Is invertebrate conservation in Great Britain best achieved by policies that increase species protection?

We discuss proposals to extend the list of protected insect species in Great Britain and question whether existing species protection measures are appropriate for insects whose ecology is substantially unknown. We highlight the practicalities of applying such measures to very poorly known taxa, whose identification depends upon highly experienced specialists and a tiny pool of relevant expertise. We propose a seven-point plan that would strengthen invertebrate conservation in Great Britain. Our proposals could be applied to other countries with a protected sites network and a desire to improve habitat-based insect conservation measures. Our analysis suggests that insect conservation will not be improved by legislation that restricts the potential for adhoc surveillance that currently provides almost all the data used to monitor rare and threatened insects. We highlight the need for Improvements in the understanding of insect micro-habitat requirements amongst conservation managers. Our proposed seven-point plan provides a structured approach to insect conservation that should improve identification of important insect sites, site management and landscape-scale conservation measures.


Introduction
A recent stakeholder consultation by Defra (the UK's Department for Environment, Food and Rural Affairs) sought views on possible additions to Schedule 5 of the Wildlife and Countryside Act 1981 (WCA, 1981 hereafter). This Schedule identifies species that deserve the highest level of protection in Great Britain (GB) 1 and lists those animals for which specific parts of the schedule apply. Those criteria relevant to invertebrates are: 1. Animals which are protected from killing and taking (Sect. 9.1) separated into • Animals which are protected from intentional killing or injuring (Sect. 9.1a); and • Animals which are protected from taking (Sect. 9.1b).
2. Animals which are protected from being possessed or controlled (live or dead) (Sect. 9.2). 3. Animals which are protected from disturbance (Sect. 9.4) separated into: • Animals which are protected from intentional damage or destruction to any structure or place used for shelter or protection (Sect. 9.4a); • Animals which are protected from intentional disturbance while occupying a structure or place used for shelter or protection (Sect. 9.4b); and • Animals which are protected from their access to any structure or place which they use for shelter or protection being obstructed (Sect. 9.4c).
4. Animals which are protected from sale (Sect. 9.5) In a departure from previous proposals and consultations, for which specialists prepared a list based on expert opinion and knowledge of genuine threats, the latest proposed list embraces all species listed as 'Critically Endangered' in national species status reviews, regardless of the known threats. This blanket approach recalls that of the USA, where the Endangered Species Act (1973) (ESA) has been used to try to safeguard a wide spectrum of organisms (Scott et al. 2006). Yet, the ESA contains a similar disparity in insect representation: 84 insect species compared with 439 vertebrates according to the Ecological Society of America (2018).
Coincident with this consultation, an analysis of protected species by Duffus and Morimoto (2022), which includes species listed in Biodiversity Action Plans (BAP), concluded that current United Kingdom (UK) conservation policies afford insects little or no protection. This disparity between vertebrate and invertebrate conservation has long been recognized (e.g., Collen et al. 2012;Donaldson et al. 2016;Eisenhauer et al. 2019;McKinney 1999;Wilson 1987). Consequently, it might be assumed that consultation on extending protected species status is a positive move. The most important question is, however: 'Will listing more species improve invertebrate conservation?'.
In the absence of requisite knowledge, indicator or surrogate species have been used to help define suitable conservation measures, but this approach also has significant drawbacks as discussed by Caro and Doherty (1999). In a GB context, the compilation of the list of BAP priority species (JNCC 1994) demonstrates the drawbacks of extending protected species measures for insects and other invertebrates. Instead of comprehensive lists of potential assemblages, a small number of invertebrates were listed as 'priority species', these being putative proxies representative of critical habitats and associated faunas. At the time, the approach was appropriate because it was unclear how many species fitted the guidelines used to compile the list. Subsequently, this list was transposed into GB law under the Natural Environment and Rural Communities (NERC) Act (2006) despite the growing evidence that at least some species were more widely distributed than had been previously realised and were not necessarily representative of threatened habitats. That list is now immutable without a complex legislative procedure.

Ensuring site protection is effective
Once a site has been 'protected, the ongoing question must be whether or not protection is effective for the target organisms listed in its citation. Unless there is detailed knowledge of where such species occur, there may be a repeat of the unfortunate case of Cyturella albosetosa Strobl, a 1 mm long Dolichopodid fly that that was lost from Chippenham Fen when the site warden built a hut on the area where it (and several other rare species) had previously been found (Drake 2007). Fortunately, many years later, the fly was rediscovered in a base-rich fen many miles away, but it remains lost to Chippenham Fen, a highly protected site.
The need for monitoring invertebrate populations highlights a further disparity between invertebrate and vertebrate conservation. The numbers of species can be daunting and quite disproportionate to available funding (Wiens et al. 2008). For example, the true fly (Diptera) fauna of the British Isles 2 comprises around 7,200 species and the assemblage of bees, ants and wasps (Hymenoptera) comprises more than 7,700 species. Unlike vertebrates, most adult invertebrates are tiny and relatively short-lived. Furthermore, larval stages, which are often key indicators of habitat quality and health, are substantially unknown, challenging to study and their ecological requirements are, consequently, poorly understood. In the case of Cyrturella albosetosa Strobl, currently recommended for addition to Schedule 5 of the WCA 1981, it is likely to be overlooked in the field by almost all entomologists except a specialist in micro-flies or in Dolichopodidae; furthermore, nothing is known of its larval biology. Monitoring or searching for such species inevitably involves lethal methods, which would be contrary to most provisions of Schedule 5. Simply finding populations of these species could also contravene this law unless the surveyor was specifically licenced to do so.
As current UK capacity to maintain an oversight of protected insect species and their conservation status is very limited, the question arises: is it possible to use new technology to monitor more efficiently and cost-effectively? Two obvious options exist: DNA analysis of samples secured by non-specialists, and the use of machine-learning Artificial Intelligence to evaluate photographs and methods such as sticky traps (e.g., Høye 2021; Sütő 2021). Whilst both may develop to the point where they have practical applications in monitoring insects of conservation concern, we do not believe that this will happen in the foreseeable future for several reasons. The primary limitation is the level of existing taxonomic capacity that is available to develop both systems, but an additional complication is that there are numerous species complexes that are currently only separable on characters within the genitalia that require dissection to achieve a reliable identification.
Another possibility might be to make greater use of the network of active wildlife watchers and photographers to generate records of threatened species. This process is ongoing but has received comparatively little analysis. As far as we know, the most comprehensive evaluation of such records has been undertaken for hoverflies (Diptera, Syrphidae) and has shown that photography leads to datasets with strong biases and marked imperfect detection Morris 2020).
Thus, although we recognise aspects of the conclusions of Duffus and Morimoto (2022), we question the implied need for more extensive species-based protection measures from a practical perspective, as we discuss below.

Discussion
Of the 50 species of insect and spider currently protected by Schedule 5 of the British Wildlife and Countryside Act (Table 1), 34 are Lepidoptera (25 butterflies, 9 moths). Butterflies and moths attract a considerable following amongst casual observers and are intensively recorded, both by general surveillance (distribution recording, e.g., Fox et al. 2015) and by detailed repeatable surveys (Pollard 1977;Dennis et al. 2013). For these taxa, reporting and annual monitoring generate large amounts of data using a substantial network of volunteers. For example, Fox et al (2015) report 2.97 million UK butterfly records collected between 2010 and 2014.
It is, therefore, unsurprising that Lepidoptera greatly outstrip all other insect orders in biological records datasets, with over 21.5 million records held on the NBN Atlas 3 (https:// nbnat las. org/; accessed 31/03/2023) compared with 2.1 million Odonata and 2.7 million Coleoptera. Moreover, giving protection to butterflies is unlikely to have a serious negative impact on either monitoring or surveillance data because so much can be undertaken using non-lethal methods. Only a proportion of moths are, however, identifiable without lethal methods, so extending protection more widely could have an impact on surveillance using "total kill" methods such as Rothamsted moth traps (see Harrower et al. 2016 for survey results).
A very different paradigm exists for other insect orders where 7,761 Hymenoptera (19%), ~ 7,200 Diptera (18%) and 4,072 Coleoptera (10%) make up almost half of British invertebrate fauna. Despite their huge diversity, the numbers of records available are comparatively small. The largest dataset amongst these orders is for Hoverflies (Diptera, Syrphidae), which currently stands at just over 1.7 million records for a family of 284 species. Like butterflies and some moths, some hoverflies are obvious and charismatic but, many are small, black and readily overlooked or ignored because they are difficult to identify (Morris 2020).
In contrast to Duffus and Morimoto (2022), who also advocate increased species protection combined with better monitoring of invertebrate populations, we suggest that any move towards increased protection could be counterproductive for insect monitoring and conservation in the GB for the following reasons: 1. A very high proportion of British insects are below 5 mm long and require microscopy to arrive at a reliable identification to species. The numbers of people capable of such work are tiny and are insufficient to maintain existing surveillance, let alone monitoring. For example, 50% of the ~ 0.75 million records used in Ball et al. (2011) were generated by just 20 people. 2. Should it be necessary to introduce a licensing system, applicants for licences will require credentials to justify their application. Whilst such credentials may be readily assessed for known national specialists, relative novices would have far more difficulty acquiring licences. In this way, the development of a new generation of specialists could be stifled, effectively ending the chain of exper-tise. In GB, many of these specialists are volunteers whose data provision far outstrips that of 'professionals'. 3. If permission to sample insects becomes more onerous (e.g., licensing), there will be less activity by specialist entomologists and surveillance data will decline because many of these data are opportunistic and affected by prevailing weather. Consequently, it will be increasingly difficult to contextualise those records that are available and to differentiate between environmentally driven decline and invisibility due to a lack of surveillance.
The aspirations of Duffus and Morimoto (2022) are understandable, but they fail to recognise the gulf between current knowledge and the shortfall in technical capacity and requisite funding. Bearing in mind that many scarce and threatened insects have exacting habitat requirements, it is unsurprising that existing species status reviews (Bantock 2016;Chandler 2017;Ball and Morris 2014;Drake 2018;Telfer 2016;Lane 2019) do not highlight collector pressure as a serious issue. Furthermore, it is clear from our experience that there are very limited data available for invertebrate presence on existing protected sites.

A way forward
We suggest that the following programme be considered: 1. Assessment of the available capacity for delivering a robust dataset for existing protected sites and data for sites that should be considered as additions to the protected sites network. A thorough audit of both professional and non-professional capacities as they stand would seem to be needed urgently, as these contributions underpin the quality of decision-making relating to invertebrate conservation. 2. Development of a clearer understanding of the microhabitat requirements of threatened species so that site managers recognise the biotopes that support threatened species assemblages. 3. Development of better guidance for conservation professionals on the micro-habitat requirements of invertebrates to give them higher profile in conservation initiatives such as re-wildling and landscape-scale conservation enhancement. 4. Analysis of existing data to determine where threatened species occur within the protected sites network. Consider too, whether or not the majority of records are from protected sites or the species involved are effectively 'wider countryside' species, for which site protection measures may be ineffective. 5. Evaluation of the temporal structure of the data to establish whether or not there has been an ongoing history of recording at protected sites and if there is a sound knowledge of the likely occurrence of threatened invertebrates. 6. Evaluation of the intensity of recording from protected sites so that the records that exist can be contextualised: do a very few records come from a lot of recording effort, or do they come from an equally limited level of surveillance? 7. Expand the protected sites network to reflect deficiencies in coverage of rare and threatened invertebrates and to ensure adequacy of population conservation.
This first stage in developing a resilient invertebrate conservation strategy is one that could be applied throughout data-rich countries. It is fundamental to insect conservation in GB because nature conservation law, policy and funding is dominated by vertebrate and plant criteria, with extremely limited attention paid to invertebrates. Indeed, many citations for protected sites almost completely lack an invertebrate perspective and as such invertebrates do not have any profile amongst policy-makers and practitioners. Part of this problem almost certainly relates to their being small, difficult to find and, often, even more difficult to identify than vertebrates as in the case of Cyturella albosetosa cited above. As a consequence, a significant proportion of GB's invertebrate fauna is studied by a tiny number of specialists.
We argue that extending lists of protected species is a vertebrate ecologist's response to nature conservation and illustrates the ongoing, yet long-recognised, problems of taxonomic bias (Clark and May 2002) and "institutional vertebratism" (Leather 2009; Morris and Welch 2023) that have plagued invertebrate conservation for decades. The most effective way of conserving invertebrates is to get a much firmer grip on the ecology and micro-habitat requirements of these animals-and then to protect sufficient habitat from loss or damage that viable populations are maintained. Species protection measures that contribute to an ongoing loss of specialists who provide data will be counter-productive. as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http:// creat iveco mmons. org/ licen ses/ by/4. 0/.