Global Insect Biodiversity Loss

Coined as the “Sixth Mass Extinction” in reference to the increasing number of species extinctions during the Anthropocene, we find ourselves amidst a global biodiversity crisis. [9-10]. Populations of insects and other invertebrate groups are significantly decreasing, leading to an “insect armageddon” [11]. These declines are due to a number of anthropogenic factors, including climate change, which impacts life cycles, changes in geographical range, and the facilitation of invasive species through environmental changes or human-mediated dispersal [12- 15]. Anthropogenic land use further impacts native insects by reducing biodiversity and homogenising insect communities [16-18]. Furthermore, pollutants such as agrochemicals disperse out of agricultural areas and have been found to reduce biodiversity and community composition in insect communities [19-21].

Table 1. The number of results on academic search engines & databases for papers including keywords “New Zealand”&”conservation” compared to “New Zealand”, “conservation” & “insect”, including the percentage of articles containing the term “insect”.

Conservation Gaps

Points of Success

While the current state and trends of insect conservation in New Zealand appear mostly negative, there are also several examples of successful conservation, such as that of the nationally endangered robust grasshopper (Brachaspis robustus) [30-31]. In addition, the restoration of native forests is an effective and common technique often used as a conservation tool. Initially developed for the conservation of plant and bird communities, forest restoration also positively influences insect communities. Native insect diversity increases in replanted native forests, as illustrated by research showing that restored native ecosystems have higher proportions of native beetle species than non-restored reference sites [32]. A comforting prospect is that New Zealand has a track record of monitoring and eradicating invasive species with robust biosecurity protocols both preand post-border [33]. Due to this, the risk of invasive species is minimised as long as New Zealand maintains strict border security, reducing potential pressure on native insects [34]. Another major factor impacting insect populations is climate change, though, unlike specific predatory or competitive pressures, climate change is a far broader issue with wideranging impacts.

Globally, these noticeable and measurable impacts have led to increased environmental awareness and climate action [35]. Thus, while climate change poses a threat to insect populations and biodiversity, it is actively being addressed. Current climate-based policy decisions provide a source of hope in the face of the insect biodiversity crisis.

Conclusion

Current Status of NZ Insect Conservation

Establishing the current status of and threats to the biodiversity of native insects is an essential step in understanding contemporary management as well as providing direction for future conservation projects. In the DOC annual report for the year ended June 30, 2023, the threat status of resident native invertebrates was evaluated using the New Zealand Threat Classification System (NZTCS) [22-23]. In this report, ~30% of invertebrates were considered data deficient,~ 7% were considered threatened, ~31% were considered at risk, and ~32% were considered not threatened [22]. While this report evaluates all invertebrates, not just insects, it indicates some overall trends of insect threat status. There is very limited knowledge of the vast majority of New Zealand insect taxa and their conservation status. While around half (~11,000 out of ~20,000) of the estimated species have been documented, only 13% (~1400) have been assessed under the NZTCS [24]. Therefore, little can be gleaned as to the overall trends in population and abundance due to a majority of the insect population being unrepresented in this report.

The management of insect species by DOC also leaves room for improvement. Over 90% of insect groups do not have enough data to establish management strategies (Figure 1), and even for those under management, 5.2% did not meet management requirements, and 3.15% had management requirements only partially met (the species received some management in at least one site). Only 0.15% of managed species have requirements fully met in at least 90% of the sites identified as crucial for species persistence. This management is not distributed evenly across insect orders, indicating that DOC prioritises a select few insect taxa, and when it does, there is a hierarchy of orders that are managed.

Figure 1: Proportion of species in each animal group that required conservation management. Insect groups indicated by stars, total proportions for each category of insect groups indicated. Each colour represents their current management and conservation status: (a) Green: adequately met, (b) Orange: partially met, (c) Red: unmet, and (d) undocumented. Adapted from “Number of managed indigenous species 2021-2022” by The Department of Conservation. 2022.https://www.doc. govt.nz/our-work/monitoring-reporting/national-status-and-trend-reports-2021-2022/indigenous-species-2021-2022/. Note. Freshwater invertebrates are included despite the fact not all are insect species.

This begs the question of how effective New Zealand’s conservation efforts are at a landscape scale. One method for evaluating landscapelevel conservation is utilising museum records of insect specimens and mapping their location on the Protected Area Network (a database of legally protected areas). Species classified as ‘threatened’ or ‘at risk’ under the NZTCS were less likely to be present in these protected areas than species that were not [25]. This demonstrates how current protected areas are ineffective at protecting insect populations, stemming from a prioritisation of vertebrate taxa when planning protected areas. While some insect taxa may benefit from umbrella vertebrate species conservation, they are not equally protected when vertebrates are prioritised [26].

Mammalian predator removal is a conservation technique often used in New Zealand contexts as one of the most effective measures for protecting native bird species. However, when insect communities were monitored in a predator-free fenced reserve, the level of success between species was variable [27]. The majority of surveyed taxa had similar abundances both inside and outside the reserve, indicating that while fenced reserves and other predator-free areas may provide refuge for some species, they are not a universal conservation tool for insect populations. Even species that benefit from mammalian pest removal like wētā are nationally impacted due to the patchy or poor coverage of these strategies [28]. Declining wētā populations from 2014 to 2022 illustrate this. When the conservation status of 38 wētā taxa was monitored over this period, 5 improved, 19 worsened, and 14 stayed neutral [29].

However, it is not just the active management of insects that is lacking - the literature on New Zealand conservation also under-represents insects. To investigate this, the search terms “New Zealand”, ”conservation”, and ”insect” were input to scientific literature databases/search engines, and their relative occurrences were calculated to determine the proportion of New Zealand conservation articles/papers that relate to insects. The results from three databases/ search engines (Google Scholar, Scopus, and Web of Science (core collection)) show that, on average, only 3.7% of the New Zealand conservation literature is related to insects (Table 1). While this is not completely representative, it gives an indication of the general trends in the literature. As with management and conservation action, the literature is biased away from insect groups, under-representing the diversity and conservation challenges this group faces.

In order to successfully protect vulnerable native insect populations, we must develop and refine strategies that will effectively act to conserve native insect biodiversity. Understanding life history/life cycles, environmental/habitat requirements, and biotic relationships at a speciesspecific level is crucial for translocation and wider conservation efforts [31]. Thus, an overhaul of taxonomic and ecological research must be done to understand native insect biodiversity and facilitate more successful conservation efforts [36-37]. It is also important to actively engage with Māori stakeholders in translocation and conservation efforts, taking care to respect rangatiratanga and tikanga (Māori customary practices) [38].

Due to the number of taxa present in New Zealand, there must be prioritisation of specific taxa that are ecologically, culturally, or conservationally significant. Legislative protection for flagship, taonga, and ecologically significant species (eg. indicator species) provides a basis for safeguarding some of the most valuable and vulnerable taxa [39-41].

A vital part of conservation biology going forward is collaborating with Māori and integrating mātauranga Māori approaches into environmental understanding and conservation. A mātauranga Māori approach provides a knowledge base formed from a multi-generational history of observing the ecology of New Zealand. An example of this in entomology is the use of te reo Māori to understand complex relationships between multiple species, with the language naming conventions capturing spatial scales, distribution, and relationships between two insect species and plant interactions [42]. This understanding of complex relationships and systems is needed for successful insect conservation. Furthermore, working with Māori and respecting rangatiratanga (Māori selfdetermination/agency) provides opportunities for Kaitiakitanga and benefit sharing in the conservation and environmental management space [6].

Aotearoa has a long history and culture of conservation, rooted in a national identity of connection to nature. However, these conservation efforts often leave invertebrates, particularly insects, behind. Due to global changes and anthropogenic impacts on the environment, native insect populations are at risk of global and local extinction. Currently, the biodiversity of New Zealand’s native insect communities is under threat, with historical and contemporary conservation attempts generally not successful enough to maintain robust populations or improve the conservation status of insects. This largely is due to the imbalanced prioritisation of conservation efforts, skewing funding and resources towards vertebrate species, particularly birds. Insect conservation in New Zealand is not all doom and gloom, however, as there is a growing awareness and agency to protect insect species. While some traditional, vertebrate-centric conservation strategies may work, others do not, and innovation and further understanding of species, ecosystems, and relationships are needed. The most important thing is developing a better understanding of insect species, from taxonomy, distribution, and ecological relationships. Establishing effective partnerships with Māori, where mātauranga Māori and kaitiakitanga can be practised, is fundamental to improved conservation in New Zealand. Finally, modifying existing tools and developing new effective strategies for insect management is crucial. It is time for insects in Aotearoa to get the conservation attention they desperately need and begin prioritising the little guys before it is too late to save this invaluable group.