Macroheterocera of a mixed Calabrian black pine-European beech forest of Sila Mountains (Italy) (Insecta: Lepidoptera)

I Macroeterocera di una foresta mista di pino nero di Calabria e faggio dei monti della Sila (Italia) (Insecta: Lepidoptera)

Los Macroheterocera de un bosque mixto de pino negro de Calabria y haya de los montes de Sila (Italia) (Insecta: Lepidoptera)

Introduction

In Sila Mountains (Calabria, southern Italy) forest cover above 1,000 meters of altitude is mainly composed by Pinus nigra subsp. laricio Maire and Fagus sylvatica L. These tree species have a very different ecology and growth in very different edaphic conditions (NICOLACI et al., 2014). However, natural and anthropogenic perturbations have greatly complicated the relationships between these plants and in some places created mixed forests which are actually an artifact and are naturally evolving towards beech forests (NICOLACI et al., 2014). In some cases very old pine woodlots growth near the beech forest (PLUTINO et al., 2018).

Previous studies in southern Italy described moth communities inhabiting pure beech (INFUSINO & SCALERCIO, 2018a) and pine (SCALERCIO & GRECO, 2018) forests allowing us to easy recognize moths preferably associated to one of this forest type, not only those linked to the presence of dominant trees because of foodplant for their larvae but also those favored by more complex ecological relationships. Anyway, species trophically linked to the canopy layer are the most representative of these forest types. Beech forests inhabit a well characterized moth fauna in southern Italy, enriched by the presence of several species of great biogeographic and conservation interest (INFUSINO et al., 2016; INFUSINO & SCALERCIO, 2018). The most characteristic is Operophtera fagata (Scharfenberg, 1805) (Geometridae) very abundant and present everywhere the beech growths, but also Watsonalla cultraria (Fabricius, 1775) (Drepanidae) and Ennomos quercinaria (Hufnagel, 1767) (Geometridae) are strictly linked to this forest type (INFUSINO & SCALERCIO, 2018). Calabrian black pine forests inhabit a very different moth fauna, also very interesting from a biogeographic and conservation point of view. The most characteristic species are Thaumetopoea pityocampa ([Denis & Schiffermüller], 1775) (Notodontidae), Pennitera firmata (Hübner, [1822]) and Eupithecia indigata (Hübner, [1813]) (Geometridae) all with larvae feeding on Pinus and commonly found in this forest type (SCALERCIO & GRECO, 2018), to which can be linked also Dendrolimus pini (Linnaeus, 1758) (Lasiocampidae) and Sphinx pinastri (Linnaeus, 1758) (Sphingidae) with larvae feeding also on other conifers (BERTACCINI et al., 1995).

In this study we explored composition and diversity of moths in such mixed forests to provide a dataset useful to carry out deep ecological investigations on the relationships between biocoenoses that are potentially very different and therefore forced to coexist in a given area. This study assumes a particular relevance as we described for the first time a moth community resulting from a seminatural habitat of which evolutionary trajectory was largely determined by human activities.

Material and methods

The study area was located at the western margin of the Sila Mountains, Calabria, South Italy (Fig. 1). In order to minimize the effects of any variable linked to large spatial scales, we selected an area of approx. 7 square kilometers only, where pine and beech forests are strictly intermingled and, in some places, equally compose the tree layer. Within this area we selected three localities and in each of them we selected one stand with pine dominant, one with beech dominant, and one mixed for a total of nine stands (Table 1).

One UV LED light trap (INFUSINO et al., 2017a) was positioned in selected stands twice per month from May to November 2018, and precisely 9 and 17-V, 7 and 12-VI, 9 and 16-VII, 6 and 13-VIII, 3 and 10-IX, 1 and 8-X, and 8 and 14-XI. One additional trapping night was carried out the 24-XI-2017. Trapping nights were chosen according to weather conditions favorable to the activity of moths, i.e. with low moonlight, low wind speed, temperature near to the mean of the period, with no or light rain.

Specimens has been identified at species level and counted in laboratory. Some specimens were dissected and identified on the basis of genitalia. Few specimens were submitted to DNA barcoding following the Canadian Centre for DNA Barcoding protocol (http://www.boldsystems.org/index.php/resources/handbook?chapter=1_gettingstarted.html), and sequences has been deposited in the Barcoding of Life Database (BOLD) platform. Nomenclature follows KARSHOLT & NIEUKERKEN (2013). Voucher specimens are deposited in the Lepidoptera Collection of the Research Centre for Forestry and Wood, Rende, Italy.

Results and discussions

COMMUNITY COMPOSITION

We found 11,967 specimens belonging to 312 species (Appendix 1). The family of Noctuidae was the most species rich, but Geometridae were largely the most abundant (Table 2). Remarkable was the high richness of Notodontidae, trophically related to deciduous trees, and the low richness of Erebidae, mostly represented here by lychenophagous taxa. The thirteen most abundant species represent the 50% of the total abundance, whilst 73 species were singletons and 29 doubletons (Fig. 2). The most abundant species was Operophtera fagata (n=1313), characteristic for beech forests, followed by Alcis repandata (n=722), common in mountain forests, Lymantria monacha (n=539), usually associated to beeches, and Dendrolimus pini (n=398), associated to conifer woodlots.

Eight species (n=2,237), representing the 18.7% of the whole community, are strictly linked to the dominant tree species, but with those linked to beeches (Opeophtera fagata, Ennomos quercinaria, Watsonalla cultraria, Cyclophora linearia) more abundant (n=1806) than those feeding on pines (n=431), namely, listed according to their abundance, Pennithera firmata, Eupithecia indigata, Thaumetopoea pityocampa, and Panolis flammea. This can be due to the climatic and edaphic conditions of the study area which tend to be more favorable to the beech than to the pine as demonstrated by the presence of beech renewal also in pine-dominated sites that probably will tend to naturally evolve towards a beech forest (NICOLACI et al., 2014), explaining also the absence of pine feeding moths among the top four species.

In pure Calabrian black pine forests SCALERCIO & GRECO (2018) reported 11 species with conifer feeding larvae. In mixed forests we found all these species, three of which primarily feeding on Abies alba Mill., two on other conifers, Lymantria monacha feeding primarily on beeches, and Eupithecia subfuscata, a species erroneously reported as a conifer feeder as it is polyphagous on several herbaceous plants (MIRONOV, 2003). However, the abundance of pine feeding species was quite different in pure forests as T. pityocampa and P. flammea were more abundant than in the mixed forest (Fig. 3). Although comparisons of moth abundances between different years can be affected by their natural population dynamic (BERRYMAN, 1996), we can in any case argue that probably T. pityocampa in the studied mixed forest can be disadvantaged by lower temperatures and greater canopy shadowing than in pure pine forests, both known to be detrimental for larval development (BUFFO et al., 2007).

In mixed forests we found all the species typically linked to pure beech forests previously observed in the Calabria region (INFUSINO & SCALERCIO, 2018a), with small changes of their ranking. O. fagata was always the most abundant, whilst only C. linearia showed a significantly lower abundance (Fig. 3). In definitive, in mixed forests we found a perfect mix of the species trophically linked to the pure forests, with adjustment of their abundance according to local abiotic parameters. Interestingly we found five species that we can consider characteristics of the silver fir woodlots of the Serre Mountains (INFUSINO & SCALERCIO, 2018b), namely Thera britannica, T. variata, Peribatodes secundaria, Pungeleria capreolaria, and Macaria liturata. These species, feeding on Abies alba, cannot be considered as occasionally present in the study area because we observed young silver fir trees in beech woodlots. However, their presence led us to suppose a natural evolution of the forest cover, at least in some places and in absence of perturbations, towards a mixed forest with Abies alba Mill. and Fagus sylvatica because of edaphic and microclimatic conditions, a forest habitat of community interest listed in the Habitat Directive (9220* Apennine beech forests with Abies alba and beech forests with Abies nebrodensis (Lojac) Mattei).

We found that several species with larvae trophically linked to the undergrowth flora (e.g. Mesotype parallelolineata, Diarsia mendica, Gnophos furvata) were more abundant in mixed than in beech forests (Fig. 3). This is probably due to the higher cover and diversity of herbs and shrubs growing in pine than in beech forests that is partially preserved in mixed forests. On the opposite, the more mesophilic microclimate of mixed forests compared to pine woodlots led to a strong decrease of thermophilic species such as Tephronia sepiaria and Colostygia sericeata (Fig. 3). Mixed forests appeared to be the optimal habitat for seven species that here were more abundant than in both pure forests (Fig. 3). It is also interesting to underline that no species was lesser abundant in mixed than in both pure forest types prevailing in mixed forests an additive process for the fauna.

Among species found with few individuals a large ecologically homogeneous group is composed by Cyclophora ruficiliaria, C. porata, C. suppunctaria, Adactylotis contaminaria, Catocala nymphagoga, and Lasiocampa quercus feeding mainly on Quercus that likely are sporadically present in the surroundings of sampled sites. With clear affinity to warmer places are Xanthia ruticilla, Rodostrophia calabra, Hypena lividalis, Agrotis trux, Synopsia sociaria, and Trigonophora flammea, the last of which has been found in more sites and with more individuals in pure pine forests (SCALERCIO & GRECO, 2018).

We recognized 34 ubiquist species composing the 10.9% of the total abundance. Most abundant were Peribatodes rhomboidaria (n=360), Noctua pronuba (n=214) and Idaea degeneraria (n=141), accompanied by several species belonging to the genera Agrotis, Noctua, Mythimna, Idaea and Scopula.

SEASONAL CHANGES IN COMMUNITY COMPOSITION

In April dominant species were Cerastis rubricosa, Orthosia cerasi and O. incerta (Fig. 4), accompanied by some individuals of O. gothica and Panolis flammea, few overwintering Conistra vaccinii and C. rubiginea, and other early-spring active species. Remarkable was the presence of several O. populeti in areas were some trees of Populus tremula are present. As the season proceeded, Eupithecia indigata, Agrotis cinerea and Colocasia coryli replaced previously dominant species, some of which are still present with few individuals. Diarsia mendica characterized late spring communities dominated also by some species that we found for a long period such as Peribatodes rhomboidaria and Epirrhoe galiata. The highest species richness was found during the first half of the summer when most abundant species were Fagivorina arenaria, showing a long fly period, and Dendrolimus pini that was among the most abundant also in mid-Summer together with Lymantria monacha and Ennomos quercinaria (Fig. 4). Communities sampled in September were characterized by Mesotype parallelolineata and started to be abundant also Pennithera firmata that was the dominant species in October with Tiliacea aurago. Late Autumn was characterized by Epirrita christyi and by Operophtera fagata, the most abundant species of mixed Calabrian black pine-beech forest (Fig. 4).

FAUNISTIC INSIGHTS

In the study area we confirmed the presence of some very interesting species, known in the Peninsular Italy only for Sila Mountains or in very few additional localities. Acossus terebra was recently confirmed in only two localities (SCALERCIO & GRECO, 2018; LEONETTI et al., 2019) 40 years after the first finding (PARENZAN, 1982). Our new findings in the western borders of the Sila Grande, the northern part of the Sila Mountains, significantly extended the range of this species as previous localities were located near the eastern (SCALERCIO & GRECO, 2018) and northern (PARENZAN, 1982; LEONETTI et al., 2019) borders of this geographic area. Very interesting were also the following species: Alsophila aceraria, known in Calabria only in the study area (GRECO et al., 2018); Itame messapiaria, endemic of the Sila, found in several places above the 1100 meters of altitude; Metachrostis dardouini, rare in the Alps and previously known in only two localities of the Calabria region and in few additional localities of the Apennines (ZANGHERI, 1963; PARENZAN & PORCELLI, 2006); Dichagyris (Dichagyris) signifera, in Italy known only for the Alps and the Sila Mountains (SCALERCIO & GRECO, 2018), but recently found also in the Aspromonte Massif (locality Tre Limiti, 25-VII-2018, Francesco Parisi, Elvira Castilione and Francesco Manti legit); Eupithecia indigata, characteristic species for Calabrian black pine forests known with certitude in Italy only for the Alps and the Calabria region (MIRONOV, 2003; SCALERCIO & GRECO, 2018).

Although recent studies significantly improved the knowledge on the moth fauna of the Sila Mountains (SCALERCIO & GRECO, 2018; LEONETTI et al., 2019), we added 7 species not recorded so far: Eumannia lepraria (Rebel, 1909), Hydrelia flammeolaria (Hufnagel, 1767), Pasiphila rectangulata (Linnaeus, 1758), and Polyphaenis sericata (Esper, 1787) previously found in few Calabrian localities; Eupsilia transversa (Hufnagel, 1766) and Noctua orbona (Hufnagel, 1766) not found southward of the Polino Massif so far; Autophila (Autophila) cfr. dilucida (Hübner, [1808]), found in only one specimen that showed a great COI divergence (3.53%) (BOLD sequence ID: BCLEP459-18) from the other European populations belonging to this species, deserving deep taxonomic investigations.

In this paper we also correct some mistakes present in literature concerning the fauna of Sila Mountains. Ligdia adustata has been erroneously reported for Vivaio Sbanditi (INFUSINO et al., 2017), these specimens belonging to Lomaspilis marginata. Pterostoma palpina has not been found in Fallistro and Vivaio Sbanditi (LEONETTI et al., 2019), these records refer to Poecilocampa alpina. Apamea ferrago has been erroneously listed in LEONETTI et al. (2019), but these data refer to Mythimna ferrago. Mesogona oxalina is absent in the Sila as the records in SCALERCIO & GRECO (2018) must be attributed to M. acetosellae. Dryobotodes eremita has been erroneously reported for the locality Fossiata (LEONETTI et al., 2019), the correct name for these specimens is Hada plebeja. Scotopteryx mucronata reported in LEONETTI et al. (2019) is S. chenopodiata.

Conclusions

In this paper we described the moth community of mixed Calabrian black pine-European beech forests, analyzing the community from a functional point of view. We found that mixed Calabrian black pine-beech forests of Sila Mountains inhabit a perfect mix of moth species characteristic of the pure forest types, but probably this is only a temporary situation. Based on observed moth species and their distribution, we can corroborate the natural evolution of the mixed pine-beech forests of anthropogenic origin towards beech forests associated to silver fir in most humid and cold places as predicted by NICOLACI et al. (2014). In fact, we found evidences that moth species usually found in beech forests are more common and diverse than those having functional relationships with Calabrian black pines, and that a relevant portion of species characteristic of silver fir forests have been found. Furthermore, this study added seven species to the fauna of the Sila Mountains, underlying also the presence of taxa that deserve accurate taxonomic studies.

Acknowledgments

I would like to thank Silvia Greco, Francesco Leonetti, Annamaria Ienco and Carlo Di Marco for their help in field work. I kindly thank the Sila National Park for the collecting permit. The work was partially supported by the Project REFORM SUMFOREST.

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