Matthew W. F. Howse

In Aotearoa New Zealand (A-NZ), Norway rats ‘ Rattus norvegicus ’ have a grievous effect on many taonga ‘culturally prized’ species of flora and fauna. This is of concern to Indigenous Māori as customary and future guardians of the natural environment. This ecological crisis has prompted consideration of new management tools to aid the existing suite of tools. Scientists are exploring a next-generation transgenic tool, single-sex offspring selection (SSOS), theoretically capable of producing a landscape-scale population-collapse for Norway rats. As novel biotechnologies, like SSOS, are often framed within Western-scientific understandings, this research sought to recentre Māori opinions in Predator-free Aotearoa 2050-focused discourse and gauge the degrees of acceptability – or otherwise – of SSOS. 20 participants engaged with a video ‘primer’ explaining SSOS, of which 18 undertook Q-Method preference rankings, and semi-structured one-on-one interviews or focus groups to determine degree of acceptance for various aspects of SSOS in pest control. Data analysis identified three ‘factors’ that capture the divergent views subgroups have about SSOS: those being, Factor 1, Kia māia ‘Be bold’ as the potential benefits of SSOS warrant further exploration; Factor 2, Kia tūpato ‘Be careful’ to ensure risks are mitigated as we await ‘proof of concept’; and Factor 3, Kia mataara ‘Be alert’ to the potential for unintended consequences. Overall, while most support ongoing research into next-generational rat-control methods, including SSOS, the consensus view, Kia tika ‘Be just, correct’ indicates such support is caveated with concerns about safety and risk, and the degree to which Māori, as an 1840 Tiriti o Waitangi co-signatory, exercise tino rangatiratanga ‘absolute chieftainship’ over the decision-making and management of taonga , invasive, and transgenic species alike.

Social support for pest management programs is essential to their success. In this study, we explored stakeholder perceptions of current wasp management and what attempting eradication means for them. Local stakeholders involved in 7 conservation or pest management projects across Aotearoa New Zealand were interviewed. Q‐method analysis identified two major perspectives across the participants. A target‐driven and ambitious perspective emerged where eradication of invasive wasps was the objective and any control method deemed effective could be used to achieve that goal. Negative impacts of management could be justified by removing the larger negative impact of wasps on the environment. The second perspective identified agreed that wasps must be managed but were characterised as more holistically minded. Control methods perceived to have negative impacts to the wider ecosystem were deemed less acceptable. Education and engagement were highlighted as essential to increase local support for future wasp management. Developing pest management strategies informed by mana whenua is especially crucial, and hapū enabled to draw on their mātauranga Māori may provide new insights into developing effective and acceptable pest management practices. Emphasis not just on technical but social and cultural aspects of wasp eradication and control will be vital for successful wasp management. Glossary of Māori words: Hapū: subtribal group; iwi: tribal group; maramataka: Māori lunar calendar; mātauranga Māori: Māori knowledge systems; mauri: life force or vital essence; taonga: precious thing or treasure; tapu: sacred, restricted or prohibited; te ao Māori: Māori worldview; tohu: a sign or indication; whakapapa: genealogy or line of descent

Studying the efficacy of control methods is paramount to successful management of invasive pests and understanding why some colonies survive is important to improve management practices. Here, the bait Vespex® was used to control invasive wasps across 64 ha of forest in an invaded range near Hanmer Springs, New Zealand. Bait was applied across a standard 50 m by 300 m arrangement and made available for 3 days. Nest mortality rates after 19 days were 29.8%, although nearly all nests were affected with a median overall reduction in nest traffic of 96.5%. The results from logistic regression showed that, all else remaining equal, larger wasp nests, nests further from bait stations, and more isolated nests exhibited lower rates of mortality after baiting. Investigating the change in activity at surviving nests, the results from beta regression suggest that declines in nest traffic were less severe with increasing distance to the nearest bait, but more severe with increasing nest size. These results indicate that while smaller nests are at a higher risk of being killed by the bait, they may not encounter bait as regularly as larger nests. Bait uptake varied considerably across bait stations. Wasp nests were not randomly or uniformly distributed in space, and instead were aggregated across our treatment area, likely due to some aspects of environmental conditions. We suggest further research to be focused on developing an understanding of the drivers of wasp nest development and foraging behaviour, to produce a more flexible baiting procedure that will increase both baiting efficiency and efficacy.

Social insects are successful and globally significant invaders. Compared to ongoing suppression, eradication is seen as an ideal solution and cost effective in the long term. The success of eradication attempts is not guaranteed and identifying key factors that could influence the success of such management programs would be beneficial. In this study, 239 eradication attempts were compiled and analysed to identify why eradication attempts fail, with a focus on how eusociality of the target species impacts eradication success. All else remaining constant, the odds of successful eradication were 79% lower when targeting social species compared to non-social insects. Eradication success was shown to increase when comparing more recent attempts to earlier ones but was found to decrease as the duration of the attempt went on. Eradication attempts that occurred on islands, and those that targeted species with a broader host range, were also associated with increased success. A review of cited reasons for eradication failure highlighted the importance of employing effective control treatments, management, and monitoring systems, as well as garnering adequate social and political support. This study indicates how social insects are particularly challenging to eradicate; it also notes the importance of considering both logistical and biological aspects of any eradication, before initiating eradication attempts.

Social wasps are invasive in many regions around the world. In their new communities, introduced predators such as these wasps may be beneficial as consumers of exotic pests, but they will also consume native species. Here, we examined the diet of the exotic European paper wasp (Polistes dominula) and the closely related congener, Polistes chinensis, in a region of New Zealand where they co-occur. DNA barcoding was used to analyse their diet. The diet of both wasp species was largely Lepidopteran but other orders such as Hemiptera, Diptera and Coleoptera were also represented. Our analysis showed substantial site-to-site variation in diet. The two wasps differed significantly in their prey, although these differences appear to be driven by taxa identified from a small number of DNA reads in a small number of samples. Native and introduced fauna were represented in the diets of both wasps and included important agricultural pests. Of the 92 prey taxa able to be identified to species level, 81 were identified as exotic or introduced to New Zealand. The remaining 11 were species native to New Zealand. However, our estimates suggest over 50% of the prey DNA in the wasp diet is derived from native species. These wasps are abundant in some coastal and urban habitats, where they are likely to consume pest species as well as native species of conservation importance. The ecosystem services or costs and benefits provided by these invasive species are likely to be contingent on the prey communities and habitats they occupy.

The direct and indirect impacts that invasive predators have on communities within their invaded range are poorly understood, particularly in the early stages of invasion. Through top‐down control of their prey, predators have the capacity to trigger cascading effects on lower trophic levels. We found the recent arrival of the invasive paper wasp Polistes dominula Christ has been associated with substantial declines in local butterfly abundance in New Zealand. One of the butterfly species we observed to be affected is the monarch, Danaus plexippus Linnaeus with densities reduced by 66% at the study site. Field experiments were conducted to examine the strength of the predation pressure exerted by P. dominula on monarch caterpillars and the cascading effects on milkweed ( Gomphocarpus physocarpus E. Mey.) fitness. A survival study of monarch caterpillars was conducted across three habitat types (coastal, forest, and suburban). Caterpillar survival in suburban areas was lowest, with only 45% of caterpillars remaining after just 6 h of exposure to wasp foraging. Predation by P. dominula explained 85% of caterpillar deaths within the trial period. The cascading effects of P. dominula presence were quantified through changes in the height, foliage, and reproductive output of milkweed plants. Monarch caterpillar predation by P. dominula was found to have a positive effect on milkweed fitness. This study demonstrates a strong trophic cascade initiated by an invasive predator. These findings highlight the impacts an invasive species can have on local communities beyond their direct predatory effects.

Species distribution models (SDMs) are tools used by ecologists to help predict the spread of invasive species. Information provided by these models can help direct conservation and biosecurity efforts by highlighting areas likely to contain species of interest. In this study, two models were created to investigate the potential range expansion of Polistes dominula Christ (Hymenoptera: Vespidae) in the southern hemisphere. This palearctic species has spread to invade North and South America, South Africa, Australia, and more recently New Zealand. Using the BIOCLIM and MAXENT modelling methods, regions that were suitable for P. dominula were identified based on climate data across four regions in the southern hemisphere. In South America areas of central Chile, eastern Argentina, parts of Uruguay, and southern Brazil were identified as climatically suitable for the establishment of P. dominula. Similarly, southern parts of South Africa and Australia were identified by the model to be suitable as well as much of the North Island and east of the South Island of New Zealand. Based on outputs from both models, significant range expansion by P. dominula is possible across its more southern invaded ranges.