First record of Leptoglossus occidentalis Heidemann, 1910 (Hemiptera, Coreidae) in the Canary Islands, a novel pine pest detected through citizen science in an oceanic archipelago

Abstract

The 'western seed bug', known as Leptoglossus occidentalis , is considered a global invasive species that has experienced a recent rapid expansion worldwide, becoming an important pest species for coniferous forests.
With the 'Canary Islands early-warning network for the detection and intervention of invasive exotic species' (RedEXOS), this species was detected for the first time in the Canarian rchipelago in an urban area in the eastern part of the sland of Gran Canaria. This early detection is crucial for understanding the potential damage in one of the islands with the highest surface area of natural endemic pine forest.

Full text

Biodiversity Data Journal 11: e109851
doi: 10.3897/BDJ.11.e109851
Taxonomy & Inventories
First record of Leptoglossus occidentalis
Heidemann, 1910 (Hemiptera, Coreidae) in the
Canary Islands, a novel pine pest detected
through citizen science in an oceanic archipelago
David Lugo , Daniel Suárez , Sonia Martín , Óscar Martín Afonso , Alicia Martín , Carlos Ruiz
‡ Departamento de Biología Animal, Edafología y Geología, Grupo de Sistemática, Biogeografía y Evolución de Artrópodos
de Canarias, University of La Laguna, Tenerife, Canary Islands 38200, San Cristóbal de La Laguna, Spain
§ Island Ecology and Evolution Research Group, Institute of Natural Products and Agrobiology (IPNA-CSIC), Astrofísico
Francisco Sánchez 3, La Laguna, Tenerife, Canary Islands 38206, San Cristóbal de La Laguna, Spain
| Servicio de Biodiversidad, Dirección General de Lucha contra el Cambio Climático y Medio Ambiente. Consejería de
Transición Ecológica, Lucha contra el Cambio Climático y Planificación Territorial, Gobierno de Canarias, Las Palmas de Gran
Canaria, Spain
¶ Gestión y Planeamiento Territorial y Medioambiental, Las Palmas de Gran Canaria, Spain
Corresponding author: David Lugo (dlugoper@ull.edu.es)
Academic editor: Nikolay Simov
Received: 21 Jul 2023 | Accepted: 18 Aug 2023 | Published: 11 Sep 2023
Citation: Lugo D, Suárez D, Martín S, Afonso ÓM, Martín A, Ruiz C (2023) First record of Leptoglossus
occidentalis Heidemann, 1910 (Hemiptera, Coreidae) in the Canary Islands, a novel pine pest detected through
citizen science in an oceanic archipelago. Biodiversity Data Journal 11: e109851.
https://doi.org/10.3897/BDJ.11.e109851
Abstract
Background
The 'western seed bug', known as Leptoglossus occidentalis, is considered a global
invasive species that has experienced a recent rapid expansion worldwide, becoming an
important pest species for coniferous forests.
‡ § | ¶ ¶ ‡
© Lugo D et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY
4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are
credited.

New information
With the 'Canary Islands early-warning network for the detection and intervention of
invasive exotic species' (RedEXOS), this species was detected for the first time in the
Canarian archipelago in an urban area in the eastern part of the island of Gran Canaria.
This early detection is crucial for understanding the potential damage in one of the islands
with the highest surface area of natural endemic pine forest.
Keywords
Coreidae, citizen science, Macaronesia, exotic species, DNA barcoding, new record
Introduction
The genus Leptoglossus Guérin-Méneville, 1831 (Hemiptera, Coreidae, Anisoscelini)
harbours up to 62 species with a Neotropical origin, most of them distributed in Central and
South-America (Faúndez et al. 2017). The genus is characteried by a hind tibiae dilation
that is lanceolate or conspicuously phylliform with one or more emarginations. In most
cases, they are widely expanded, with a body surface scarcely pilose and the first antennal
segment is equal to or longer than the head (Brailovsky and Barrera 2013). Leptoglossus
occidentalis Heidemann, 1910, also known as ‘American pine bug’ or ‘western conifer seed
bug’, is native to the western part of North America, being present in Canada and the
United States (Bánki et al. 2023). Currently, it is considered a global invasive species due
to its spread across Europe, Asia, Africa and South America (Brailovsky 2014, Lesieur et
al. 2014, Faúndez et al. 2017, Lesieur et al. 2018, van der Heyden 2019b, Carpintero et al.
2019,Carpintero et al. 2019). In Europe, it was first detected in northern Italy in 1999
(Taylor et al. 2001). Three years later, the species was present in the south of the country.
In Spain, it was first reported in Barcelona in 2003 and quickly colonized the entire Iberian
Peninsula, reaching the Atlantic coast in less than seven years in three independent events
(Gallego et al. 2013, Farinha et al. 2023). In less than fifteen years, this species has
colonized the entire European continent, with Norway being the northernmost point and
Sicily the southernmost (Maltese et al. 2009, Mjøs et al. 2010). It is estimated that the
species has expanded at a rate of 160 km/year, higher than the estimation of 90 km/year
observed in the USA (Gall 1992). In South America, the first reports of the species were
from Chile and Argentina in 2017 (Faúndez et al. 2017, Carpintero et al. 2019), followed by
a recent expansion to Uruguay (2019), Brazil (2020) and Paraguay (2021) (Faúndez and
Silvera 2019, van der Heyden and Faúndez 2020, Garcete-Barret et al. 2021). In Africa,
the species was detected in Tunisia (2013), Morocco (2015) and South Africa (2020)
(Jamâa et al. 2013, Gapon 2015, van der Heyden and Faúndez 2020, Giliomee and
Rayner 2021). In Asia, it has been reported in Japan (Ishikawa and Kikuhara 2009), China
and South Korea (Zhu 2010, Ahn et al. 2013). Additionally, the species was detected in the
Middle East, with reports in Turkey (2011), Lebanon (2015) and Israel (2018) (Fent and
Kment 2011, Nemer et al. 2019, van der Heyden 2019b).
2Lugo D et al

The characteristic biology of this species (i.e. adults forming aggregations) has facilitated
its human-mediated long-distance expansion, particularly through the transportation of
large aggregations in commercial containers and other artificial structures. Adult specimens
have been detected in containers with tree trunks and wood panels (Dusoulier et al. 2007,
Faúndez et al. 2017). Specimens have also been observed near naval ports in areas such
as Venice, Barcelona, Le Havre and Weymouth (Lesieur et al. 2014). This process also
determines the pathways by which the species reaches islands, as observed in Sicily,
Corsica, Great Britain, Mallorca, Malta, Crete or Menorca (Sciberras and Sciberras 2010,
Pérez Valcárcel and Prieto Piloña 2010, Fent and Kment 2011, van der Heyden 2017, van
der Heyden 2019a). Likewise, it possesses a remarkable capacity for flight, which is
involved in dispersal and rapid expansion between territories, as observed in the Northern
Sporades (Petrakis 2011, Langourov et al. 2022). Insular ecosystems harbour unique flora
and fauna which are particularly vulnerable to the arrival of exotic species (Reaser et al.
2007). To date, the unique report of L. occidentalis for an oceanic island was made in 2013
on the sland of Madeira, where several specimens were collected from trees of Pinus
pinaster Ait, 1789 and Pinus halepensis Mill, 1768 (Bella and Aguiar 2020). In the Canary
Islands, another oceanic archipelago of the Macaronesian egion, 22 Coreidae species
have been reported, with Leptoglossus gonagra (Fabricius, 1775) being the only
introduced species from this family so far (Roca-Cusachs et al. 2020). Here, we report L.
occidentalis for the first time for the Canary Islands, discuss potential threats for native
biodiversity and the role of citizen science in the early detection of such invasion.
Materials and methods
Specimens were identified from material collected in Gran Canaria and confirmed by DNA
barcoding. Monitoring data have been obtained using the RedEXOS online platform
(Gobierno de Canarias 2023), a freely available tool with smartphone application created
by the Canary Island Government, as an early detection network specifically developed to
detect invasive alien species. DNA was extracted from a specimen with the Mag-Bind
Blood & Tissue DNA HDQ 96 kit (Omega Bio-Tek GA, USA) using a KingFisher Flex
(Thermofisher) and DNA concentrations were measured using Tecan Infinite 200 Pro
(Configuration: Infinite M Nano+). The 5’ region (658 bp) of the mtDNA COI gene was
amplified using FoldF and FoldR primers (Yu et al. 2012). PCR reaction conditions were as
follows: initial denaturation at 95°C for 4 min, followed by 42 cycles of 95°C for 45 s, 46°C
for 45 s and 72°C for 90 s and a final extension of 72°C for 10 min. DNA extract (2 μl) was
amplified with 23 μl of PCR mix (for a total volume of 25 μl), comprised of 14.4 μl of water,
2.5 μl of 10x NH buffer (Bioline), 1.5 μl of 50 mM MgCl (Bioline), 2 μl of 2.5 mM dNTPs
(Bioline), 0.5 μl of BSA (20 mg/ml), 1 μl of each primer (10 μM) and 0.1 μl of Taq
polymerase (BIOTAQ). PCR products were sequenced using the Sanger DNA sequencing
service of Macrogen (www.macrogen.com). Sequences were then edited in Geneious
2021.1.1 (www.geneious.com) and compared to the ‘nucleotide’ database of GenBank
(www.ncbi.nlm.nih.gov/genbank) using BLAST (Altschul et al. 1990). The identification was
confirmed using the Barcode of Life Data Systems (BOLD) identification engine, which
conducted a comprehensive search through the complete DNA barcode records in BOLD
4 2
First record of Leptoglossus occidentalis Heidemann, 1910 (Hemiptera, Coreidae) ... 3

to find a suitable match. A dataset was assembled including our sequenced barcode and a
set of available barcode sequences of L. occidentalis. A haplotype network was made
using the median joining method (Bandelt et al. 1999) in Popart software (Leigh and Bryant
2015). The barcode sequence was deposited in GenBank (accession code OR268561).
Taxon treatment
Leptoglossus occidentalis Heidemann, 1910
Materials
a. scientificName: Leptoglossus occidentalis Heidemann, 1910; taxonID: https://
www.gbif.org/es/species/5156102; scientificNameID: Leptoglossus occidentalis; family:
Coreidae; genus: Leptoglossus; specificEpithet: occidentalis; scientificNameAuthorship:
Heidemann, 1910; islandGroup: Canary Islands; island: Gran Canaria; country: Spain;
stateProvince: Las Palmas; municipality: Las Palmas; locality: Tafira Alta;
decimalLatitude: 28.0524757; decimalLongitude: -15.4659979; georeferenceProtocol:
GPS; eventDate: 23/03/2023; eventRemarks: On floor; individualCount: 1; identifiedBy:
Oscar Afonso; dateIdentified: 2023; occurrenceID: 24BB4C7B-9818-5C17-
A658-6676CD4B2EC4
b. scientificName: Leptoglossus occidentalis Heidemann, 1910; taxonID: https://
www.gbif.org/es/species/5156102; scientificNameID: Leptoglossus occidentalis; family:
Coreidae; genus: Leptoglossus; specificEpithet: occidentalis; scientificNameAuthorship:
Heidemann, 1910; islandGroup: Canary Islands; island: Gran Canaria; country: Spain;
stateProvince: Las Palmas; municipality: Las Palmas; locality: Tafira Alta;
decimalLatitude: 28.0524757; decimalLongitude: -15.4659979; georeferenceProtocol:
GPS; eventDate: 03/16/2023; eventRemarks: On floor; individualCount: 1; identifiedBy:
Oscar Afonso; dateIdentified: 2023; occurrenceID: AA6B1220-B3FF-5F7C-
AE72-57F41C88FB19
c. scientificName: Leptoglossus occidentalis Heidemann, 1910; taxonID: https://
www.gbif.org/es/species/5156102; scientificNameID: Leptoglossus occidentalis; family:
Coreidae; genus: Leptoglossus; specificEpithet: occidentalis; scientificNameAuthorship:
Heidemann, 1910; islandGroup: Canary Islands; island: Gran Canaria; country: Spain;
stateProvince: Las Palmas; municipality: Las Palmas; locality: Tafira Alta;
decimalLatitude: 28.0524757; decimalLongitude: -15.4659979; georeferenceProtocol:
GPS; eventDate: 03/15/2023; eventRemarks: On floor; individualCount: 1; identifiedBy:
Oscar Afonso; dateIdentified: 2023; occurrenceID: 47CF4968-98C4-55B5-
B3E4-24C92DF27E4A
d. scientificName: Leptoglossus occidentalis Heidemann, 1910; taxonID: https://
www.gbif.org/es/species/5156102; scientificNameID: Leptoglossus occidentalis; family:
Coreidae; genus: Leptoglossus; specificEpithet: occidentalis; scientificNameAuthorship:
Heidemann, 1910; islandGroup: Canary Islands; island: Gran Canaria; country: Spain;
stateProvince: Las Palmas; municipality: Las Palmas; locality: Tafira Alta;
decimalLatitude: 28.0524757; decimalLongitude: -15.4659979; georeferenceProtocol:
GPS; eventDate: 03/08/2023; eventRemarks: On floor; individualCount: 1; identifiedBy:
Oscar Afonso; dateIdentified: 2023; occurrenceID: 3BD69B29-A18D-57B3-96E2-
FD3781BBB995
e. scientificName: Leptoglossus occidentalis Heidemann, 1910; taxonID: https://
www.gbif.org/es/species/5156102; scientificNameID: Leptoglossus occidentalis; family:
4Lugo D et al

Coreidae; genus: Leptoglossus; specificEpithet: occidentalis; scientificNameAuthorship:
Heidemann, 1910; islandGroup: Canary Islands; island: Gran Canaria; country: Spain;
stateProvince: Las Palmas; municipality: Las Palmas; locality: Tafira Alta;
decimalLatitude: 28.0524757; decimalLongitude: -15.4659979; georeferenceProtocol:
GPS; eventDate: 03/03/2023; eventRemarks: On floor; individualCount: 1; identifiedBy:
Oscar Afonso; dateIdentified: 2023; occurrenceID: 0C358B4C-C079-5307-A5F9-
A6EAAF9B3BED
f. scientificName: Leptoglossus occidentalis Heidemann, 1910; taxonID: https://
www.gbif.org/es/species/5156102; scientificNameID: Leptoglossus occidentalis; family:
Coreidae; genus: Leptoglossus; specificEpithet: occidentalis; scientificNameAuthorship:
Heidemann, 1910; islandGroup: Canary Islands; island: Gran Canaria; country: Spain;
stateProvince: Las Palmas; municipality: Las Palmas; locality: Tafira Alta;
decimalLatitude: 28.0524757; decimalLongitude: -15.4659979; georeferenceProtocol:
GPS; eventDate: 03/01/2023; eventRemarks: On floor; individualCount: 1; identifiedBy:
Oscar Afonso; dateIdentified: 2023; occurrenceID:
6820D899-2233-5E6F-8905-6FBBF285F182
g. scientificName: Leptoglossus occidentalis Heidemann, 1910; taxonID: https://
www.gbif.org/es/species/5156102; scientificNameID: Leptoglossus occidentalis; family:
Coreidae; genus: Leptoglossus; specificEpithet: occidentalis; scientificNameAuthorship:
Heidemann, 1910; islandGroup: Canary Islands; island: Gran Canaria; country: Spain;
stateProvince: Las Palmas; municipality: Las Palmas; locality: Tafira Alta;
decimalLatitude: 28.0524757; decimalLongitude: -15.4659979; georeferenceProtocol:
GPS; eventDate: 02/14/2023; eventRemarks: On floor; individualCount: 1; identifiedBy:
Oscar Afonso; dateIdentified: 2023; occurrenceID: 1F9BE725-
E22F-5E08-9E31-4BDD8DBCF031
h. scientificName: Leptoglossus occidentalis Heidemann, 1910; taxonID: https://
www.gbif.org/es/species/5156102; scientificNameID: Leptoglossus occidentalis; family:
Coreidae; genus: Leptoglossus; specificEpithet: occidentalis; scientificNameAuthorship:
Heidemann, 1910; islandGroup: Canary Islands; island: Gran Canaria; country: Spain;
stateProvince: Las Palmas; municipality: Las Palmas; locality: Tafira Alta;
decimalLatitude: 28.0524757; decimalLongitude: -15.4659979; georeferenceProtocol:
GPS; eventDate: 02/14/2023; eventRemarks: On floor; individualCount: 1; identifiedBy:
Oscar Afonso; dateIdentified: 2023; occurrenceID: 83B0A1F7-D767-5234-B066-
D81688B7BFCD
i. scientificName: Leptoglossus occidentalis Heidemann, 1910; taxonID: https://
www.gbif.org/es/species/5156102; scientificNameID: Leptoglossus occidentalis; family:
Coreidae; genus: Leptoglossus; specificEpithet: occidentalis; scientificNameAuthorship:
Heidemann, 1910; islandGroup: Canary Islands; island: Gran Canaria; country: Spain;
stateProvince: Las Palmas; municipality: Las Palmas; locality: Tafira Alta;
decimalLatitude: 28.0524757; decimalLongitude: -15.4659979; georeferenceProtocol:
GPS; eventDate: 12/20/2022; eventRemarks: On floor; individualCount: 1; identifiedBy:
Oscar Afonso; dateIdentified: 2022; occurrenceID: 88CDAA00-8ABB-5E75-AEFF-
C7ECE6AFB6B4
j. scientificName: Leptoglossus occidentalis Heidemann, 1910; taxonID: https://
www.gbif.org/es/species/5156102; scientificNameID: Leptoglossus occidentalis; family:
Coreidae; genus: Leptoglossus; specificEpithet: occidentalis; scientificNameAuthorship:
Heidemann, 1910; islandGroup: Canary Islands; island: Gran Canaria; country: Spain;
stateProvince: Las Palmas; municipality: Las Palmas; locality: Tafira Alta;
decimalLatitude: 28.0524757; decimalLongitude: -15.4659979; georeferenceProtocol:
GPS; eventDate: 11/18/2022; eventRemarks: On floor; individualCount: 1; identifiedBy:
First record of Leptoglossus occidentalis Heidemann, 1910 (Hemiptera, Coreidae) ... 5

Oscar Afonso; dateIdentified: 2022; occurrenceID: A7194FAB-F818-5CD2-
A28F-2A71D8C3A089
k. scientificName: Leptoglossus occidentalis Heidemann, 1910; taxonID: https://
www.gbif.org/es/species/5156102; scientificNameID: Leptoglossus occidentalis; family:
Coreidae; genus: Leptoglossus; specificEpithet: occidentalis; scientificNameAuthorship:
Heidemann, 1910; islandGroup: Canary Islands; island: Gran Canaria; country: Spain;
stateProvince: Las Palmas; municipality: Las Palmas; locality: Tafira Alta;
decimalLatitude: 28.0524757; decimalLongitude: -15.4659979; georeferenceProtocol:
GPS; eventDate: 11/02/2022; eventRemarks: On floor; individualCount: 1; identifiedBy:
Oscar Afonso; dateIdentified: 2022; occurrenceID: B60A8D20-9495-50A0-
B910-251E2A80C92C
l. scientificName: Leptoglossus occidentalis Heidemann, 1910; taxonID: https://
www.gbif.org/es/species/5156102; scientificNameID: Leptoglossus occidentalis; family:
Coreidae; genus: Leptoglossus; specificEpithet: occidentalis; scientificNameAuthorship:
Heidemann, 1910; islandGroup: Canary Islands; island: Gran Canaria; country: Spain;
stateProvince: Las Palmas; municipality: Las Palmas; locality: Tafira Alta;
decimalLatitude: 28.0524757; decimalLongitude: -15.4659979; georeferenceProtocol:
GPS; eventDate: 10/28/2022; eventRemarks: On floor; individualCount: 3; identifiedBy:
Oscar Afonso; dateIdentified: 2022; occurrenceID: 88270BC1-3CB6-5716-89EB-
F77331E05D74
m. scientificName: Leptoglossus occidentalis Heidemann, 1910; taxonID: https://
www.gbif.org/es/species/5156102; scientificNameID: Leptoglossus occidentalis; family:
Coreidae; genus: Leptoglossus; specificEpithet: occidentalis; scientificNameAuthorship:
Heidemann, 1910; islandGroup: Canary Islands; island: Gran Canaria; country: Spain;
stateProvince: Las Palmas; municipality: Las Palmas; locality: Tafira Alta;
decimalLatitude: 28.0524757; decimalLongitude: -15.4659979; georeferenceProtocol:
GPS; eventDate: 10/25/2022; eventRemarks: On floor; individualCount: 1; identifiedBy:
Oscar Afonso; dateIdentified: 2022; occurrenceID:
FE9FB03B-1995-5459-9D84-71DBC725F133
n. scientificName: Leptoglossus occidentalis Heidemann, 1910; taxonID: https://
www.gbif.org/es/species/5156102; scientificNameID: Leptoglossus occidentalis; family:
Coreidae; genus: Leptoglossus; specificEpithet: occidentalis; scientificNameAuthorship:
Heidemann, 1910; islandGroup: Canary Islands; island: Gran Canaria; country: Spain;
stateProvince: Las Palmas; municipality: Las Palmas; locality: Tafira Alta;
decimalLatitude: 28.0524757; decimalLongitude: -15.4659979; georeferenceProtocol:
GPS; eventDate: 11/29/2022; eventRemarks: On floor; individualCount: 4; identifiedBy:
Oscar Afonso; dateIdentified: 2022; occurrenceID: 5A0FA7FA-
A33C-53CE-8787-5BE30839F104
o. scientificName: Leptoglossus occidentalis Heidemann, 1910; taxonID: https://
www.gbif.org/es/species/5156102; scientificNameID: Leptoglossus occidentalis; family:
Coreidae; genus: Leptoglossus; specificEpithet: occidentalis; scientificNameAuthorship:
Heidemann, 1910; islandGroup: Canary Islands; island: Gran Canaria; country: Spain;
stateProvince: Las Palmas; municipality: Las Palmas; locality: Tafira Alta;
decimalLatitude: 28.0524757; decimalLongitude: -15.4659979; georeferenceProtocol:
GPS; eventDate: 10/05/2022; eventRemarks: On floor; individualCount: 1; identifiedBy:
Heriberto Lopez; dateIdentified: 2022; institutionID: IPNA-CSIC; collectionID: BC1481;
occurrenceID: 341CFD2E-1E2F-5083-9878-014687D7EEFC
6Lugo D et al

Diagnosis
Adult specimens measure between 1.5 and 2.5 cm (total length) and have a brown
or
black body colouration. It can be distinguished from L. gonagra by its broadly rounded
humeral angles of the pronotum, a brown pronotal disc with several round black spots,
underside of body without contrasting large yellow spots and smaller and narrower
foliar dilations of the tibiae (Fig. 1A). In contrast, L. gonagra has humeral angles of the
pronotum that end in a spine, an orange line crossing the anterior part of the pronotal
disc, underside of body covered with large contrasting yellow spots and larger and
wider leaf-shaped dilations of the posterior tibiae with teeth on the external part
(Fig. 1B).
Figure 1.
Habitus, distribution and genetic data of Leptoglossus occidentalis. A Dorsal photo of L.
occidentalis, with reduced dilatations in the hind tibias (photo: Manuel Arechavaleta). B Dorsal
photo of L. gonagra with marked orange dots and teeth in the hind tibia´s dilatations (photo:
Daniel Suárez). C Map of the sland of Gran Canaria showing the presence of Leptoglossus
occidentalis (red dot) and the distribution of Pine forest of Gran Canaria (blue). Nearby pine
cores (2 km) are marked with red arrows in the red inset. The location of Gran Canaria within
the Canary Islands is marked with a red square in the black inset. D Haplotype network for L.
occidentalis, based on sequence variation of the COI barcode region. An asterisk indicates the
haplotype from Gran Canaria.
First record of Leptoglossus occidentalis Heidemann, 1910 (Hemiptera, Coreidae) ... 7

Distribution
North America, Canada, United States, South America, Europe, Asia and
Africa
(Brailovsky 2014, Lesieur et al. 2014, Faúndez et al. 2017, Carpintero et al. 2019, van
der Heyden and Faúndez 2020, Bánki et al. 2023).
Habitat: The current distribution of the species can be found at Fig. 1C. The first
individual was detected in Tafira Alta, Las Palmas de Gran Canaria (28.0524757,
-15.465979), in early October 2022. Since then, the locality has been monitored by
technicians during five months and fourteen additional individuals have been found
(see 'Materials and Methods').
Genetic data: A 658-bp fragment was succesfully amplified (GenBank accession code:
OR268561). BOLD identification resulted at species level identification with a 100%
correlation, with the specimen from Gran Canaria sharing haplotype with continental
specimens from Canada, Germany, Hungary, USA and South Korea (Fig. 1D).
Discussion
In their native area, the life cycle of L. occidentalis is univoltine, forming aggregations to
hibernate in autumn (Pérez Valcárcel and Prieto Piloña 2010). These can be found under
the bark of logs, in cracks or in human-made structures. They can also become a nuisance
pest in houses by entering through small cracks and crevices in buildings (Gall 1992).
However, outside their native range, the species has become bivoltine and polyvoltine, with
a peak of activity in October and December, when aggregations search for hibernation
shelters (Pérez Valcárcel and Prieto Piloña 2010).
This species lays eggs on the needles of conifers. It primarily feeds on the reproductive
structures of different conifer species, such as pines (Pinus spp.), spruces (Picea spp.) and
firs (Abies spp.), causing a reduction in fertility. This can occur through the induction of
abortion in the early stages of development (Connelly and Schowalter 1991) or the
damage mature pine cones, resulting in a lack of germination (Bates et al. 2001, Bates et
al. 2002, Lesieur et al. 2014). Adults and nymphs may occasionally puncture plant tissues
to access the xylem and hydrate themselves, leading to damage to needles, bark and
branches. Due to their ability to feed on different species of pine trees and the damage
they cause to commercially valuable species, there is concern about their impact on the
endemic ‘Canary pine’ (Pinus canariensis C. Sm. ex DC. in Buch). The recent arrival and
establishment of this species could lead to a significant reduction in fertility and the seed
bank of the ‘Canary pine’. Currently, L. occidentalis appears to be located outside the core
areas of the natural pine forest, but close to fragment areas that could connect with the
core areas (Fig. 1C). Due to their high dispersal abilities, there is a great possibility for this
species to spread throughout the Island. Additionally, its aggregation behaviour and its
human-mediated long-distance expansion could enhance its spread across the
Archipelago. Continuing with monitoring is thus crucial, as the deterioration of the Island's
natural pine forest ecosystems can have cascading effects. Leptoglossus occidentalis may
8Lugo D et al

directly impact on Canary pine seeds, depriving food resources for other native species,
such as the ‘Gran Canaria Blue Chaffinch’ (Fringilla polatzeki Hartert, 1905). This bird
species is listed as ‘in danger of extinction’ in the Catalogue of Threatened Species of the
Canary Islands and on the IUCN Red List. It is also considered a priority species in Annex I
of the Birds Directive 79/409/EEC.
The role of citizen science as a tool for early detection is crucial in order to make
appropriate and successful control efforts and reduce considerable time in eradication
(Larson et al. 2020). Institutional proposals, such as the Canary Island Government with
the RedEXOS online platform, are key to preventing uncontrolled expansions and
subsequent unnoticed colonisations (e.g. Rodríguez et al. (2021), Scholz et al. (2021)).
Any suspicious or unusual location of unknown species in the territory should alert
institutions and experts in biological invasions (Thomas et al. 2017). The role of both
citizen science through the use of the RedEXOS app, as well as a pertinent institution to
monitor the current distribution and to sample potential habitat areas on the Island, is
crucial in order to assess the current distribution of the species, which can expand
hundreds of kilometres each year without difficulty.
Acknowledgements
The authors wish to express their gratitude to the RedEXOS field team for collecting and
photographing individuals. We would also like to thank the Biodiversity Administration of
the Canary Islands Government for their support and for granting a sampling permit (Ref.
No. Expte. 8-2023/02031250549). DNA barcoding was conducted under the project
‘CanaryBarcode: hacia el inventariado genómico de la biodiversidad de Canarias’, funded
by Agencia Canaria de Investigación, Innovación y Sociedad de la Información (ACIISI),
Gobierno de Canarias (ProID2021010093), awarded to Brent C. Emerson (IPNA-CSIC).
We are very grateful to Heriberto López (IPNA-CSIC) for his assistance in DNA barcoding
and to Manuel Arechavaleta (Servicio de Biodiversidad, Gobierno de Canarias) for allowing
us to use his photo to illustrate paper. We also wish to thank Brent C. Emerson for
providing a revision of the language style.
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