Introduction

The high Arctic archipelago Svalbard is among the best-studied Arctic regions in terms of biodiversity (Prestrud et al. 2004; Johansen et al. 2012). Despite its isolation, invasions have also occurred in this area and are widely recognised as constituting a serious risk to the Arctic region (Coulson et al. 2013; Wisz et al. 2015). Additional factors are the rapid climate change in the region and increases in human activity (Ware et al. 2011, 2014, 2016). Most of the alien species that have been introduced to Svalbard are plants. The percentage of alien plant taxa that was recorded in Svalbard (57%) compared to native species is higher than that recorded in other Arctic regions (Alsos et al. 2015). The highest species diversity and abundance of aliens were recorded in or close to the human settlements of Barentsburg, Pyramiden or Longyearbyen on the largest island Spitsbergen (Liška and Soldán 2004; Roalsø 2012). However, in the harsh Arctic conditions, only a few of the introduced plant species have established stable populations (Alsos et al. 2007). The current alien terrestrial invertebrate fauna of Svalbard consists of a relatively few species and none of them have yet displayed invasive tendencies (Coulson 2015).

The aphid fauna of Svalbard is extremely limited and comprises two endemic species—Acyrthosiphon svalbardicum (Heikinheimo) (Hodkinson et al. 2002) and Sitobion calvulus (Ossiannilsson) (Hodkinson et al. 2004). Non-native species of this group of insects have not as yet been recorded.

During the investigation, which was conducted in August 2018, we had the opportunity to collect aphids (Insecta, Hemiptera, Aphididae) in Longyearbyen, which is the largest settlement in Svalbard, and its vicinity, as well as in the research town of Ny-Ålesund, both of which are located on the island of Spitsbergen in Svalbard. One of the results of our field study revealed the first detection of the alien aphid species Myzus (Nectarosiphon) persicae (Sulzer) in the Svalbard archipelago. The green-peach aphid is a polyphagous generalist that is globally distributed and is listed among the 14 species of the greatest economic importance that has a pest status (van Emden and Harrington 2007).

Materials and methods

Longyearbyen is the largest populated settlement on the Svalbard archipelago, and is located in the High Arctic, 78° North. Longyearbyen lies on Spitsbergen on the southern side of Adventfjorden, and is stretched out along the Longyear River. The surveys that are reported here were primarily carried out in the town and its vicinity (Fig. 1).

Fig. 1
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Collecting area

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The investigation was conducted for a period of two weeks from 10 to 24 August 2018. The permission for the research application for RiS-ID 10,994 (including aphid collection) was issued by the Governor of Svalbard.

The aphids were collected directly from the host plants with a fine hair brush and placed into Eppendorf tubes containing 70% ethanol. The location, sampling date and host plant name were recorded on the labels that were placed onto the tubes. Adult wingless or winged females were slide-mounted using the method of Kanturski and Wieczorek (2012) and identified to the species level. The slides were examined using a Nikon Ni-U light microscope equipped with a phase contrast system. Field photographs were taken using an iPhone 7 camera with the OlloClip Macro Pro Lens Set. Samples were identified by K. Wieczorek based on their morphological diagnostic features using the standard literature-based keys (Blackman 2010; Blackman and Eastop 2006, 2018). The aphid material is deposited in the collection of the Department of Zoology, University of Silesia in Katowice, Katowice, Poland (DZUS):

DZUS 23/8.18_6 Myzus (Nectarosiphon) persicae, three alate viviparous females, Longyearbyen, Norway, 23.08.2018, Viola tricolor, K.Wieczorek leg.; DZUS 23/8.18_7 Myzus (Nectarosiphon) persicae, two alate viviparous females, one apterous viviparous female, Longyearbyen, Norway, 23.08.2018, Dianthus caryophyllus (Pink Kisses), K.Wieczorek leg.; DZUS 23/8.18_8 Myzus (Nectarosiphon) persicae, four alate viviparous females, Longyearbyen, Norway, 23.08.2018, Petunia × hybrida, K.Wieczorek leg.

Results and discussion

Living specimens of a virginoparous generation of Myzus (Nectarosiphon) persicae were collected from plants displayed in front of one of the shops in the main street of Longyearbyen (78º13′02.77″N 15º38′08.69″E) (Fig. 1). Aphids were found on three different decorative plants: Viola tricolor (Violaceae) (Fig. 2a), Dianthus caryophyllus (Pink Kisses) (Caryophyllaceae) (Fig. 2b) and Petunia × hybrida (surfinia) (Solanaceae) (Fig. 2c). All of these are annuals or short-lived perennials that are commonly used as ornamental plants. They can tolerate relatively harsh conditions. The abovementioned plants are secondary hosts for M. (N.) persicae as its primary host Prunus spp. is absent in Svalbard. The highest density of adult and immature morphs were observed on Viola tricolor (on both sides of older leaves, Fig. 2d) and Dianthus caryophyllus (Pink Kisses) (under the inflorescence and between the petals, Fig. 2e, f). Surfinia was the least infested—only a small number of winged viviparous females were observed (Fig. 2g). The aphids were clearly visible on all the plants. The exceptions were the immature morphs, which were hidden in the petals of Dianthus. The immature morphs and winged morphs had the largest percentage share in the observed colonies (Table 1). Since neither oviparous females nor males (the sexual generation) were found in August and it is lack of its secondary host—Prunus spp., this species reproduces by anholocycly (permanent parthenogenesis) in high Arctic conditions of the Svalbard archipelago.

Fig. 2
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The green-peach aphid Myzus (Nectarosiphon) persicae and its host plants: aViola tricolor; bDianthus caryophyllus (Pink Kisses); cPetunia × hybrida; d, e winged viviparous female and immature ones; f wingless viviparous females and immature ones; g winged viviparous female

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Table 1 The number of morphs of the green-peach aphid Myzus (Nectarosiphon) persicae observed on its host plants
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The infected plants came from the only supermarket on the archipelago, which had brought them from the mainland of Norway in June 2018. The plants were purchased also in June, and at the end of August, they were still in good condition with no visible signs of damage despite the aphids that were feeding on them. The owners of the plants were neither aware that the plants were infected nor of the presence of aphids. Similarly, the supermarket staff who are responsible for the live green plants did not register the presence of aphids on the imported plants. Although the average summer temperatures in Longyearbyen are quite low (3–7 °C), both the aphids and plants were in good condition, probably because they were kept in a closed room at night (which is required as polar bears roam through the town during the night). No other species of aphids (native or alien) or additional records of M. (N.) persicae in the studied area were found.

Unintentional introductions present the greatest threats to the Arctic and Antarctic ecosystems (Frenot et al. 2005; Snyder and Anions 2008; Chown et al. 2012; Hughes et al. 2015; Chown and Convey 2016; Chan et al. 2018). Alsos et al. (2015) stated that the ornamental plant trade and introduction through agriculture are of limited relevance in the high Arctic—only one observation of potato cultivation and one of the ornamental plant Viola tricolor exist, both from Longyearbyen. However, during our brief stay in Longyearbyen, we observed more examples of ornamental plants that were placed in front of shops or hotels and a wide variety of domestic pot plants available at the local supermarket. In this aspect, M. (N.) persicae, as a highly polyphagous species that is associated with more than 40 plant families and over 400 species (a secondary hosts) (Blackman and Eastop 2000), has also an advantage in colonising new areas. Moreover, it can transmit more than 100 plant viruses and its high levels of resistance to almost all classes of insecticides are well recognised (Bass et al. 2014). It has been proved that in similar harsh conditions, the introduced aphids, at least in some cases, prefer native host plants to exotic host plants (Hullè 2012). They can also transfer viruses (e.g. Barley yellow dwarf virus) to native plant species (Svanella-Dumas et al. 2013).

Our observation is the first one to record this non-native, potentially invasive and extremely harmful aphid species that has been collected in the archipelago. Whether the recorded population of M. (N.) persicae survived in small populations for a short time period and either died out naturally or were removed by human intervention (our recommendation for the owners was to destroy all infested plants) remains a speculation. However, our results suggest that a stricter approach to regional biosecurity needs to be considered in order to avoid the risks of further unintentional introductions. An additional challenge is to increase the public awareness of invasive and alien species of aphids in the fragile ecosystem of Svalbard. Such baseline information is critical for creating the appropriate management strategies.