is sporadically grown as a food plant.
General comments:
Landcare Research (2024e) - in the early-1990s, as part of their biocontrol programmes against L. salicaria, USA and Canada deployed the same four insect species that have been approved for release in New Zealand (Neogalerucella calmariensis, Neogalerucella pusilla, Hylobius transversovittatus and Nanophyes marmoratus). The agents have proven to be effective there, with populations of the weed reduced by up to 90% at some sites within the first decade. This presented an opportunity for New Zealand to piggy-back on these well-established programmes using the host range testing data and evidence from the field [see Landcare Research (2023k) entry in ‘Impacts on non-targets’ section above] to support a release application to the EPA for all four agents.
EPA Applications:
EPA (2024a) - 22 August 2023: application by Horizons Regional to import and release four Coleoptera insects (Neogalerucella calmariensis, Neogalerucella pusilla, Hylobius transversovittatus, and Nanophyes marmoratus) to control purple loosestrife (Lythrum salicaria). EPA Application # APP204535, approved without controls 7 May 2024.
References
EPA (2024a). Application to EPA (APP204535) to import and release four Coleoptera insects (Neogalerucella calmariensis, Neogalerucella pusilla, Hylobius transversovittatus, and Nanophyes marmoratus) to control purple loosestrife (Lythrum salicaria). Environmental Protection Authority website https://www.epa.govt.nz/database-search/hsno-application-register/view/APP204535
Landcare Research (2023k). Application to EPA (APP204535) to release new organisms: Neogalerucella calmariensis, Neogalerucella pusilla, Hylobius transversovittatus and Nanophyes marmoratus. Environmental Protection Authority website https://www.epa.govt.nz/assets/FileAPI/hsno-ar/APP204535/APP204535-1.-Application.pdf
Landcare Research (2024e). New EPA approvals. Weed Biocontrol: What's New? August 2024, 109: 4 https://www.landcareresearch.co.nz/publications/weed-biocontrol/weed-biocontrol-articles/new-epa-approvals/
Landcare Research (2025g). Who's who in biological control of weeds? Weed Biocontrol: What's New? August 2025, 113: 10-11 https://www.landcareresearch.co.nz/assets/Publications/Weed-biocontrol/Issue-113/weed-biocontrol-issue-113.pdf
