Diversity of Lepidoptera (Insecta) recorded in a forest nursery of Nordeste County on São Miguel Island (Azores)

Abstract Background The diversity of moth species (Insecta, Lepidoptera) recorded in the forest nursery of Nordeste County on São Miguel Island (Azores) is given. Adults were sampled between March and December 2019 using three methods: (i) light trap to catch Noctuidae species, (ii) open-sided delta trap baited with a synthetic female sex pheromone lure to attract Epiphyaspostvittana (Walker) males and (iii) entomological net to collect microlepidopteran moths. This contribution focuses mainly on the diversity of moths present in one forest nursery of Nordeste County of São Miguel Island (Azores), especially on the species associated with endemic and native plant species. It also contributes to better plan strategies for integrated protection and conservation measures, since nurseries host a great diversity of plants from the Laurel Forest, which may attract many lepidopteran species. New information A total of 10160 adults belonging to 33 lepidopteran species were recorded and listed by families, including: Argyresthiidae, one species (3%), Crambidae, four species (12%), Erebidae, one species (3%), Geometridae, five species (15%), Noctuidae, 18 species (55%), Sphingidae, one species (3%), Tineidae, one species (3%) and Tortricidae, two species (6%). The families Noctuidae, Geometridae and Crambidae were the most diverse. Those with the highest abundance of adults were the Noctuidae family, followed by the Geometridae, Crambidae, Tortricidae and Tineidae. The number of caught adults was consistently higher during spring and summer, decreasing sharply in late autumn. For 13 species caught in the light trap, the adult sex ratio was favourable to females. An analysis of the colonisation status, feeding and primary hosts of these endemic, native or exotic moth species contributes to our understanding of the factors that may lead to their establishment in Laurel Forest environments and to what extent there is a need to monitor and control them mainly with biological control agents.


Introduction
The Laurel Forests of these islands have been significantly impacted by human activities, mainly due to dramatic land-use changes (only about 5% of the original forests remain; , habitat degradation and the introduction of exotic and invasive species , Borges et al. 2013, Terzopoulou et al. 2015. Currently, the Official Forestry Services rear endemic and native Azorean plant species to seek the restoration of the Laurel Forest and areas with high erosion risk or sensitive from the hydrological point of view, to promote awareness-raising activities and support forestation by private landowners (Rosagro et al. 2019). To this end, in São Miguel Island, thousands of the endemic and native plants are annually reared in two forest nurseries located in Povoação (Furnas) and Nordeste Counties. The plants reared in these forest nurseries are highly susceptible to attack by insect pests, such as aphid and lepidopteran species (Rosagro et al. 2019).
According to the most recent list of terrestrial organisms of the Azores (updated from , Vieira et al. 2021, arthropods are the most diverse taxon, both in absolute richness (about 2364 taxa) and in number of endemic species and subspecies (about 274) (updated from . Nevertheless, most of the arthropods (58%; Borges et al. 2005) are considered introduced. Amongst the most diverse insects, we found the butterflies and moths (Lepidoptera) with 158 species and subspecies, including 40 endemics (updated from , Vieira et al. 2021. About one third of Lepidoptera were considered as being in the Azores as a consequence of human introductions , in which snout moths (Pyralidae), fungus moths (Tineidae) and leaf-rollers (Tortricidae) are the families with the highest number of introduced taxa. Furthermore, at the same time that the number of Azorean endemic species has continued to increase with new species descriptions (e.g. Wagner 2014, Wagner 2015, Pérez Santa-Rita et al. 2020, some exotic species have also been recorded for the islands (Wagner and Hausmann 2014, Vieira 2020a, Vieira 2020b.
Most studies about Lepidoptera from the Azores focus on species description, ecology and distribution, providing crucial information for the conservation of this taxon (e.g. Wagner 2014, Wagner 2015. However, there is still poor knowledge about the potential risk of most Microlepidoptera as pests to their host plants, as well as the colonisation status of many moth species.

General description
Purpose: This contribution focuses mainly on the diversity of moths present in one forest nursery of Nordeste County of São Miguel Island (Azores), especially species associated with endemic and native plant species. It also contributes to better plan strategies of integrated protection and conservation measures, since nurseries host a great diversity of plants from the Laurel Forest, which may attract many lepidopteran species.

Project description
Title: Diversity of Lepidoptera recorded in a forest nursery of Nordeste County on São Miguel Island (Azores) Personnel: Virgílio Vieira, Luísa Oliveira, António O. Soares, Paulo A. V. Borges, Isabel Borges, João Tavares Study area description: The current study was performed in São Miguel Island (ca. 750 km ), the largest in the Archipelago of the Azores, located in the North Atlantic, roughly between the coordinates 37°54'38'' to 37°42'13''N latitude and 25°08'03'' to 25°51'17''W longitude. The climate is temperate oceanic, with regular and abundant rainfall, high levels of relative humidity and persistent winds, mainly during the winter and autumn seasons. The study was conducted in the Nordeste Nursery Recreational Forest Reserve located in Nordeste County (37°49'43.9"N, 25°08'59.5"W) at about 180 metres of altitude.
Design description: Data from pheromone trap, light trap and entomological net sampling were analysed to assess differences in species richness, abundance and phenology of lepidopteran species and families. Adult sex ratio expressed as percentage of females was calculated for 14 Noctuidae species captured in the light trap following the formula: % females = (number of females/total of adults) x 100. All statistical analysis were performed using SPSS Statistics v. 27 software. Funding: Regional funds, through Official Forestry Services from Regional Government of the Azores, within the research project MoCIL "Monitorização e Controlo Integrado de Lepidópteros em Viveiros Florestais (Nordeste e Furnas) na ilha de São Miguel -Açores", FCT -Fundação para a Ciência e a Tecnologia, I.P., under the project UIDP/05292/2020 and UIDB/05292/2020 and AZORESBIOPORTAL-PORBIOTA (ACORES-01-0145-FEDER-000072) (2019-2022).

Sampling methods
Description: The study covers the nocturnal lepidopterans that attack endemic and native Azorean forest plants reared in the nursery.
Sampling description: Samples of adult moths were collected between March and December 2019 (i.e. 38 weeks), as generally few lepidopteran species are active during winter. Adults were monitored from dusk (18:00 h) to dawn (06:00 h) using an omnidirectional light trap, equipped with a TLD 18W lightbulb, according to the methodology used by Tavares (1989). Additionally, the Epiphyas postvittana population was monitored from May to December 2019 (i.e. 31 weeks), using open-sided delta traps baited with a synthetic female sex pheromone lure (containing: E11-14Ac, E9E11-14Ac) to attract males (see ). The light trap and open-sided delta trap, spaced 300 m apart, were installed one metre over the ground level at the edge of the nursery for Azorean endemic forest plants, which included Erica azorica, Vaccinium cylindraceum (both Ericaceae), Ilex azorica (Aquifoliaceae), Juniperus brevifolia (Cupressaceae), Laurus azorica (Lauraceae), Viburnum treleasei (Adoxaceae), Prunus azorica (Rosaceae), Picconia azorica (Oleaceae), Frangula azorica (Rhamnaceae) and one native species, Morella faya (Myricaceae), which are listed in the IUCN Red List (see Rosagro et al. 2019. Throughout the study, adults were collected weekly in both trap types and lures changed once a month. In addition, the plants reared in the forest nursery were sampled once a week to collect microlepidopteran moths using a standard entomological net (35 cm diameter, 140 cm handle), which were immediately identified and released on site if the specimens did not need to be observed more carefully in the laboratory. Sweeping occurred during day hours.
Quality control: All individuals caught in the traps were first sorted by Virgílio Vieira, João Tavares or Luisa Oliveira. Current taxonomic affiliation follows Vives-Moreno (Vives-Moreno 2014).

Taxonomic coverage
Description: The sampling programme targeted lepidopteran species (Insecta: Lepidoptera)

Description:
The following data include all the records for which a taxonomic identification of the species was possible. The dataset submitted to GBIF (Global Biodiversity Information Facility) is structured as a sample event dataset, with two tables: in the current event table, the data in this sampling event resource have been published as a Darwin Core Archive (DwCA), which is a standardised format for sharing biodiversity data as a set of one or more data tables. The core data file contains three records (eventID). This IPT (integrated publishing toolkit) archives the data and thus serves as the data repository. The data and resource metadata are available for download from Vieira et al. (2022).

Column label Column description
eventID Identifier of the events, unique for the dataset.
stateProvince Name of the region of the sampling site.
islandGroup Name of archipelago.
island Name of the island. year Year of the event.
sampleSizeValue A numeric value for a measurement of the size (time duration, length, area or volume) of a sample in a sampling event. sampleSizeUnit The unit of measurement of the size (time duration, length, area or volume) of a sample in a sampling event.
Data set name: Description: The following data include all the records for which a taxonomic identification of the species was possible. The dataset submitted to GBIF (Global Biodiversity Information Facility) is structured as a sample event dataset, with two tables: in the current event table, the data in this sampling event resource have been published as a Darwin Core Archive (DwCA), which is a standardised format for sharing biodiversity data as a set of one or more data tables. The core data file contains 33 records (occurrenceID). This IPT (integrated publishing toolkit) archives the data and thus serves as the data repository. The data and resource metadata are available for download from Vieira et al. (2022).

Column label Column description
eventID Identifier of the events, unique for the dataset.
type Type of the record, as defined by the Public Core standard.
licence Reference to the licence under which the record is published. institutionID The identity of the institution publishing the data. collectionID The identity of the collection publishing the data. institutionCode The code of the institution publishing the data. collectionCode The code of the collection where the specimens are conserved.
datasetName Name of the dataset. basisOfRecord The nature of the data record. scientificNameAuthorship Name of the author of the lowest taxon rank included in the record.
Weekly abundance of the most frequent nocturnal lepidopterans were similar to those observed in previous studies conducted in the Azores (e.g. Tavares 1989, Carvalho et al. 1999, Vieira et al. 2004). In particular, for M. unipuncta, it was observed that, after three remarkable peaks of captures in early July, August and September, there was a steady decline to the lowest values in mid-October, in addition to the low number of adults captured (nil in some weeks) in early winter and spring. The number of adults captured varies significantly depending on the type of trap (light trap or sex pheromone trap), location and season (Vieira et al. 2004). The collected moths were from the adult stage, but larvae of the most abundant species do not feed on woody plants.
Sampling of Microlepidoptera moths on young forest plants reared in the Nordeste Nursery using an entomological net showed that the most common moths are endemic species that appear associated with their known host plants (Table 3) (see Silva et al. 1995, Nuss et al. 1997, Wagner 2014, Wagner 2015. Argyresthia atlanticella is the second most common lepidopteran in the Azores (Peres Santa-Rita et al. 2020), but in the nurseries, they have population densities with low numbers of individuals (Table 1), which is, amongst other factors, related to their nocturnal (rather than diurnal) activity and some of these species are effectively rare or have a conservation status of vulnerable.    Table 3 shows that 33 lepidopterans recorded are classified with the colonisation status of endemic (10 species), native (16), introduced (4) and introduced/naturalised (3). Regarding their feeding mode, 23 are generalists or polyphagous and 10 are specialists and the larvae can feed on plants of the Laurel Forest (14 species), endemic / native (23 species) and non-native (23 species).
According to previous studies and our field observations, many of the moth species recorded in this study (see Tables 1, 3) Silva et al. 1995, Nuss et al. 1997, Wagner 2014, Wagner 2015, Pérez Santa-Rita et al. 2020. Other studies (Ribeiro et al. 2005, Rego et al. 2019 show that these species are associated with different hosts (e.g. A. fortunata on E. azorica), but neither shows that their impact severely affects plant fitness/reproduction. In addition, herbivore abundance may match host plant abundance, not being necessarily a pest.

Conclusions
Our results provide information on the diversity of moths (Insecta, Lepidoptera) present in Nordeste County, whose adults were sampled in the Nordeste Forest Nursery. A total of 10160 adults belonging to 33 lepidopteran species were recorded and listed by families, including: Argyresthiidae, Crambidae, Erebidae, Geometridae, Noctuidae, Sphingidae, Tineidae and Tortricidae.
In general, the temporal profile of the abundance of adults caught in a light trap and a sex pheromone trap reveals that the Noctuidae, followed by the families Geometridae and Crambidae, have the highest species diversity and that these have high population densities during spring and summer, decreasing sharply in late autumn. In addition, for 13 species caught in the light trap, the adult sex ratio was favourable to females.
From the literature and our field observations, we conclude that many of the moth's species recorded have little economic importance in the Azores Archipelago, but others may constitute a potential risk as pests (e.g. species from families of Noctuidae, Tortricidae and Crambidae) of introduced/naturalised and/or endemic/natives plants. In fact, the high abundance of adult moths observed for some species whose larvae feed preferentially on native and/or exotic herbaceous plants does not generally represent very serious damage to endemic and native forest plants of the Azores.
An analysis of the colonisation status of the lepidopteran moth species and their feeding and primary host plants associated with the Laurel Forest, native or non-native Azorean plants, suggests that forest nurseries may help us to understand the establishment of lepidopteran moths (endemic, native or exotic species) in Laurel Forest environments.
Finally, more studies are needed to understand two fundamental objectives; first, to know the potential damage caused by moth species on endemic and native Azorean plants; second, to assess the conservation status of all these moth species and to advise on possible future research and conservation actions critical to the long-term survival of the most endangered species.