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Preliminary conservation status and needs of an oceanic island fauna: The case of Seychelles insects

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Islands are generally reported to have much higher extinction rates and levels of threat than continental areas. This perception is based largely on studies of vertebrates. A recent assessment of the biodiversity of the Seychelles islands enables the status of a range of taxonomic groups to be compared. A high proportion of the fauna is found to be threatened, with Dictyoptera being the most threatened insect order (51% of 34 native species) followed by Orthoptera (47% of 68 species). Lower levels of threat are found in Diptera (28% of 562 species), Dermaptera (24% of 21 species) and Lepidoptera (21% of 517 species). Differences between the orders relate mainly to distribution patterns, with the most threatened orders having the highest proportions of endemic and restricted range species. The main threats for most orders are habitat deterioration due to invasion by introduced plant species, sea level rise and climate change. These threat factors are different from those reported to affect vertebrates, which are generally considered to be threatened by introduced predators resulting in critically low population sizes. These findings indicate that conservation sources would be more useful and cost effective for insect conservation if directed to habitat maintenance and restoration rather than to alien predator control.
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ORIGINAL PAPER
Preliminary conservation status and needs of an oceanic island
fauna: the case of Seychelles insects
Justin Gerlach
Received: 31 January 2008 / Accepted: 5 March 2008 / Published online: 19 March 2008
ÓSpringer Science+Business Media B.V. 2008
Abstract Islands are generally reported to have much
higher extinction rates and levels of threat than continental
areas. This perception is based largely on studies of ver-
tebrates. A recent assessment of the biodiversity of the
Seychelles islands enables the status of a range of taxo-
nomic groups to be compared. A high proportion of the
fauna is found to be threatened, with Dictyoptera being the
most threatened insect order (51% of 34 native species)
followed by Orthoptera (47% of 68 species). Lower levels
of threat are found in Diptera (28% of 562 species), Der-
maptera (24% of 21 species) and Lepidoptera (21% of 517
species). Differences between the orders relate mainly to
distribution patterns, with the most threatened orders hav-
ing the highest proportions of endemic and restricted range
species. The main threats for most orders are habitat
deterioration due to invasion by introduced plant species,
sea level rise and climate change. These threat factors are
different from those reported to affect vertebrates, which
are generally considered to be threatened by introduced
predators resulting in critically low population sizes. These
findings indicate that conservation sources would be more
useful and cost effective for insect conservation if directed
to habitat maintenance and restoration rather than to alien
predator control.
Keywords Climate change Conservation Insects
Invasive species Seychelles
Introduction
It is widely accepted that island ecosystems are particularly
vulnerable to extinction (Mueller-Dombois 1981; Loope
and Mueller-Dombois 1989; D’Antonio and Dudley 1995);
in support of this is the high rate of extinction of birds and
reptiles on islands, compared to continental areas (Baille
et al. 2004), with high susceptibility to invasion by alien
species (Donlan et al. 2003a; Reaser et al. 2007). Although
this is well established in literature there have been no
comprehensive surveys of the status of island biodiversity,
with studies limited to vertebrates, some plant groups and a
small number of conspicuous invertebrate taxa. The
invertebrates reported are mainly molluscs threatened with
particular invasive predators (Hadfield et al. 1993; Coote
and Loeve 2003) and large, charismatic insects such as the
New Zealand Weta (Sherley 1998) and the Fregate island
giant tenebrionid beetle (Polposipus herculeanus) (Fergu-
son and Pearce-Kelly 2005).
In 2000–2005 the Indian Ocean Biodiversity Assess-
ment (IOBA) provided a comprehensive survey of the
biodiversity of the Seychelles islands. This is producing a
series of taxonomic reviews and Red List assessments of
all the species recorded in Seychelles. These assessments
provide a comprehensive review of the status of the insect
fauna, allowing this to be compared to existing assessment
of the vertebrate fauna in order to answer the question of
whether or not island faunas are particularly vulnerable or
whether this is an artefact of the small size of vertebrate
island populations. The Red Listing process is ongoing.
The orders that have been completed are evaluated here.
The Seychelles islands comprise 115 islands in the
western Indian Ocean. These form two main groups; the
northern granitic islands and the southern, coralline
islands. The southern islands are less than 10 m above
J. Gerlach (&)
Nature Protection Trust of Seychelles, 133 Cherry Hinton Road,
Cambridge CB1 7BX, UK
e-mail: jstgerlach@aol.com
123
J Insect Conserv (2008) 12:293–305
DOI 10.1007/s10841-008-9156-3
sea level, representing raised coral atolls or sand cays.
This results in limited habitat variation and correspond-
ingly low species diversity. The granitic islands are the
remnants of the Seychelles microcontinent which was
isolated following the break-up of Gondwanaland 65–
100 million years ago. These are high islands reaching
905 m above sea level. This results in great habitat
diversity and high rainfall, contribution to the growth of
diverse rain forest habitats.
Methods
Collection
During the IOBA collections were made in 135 localities
on 52 islands. These included all but three of the islands
where collections had been made by previous expeditions
and encompassed the recorded range of over 99% of the
species recorded before 2000. 78,369 insect specimens
were collected, with surveys in both the wet and dry sea-
sons in order to account for any seasonality in abundance
or activity of the animals.
Identification
For most families identification was carried out by expert
taxonomists. Some families were represented by a small
number of species and were identified using existing lit-
erature on the Seychelles fauna. Identifications were
combined with taxonomic revisions, ensuring that recently
collected material data are directly comparable with his-
torical data.
Assessment
Red List assessments of the insects are complete for Der-
maptera (21 native species), Dictyoptera (34), Diptera
(562), Embioptera (2), Isoptera (7), Lepidoptera (517),
Mantodea (5), Orthoptera (68) and Phasmatodea (6).
Assessments are ongoing for Coleoptera, Ephemeroptera,
Hemiptera, Hymenoptera, Mallophaga, Neuroptera,
Odonata, Psocoptera, Siphonaptera, Thysanoptera and
Trichoptera.
For the Red List assessment all historical distribution
records were compiled, providing a quantified distribution
range. Population sizes were not quantified for any taxa.
Changes in distribution are indicated by the absence of
specimens from historical localities. For species known
only from 1 to 2 specimens the significance of this cannot
be assessed. However if a species was locally abundant in
1905–1909 but could not be found at that locality in 2000–
2005 it was considered to have declined. The IUCN Red
List criteria used in the assessments are summarised in
Table 1.
In interpreting the criteria each island was considered a
separate location. Species which were not found in a
location where they had been recorded historically but
were collected elsewhere were considered to have declined
locally. Other species which were recorded from a histor-
ical location but were not located by the present study were
considered Data Deficient if recorded from habitat which
remains available or if they were known only from a single
specimen. Species not located but recorded from threatened
habitats (such as marshes) were considered threatened due
to the deterioration of that habitat.
Results and discussion
Taxonomy
High levels of threat were found in most orders although
there are notable differences in the level of threat between
different taxa with high levels of threat in Dictyoptera
(51%) and Orthoptera (47%) and moderate levels in Dip-
tera (24%), Dermaptera (24%) and Lepidoptera (21%). The
small orders have variable levels of threat: 33% of Phas-
matodea, 28% of Isoptera, 0% of Mantodea and
Embioptera. In part this relates to the proportion of ende-
mic species, with 24% endemic in Dermaptera, 49% in
Leidoptera and 51% in Diptera, 87% of Dictyoptera and
59% in Orthoptera, in the largest orders. Levels of ende-
mism are again variable in the smaller orders: 100% of
Table 1 IUCN Red List criteria used in the Seychelles assessments
Factor Measurement Critical points Criterion
Number of locations 1 (CR), \5 (EN), \10 (VU) B1&2a
Geographic range Extent of occurrence \100 k
2
(CR), \5000 km
2
(EN), \20,000 km
2
(VU) B1
Area of occupancy \10 km
2
(CR), \500 km
2
(EN), 2,000 km
2
(VU) B2
Declines Extent of occurrence B1bi&2bi
Area of occurrence B1bii&2bii
Quality of habitat B1biii&2biii
294 J Insect Conserv (2008) 12:293–305
123
Phasmatodea, 57% in Isoptera, 25% in Mantodea, and 0%
of Embioptera. Within all groups the endemic species have
higher levels of threat than indigenous species, largely due
to their more restricted distributions, reflected by the dif-
ferences in average area of occupancy and especially extent
of occurrence (Figs. 1,2).
Geography
Different geographical areas also have different levels of
threat, with higher levels of threats in the coral islands than
the granitics for Lepidoptera (52%, compared to 32%),
Diptera (68% compared to 15%) and Dictyoptera (57%
compared to 55%). In contrast the Orthoptera have fewer
threatened species on the coral islands (35%) than the
granitics (46%). Too few species of the other taxa are
present on the coral islands for meaningful comparison.
These differences can be equated to the composition of the
fauna: most Diptera and Lepidoptera on coral islands do
not occur on the granitics, being southern atoll endemics of
Afro-Malagasy colonists; coral island Dictyoptera are
restricted to a small number of mainly endemic species,
again with very few shared with the granitic islands; the
Orthoptera have a higher proportion of taxa shared with the
granitic islands, dominated by the wide-ranging acridid
grasshoppers and tetrigid katydids.
Threats
Although the main threats to species on coral and granitic
islands are ongoing or projected declines in the area of
suitable habitats in the granitic islands this is largely due to
habitat deterioration caused by alien plant species. In the
coral islands the threat is predominantly from projected sea
level rise as 90% of the land area of these islands is no
more than 1 m above sea level. Habitat degradation due to
Lepidoptera
0
100
200
300
DD LC EN EX
Diptera
0
40
80
120
160
Dictyoptera
0
5
10
15
Isoptera
0
1
2
3
4
5
Mantodea
0
1
2
3
4
Phasmatodea
0
1
2
3
Embioptera
0
1
2
Orthoptera
0
5
10
15
20
25
30
35
VU
CR
DD LC EN EX
VU
CR
DD LC EN EX
VU
CR
DD LC EN EX
VU
CR
DD LC EN EX
VU
CR
DD LC EN EX
VU
CR
DD LC EN EX
VU
CR
DD LC EN EX
VU
CR
Fig. 1 Numbers of threatened
species of Seychelles insects.
Grey bar—indigenous species,
black bar—endemic species
J Insect Conserv (2008) 12:293–305 295
123
invasion by the alien plants Cinnamomum verum,Psidium
cattleianum and Falcataria moluccana is the major threat
for most taxa; 67% of threatened Lepidoptera, 69% of
threatened Dictyoptera and 78% of threatened Orthoptera.
This is followed by sea level rise (Lepidoptera 30%,
Dictyoptera 19% and Orthoptera 22%), development (12%
of threatened Dictyoptera), climate change (Lepidoptera
2%, Orthoptera 3%) and association with restricted range
taxa (Lepidoptera 2%). Close association with particular
food plants contributed to threatened status within Phas-
matodea where the two threatened species are both
Endangered by restricted range combined with habitat
deterioration, both have close food plant associations—the
birds nest fern Asplenium nidus in the case of Casuius
scotti and endemic palms in the case of Graffaea seyc-
hellensis. Of the Lepidoptera three indigenous species are
threatened due to a restricted association with a Vulnerable
plant species (Epermenia cf. moza associated with Sche-
fflera procumbens,Herpetogramma licarsisalis with
Pseuderanthemum tunicatum and Bocana sp. with Procris
insularis), or a Critically Endangered animal species
(Crypsithyrodes concolorella associated with the Sey-
chelles sheath tailed bat Coleura seychellensis).
Diptera are the only order that does not fit this pattern. In
this group the main threat is sea level rise (68% of threa-
tened species) followed by habitat deterioration (39%) and
climate change (2%). This difference may be an artefact of
the relatively high proportion of Data Deficient Diptera,
which comprise 35% of species, compared to 6–24% in
other orders. The Data Deficient species are predominantly
(76%) species known from a small number of specimens
from one locality. For these the data are too limited to
allow identification of any habitat association; they may be
threatened or even extinct but cannot be assessed on the
available information.
One of the most threatened habitats in Seychelles is
marsh habitat; this has been largely drained and the few
remaining areas are being drained and developed rapidly.
Of the 14 Lepidoptera associated with marshes 86% are
threatened and 100% of the 37 marsh associated Diptera, of
the other groups studied here few are associated with
marshes—only 2 Orthoptera (both Least Concern) and only
one Dictyoptera (Critically Endangered).
Development affects two species of cockroach (Delosia
ornata and Hololeptoblatta pandanicola). Recorded
extinction levels are low; 1 Diptera, 2 Lepidoptera and 1
Dictyoptera may be extinct. Actual extinction levels may
be higher as a high proportion of taxa have not been located
since 1909 but are not listed as extinct as they may survive
in unexplored areas of habitat. These are listed as Endan-
gered if associated with a deteriorating habitat or Data
Deficient if known just from a single specimen.
The varied effects of geographical distribution and
ecology on threatened status are shown by a comparison of
the Lepidoptera families. Within the Lepidoptera particu-
larly high threat levels are apparent in the Tineidae (62% of
47 species) and Oecophoridae (55% of 21 species). These
are diverse families of small moths, with high levels of
narrow geographical endemism, including many island
Fig. 2 Comparison of ranges (km
2
) of endemic and indigenous
species: (a) extent of occurrence; (b) area of occupancy. White =-
mean range of indigenous species; black =mean range of endemic
species. Orders are ranked by degree of threat (order with the highest
proportion of threatened species first)
296 J Insect Conserv (2008) 12:293–305
123
radiations (Robinson and Tuck 1997). Low levels of threat
are found in the widespread grass-associated Pterophoridae
(0%) and in the equally widespread Geometridae (0%). The
effects of dispersal ability allowing wide distributions and
of polyphagy are shown by the low threat levels for the
Nocutidae (8%) and Nolidae (14%). Other families of large
Lepidoptera with active flight are more specific in their
larval feeding habits and have higher levels of threat, such
as the Nymphalidae (27%), Arctiidae (31%) and Sphingi-
dae (31%).
The highest recorded levels of threat (i.e. the highest
proportion of threatened species) are found on tropical
islands (Mueller-Dombois 1981; Loope and Mueller-
Dombois 1989; D’Antonio and Dudley 1995). This is
reflected in bird data where over half the world’s threa-
tened birds are island species (Baille et al. 2004). These
comparisons are based largely on data for vertebrates, for
which the main threats are invasive species. Two thirds of
island birds are threatened by invasive species (Baille et al.
2004), almost all of which are mammalian predators. It is
widely accepted that island faunas (and endemic species in
particular) are threatened by introduced predators, as
reported for birds (Blackburn et al. 2004,2005; Jamieson
2006). It is often stated that island endemics have evolved
in the absence of predators (e.g. Groombridge 2007).
Whilst this is true of bird faunas with regard to mammalian
predators and for some islands, it does overlook reptile
predators on other islands and does not apply to most
invertebrates which are subject to a range of invertebrate
and avian predators even in the absence of native mam-
mals. Accordingly this cannot be considered a general
explanation for the vulnerability of island taxa. This sus-
ceptibility to the impacts of invasives are thought to be due
to attributes such as reduced dispersal ability and low
population sizes. Island species are generally assumed to
have lower dispersal abilities, due to reduced willingness to
disperse or reduced flight abilities (Reaser et al. 2007).
Flightlessness is rare in the Seychelles fauna, but has
been recorded in birds (one species), beetles (10 species)
and cockroaches. As noted above, threat levels are high in
the Dictyoptera and this may correspond to a tendency to
wing reduction and loss in the endemic cockroaches. No
flightless species have been identified in any of the other
groups studied here; females of some Diptera are flightless,
but these are introduced (Phoridae) or widespread intertidal
species (Chironomidae). As a generalization reduced flight
ability is not an explanation for the high threat levels faced
by Seychelles insects, although it may be an additional
factor for a small number of species.
Island populations are generally smaller than continental
ones, which combined with isolation makes island ecosys-
tems highly sensitive to disturbance (Reaser et al. 2007).
Population size may be particularly important as it has been
suggested that genetic factors (principally inbreeding) are
important in the decline of island populations, with island
populations having lower genetic diversity than continental
ones (Frankham 1998,2005; Frankham et al. 2002;
Spielman et al. 2004; Groombridge 2007). Some studies
suggest that although extinction due to genetic factors such
as inbreeding may be significant it may also be slow in
comparison with rapid declines due to predation (Jamieson
et al. 2006). Other influences include low population growth
rates and additional effects of habitat loss contributing to
genetic deterioration (Jamieson 2006).
In common with other island groups, Seychelles verte-
brates are largely threatened by factors leading to critical
population size (Gerlach 2007). There is no evidence that
similar factors apply to any of the insects evaluated here
although predation has been speculated to affect Orthoptera
(Matyot 1998). Population declines due to introduced
predators were considered a risk for the flightless Fregate
giant tenebrionid beetle Polposipus herculeanus but this
has not been substantiated (Gerlach 2005). The status of
this species is currently being re-evaluated. Some large
invertebrate species have high population densities on rat-
free islands but are scarce (or absent) on the largest islands.
The distributions of such species as the Seychelles giant
millipede Sechelleptus seychellarum, the whip-scorpion
Phrynicticus scaber and the large snail Stylodonta un-
identata superficially appear to be influenced by rats but
this is disproved by the survival of substantial populations
of these species on Silhouette island where rats are highly
abundant. Their absence from the largest islands (Mahe
´and
Praslin) may be due to the introduced tenrec Tenrec
ecaudatus which may be assumed to be a significant alien
predator on those two islands. Thus predation may be a
significant factor for some large invertebrate species when
faced by a particular predator, but the impacts have not
been reliably demonstrated to date. Invasive insects may
also have caused population declines, but this is similarly
speculative. The absence of any conclusive evidence of
invasive ant impacts beyond short-term impacts of tem-
porary population explosions in the crazy ant Anoplolepis
longipes, has been suggested to be due to the undetected
impacts of earlier introductions of species such as Pheidole
megacephala in the nineteenth and twentieth centuries
(Gerlach 2004). The lack of unequivocal examples of
critical population sizes as threats to Seychelles insects
may be due in part of a lack of information on invertebrate
population sizes or may reflect higher population densities
in invertebrates. This is supported by the assessments of
Mollusca where population sizes have been estimated
(Gerlach 2006); although threat levels are high (61%), none
is listed as threatened based on critical population sizes,
rather they are threatened by the habitat (98%) and climate
(12%) factors identified here for insects.
J Insect Conserv (2008) 12:293–305 297
123
Invasives are considered to be the main causes of
extinction on islands (Veitch and Clout 2002; Donlan et al.
2003b). For the Seychelles fauna this results predominantly
from habitat deterioration, with introduced predators being
a significant factor only in some vertebrate species. This
suggests that conservation efforts focusing on invasive
predator control may do little to halt biodiversity loss.
More attention needs to be paid to maintaining functional
ecosystems and restoring degraded areas. Healthy ecosys-
tems may be more resilient to disturbance and such
resilience is essential to minimise future problems; it has
long been noted that climate change may exacerbate the
impacts of invasions.
Although extinction rates are high on islands (Mueller-
Dombois 1981; Loope and Mueller-Dombois 1989;
D’Antonio and Dudley 1995) few species have become
extinct in Seychelles. Periods of major habitat loss may
have caused unrecorded extinctions (especially when
lowland areas were cleared during the early years of human
settlement in the early 1800s and in the late nineteenth
century and early twentieth centuries when coconut plan-
tations were expanded. The low numbers of extinctions
over most of the twentieth century reflect a reduction in
rate of conversion of forests to plantations. Since the 1770s
invasive species have been spreading and since the late
twentieth century they have caused major modifications of
habitat structure. The problems faced by Seychelles bio-
diversity are further exacerbated by rapid increases in
infrastructure development. This is placing increasing
stress on an already seriously compromised ecosystem. In
this situation it is probable that the historically low
extinction rate will rise in the near future.
Appendix
Appendix List of threatened insects included in the present study
Class Family Species Seychelles Red List status
Lepidoptera Tineidae Erechthias calypta VU (D2)
Erechthias methodica EN (B1abv,2abv)
Erechthias molynta EN (B1abv,2abv)
Erechthias polyplaga VU (D2)
Erechthias trichodora EN (B1abv,2abv)
Amphixystis crobylora VU (D2)
Amphixystis cyanodesma CR (B1abv,2abv)
Amphixystis ensifera VU (D2)
Amphixystis fricata EN (B1abv,2abv)
Amphixystis ichnora EN (B1abv,2abv)
Amphixystis lactiflua EN (B2abiii)
Amphixystis nephalia EN (B1abv,2abv)
Amphixystis polystrigella EN (B1abv,2abv)
Amphixystis rhothiaula VU D2
Amphixystis rorida EN (B1abv,2abv)
Amphixystis roseostrigella VU (D2)
Opogona florea VU (D2)
Opogona heliogramma CR (B1abv,2abv)
Opogona sacchari EN (B1abv,2abv)
Afrocelestis lochaea EN (B2abiii)
Crypsithyrodes concolorella VU (D2)
Tinea coronata EN (B1abv,2abv)
Tinea cursoriatella LC
Tinea milichopa VU (D2)
Gracillariidae Acrocercops angelica EN (B1abv,2abv)
Caloptilia tirantella VU (D2)
Cuphodes luxuriosa EN (B1abv,2abv)
Cuphodes tridora VU (D2)
Parectopa parolca EN (B1abv,2abv)
Oecophoridae Pachnistis fulvocapitella EN (B1abv,2abv)
298 J Insect Conserv (2008) 12:293–305
123
Appendix continued
Class Family Species Seychelles Red List status
Bigotianella menaiella VU (D2)
Bigotianella simpsonella VU (D2)
Bigotianella tournefortiaecolella VU (D2)
Chanystis syrtopa VU (D2)
Anachastis digitata VU (D2)
Cophomantella cubiculata VU (D2)
Paraclada tricapna CR (B1abiii)
Blastobasidae Blastobasis intrepida EN (B1abv,2abv)
Gelechiidae Apocritica chromatica VU (D2)
Helcystogramma effera EN (B1abv,2abv)
Thiotricha tenuis subtenuis EN (B1abv,2abv)
Momphidae Ascalenia isotacta EN (B2abiii)
Cosmopteryx flavofasciata EN (B1abv,2abv)
Cosmopteryx mimetis EN (B1abv,2abv)
Lymnaecia superharpalea VU (D2)
Stagmatophora acris EN (B1abv,2abv)
Stagmatophora hieroglypta EN (B1abv,2abv)
Metachandidae Metachanda coetivyella VU (D2)
Metachanda columnata VU (D2)
Metachanda crypsitricha EN (B1abv,2abv)
Metachanda glaciata CR (B1abv,2abv)
Metachanda hydraula CR (B1abv,2abv)
Metachanda noctivaga EN (B1abiii,2abiii)
Metachanda plumbaginella EN (B1abv,2abv)
Epermeniidae Epermenia cf. moza VU (D2)
Lyonetiidae Lyonetia probalactis EN (B1abv,2abv)
Heliodinidae Epicroesa sp. VU (D2)
Stathmopoda glyphanobola VU (D2)
Pyralidae Glaucochrais muscela EN (B1abv,2abv)
Crocidolomia pavonana EN (B1abv,2abv)
Noorda blitealis EN (B1abv,2abv)
Achyra massalis EN (B1abv,2abv)
Syllepte derogata EN (B1abv,2abv)
Cadarena pudoraria EN (B1abv,2abv)
Cnaphalocrocis trapezalis EN (B1abv,2abv)
Eurrhyparodes tricoloralis EN (B1abv,2abv)
Herpetogramma licarsisalis VU (D2)
Herpetogramma phaeopteralis EN (B1abv,2abv)
Lamprosema charesalis EN (B1abv,2abv)
Lamprosema delhommealis EN (B1abv,2abv)
Mimudea ablactis EN (B1abv,2abv)
Piletocera basalis EN (B1abv,2abv)
Pycnarmon diaphana EN (B1abv,2abv)
Syllepte sabinusalis VU (D2)
Stemorrhages sericea EN (B1abv,2abv)
Ancylosis niveicostella VU (D2)
Ematheudes nigropunctata EN (B1abv,2abv)
Ptyobathra irregularis VU (D2)
J Insect Conserv (2008) 12:293–305 299
123
Appendix continued
Class Family Species Seychelles Red List status
Pyralis manihotalis EN (B1abv,2abv)
Choreutidae Anthophila gratiosa VU (D2)
Anthophila quincyella VU (D2)
Tortricidae Cryptophlebia caeca VU (D2)
Olothreutes conchopleura CR (B1abiii,2abiii)
Olothreutes hygrantis VU (D2)
Arctiidae Argina astraea EN (B1abv,2abv)
Exilisia subfusca VU (D2)
Mahensia seychellarum VU (D2)
Utetheisa lotrix VU (D2)
Utetheisa pulchella VU (D2)
Noctuidae Progonia patronalis EN (B1abv,2abv)
Acontia zelleri VU (D2)
Gesonia pansalis EN (B1abv,2abv)
Rhesala moestalis EN (B1abv,2abv)
Bocana sp. VU (D2)
Porphyrinia cf. ragusanoides VU (D2)
Spodoptera cilium EN (B1abv,2abv)
Nolidae Celama tarzanae VU (D2)
Maceda mansueta EN (B1abv,2abv)
Sphingoidea Cephonodes tamsi CR (C1)
Macroglossum alluaudi VU (D1)
Nephele leighi Extinct ?
Temnora fumosa pekoveri VU (B1abiii,2abiii)
Hesperiidae Pelopidas m. mathias VU (D2)
Nymphalidae Euploea mitra EN (B1abv,2abv)
Junonia rhadama VU (D2)
Phalanta philiberti Extinct
Isoptera Kalotermitidae Glyptotermes scotti EN (D2)
Procryptotermes fryeri CR (D2)
Dictyoptera Blatellidae Miriamrothschildia sp. EN (B12abiii)
M. aldabrensis EN (B12abii)
M. biplagiata EN (B12abiii)
M. mahensis EN (B12abiii)
Margatteoidea amoena Ex ?
Hololeptoblatta minor EN (B12abiii)
H. pandanicola CR (B12abiii)
‘Theganopteryx’ grisea CR (B12abiii)
‘T.’ liturata CR (B12abiii)
‘T.’ lunulata EN (B12abiii)
‘T.’ minuta EN (B12abiii)
‘T.’ scotti CR (B12abiii)
Delosia ornata CR (A3c, B12abi,ii,iii)
Sliferia similis CR (B2abiii)
Balta crassivenosa CR (B12abiii)
Nocticolidae Nocticola gerlachi EN (B2abiii)
Blattidae Neostylopyga rhombifolia VU (D2)
Polyphagidae Holocompsa pusilla CR (B12abiii)
300 J Insect Conserv (2008) 12:293–305
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Appendix continued
Class Family Species Seychelles Red List status
Dermaptera Anisolabididae Antisolabis scotti EN (B2abiii)
A. seychellensis CR (B2abiii)
Forficulidae Hypurgus ova VU (D2)
Spongiphoridae Chaetolabia fryeri CR (B12abiii)
Chaetospania gardineri EN (B12abiii)
Orthoptera Mogoplistidae Arachnocephalus medvedevi EN (B2abi,ii,iii)
A. subsulcatus EN (B2abi,ii,iii)
Ectatoderus aldabrae EN (B2abi,ii,iii)
E. nigriceps EN (B2abi,ii,iii)
Ectatoderus squamiger EN (B2abi,ii,iii)
Ornebius stenus EN (B2abi,ii,iii)
O. syrticus EN (2abi,ii,iii)
Malgasia sp. EN (2abi,ii,iii)
Gryllidae Gryllapterus tomentosus EN (B12abiii)
Phaeogryllus fuscus EN (B12abiii)
Phalangacris alluaudi VU (D2) ?????
Seychellesia longicercata EN (B2abiii)
S. nitidula CR (B2abiii)
S. patellifera EN (B2abiii)
Chorthippus parvulus EN (B2abiii)
Trigonidium (Metioche) bolivari EN (B2abiii)
Z. major EN (B2abiii)
Scottiola sp. EN (B12abiii)
S. salticiformis EN (B12abiii)
Fryerius aphonoides EN (B2abiii)
Orthoxiphus nigrifrons EN (B2abiii)
Phaloria (P.) i. insularis EN (B2abiii)
Subtiloria succineus EN (B2abiii)
Tettigonidae Brachyphisis visenda EN (B2abiii)
Odontolakis cf. sexpunctatus EN (B12abiii)
Plangia ovalifolia EN (B2abiii)
Acrididae Pternoscirtus aldabrae EN (B2abiii)
Tetrigidae Coptotiggia cristata CR (B12abiii)
Amphinotus (?) nymphula EN (B2abiii)
A. (?) pupulus EN (B2abiii)
Procytettix fusiformis CR (B12abii,iii)
P. thalassanax EN (B2abiii)
Phasmatodea Ionchodidae Carausius scotti EN (B12abiii)
Platycranidae Graffaea seychellensis EN (B2abiii)
Diptera Sciaridae Epidapus pallidus VU (D2)
Lobosciara adebratti VU (D2)
Pseudolycoriella setigera VU (D2)
Cecidomyiidae Asinapta northi VU (D2)
Seychellepidosis spinosus EN (B12abiii)
Lepidodiplosis filipes VU (D2)
Culicidae Uranotaenia nepenthes VU (D2)
Ceratopogonidae Forcipomyia psilonata EN (12abiii)
Forcipomyia sexannulata CR (12abiii)
J Insect Conserv (2008) 12:293–305 301
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Appendix continued
Class Family Species Seychelles Red List status
Forcipomyia vesicula EN (12abiii)
Forcipomyia pulcherrima EN (12abiii)
Forcipomyia hutsoni EN (12abiii)
Dasyhelea cogani EN (12abiii)
Dasyhelea fenerivensis EN (12abiii)
Dasyhelea hutsoni EN (12abiii)
Dasyhelea inconspicuosa EN (12abiii)
Dasyhelea monosticta EN (12abiii)
Dasyhelea nigricans EN (12abiii)
Dasyhela tamsi CR (12abiii)
Culicoides adamskii EN (12abiii)
Culicoides leucostictus CR (12abiii)
Metacanthohelea cogani EN (12abiii)
Stilobezzia spirogyrae EN (12abiii)
Nilobezzia scotti CR (12abiii)
Bezzia africana EN (12abiii)
Bezzia ornatissima CR (12abiii)
Chironomidae Tanypus complanatus VU (D2)
Larsia pallidissima VU (D2)
Clunio gerlachi VU (D2)
Semiocladius brevicornis VU (D2)
Pseudosmittia triangular CR (12abiii)
Pseudosmittia remigula VU (D2)
Tanytarsus sp. n. VU (D2)
Tanytarsus pallidulus VU (D2)
Polypedilum brunneicorne EN (12abiii)
Polypedilum glabripenne VU (D2)
Polypedilum melanophilum VU (D2)
Chironomus seychelleanus EN (12abiii)
Psychodidae Clogmia n. sp. VU (D2)
Trichopsychoda cf. africanus VU (D2)
Scatopsidae Rhegmoclemina botulus VU (D2)
Tipulidae Idiocera aldabrensis EN (12abiii)
Erioptera maculosa EN (12abiii)
Atypophthalmus mahensis CR (1abiii)
Orimarga fryeri EN (12abiii)
Stratiomyiidae Cardopomyia robusta EN (12abiii)
Odontomyia sp. EN (12abiii)
Oplodontha pulchripes EN (12abiii)
Bombyliidae Geron dilutus EN (12abiii)
Geron seychellarum VU (D2)
Anthrax johanni EN (12abiii)
Exoprosopa aldabrae EN (12abiii)
Micomitra famula EN (12abiii)
Villa aldabrae EN (12abiii)
Asilidae Trichardis nigrescens EN (12abiii)
Dolichopodidae Aldabromyia plagiochaeta EN (12abiii)
Amblypsilopus pallidicornis EN (2abiii)
302 J Insect Conserv (2008) 12:293–305
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Appendix continued
Class Family Species Seychelles Red List status
Austrosciapus sp. S41 EN (12abiii)
Ethiosciapus prysjonesi EN (12abiii)
Mascaromyia leptogaster EN (12abiii)
Mascaromyia sp. S40 EN (12abiii)
Hydrophorus praecox VU (12abiii)
Thinophilus indigenus EN (12abiii)
Hercostomus sp. S48 EN (12abiii)
Lichtwardtia aldabrensis EN (12abiii)
Paraclius solivagus EN (12abiii)
Tachytrechus tessellatus EN (12abiii)
Medetera pachyneura EN (12abiii)
Diaphorus sp. S11 EN (12abiii)
Diaphorus sp. S45 EN (12abiii)
Acropsilus errabundus EN (12abiii)
Chaetogonopteron marronense VU (D2)
Chaetogonopteron seychellense VU (D2)
Chaetogonopteron aldabricum EN (12abiii)
Sympycnus allotarsis EN (12abiii)
Hybotidae Parahybos iridipennis EN (12abiii)
Phoridae Chonocephalus modestus VU (D2)
Dohrniphora papuana EN (12abiii)
Megaselia aldabrae EN (12abiii)
Megaselia extans VU (D2)
Megaselia frontata VU (D2)
Megaselia pseudomera VU (D2)
Megaselia senegalensis EN (12abiii)
Megaselia sp. A CR (12abiii)
Megaselia sp. B CR (12abiii)
Puliciphora exachatina CR (12abiii)
Pipunculidae Eudorylas semiopacus EN (12abiii)
Muscidae Atherigona cornicauda EN (12abiii)
Atherigona orientalis VU (D2)
Coenosia setalis EN (12abiii)
Limnophora sp. EN (12abiii)
Lispe bengalensis EN (12abiii)
Lispe sp. EN (12abiii)
Lispe sp.n. EN (12abiii)
Hippoboscidae Olfersia aenescens EN (12abiii)
Olfersia spinifera EN (12abiii)
Platystomatidae Naupoda inscripta VU (D2)
Tephritidae Philophylla seychellensis EN (12abiii)
Psednometopum aldabrense EN (12abiii)
Taomyia ocellata Extinct ?
Lauxaniidae Homoneura funebricornis EN (12abiii)
Homoneura laticosta EN (12abiii)
Homoneura mahensis EN (12abiii)
Homoneura terminalis EN (12abiii)
Clusiidae Heteromeringia nigrifrons EN (12abiii)
J Insect Conserv (2008) 12:293–305 303
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... Of the cockroach species, Margatteoidea amoena is listed as extinct, eight species are listed as critically endangered, and seven are listed as endangered. Although this list is probably not representative for cockroaches as a whole, as just three genera account for 15 of the assessed species and all the available evaluations are based on a biodiversity survey of the Seychelles (Gerlach 2008), it does con vey an impression of a large proportion of cockroach species being threatened. The larg est number of cockroach species live in humid tropical and subtropical forest (Beier 1974), a habitat under intense threat from logging and clearing of land for agriculture; thus, a large proportion of cockroach species are likely to be under threat or to have gone extinct as a result of these activities. ...
... The larg est number of cockroach species live in humid tropical and subtropical forest (Beier 1974), a habitat under intense threat from logging and clearing of land for agriculture; thus, a large proportion of cockroach species are likely to be under threat or to have gone extinct as a result of these activities. However, in the Seychelles study, the greatest threat to cock roaches did not come from wholesale destruc tion of habitat, such as logging or clearing, but from habitat deterioration caused by invasive plants (Gerlach 2008). Cockroaches are the most threatened insect order on the Seychelles, with 51% of 34 native species being threatened and 28% of native termite species being threat ened (Gerlach 2008). ...
... However, in the Seychelles study, the greatest threat to cock roaches did not come from wholesale destruc tion of habitat, such as logging or clearing, but from habitat deterioration caused by invasive plants (Gerlach 2008). Cockroaches are the most threatened insect order on the Seychelles, with 51% of 34 native species being threatened and 28% of native termite species being threat ened (Gerlach 2008). ...
Chapter
This chapter focuses on cockroaches but briefly treats termites. Cockroaches can be important pollinators in the canopy of tropical forests. Termites are an important component of tropical ecosystems. The chapter shows major groups of Blattodea with numbers of known species. Some recent estimates place the origin of the present diversity of Blattodea 275‐257 million years ago, although other estimates place it much later, 190‐185 mya. The Blattodea are divided into three superfamilies: Corydioidea, Blaberoidea, and Blattoidea. Cryptocercus cockroaches share a number of important characteristics with lower termites: wood‐feeding, obligate symbiotic relationship with hypermastigid and oxymonadid gut flagellates that help to break down cellulose, flagellate transfer to nymphs through anal trophallaxis, and some degree of sociality. Cockroaches have been used in the treatment of a wide variety of diseases around the world and are still used today in traditional and folk medicine.
... Island endemic species, due to their limited geographic ranges and complex evolutionary histories, and to the precarious equilibrium of island environments, are significantly more threatened by extinction compared to mainland taxa (Simberloff 2000, Gerlach 2008, Russell & Kueffer 2019. Despite accounting for less than 6 % of the planet's surface, islands represent central hotspots for biodiversity harbouring almost 50 % of the species globally classified as threatened (Walker & Bellingham 2011, Spatz et al. 2017. ...
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... On these islands, seven butterfly species or subspecies are now considered extinct (Table 1) and five species or subspecies are evaluated as threatened taxa (Bernardi 1996; UICN France et al. 2013;Lawrence 2014). Despite that critical situation, not many conservation initiatives specifically targeting insects have been undertaken in the region (Déségaulx-de-Nolet 1981;Motala et al. 2007;Gerlach 2008). Until now, butterflies have benefited from the establishment of the national parks both on Réunion and Mauritius and from the weed removal in protected areas (Florens et al. 2010). ...
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... This short communication represents a call for biodiversity inventories of the Mascarene Islands and conservation awareness for invertebrate taxa. The Mascarene stick insects can serve as large-bodied and charismatic flagship species for conservation, as the wetas (Anostostomatidae) have in New Zealand (Watts et al. 2008) and giant tenebrionid beetle (Polposipus herculeanus) for the Seychelles (Gerlach 2008). Ongoing ecological restoration efforts of the Mascarene Islands and elsewhere would benefit from the directed study of oft-neglected invertebrates to supplement knowledge of species biology and their ecological interactions. ...
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... For certain butterfly species, the life cycle, daily activity, habitat preference, larval and imago feeding sources, and morphological variability were examined (Lawrence 2004(Lawrence , 2009(Lawrence , 2014. Gerlach (2008) estimated the conservation status of lepidopteran species and other insect taxa of the Seychelles islands and determined that 21% of Lepidoptera taxa are threatened, including 102 moth and four butterfly species. ...
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We report recent records of 17 Lepidoptera species from 15 genera and 11 families, which were collected on the Inner Seychelles in January 2013. From Praslin Island, 11 species, including two Seychelles endemics, were recorded for the first time. These records have significantly expanded the list of the lepidopteran fauna of Praslin to 54 species. Four species were newly collected after a long-term (ca. 50 years) absence of their specimens in samples from the Seychelles archipelago. In addition, seven species were rediscovered from separate islands. Our findings highlight that there is some evidence of faunal exchange between the two largest islands of the granitic Seychelles and that the lepidopteran fauna of Praslin has been largely underestimated.
... Islands surrounded by water (in contrast to habitat islands) deserve special attention as an example of naturally fragmented areas. Island populations are more susceptible to extinction than mainland populations, whether threatened by alien species or habitat loss (Frankham 1995(Frankham , 1998Gerlach 2008;Dennis et al. 2008;New 2008), and may be more sensitive to genetic factors (bottlenecks and genetic drift) causing population decline as consequence of loss of genetic variation and inbreeding than mainland populations because of small effective population size, N e , and reduced immigration (Frankham 1997). Loss of genetic variation means that populations may be less equipped to evolve in response to environmental change whilst inbreeding is associated with inbreeding depression in normally outbred populations . ...
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Minimizing the impact of invasive alien species (IAS) on islands and elsewhere requires researchers to provide cogent information on the environmental and socioeconomic consequences of IAS to the public and policy makers. Unfortunately, this information has not been readily available owing to a paucity of scientific research and the failure of the scientific community to make their findings readily available to decision makers. This review explores the vulnerability of islands to biological invasion, reports on environmental and socioeconomic impacts of IAS on islands and provides guidance and information on technical resources that can help minimize the effects of IAS in island ecosystems. This assessment is intended to provide a holistic perspective on island-IAS dynamics, enable biologists and social scientists to identify information gaps that warrant further research and serve as a primer for policy makers seeking to minimize the impact of IAS on island systems. Case studies have been selected to reflect the most scientifically-reliable information on the impacts of IAS on islands. Sufficient evidence has emerged to conclude that IAS are the most significant drivers of population declines and species extinctions in island ecosystems worldwide. Clearly, IAS can also have significant socioeconomic impacts directly (for example human health) and indirectly through their effects on ecosystem goods and services. These impacts are manifest at all ecological levels and affect the poorest, as well as richest, island nations. The measures needed to prevent and minimize the impacts of IAS on island ecosystems are generally known. However, many island nations and territories lack the scientific and technical information, infrastructure and human and financial resources necessary to adequately address the problems caused by IAS. Because every nation is an exporter and importer of goods and services, every nation is also a facilitator and victim of the invasion of alien species. Wealthy nations therefore need to help raise the capacity of island nations and territories to minimize the spread and impact of IAS.
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The biological diversity of our planet is being depleted due to the direct and indirect consequences of human activity. As the size of animal and plant populations decrease, loss of genetic diversity reduces their ability to adapt to changes in the environment, with inbreeding depression an inevitable consequence for many species. This textbook provides a clear and comprehensive introduction to the importance of genetic studies in conservation. The text is presented in an easy-to-follow format with main points and terms clearly highlighted. Each chapter concludes with a concise summary, which, together with worked examples and problems and answers, emphasise the key principles covered. Text boxes containing interesting case studies and other additional information enrich the content throughout, and over 100 beautiful pen and ink portraits of endangered species help bring the material to life.
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