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Mitigating the extinction risk of globally threatened and endemic mountainous Orthoptera species: Parnassiana parnassica and Oropodisma parnassica

September 2024
Insect Conservation and Diversity 18(123)

DOI:10.1111/icad.12784

License
CC BY-NC 4.0

Authors:

Apostolis Stefanidis

University of Ioannina

Konstantinos Kougioumoutzis

University of Patras

Dina Zografou

University of Ioannina

Georgios Fotiadis

Agricultural University of Athens

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Orthoptera species are vulnerable to extinction on a global scale. Greece hosts 35% (380 species) of the European Orthoptera fauna with a high degree of endemic (37%) and threatened species (37%). We sampled 46 plots (100 m ² ) to investigate the distribution and ecological requirement of two Greek mountain endemic and red‐listed species: Parnassiana parnassica (Ramme, 1926; Orthoptera: Tettigoniidae; Critically Endangered [CR]) and Oropodisma parnassica (Scudder, 1897; Orthoptera: Caelifera; Endangered [EN]). Species had a restricted geographical range, with two isolated populations confined to high altitudes (1527–2320 m) of Mts. Parnassos and Elikonas. Species distribution models showed that slope affected their suitable habitat, together with the topographic position index and the annual temperature range ( P. parnassica ), and the amount of green vegetation and evapotranspiration ( O. parnassica ). Connectivity analysis showed that P. parnassica ‐suitable habitat consisted of few larger and well‐connected patches (26 patches: effective mesh size of 1.57 km ² ) and that O. parnassica ‐suitable habitat consisted of more but smaller and less connected patches (56 patches: effective mesh size of 0.3 km ² ). Generalised linear models showed that the population density of P. parnassica was negatively influenced by the height of herbaceous vegetation and that of O. parnassica was positively influenced by altitude. The species face three main imminent threats: land take, wildfires and global warming, whereas livestock grazing seems to have a positive impact and skiing a neutral impact on their populations. We assessed both species as EN after International Union for Conservation of Nature (IUCN) criteria and a suite of conservation measures are suggested for their status improvement.

Study area across the distribution ranges of the target species at Parnassos and Elikonas Mts., and localities visited in the period 2021–2023: Presence of P. parnassica (orange dot), O. parnassica (blue dot), species co-occurrence (grey dot) and species recorded absence (cross).

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Habitat suitability maps for the target species within their potential distribution areas, as defined by the International Union for Conservation of Nature (IUCN). Panels (a) and (b) illustrate the habitat suitability for P. parnassica, with an extrapolation threshold of 35.1. Panels (c) and (d) show the habitat suitability for O. parnassica, with an extrapolation threshold of 28.8. The maps depict continuous habitat suitability values.

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ORIGINAL ARTICLE

Mitigating the extinction risk of globally threatened

and endemic mountainous Orthoptera species:

Parnassiana parnassica and Oropodisma parnassica

Apostolis Stefanidis

| Konstantinos Kougioumoutzis

| Konstantina Zografou

Georgios Fotiadis

| Olga Tzortzakaki

| Luc Willemse

| Vassiliki Kati

Department of Biological Applications and

Technology, University of Ioannina,

Ioannina, Greece

Department of Biology, University of Patras,

Patras, Greece

Department of Forestry and Natural

Environment Management, Agricultural

University of Athens, Karpenisi, Greece

Naturalis Biodiversity Center, Leiden,

The Netherlands

Correspondence

Vassiliki Kati, Department of Biological

Applications and Technology, University of

Ioannina, Ioannina University Campus,

45110 Ioannina, Greece.

Email: vkati@uoi.gr

Funding information

Management Agency of Parnassos National

Park (NECCA), Grant/Award Number:

5032966; Hellenic Foundation for Research

and Innovation, Grant/Award Number: 11266

Editor: Raphael K. Didham and Associate

Editor: Og DeSouza

Abstract

1. Orthoptera species are vulnerable to extinction on a global scale. Greece hosts 35%

(380 species) of the European Orthoptera fauna with a high degree of endemic

(37%) and threatened species (37%).

2. We sampled 46 plots (100 m

) to investigate the distribution and ecological

requirement of two Greek mountain endemic and red-listed species: Parnassiana

parnassica (Ramme, 1926; Orthoptera: Tettigoniidae; Critically Endangered [CR])

and Oropodisma parnassica (Scudder, 1897; Orthoptera: Caelifera; Endangered

[EN]). Species had a restricted geographical range, with two isolated populations

confined to high altitudes (1527–2320 m) of Mts. Parnassos and Elikonas.

3. Species distribution models showed that slope affected their suitable habitat, together

with the topographic position index and the annual temperature range (P. parnassica),

and the amount of green vegetation and evapotranspiration (O. parnassica).

4. Connectivity analysis showed that P. parnassica-suitable habitat consisted of few

larger and well-connected patches (26 patches: effective mesh size of 1.57 km

)

and that O. parnassica-suitable habitat consisted of more but smaller and less con-

nected patches (56 patches: effective mesh size of 0.3 km

5. Generalised linear models showed that the population density of P. parnassica was

negatively influenced by the height of herbaceous vegetation and that of

O. parnassica was positively influenced by altitude.

6. The species face three main imminent threats: land take, wildfires and global warm-

ing, whereas livestock grazing seems to have a positive impact and skiing a neutral

impact on their populations.

7. We assessed both species as EN after International Union for Conservation of

Nature (IUCN) criteria and a suite of conservation measures are suggested for their

status improvement.

KEYWORDS

bush crickets, connectivity, endemism, grasshoppers, habitat suitability, insects, IUCN, mountain

ecosystems, threats

Received: 28 June 2024 Accepted: 11 September 2024

DOI: 10.1111/icad.12784

This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any

medium, provided the original work is properly cited and is not used for commercial purposes.

Insect Conserv Divers. 2024;1–15. wileyonlinelibrary.com/journal/icad 1

INTRODUCTION

Insects represent the largest percentage of the world’s organisms with

consensus estimates calculating up to 5.5 million species globally

(Stork, 2018). They are key components in the provision, regulation

and dynamics of many ecosystem services, such as pollination, pest

control and nutrient recycling (Noriega et al., 2018). Over 40% of

insect species are in decline due to habitat loss stemming from inten-

sive agriculture and artificial land generation, pesticide use, invasive

species and climate change (Goulson, 2019) Data from the Interna-

tional Union for Conservation of Nature (IUCN) on the extinction risk

of 12,568 insect species pinpoints that a quarter of them are near-

threatened, threatened or extinct (IUCN, 2024), while one third of the

insects with documented population trends show declining population

trends (Dirzo et al., 2014).The documented decline in insect biomass

can trigger negative cascading effects on food webs and ecosystem

services (Hallmann et al., 2017; Yang & Gratton, 2014). Insect extinc-

tions will impact the ecosystem in its entirety, as insects are intercon-

nected with many vital roles, a risk that has been strongly highlighted

worldwide (Cardoso et al., 2020).

Orthoptera is an important insect group counting about 30,000

species globally (Cigliano et al., 2024) that plays a pivotal role in food

webs as a food source for vertebrates (Belovsky & Slade, 1993; Parr

et al., 1997) and arthropod predators (Curry, 1993). They have specific

microhabitat preferences (Guido & Gianelle, 2001) and are related to

vegetation structure (Poniatowski & Fartmann, 2008), rendering them

good indicators of ecosystem naturalness (Aleksanov et al., 2023;

Báldi & Kisbenedek, 1997), vegetation succession (Marini et al., 2009;

Schirmel et al., 2011) and microclimatic gradients at fine scale

(Gardiner & Hassall, 2009). They are the fourth most-threatened order

globally (after Trichoptera, Coleoptera-dung beetles and Lepidoptera)

(Sánchez-Bayo & Wyckhuys, 2019), and more than one third of them

are red-listed at a global scale (35%: 520 species) (IUCN, 2024). In

Europe, one fourth of its Orthoptera fauna is threatened (270 species)

due to human pressures such as livestock grazing, arable farming,

increasing wildfire frequencies and touristic development (Hochkirch

et al., 2016). In Greece, 37% of the Orthoptera fauna is threatened,

and this higher degree of threat is of particular conservation impor-

tance at regional and global scale, given the great species richness of

the country (380 Orthoptera species: over one third of European spe-

cies) and its high degree of endemism (37%: 141 endemic species)

(Willemse et al., 2018). Research and conservation actions for the

90 endemic and threatened Orthoptera species in Greece should be a

top priority, as the improvement of their population status would lead

to the improvement of their global assessment.

The globally threatened and endemic Orthoptera species of

Greece have a very restricted geographic range and they are encoun-

tered in ‘ecological islands’(Kenyeres et al., 2009), namely in caves,

islands and high mountains. Remote mountainous ecosystems are

understudied despite their great ecological value (EEA, 2010), their

value as centres of endemism and as refugia for species in the light of

climate change (Schickhoff et al., 2021; Spehn et al., 2010). A synergy

of elevational gradients and dynamics in climate, hydrology and water

chemistry contributes to the formation of a high diversity of micro-

habitats, hosting numerous species in comparably small areas

(McCain & Colwell, 2011), also explaining their high degree of ende-

mism (Rahbek et al., 2019). Mountains offer valuable opportunities to

study species distributions and the mechanisms influencing them

(Barve & Dhondt, 2017; Graham et al., 2014), but these ecosystems

are fragile, holding the greatest proportion of species facing imminent

extinction (46% of trigger species) (IPBES, 2018) and particularly so in

the Mediterranean, which faces a more pronounced warming (Cramer

et al., 2018).

Montane endemic Orthoptera species are often known only from

a few localities where they were recorded several decades ago

(Willemse et al., 2018), and the ecological gap in knowledge is sub-

stantial. Their risk assessment after the IUCN criteria has so far relied

mainly on the restricted geographic range (criterion B), in combination

with other criteria (IUCN SPC, 2024) that are usually rated through

expert opinion and rarely so on a quantitative basis (Kati et al., 2006).

Such assessments involve de facto some degree of subjectivity, given

that information is largely missing and can only be inferred. There is a

pronounced need to collect extensive field data for poorly known spe-

cies, to employ quantitative tools to assess their current and potential

distribution, their habitat quality and fragmentation and to gain a dee-

per understanding of the ecological requirements of the species at a

fine scale, under the scope to guide well-informed conservation

actions mitigating species extinction risk (Jackson & Robertson, 2011;

Thomaes et al., 2008). Several modern tools are available in this direc-

tion. Species distribution models (SDMs) are one of them (Araújo &

New, 2007; Marmion et al., 2009), combining species occurrence

records with a set of environmental predictor variables to predict

potential distributions, allowing extrapolation in space and time

(Elith & Leathwick, 2009; Peterson, 2001). Furthermore, understand-

ing and quantifying habitat fragmentation and its effect on species

populations is essential for directing management and conservation

actions (Miller-Rushing et al., 2019), particularly for species with

restricted geographic ranges (May et al., 2019). Small, spatially iso-

lated patches may not be able to sustain viable subpopulations

(Haddad et al., 2015), although this remains a subject of debate

(Fahrig et al., 2019). For instance, deciding whether a population is

‘severely fragmented’or not after the IUCN criteria should rely on a

quantitative analysis of the connectivity of suitable habitat patches.

Our study focuses on two high-altitude Orthoptera species of

Greece that are endemic and globally threatened, namely Parnassiana

parnassica (Ramme, 1926; Critically Endangered [CR]) and Oropodisma

parnassica (Scudder, 1897; Endangered [EN]) (Willemse, Hochkirch,

Heller, et al., 2016; Willemse, Hochkirch, Kati, et al., 2016). The genus

Parnassiana is entirely endemic to Greece, comprising 13 mountain-

dwelling species that are all red-listed and hence globally threatened

(Hochkirch et al., 2016). They are small to medium-sized (14–18 mm),

cryptic, short-winged bush crickets, with adults usually appearing

August. They produce a song consisting of scratching sounds lasting

0.5–2.5 s, typically produced in the evening and the night (Willemse

et al., 2018) The genus Oropodisma comprises 10 mountain-dwelling

species, that are all, except one, Greek endemics and are all red-listed

2STEFANIDIS ET AL.

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(Hochkirch et al., 2016). They are also small to medium-sized (13–

23 mm), compact, apterous grasshoppers, appearing in adult form in

August, with no sound production documented (Willemse

et al., 2018). Parnassiana parnassica and O. parnassica are known to be

genetically distinct from the other species of the same genera

(Grzywacz et al., 2017; La Greca & Messina, 1976). Each species has

been reported so far only from two to three localities and has been

considered to exhibit a declining population trend due to various pres-

sures such as livestock grazing and tourism (Willemse, Hochkirch,

Heller, et al., 2016; Willemse, Hochkirch, Kati, et al., 2016). This is the

first ecological study for the target species and any species of the gen-

era Parnassiana and Oropodisma. We aim to provide an integrated

picture of the ecological profile of the two species and apply quantita-

tive tools in the assessment process of the conservation status of the

species, as a guideline for other poorly known species with restricted

geographic ranges. We set five distinct objectives for both target

species: (1) delineate their current distribution pattern; (2) model their

potential global distribution based on habitat suitability mapping;

(3) quantify the connectivity of suitable habitat patches, reflecting the

degree of habitat fragmentation; (4) investigate the environmental

factors that shape suitable habitat and affect species population

density; (5) update the IUCN Red List status of the species after IUCN

criteria and (6) synthesise our findings in concrete measures for the

conservation of the species from a conservation management

perspective.

MATERIALS AND METHODS

Study area

The study area comprises the global distribution range of the two tar-

get species, according to IUCN assessments (Willemse, Hochkirch,

Heller, et al., 2016; Willemse, Hochkirch, Kati, et al., 2016). It encom-

passes two mountains of central Greece: Mt. Parnassos (268 km

)

ranging from 800 to 2457 m, and Mt. Elikonas (150 km

), being a

complex of minor mountains (500–1748 m) (Figure 1).

The climate is continental: the mean annual temperature for the

years 2021–2023 was 13.8C (±3.5C) (temperature range from 7C

to 32C), and the mean annual rainfall was 1000 mm (±73 mm)

(NOA, 2024). Endemic fir forests (Abies cephalonica) dominate at mid-

altitudes in the two mountains, interspersed with pine stands (Pinus

nigra) on Mt. Parnassos, whereas the zone above the tree line includes

mountainous grasslands, heaths and rocky slopes. Mt. Parnassos has

been declared a national park since 1938, currently being a site of the

Natura 2000 network of protected areas in Europe (GR2450005),

hosting 35 habitat types and rich fauna and flora (SDF, 2020), but

Mt. Elikonas is under no protection status. Livestock grazing and tour-

ism are the two main human activities above the tree line on

Mt. Parnassos, where the oldest and largest ski resort in Greece is

located. No such activities occur on Mt. Elikonas, but there are plans

for constructing wind power stations (RAE, 2024).

Orthoptera sampling

We carried out field surveys for three consecutive years (2021, 2022,

and 2023) during August, that is, at the peak adult activity period of

the species (Willemse et al., 2018). We surveyed a total of 103 sites

within the study area (Figure 1). We attempted to cover different

localities deemed adequate microhabitats for the species across the

distribution range of the species, that is, mountainous grasslands

above the tree line and forest clearings. We employed the time-

constrained visit method, actively searching for the target species in

each site for 45 min (46 sites with species occurrence). In almost all

cases, upon encountering the species, we delineated a quadrat of a

standard area of 100 m

and counted the number of individuals

(40 quadrats). Quadrats were spaced at least 100 m apart, given the

low dispersal ability of both flightless target species (Reinhardt

et al., 2005).

Microhabitat parameters

We recorded 12 microhabitat parameters at each quadrat with

species occurrence (Table 1): altitude (Al), slope (Sl) and the

ground cover of soil (So), rocks (R), stones (St) and vegetation (Vg).

Vegetation included herbaceous plants (Hcover), characterised by

non-woody stems or roots, and robust herbaceous plants and

shrubs (Rpcover), distinguished by either a woody stem or a woody

base or both following the definitions provided by (Strid, 1986).

Plant species identification was mainly conducted in situ, and

some specimens were collected andidentifiedinthelabusinga

stereoscope. We also considered the vegetation structure in the

plot by measuring the mean and maximum height of both herba-

ceous (Ghmean, Ghmax) and robust/shrubby vegetation (Rpmean,

Rpmax).

Environmental data

We considered a dataset of 27 variables, including 22 bioclimatic,

4 topographic and 1 vegetation-related variable, at a spatial

resolution of 100 100 m cells (Table S1). We calculated the

bioclimatic variables used in the SDMs with the ClimateEU v4.63

(Marchi et al., 2020), the ‘dismo’1.1.4 (Hijmans et al., 2017)and

‘envirem’2.2 (Title & Bemmels, 2018) R packages, adhering to

methodologies described in Hamann et al. (2013), Marchi et al.

(2020) and Wang et al. (2012). We calculated topographical metrics

using functions from ‘raster’2.6.7, ‘terra’1.7.46 (Hijmans, 2023),

and ‘spatialEco’1.2-0 R packages (Evans, 2019). We tested

variables for collinearity, using Spearman rank correlation (<j0.7j)

and variance inflation factors (VIF <5) (Dormann et al., 2013)with

the ‘collinear’1.1.1 R package (Benito, 2023). We used a set of

12 independent variables to feed the SDMs (nine variables per

species) (Table S1).

CONSERVATION OF MONTANE ORTHOPTERA 3

Data analysis

Current distribution area and related metrics

To delineate the current distribution area of each species, we considered a

buffer zone of 1 km around the species occurrences and calculated the

merged area of the zones. We utilised all presence data to calculate the area

of occupancy (AOO) and the extent of occurrence (EOO), using the Geos-

patial Conservation Assessment Tool (GeoCAT) (Bachman et al., 2011). The

AOO is a scaled metric that represents the area of suitable habitat currently

occupied by the taxon and is calculated as the sum of occupied cells of

22 km, often reflecting the population size of the taxon. The EOO is a

measure of the spatial spread of the areas currently occupied by the taxon,

including areas of non-suitable habitats.Itiscalculatedastheareacontained

within the shortest continuous imaginary boundary encompassing sites of

present occurrence and reflects the spread of risks from threatening factors

across the taxon’s geographical distribution area (IUCN SPC, 2024).

Species distribution models

We used species distribution modelling to predict the suitable habitat

of both target species within their distribution ranges. First, we

cleaned the data utilising the ‘clean_coordinates’from the ‘Coordina-

teCleaner’2.0.18 R package (Zizka et al., 2019). We then removed

duplicate occurrences using the ‘elimCellDups’function from the

‘enmSdm’0.5.3.3 R package (Smith, 2020), followed by spatial thin-

ning of the data with the ‘thin’function from the ‘spThin’0.1.0 R

package (Aiello-Lammens et al., 2015), as per Aiello-Lammens et al.

(2015) and Robertson et al. (2016). The final dataset comprised

33 records for each species at a scale of 100 100 m cells.

Second, as the occurrence-to-predictor ratio for both species was

below 10:1, we employed an ensemble of small models (ESMs) to pre-

cisely model their realised climatic niches, as ESMs were developed to

build reliable and robust SDMs for rare species (Breiner et al., 2015).

We specifically utilised the Random Forest algorithm via the ‘ecospat’

3.1 R package (Broennimann et al., 2021). Pseudo-absences were gen-

erated with the ‘sample_pseudoabs’function from the ‘flexsdm’1.3.3

R package (Velazco et al., 2022), within a geographical buffer and

were environmentally constrained (Barbet-Massin et al., 2012). We

then partitioned data into four blocks of presences and pseudo-

absences, using the ‘BIOMOD_CrossValidation’function from the

‘biomod’4.2.4 R package (Thuiller et al., 2023). Third, we evaluated

model performance with several metrics following the recommenda-

tions of Collart et al. (2021) and Konowalik and Nosol (2021). Fourth,

we selected only the models with a value of True Skill Statistic (TSS)

FIGURE 1 Study area across the distribution ranges of the target species at Parnassos and Elikonas Mts., and localities visited in the period

2021–2023: Presence of P. parnassica (orange dot), O. parnassica (blue dot), species co-occurrence (grey dot) and species recorded absence

(cross).

4STEFANIDIS ET AL.

≥0.4 (Liu et al., 2016) out of 36 ESMs produced for each species, to

generate binary maps (presence–absence).

Fifth, we produced the final species maps (habitat suitability and

binary maps) by excluding the cells that had high extrapolation values.

There are two types of extrapolation: univariate (which extends

beyond the observed training conditions) and combinatorial (which

occurs within the observed range of training conditions). We created

the extrapolation uncertainty maps by employing the ‘Shape’metric

using the function ‘extra_eval’from the ‘flexsdm’1.3.3 R package

(Velazco et al., 2022). In line with guidelines from Velazco et al.

(2024), we investigated several distance thresholds for both species

regarding their extrapolation values (the following values represent in

order the p25, median, p75, p100: O. parnassica: 28.8, 37.5, 48, 353;

P. parnassica: 35.1, 44.9, 56.8, 359) for model prediction truncation.

This strategy provides a safeguard against potential prediction errors

(Elith et al., 2010). Considering the extreme rarity and limited geo-

graphic distribution of the target species, we generated habitat suit-

ability maps setting thresholds at 28.8 for O. parnassica and 35.1 for

P. parnassica (Velazco et al., 2024). As a result, we assigned these high

extrapolation areas a suitability value of 0, indicating their exclusion

from the models’predictive capabilities.

The model was tested with the preliminary dataset of species

occurrence collected during the first 2 years (56 occurrences in total).

It indicated 10 sites (100 100 m cells) of high habitat suitability for

both species (top 20%) that were not covered by our sampling. We

visited them in the year 2023 and found P. parnassica in 9 sites and

O. parnassica in all 10 sites.

Suitable habitat patch connectivity

We calculated the connectivity of suitable habitat patches by computing

the number of patches, the patch cohesion index (Schumaker, 1996), the

patch area and the effective mesh size (McGarigal, 2002), using the

‘landscapemetrics’2.0.0 R package (Hesselbarth et al., 2019). Greater

values of the patch cohesion index and the effective mesh size indicate

less fragmented suitable habitat.

Generalised linear models

We used generalised linear models to identify the microhabitat

parameters (explanatory variables) that potentially influence the target

species population density (response variable). Thirteen explanatory

variables were considered, including 12 continuous variables derived

from quadrat sampling and 1 nominal variable representing sampling

sites (Table 1).

We created two datasets, each one corresponding to a target

species, and we ran the models for each one. To select the environ-

mental variables, first, we tested for multi-collinearity using Spearman

rank correlation (r<j0.55j) and VIF (<5) (Dormann et al., 2013). Sec-

ond, we checked for influential values (outliers) and one record was

omitted from the dataset of P. parnassica. In the O. parnassica dataset,

no participant coefficient had a Cook’s distance value over 1, so all

observations were retained in the model (Cook, 2011). Third, we stan-

dardised all continuous numerical values, by subtracting their mean

TABLE 1 Environmental parameters, habitat types, and dominant plant species recorded in the quadrats of Parnassiana parnassica and

Oropodisma parnassica occurrences.

Variable

P. parnassica O. parnassica

Mean Min–max Mean Min–max

Topography Elevation (m) 2002 1527–2320 2052 1527–2320

Slope (

)152–45 18 2–45

Ground Cover Soil cover (%) 8.53 0–75 4.21 0–15

Rock cover (%) 11.73 0–50 12.34 0–55

Stone cover (%) 27.23 5–85 41.34 5–10

Total vegetation cover (%) 52.51 5–95 42.11 0–100

Vegetation cover Herb/grass cover (%) 60.67 5–95 63.28 1–100

Shrub/robust plant cover (%) 39.33 5–95 36.72 0–99

Vegetation structure Grass/herb height (cm) 25.58 10–86 22.71 7.25–86

Shrub/robust plant height (cm) 17.43 5–145 36.72 10–145

Percentage of plots (%)

Habitat type ‘Endemic oro-Mediterranean heaths with gorse’(4090) 69 60

‘Alpine and Boreal heaths’(4060) 11 24

Dominant plant species Astragalus creticus 56.7 44.8

Festuca jeanpetrii 36.7 27.6

Festuca varia 16.7 13.8

Dactylis glomerata 16.7 13.8

Note: The total vegetation cover is divided into herbaceous plants cover and robust herbaceous plants and shrubs cover.

CONSERVATION OF MONTANE ORTHOPTERA 5

and dividing by their standard deviations. Finally, we selected the

most influential variables to get closer to a ratio of 10 events per vari-

able (Peduzzi et al., 1996), using the Least Absolute Shrinkage Opera-

tor (LASSO) regularisation path (Tibshirani, 1996). However, when

applying LASSO regression to the O. parnassica dataset, all coeffi-

cients were driven to zero, suggesting potential over-regularisation.

To address this issue, we turned to elastic net regression for that data-

set, which combines both L1 (LASSO) and L2 (ridge) penalties (Zou &

Hastie, 2005). For this process, we used the function ‘cv.glmnet’from

the ‘glmnet’4.1-8 R package (Friedman et al., 2010) and reduced the

randomness of the function by doing 1000 irritations and choosing

the lambda with the minimum average error.

We carried out generalised linear models (GLM) to model the

population density of both species. We used Poisson distribution for

the five variables selected for P. parnassica, and negative binomial dis-

tribution, for the four variables selected for O. parnassica, accounting

for overdispersion. Subsequently, we fitted generalised linear mixed

effects models (GLMM) for each dataset, incorporating the site as a

random effect using the ‘lme’4 1.1-34 R package (Bates et al., 2015).

We assessed the necessity of including sites nested within years as a

random effect via likelihood ratio tests (LRT) comparing GLMs and

GLMMs for each dataset (Bolker et al., 2009). The difference in

log-likelihoods between the two models was calculated, and the

test statistic was derived from the chi-squared distribution. For both

datasets, a large p-value (>0.05) indicated no significant improvement

in model fit when including the random effect.

We continued with GLMs for both datasets, using a multi-model

inference approach, to identify confidence sets of best models

(Burnham & Anderson, 2002). We compared 32 models for

P. parnassica and 16 for O. parnassica, with all possible combinations

of variables using the ‘dredge’function from ‘MuMIn’1.47.5 R pack-

age (Barton, 2022). We ranked models according to their Akaike Infor-

mation Criterion value for small-sample size (AICc) to identify those

with the best fit. We considered models with ΔAICc <2 as good as

the ‘best’model (the one with the lowest AICc value) (Richards, 2005)

and then we employed model averaging to reduce model selection

uncertainty (Burnham & Anderson, 2002). To evaluate the relative

importance of each variable for each dataset, we summed the Akaike

weights across all models that included the covariate under consider-

ation (Burnham & Anderson, 2002). We measured the goodness-of-fit

of the models with Maximum-Likelihood pseudo-R

using the ‘pR2’

function from ‘pscl’1.5.9 R package (Jackman, 2020). We performed

all statistical analyses in the R software environment, version 4.3.3

(R Core Team, 2024).

RESULTS

Current distribution pattern

Both species presented a limited distribution range: P. parnassica occurred

in 33 sites out of the 103 sites visited with an estimated distribution area

of 31 km

and an average density of 2.5 individuals/m

.Oropodisma

parnassica wasrecordedin36siteswithanestimateddistributionareaof

36 km

with an average density of 8.7 individuals/m

(Figure 1). An impor-

tant part of the distribution areas of the two species overlapped (27 km

AOO and the EOO for P. parnassica were 28 and 78 km

, respectively,

and for O. parnassica were 44 km

and 108 km

, respectively (Figure S1).

The species distribution area overlapped with the ski resort infrastructure

of Parnassos and with Parnassos’roadless area (Figure S2).

Potential distribution pattern

The area of suitable habitat for P. parnassica was 5 km

, encompassing

26 patches of an average patch area of 0.99 km

(± 4.98 km

). The

respective area of suitable habitat for O. parnassica was smaller, totalling

3.28 km

, and consisted of consisting of a greater number of smaller

patches: 56 patches with an average size of 0.16 km

(±0.81 km

Mt. Parnassos hosted the greatest part of suitable areas for both

P. parnassica and O.parnassica (99% for each), while in Mt. Elikonas the

suitable areas were restricted to its summit (0.02 km

)(Figure2;

Figure S3). Both models exhibited high performance (TSS - True Skill sta-

tistic and AUC- Area Under the Curve ranging from 0.98 to 1).

Connectivity of suitable habitats

The connectivity among patches for P. parnassica was high, showing a

patch cohesion index of 98.66% and an effective mesh size of

1.57 km

. It was lower for O. parnassica, showing a patch cohesion

index of 95.1% and an effective mesh size of 0.3 km

Habitat

Microhabitat description

We recorded both species in altitudes ranging from 1527 to 2320 m

(Table 1). The typical habitat for both species consisted of mountain-

ous grasslands classified as ‘Endemic oro-Mediterranean heaths with

gorse’(4090) or as ‘Alpine and Boreal heaths’(4060) according to the

European Habitats Directive (92/43/EEC). Although rarely, we also

found P. parnassica in fir forest clearings. The phytosociety related to

the species’habitats was the Daphno-Festucetea, which includes the

xerothermic grasslands with dwarf shrubs of the Greek mainland

(Mucina et al., 2016). The dominant plant species recorded were

Astragalus creticus,Festuca jeanpetrii,F. varia and Dactylis glomerata,

out of the 28 plant species (10 families) recorded in the quadrats with

species occurrences (Table S1). Parnassiana parnassica preferred

medium slopes above the tree line, covered by extensive herbaceous

vegetation of medium height, patches of stony substrates and less

bare soil, and substantial cover of low bushes, mainly of the A. creticus

(Table 1). Oropodisma parnassica favoured steeper slopes with impor-

tant herbaceous vegetation cover of medium height. This species pre-

ferred habitats with a substantial cover of stony and rocky substrate

6STEFANIDIS ET AL.

(>50%) and typically hid under loose stones and less under short

thorny bushes such as A. creticus.

Predictors of habitat suitability

Considering the predictors with an importance value (>1), Topographi-

cal Position Index (TPI) (elevation difference between the species cell

and vicinal cells) was the main environmental variable well predicted

the suitable habitat for P. parnassica, followed by slope and TAR (tem-

perature annual range). The respective variables for O. parnassica in

descending order were the NDVI (Normalised Difference Vegetation

Index), followed by slope and the PETWQ (Potential Evapotranspira-

tion of the Wettest quarter) (Figure 3).

Predictors of species population densities

Our confidence sets included four models for P. parnassica and three

models for O. parnassica (ΔAICc <2). Models accounted for

approximately a quarter of the variation in the population densities of

the species, with pseudo-R

ranging from 0.22 to 0.25 for

P. parnassica and from 0.20 to 0.23 for O. parnassica (Table S3). The

population density of P. parnassica was negatively influenced by the

mean height of herbaceous vegetation (Ghmean), whereas the popula-

tion density of O. parnassica was positively influenced by the altitude

(Alt) (Table 2). The shrubby vegetation cover, rock, and soil cover did

not significantly affect the species population densities.

DISCUSSION

Distribution patterns and connectivity

The global distribution area of each species is very restricted, confined

to only two mountains: Parnassos and Elikonas (Figure 1, Figure S1).

The distribution pattern consists of two isolated nuclei: one large

nucleus on Mt. Parnassos and a small one on Mt. Elikonas. Given the

limited dispersal ability of both flightless grasshoppers (Weyer

et al., 2012), and the great distance between the two mountains

FIGURE 2 Habitat suitability maps for the target species within their potential distribution areas, as defined by the International Union for

Conservation of Nature (IUCN). Panels (a) and (b) illustrate the habitat suitability for P. parnassica, with an extrapolation threshold of 35.1. Panels

(c) and (d) show the habitat suitability for O. parnassica, with an extrapolation threshold of 28.8. The maps depict continuous habitat suitability

values.

CONSERVATION OF MONTANE ORTHOPTERA 7

(about 30 km), we believe that the populations in the two

mountains are isolated.

On Mt. Parnassos, we found P. parnassica and O. parnassica in a

few patches, but their patch cohesion index was high, indicating satis-

factory connectivity of suitable habitats within each mountain

(Schumaker, 1996). Therefore, the populations of both species cannot

be considered as severely fragmented, after the IUCN guideline (IUCN

SPC, 2024). Connectivity measures were better in P. parnassica, indi-

cating larger and better-connected habitat patches that allow the free

movement of the species among patches and the subsequent genetic

flow, although the process might be slow due to the limited dispersal

ability of the species. Patches should be large enough to function as

stepping stones among subpopulations (Saura et al., 2014), a condition

that seems to be satisfied for P. parnassica, but not for O. parnassica.

Its patch area was too low and might discourage O. parnassica from

crossing the habitat patch boundaries and colonising vicinal suitable

habitat patches (Schtickzelle et al., 2006). Its habitat presented a more

fragmented pattern, with numerous small-sized patches with medium

connectivity. On one hand, the effective mesh size was small, but on

the other hand the patch cohesion index was high, suggesting some

dispersal among habitat patches, but at a slower rate than

P. parnassica.

The populations of Mt. Elikonas seem to be particularly vulnerable

to extinction, due to the very small extent of suitable habitat confined to

the summit of the mountain. Habitat destruction stemming from natural

disasters or human-induced land use change and habitat degradation can

cause fast decline in small populations, affecting particularly rare species

with limited dispersal ability (Walker & Gilbert, 2023).

Habitat suitability

Our results showed that both species preferred habitats with medium

slopes between 10 and 20 degrees, in line with quadrat data (average

FIGURE 3 Response curves for key predictors of the target species’distribution: TPI: Topographical Position Index (m), TAR: Temperature

Annual Range (degrees C, 28.9–31.9), Slope (degrees), NDVI: Normalised Difference Vegetation Index (0.07–0.75), PETWQ: Potential

evapotranspiration of the wettest quarter (mm/ month, 58.46–239.74). The suitability scores for the target species are quantified on a scale from

0 to 845 or 889 (depending on the species), indicating the range of habitat suitability. Numbers in parentheses indicate a range of values in the

study area.

TABLE 2 Model-averaged coefficients for all variables that were included in the set of best-ranked models (i.e., those with ΔAICc <2), the p-

value, and cumulative model weights (i.e., summed Akaike weights), indicating the relative importance of each variable (Ghmean: mean height of

herbaceous vegetation, Rpcover: shrubby vegetation cover, Alt: altitude, Sl: slope, So: soil cover, R: rock cover).

Species Variable Coefficient Pr(>jzj) Cumulative weight

Parnassiana parnassica Ghmean 0.0450 0.0075*0.775

Rpcover 0.0054 0.3189 0.159

Alt 0.0006 0.3736 0.145

Sl 0.0101 0.4190 0.133

Oropodisma parnassica Alt 0.0026 0.0029*0.750

So 0.0442 0.2688 0.190

R0.0149 0.2273 0.175

*p< 0.01.

8STEFANIDIS ET AL.

slopes of 15for P. parnassica and 18for O. parnassica) (Figure 3,

Table 1). Slope affects local temperature and water balance at a fine

scale, offering different microclimatic conditions on mountainous ter-

rains (Scherrer et al., 2011). It also influences local vegetation, and the

availability of basking spots for Orthoptera (Gardiner, 2022), which

are important for montane species thermoregulation (Samietz

et al., 2005). Orthoptera utilise the different slopes to modulate their

body temperature by positioning in sunlight at steeper slopes with

less vegetation or more shaded spots (Anderson et al., 1979;

Chappell, 1983;O’Neill & Rolston, 2007). The medium slopes selected

by the two target species seem to satisfy their thermoregulation

needs.

The most influential factor for the habitat of P. parnassica was the

TPI. This species preferred localities that were slightly more elevated

(by 8 m) than adjacent areas. These elevated regions likely enhance

sunlight exposure, as Orthoptera at higher elevations exhibit

increased mobility and basking behaviour compared with those at

lower elevations (Samietz et al., 2005). The species was also very sen-

sitive to the range between the highest and lowest temperature

recorded each year (temperature annual range-TAR). TAR ranged from

28.9 to 31.9 in the study area, but the species preferred a TAR of

29C with an upper threshold of tolerance of 30C. An upward shift

of the target species is expected in Mt. Parnassos to cope with TAR

stability, but further research is recommended on the effect of global

warming on local climate and the individual responses of the species.

The most influential factor for the habitat of O. parnassica was

the Normalised Difference Vegetation Index (NDVI), reflecting the

amount of green healthy vegetation in the habitats of the species.

NDVI is often used to monitor Orthoptera habitats (Deveson, 2013).

In the case of O. parnassica, the NDVI had a flat response curve,

showing that the species can tolerate very low up to great amounts of

green vegetation and suggesting that NDVI may contribute to the

model’s predictive accuracy, likely through stabilisation or interaction

with other variables, rather than exerting a direct effect (Figure 3).

The Potential Evapotranspiration of the Wettest Quarter (PETWQ)

was another factor shaping the habitat of O. parnassica, indicating the

potential amount of water loss that is evaporated and transpired by

plants during the 3 months receiving the most precipitation. PETWQ

presents a peak at 200 mm in the suitable habitats for the species and

a weaker peak at 70 mm, related to the xero-thermophilic character

of the species. This potential is quite high compared with the study

area (59–240 mm). Further research is needed to investigate the

response of the species to the changing NDVI trends, and

the expected increased rates of potential evapotranspiration related

to water stress in Mediterranean mountains due to global warming

(Arrogante-Funes et al., 2018; Unnisa et al., 2023).

Microhabitat selection

On a finer scale, we showed that the population densities of

P. parnassica decreased with the increase in the mean height of herba-

ceous vegetation (Table 2). Vegetation height is known to affect the

abundance and richness of Orthoptera species (Gardiner et al., 2002;

Theron et al., 2022). Tall grass vegetation impedes the survival of

Orthoptera species by obstructing oviposition and basking activities

(Gardiner, 2018; Wingerden et al., 1992). The mild grazing of mixed

sheep and goat herds on Mt. Parnassos, and the absence of cattle

seem to favour P. parnassica populations, by maintaining a medium

vegetation high of around 26 cm. Although extreme grazing regimes

of non-grazing and overgrazing are known to negatively affect insect

communities (Gardiner, 2018), mild grazing favours Orthoptera

communities (Kati et al., 2012) and particularly communities in moun-

tainous pastures (Joubert et al., 2016; Rada et al., 2014). The other

non-significant factors that positively influenced the microhabitat

selection of the species were the cover of robust plants/ shrubs, given

that the species preferred patches with a substantial cover of

A. creticus to hide, altitude (peak at 2.100 m) and slope (15) (Table 1,

Table 2).

We showed a positive correlation between the elevation and

population densities of O. parnassica, with the maximum density

recorded at 2268 m (Table 2). Although the elevation gradient is

related to a decrease in species richness and abundance (Crous

et al., 2014; König et al., 2024), O. parnassica is a montane species that

has been adapted to high altitudes. The species coexisted with

P. parnassica to a great extent (50% of quadrats), but it prevailed at

higher altitudes. In mountainous ecosystems, montane species of the

same taxonomic group often replace each other along elevational gra-

dients (Barve & Dhondt, 2017; Shepard et al., 2021). The prevalence

of O. parnassica in higher altitudes might stem from a long-term inter-

specific competition process to optimise resource utilisation strategies

(Chen et al., 2022; Freeman et al., 2022; Senior et al., 2021). This spe-

cies preferred habitats with a substantial cover of stony substrate and

typically hid under loose stones and less under short thorny bushes

such as A. creticus.AsP. parnassica, it preferred microhabitats with

medium herbaceous vegetation height (23 cm) and might be favoured

by the mild grazing of sheep/goat herds on Mt. Parnassos.

Threats and conservation implications

The species face three main imminent threats: land take, wildfires, and

global warming, whereas livestock grazing seems to have a positive

impact and skiing a neutral impact on their populations. Land take is

the conversion of natural land to artificial land leading to direct habitat

loss and is considered to be often irreversible and probably the most

severe threat to biodiversity (Kati, Kassara, et al., 2023). The primary

concern is the expansion of ski infrastructures (buildings, parking,

roads) on Mt. Parnassos (Figure S2), and the planting of new wind tur-

bines on Mt. Elikonas (RAE, 2024), which could induce habitat loss for

the species. A new road has already been constructed on Mt. Elikonas

to this aim, and although the plan has not been yet authorised, such

investments pose a direct threat to both species, given the fast devel-

opment of the wind farm industry in Greece and the substantial land

take generated (Kati, Kassara, et al., 2023). Globally threatened spe-

cies such as P. parnassica and O. parnassica should be considered by

CONSERVATION OF MONTANE ORTHOPTERA 9

the competent authorities in the environmental authorization process

of new investments, and their protection should be integrated into

the national legal frameworks. In the case of Greece, endemic and

threatened species are legally protected (Biodiversity law:

3937/31-3-2011), but they are rarely considered in the environmental

impact assessment studies for new projects. We also propose to

include the roadless area of Parnassos, an area of 66.88 km

(Kati,

Petridou, et al., 2023), as a strictly protected zone of the Natura 2000

network of Parnassos through the Special Environmental Studies that

define land uses in different zones of the Natura 2000 network, which

are currently ongoing. Road construction and artificial land generation

should be banned in this zone, in line with the recent Greek legislation

on roadless areas (Kati et al., 2022). Given the extent of the suitable

habitats within the roadless part of the mountain (Figure S3), this

measure would safeguard the habitat conservation of the species.

Wildfires could also threaten species’populations in the future.

Each mountain could lose its entire population due to a single

catastrophic event, given the frequency and extent of megafires in

Greece in recent years (Papavasileiou & Giannaros, 2022; Troumbis

et al., 2023).

Furthermore, our results showed that climate change should be

considered a threat to the species because our models pinpointed

two climatic variables to significantly influence the habitat suitability

of the target species. Parnassiana parnassica does not seem to tolerate

changes in the temperature annual range in its distribution range, and

the future response of O. parnassica to increased evapotranspiration

in unknown. Projections indicate that global warming will profoundly

impact the Mediterranean region, with summer temperatures rising

and precipitation decreasing across all seasons, especially in southern

areas (Lionello & Scarascia, 2018). Mountain regions particularly those

above the tree line are subject to rapid changes (Hotaling et al., 2017;

Pörtner et al., 2019). The response of montane species to these

changes is not fully predictable, but shifts in the elevational ranges of

montane insect species are expected (Menéndez et al., 2014). In our

case, the populations of Mt. Elikonas seem to face a high risk of

extinction, as the targe species already occupy the highest parts

of the mountain. Further research is recommended on the impact of

global warming on the population of the two species, and our work

offered a first indication of the climatic variables that should be tested

under different climatic scenarios.

Although livestock grazing has been reported as a threat for both

species (Willemse, Hochkirch, Heller, et al., 2016; Willemse, Hoch-

kirch, Kati, et al., 2016), we recorded only mild traditional sheep/goat

grazing during the summer season on Mt. Parnassos and no cattle

herds. Our results showed that the current mild sheep/goat grazing

scheme maintains the herbaceous vegetation height at medium levels

(23–26 cm) favoured by the species and hence has a beneficial role

for the species populations. We note that a shift from sheep/goat to

cattle herds is currently taking place in Greece (Vrahnakis &

Kazoglou, 2022), which might negatively impact Orthoptera popula-

tions, as cattle overgrazing and trampling alter soil properties and veg-

etation composition in Orthoptera habitats (Gardiner, 2018; Kruess &

Tscharntke, 2002). We stress the need to integrate the parameter of

medium herbaceous vegetation height maintenance and the ecological

requirements of threatened Orthoptera species in the grazing man-

agement plans currently under development in Greece and we sug-

gest the maintenance of the current grazing scheme of mild sheep/

goat grazing on Mt. Parnassos.

Both species seem to inhabit the skiing slopes and not to be

affected by their use for skiing during the winter on Mt. Parnassos

(Figure S3). We attribute this pattern to the absence of ski run

management practices, such as the application of fertilisers, systematic

bulldozing and artificial snow generation, which can alter vegetation

composition and negatively impact Orthoptera communities in European

mountains (Keßler et al., 2012;Wipfetal.,2005). We suggest maintain-

ing the current non-intervention practices of ski run management for the

maintenance of the species habitats on Mt. Parnassos.

Finally, we suggest the implementation of a systematic monitor-

ing scheme (Schori et al., 2020) for the two globally threatened spe-

cies by the competent authorities. Consistent monitoring will provide

essential data on population trends, aiding management decisions and

assessing the effectiveness of conservation actions (Block et al., 2001;

Lyons et al., 2008).

IUCN Red List status

Both species’estimations satisfied the criteria of a very restricted geo-

graphic range for critically endangered status (criterion B1: EOO <

100 km

) and endangered status (criterion B2: AOO < 500 km

)(IUCN

SPC, 2024). Considering the current extent of the threats for the species

(land take, wildfires, and global warming), as well as the species distribution

patter in two nuclei, two locations can be assigned to each species (Mts.

Parnassos and Elikonas) (criterion a), in the sense of two geographically dis-

tinct areas in which a single threatening event can rapidly affect all individ-

uals of the taxon present. The populations cannot be considered severely

fragmented, given the high connectivity of suitable habitats found. Con-

tinuing decline can be inferred for the area and quality of the species habi-

tat and consequently the number of mature individuals, due to former and

future land take, in combination with the negative impact of global warm-

ing (criterion b). According to the new data from the current study, the

IUCN Red List status of P. parnassica should be downgraded from critically

endangered (CR) to Endangered (EN B1ab (iii, v) +2ab (iii, v)) and for

O. parnassica should remain Endangered (EN B1ab (iii, v) +2ab (iii, v)).

Comparing our findings to the former IUCN species assessments

(Willemse, Hochkirch, Heller, et al., 2016; Willemse, Hochkirch, Kati,

et al., 2016), the EOO of P. parnassica increased by 38 km

and that

of O. parnassica decreased by 100 km

, indicating the need for field

research to update the species distribution information to support

evidence-based conservation strategies (Cook et al., 2010).

CONCLUSION

Our work employed an integrated approach to studying the ecology

of the two poorly known and globally threatened Orthoptera species,

10 STEFANIDIS ET AL.

by mapping their current distribution pattern, producing a map of suit-

able habitats, assessing habitat connectivity, and pinpointing the envi-

ronmental factors shaping the species’habitats at larger and finer

scales. It has a strong applied character, serving as a paradigm for

assessing the extinction risk of poorly known species with limited geo-

graphical range under IUCN criteria. We call for enhancing basic

research on the distribution patterns and ecology of such understu-

died globally threatened species. We particularly underline the need

for extensive field data collection combined with the use of quantita-

tive analytical tools such as species distribution modelling and habitat

connectivity metrics, to this aim.

We concluded a change of the extinction risk assessment for

P. parnassica, downgraded from the critically endangered category to

the endangered one and we confirmed the endangered status of

O. parnassica. Both species might experience habitat loss and degrada-

tion in the future stemming from land take, wildfires, and global

warming. Our research provided a guideline for the appropriate con-

servation measures to be implemented by the competent authorities

(Natural Environment and Climate Change Agency-NECCA) for the

National Park of Parnassos and the non-protected area of

Mt. Elikonas. We support the preservation of the current non-

intervention practices of ski-slope management, the maintenance of

the current mild sheep/goat grazing in the mountainous grasslands,

the legal protection of the species habitats from new land-consuming

projects and the implementation of a monitoring scheme for the pop-

ulation trends of the species. We finally showed that two climatic var-

iables influenced habitat suitability models, concluding the need for

further research on the climatic risk assessment for the target species,

projecting their distributions under different climate change scenarios.

AUTHOR CONTRIBUTIONS

Apostolis Stefanidis: Conceptualization; methodology; software; data

curation; investigation; funding acquisition; writing –original draft;

writing –review and editing; validation; formal analysis; visualization.

Konstantinos Kougioumoutzis: Methodology; software; formal analy-

sis; visualization; writing –review and editing; writing –original draft.

Konstantina Zografou: Software; formal analysis; writing –review

and editing; writing –original draft. Georgios Fotiadis: Methodology;

data curation; investigation; writing –review and editing; writing –

original draft. Olga Tzortzakaki: Investigation; formal analysis;

writing –review and editing. Luc Willemse: Investigation; validation;

writing –review and editing. Vassiliki Kati: Conceptualization; funding

acquisition; investigation; methodology; project administration;

resources; supervision; writing –original draft; writing –review and

editing.

ACKNOWLEDGEMENTS

We are grateful to the Natural Environment & Climate Change

Agency (NECCA) for providing us with a four-wheel-drive vehicle for

carrying out part of the sampling and to Vassia Margaritopoulou from

the local Management Unit of Parnassos (NECCA) for her support in

the fieldwork. We thank Elvira Sakkoudi and Ilias Blanis for their valu-

able support and help in our fieldwork and plant specimen

identification. Finally, we warmly thank Elli Tzirkalli for her scientific

support and advice during the preliminary modelling.

FUNDING INFORMATION

The research was funded by the Management Agency of Parnassos

National Park (NECCA) under the EMEPERA scheme for the project

‘Improving the knowledge of endemic and threatened insect fauna in

Parnassos’(2021–2022: code 5032966). The research work of the

first author was supported by the Hellenic Foundation for Research

and Innovation (HFRI) under the 4th Call for HFRI PhD Fellowships

(Fellowship Number: 11266: 2023–2026). The publication of the arti-

cle in OA mode was financially supported by HEAL-Link.

CONFLICT OF INTEREST STATEMENT

The authors have no relevant financial or non-financial interests to

disclose.

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are openly available in

DRYAD at https://doi.org/10.5061/dryad.xd2547ds6 (Stefanidis

et al., 2024), and the R codes used in the current work are openly

available in zenodo at https://zenodo.org/doi/10.5281/zenodo.

13684517.

ETHICS STATEMENT

All research was conducted under the appropriate annual research per-

mits issued by the Department of Forest Management of the Directorate

General of Forests and Forest Environment of the Ministry of Environ-

ment and Energy of Greece (Protocol code: 17898/705).

ORCID

Apostolis Stefanidis https://orcid.org/0009-0000-7481-6449

Konstantina Zografou https://orcid.org/0000-0003-4305-0238

Vassiliki Kati https://orcid.org/0000-0003-3357-4556

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SUPPORTING INFORMATION

Additional supporting information can be found online in the Support-

ing Information section at the end of this article.

Figure S1. The extent of occurrence (EOO) for Parnassiana parnassica

and Oropodisma parnassica.

Figure S2. Target species occurrences in relation to the ski centre area

(1.57 km

: 200 m buffer around infrastructures and ski slopes) and

the roadless area of Mt. Parnassos (66.88 km

: Kati et al., 2023).

Figure S3. Habitat suitability binary maps (presence–absence) for the

target species within their potential distribution areas, as defined by

the IUCN. Panels (a) and (b) illustrate the habitat suitability for

P. parnassica, with an extrapolation threshold of 35.1. Panels (c) and

(d) show the habitat suitability for O. parnassica, with an extrapolation

threshold of 28.8. The maps depict only the ensemble small models

with a value of True Skill Statistic (TSS) ≥0.4.

Table S1. The full dataset of 27 variables considered for the Species

Distribution Modelling, indicating the 12 variables selected. The table

presents the time period of reference and the resolution data were

available from respected sources. All the variables were created at

100 100 m resolution, using ClimateEU Software for bioclimatic

variables.

Table S2. The dominant plant species (>70% cover) and their fre-

quency (%) in the quadrats sampled for Parnassiana parnassica

(33 quadrats) and Oropodisma parnassica (36 quadrat).

Table S3. Best-ranked GLMs for P. parnassica and O. parnassica,

showing the number of parameters (k), the AIC corrected for small-

sample size (AICc), the differences in AICc (ΔAICc =AICci AICcb-

est), model’s Akaike weight (wi) and Maximum-Likelihood Pseudo-R

Only models with ΔAICc <2 were considered in model averaging

(Ghmean: mean height of herbaceous vegetation, Rpcover: shrubby

vegetation cover, Alt: altitude, Sl: slope, So: soil cover, R: rock cover).

How to cite this article: Stefanidis, A., Kougioumoutzis, K.,

Zografou, K., Fotiadis, G., Tzortzakaki, O., Willemse, L. et al.

(2024) Mitigating the extinction risk of globally threatened and

endemic mountainous Orthoptera species: Parnassiana

parnassica and Oropodisma parnassica.Insect Conservation and

Diversity,1–15. Available from: https://doi.org/10.1111/icad.

12784

CONSERVATION OF MONTANE ORTHOPTERA 15

Distribution Patterns and Habitat Preferences of Five Globally Threatened and Endemic Montane Orthoptera (Parnassiana and Oropodisma)

Article

Full-text available

Jan 2025

Greece is a European hotspot for Orthoptera (378 species), yet it has been scarcely explored. We investigated the distribution and habitat preferences of the species of two endemic Orthoptera genera, Parnassiana and Oropodisma, in the montane ecosystems of central Greece. We conducted field surveys from 2021 to 2024 in 174 sites across seven mountains. The species of both genera preferred habitats above 1500 m, with species-specific preferences for microhabitat parameters: Parnassiana species favored moderate slopes with dense shrub cover, while Oropodisma species favored substrates with intermediate stone cover and relatively high vegetation cover. Species distribution models estimated the area of suitable habitat for Parnassiana to be at 5 km2 and Oropodisma at 3.28 km2. The Normalized Difference Vegetation Index (NDVI) and potential evapotranspiration were the key environmental drivers of the habitat suitability for both genera. Generalized regression models showed that altitude positively influenced Parnassiana population density, peaking at 2200 m, whereas rock and soil cover negatively impacted Oropodisma population densities. The results emphasize the critical role of montane habitats in sustaining these species and provide essential data for future research and conservation strategies.

Micro‐ and macroclimate interactively shape diversity, niches and traits of Orthoptera communities along elevational gradients

Article

Full-text available

Jan 2024
DIVERS DISTRIB

Aim Temperature is one of the main drivers shaping species diversity and assembly processes. Yet, site‐specific effects of the local microclimate on species and trait compositions of insect communities have rarely been assessed along macroclimatic temperature clines. Location Bavarian Alps, Germany. Methods Bayesian joint species distribution models were applied to investigate how ecological and morphological traits drive variation in the climatic niches of 32 Orthoptera species on 93 grassland sites with contrasting microclimatic conditions along a steep elevational macroclimatic gradient in an Alpine region in Central Europe. Results Species richness and abundance decreased along the elevational macroclimatic gradient, and both benefitted from warm microclimate. Interactive effects of elevation and microclimate on the abundance were, however, species‐specific, and partly mediated by traits: Warm microclimatic conditions facilitated the occurrence of demanding xerophilic and late‐hatching species, resulting in marked community dissimilarities at mid‐elevations where colder sites harboured only a subset of the species. The latter mainly occurred at low elevations together with long‐winged species. Abundance peaks of non‐xerophilic species were further upslope when microclimate was warm. Intraspecifically, the body sizes and wing lengths of the larger females, but not the males, decreased with elevation akin the community mean, and brown colour morphs were more frequent at sites with warm microclimate. Main Conclusions Our nuanced results reveal that trait‐dependent responses of species to microclimate play a key role in the assembly and structuring of insect communities along macroclimatic gradients. Since microclimate preferences changed with elevation, we conclude that species temperature niches are narrower than the elevational range suggests and both macro‐ and microclimatic conditions must be considered when predicting species responses to climate change. Microclimatic contrasts among sites at similar elevations enhanced species turnover mediated by moisture preferences and phenology, highlighting the importance of mountains for conservation as climatic refugia where species with diverging niches can persist in proximity.

How far can I extrapolate my species distribution model? Exploring shape, a novel method

Article

Full-text available

Dec 2023
ECOGRAPHY

Species distribution and ecological niche models (hereafter SDMs) are popular tools with broad applications in ecology, biodiversity conservation, and environmental science. Many SDM applications require projecting models in environmental conditions non-analog to those used for model training (extrapolation), giving predictions that may be statistically unsupported and biologically meaningless. We introduce a novel method, Shape, a model-agnostic approach that calculates the extrapolation degree for a given projection data point by its multivariate distance to the nearest training data point. Such distances are relativized by a factor that reflects the dispersion of the training data in environmental space. Distinct from other approaches, Shape incorporates an adjustable threshold to control the binary discrimination between acceptable and unacceptable extrapolation degrees. We compared Shape's performance to five extrapolation metrics based on their ability to detect analog environmental conditions in environmental space and improve SDMs suitability predictions. To do so, we used 760 virtual species to define different modeling conditions determined by species niche tolerance, distribution equilibrium condition, sample size, and algorithm. All algorithms had trouble predicting species niches. However, we found a substantial improvement in model predictions when model projections were truncated independently of extrapolation metrics. Shape's performance was dependent on extrapolation threshold used to truncate models. Because of this versatility, our approach showed similar or better performance than the previous approaches and could better deal with all modeling conditions and algorithms. Our extrapolation metric is simple to interpret, captures the complex shapes of the data in environmental space, and can use any extrapolation threshold to define whether model predictions are retained based on the extrapolation degrees. These properties make this approach more broadly applicable than existing methods for creating and applying SDMs. We hope this method and accompanying tools support modelers to explore, detect, and reduce extrapolation errors to achieve more reliable models.

Diversity and Biology of Terrestrial Orthopteroids (Insecta) in the Republic of Mordovia (Russia)

Article

Full-text available

Jun 2023
Diversity

Orthopteroidea is an ecologically diverse group of incompletely transformed insects that includes several insect orders similar in development and structure. Many species from Dermaptera, Orthoptera, Mantodea, and Blattodea are sensitive to anthropogenic influences and are indicators of the external environment. Some species cause damage to agriculture and forestry; others are inhabitants of human dwellings and pests of food supplies. The aim of this study is to describe fauna of some orders of Orthopteroidea in the Republic of Mordovia, in the central part of European Russia. This study was conducted in April–October 1971, 1984, 1995, 1996, 1998, 2000, 2001, and 2004–2023. All possible habitats were studied using a variety of methods (entomological traps, pitfall traps, pan traps, etc.). An acoustic method of species identification was also used. For each observation, the coordinates of location, abundance, and dates were recorded. The dataset contains 4865 occurrences. In total, 16,644 specimens of Orthopteroidea were studied. The dataset contains 71 species including Dermaptera (4), Orthoptera (62), Mantodea (1), and Blattodea (4). Of these, 13 species are identified for the first time in the region; these mainly inhabit steppe areas. The presence of two Orthoptera species has not been confirmed yet during our studies; these species are noted in this paper according an old published paper. The biodiversity of Mordovia includes 73 species from four orders. The biology of numerous species, their seasonal dynamics, and some descriptions of biotopes and number of new species are described.

Mitigating the extinction risk of globally threatened and endemic mountainous Orthoptera species: Parnassiana parnassica and Oropodisma parnassica

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