First records of the pest leaf beetle Chrysolina (Chrysolinopsis) americana (Linnaeus, 1758) (Coleoptera, Chrysomelidae) in Cyprus - a study initiated from social media

Abstract The leaf beetle Chrysolina (Chrysolinopsis) americana (Linnaeus, 1758), commonly known as the Rosemary beetle, is native to some parts of the Mediterranean region. In the last few decades, it has expanded its distribution to new regions in the North and Eastern Mediterranean basin. Chrysolina americana feeds on plants of the Lamiaceae family, such as Rosmarinus officinalis, Lavandula spp., Salvia spp., Thymus spp. and others. Chrysolina americana is considered a pest, as many of its host plants are of commercial importance and are often used as ornamentals in house gardens and green public spaces. In this work, we report the first occurrence of C. americana in Cyprus and we present its establishment, expansion and distribution across the Island, through recordings for the period 2015 – 2020. The study was initiated from a post on a Facebook group, where the species was noticed in Cyprus for the first time, indicating that social media and citizen science can be particularly helpful in biodiversity research.


Introduction
There are currently 11 known Chrysolina species on the Island of Cyprus (Bieńkowski 2001, Bieńkowski 2010, Gruev 1995. In this study, we confirm the presence of one more species, Chrysolina (Chrysolinopsis) americana (Linnaeus, 1758). Despite its name, this species has not yet been found in the Americas. In the original description (Linnaeus 1758, page 372), Linnaeus wrote "Habitat in America". It seems that he mistakenly assumed the specimen had been collected in the Americas. The native range of the Rosemary beetle includes Mediterranean countries, such as Albania, Croatia, France, Greece, Italy, Malta, Portugal, Slovenia, Spain, Serbia, Macedonia, Algeria, Morocco, Tunisia and Turkey (Beenen and Roques 2010, Kippenberg 2010, Pasqual C et al. 2017. From 1936 onwards, the species expanded its native range and became invasive in many northern European countries (e.g. Belgium, United Kingdom, Austria, Netherlands, Latvia and Germany), as well as in Israel (Bieńkowski andOrlova-Bienkowskaja 2018, Friedman 2016).
The adults and larvae of C. americana feed on the leaves of plants in the family Lamiaceae, such as Rosmarinus officinalis, Lavandula spp., Salvia spp., Thymus spp. and others (Friedman 2016). Some of these host plants are popular aromatic plants and are commonly used in house gardens and in green public spaces (e.g. in urban parks and on roadsides). They are also cultivated commercially and have multiple usages, such as in cooking and as cosmetic aromatic ingredients. As C. americana can cause damage to the foliage of these plants, it is considered a pest of such crops. Plants like Rosmarinus officinalis and Lavandula spp. are often traded for these uses between many countries. This fact is helping the expansion of the distribution of C. americana, which was probably introduced in some countries along with the imported plants (Bieńkowski and Orlova-Bienkowskaja 2018). Adults and larvae of the Rosemary beetle can cause a small amount of damage to the leaves of host plants (MacLeod 2002). In cases where the beetle is abundant in commercial plantations of these plants, it can cause negative economic consequences as it damages usable leaves, thereby reducing the harvested yields (Bieńkowski and Orlova-Bienkowskaja 2018).
The views on the flight capability of the Rosemary beetle are conflicting. MacLeod (2002) mentioned that C. americana is flightless and spreads slowly. On the other hand, Beenen and Roques (2010) reported that this species has good flight capacity and can disperse naturally over long distances.
The Rosemary beetle was not reported in Cyprus until 2015 when a lady spotted the species. She found a large number of Rosemary beetles on a Rosmarinus officinalis in her garden and she posted a photo in the Facebook group 'Biodiversity of Cyprus', requesting identification of the species. The authors identified the species and communicated with her to collect specimens for this first record.
The objectives of this work are (i) to report the presence and confirm the reproduction of C. americana on the Island of Cyprus, (ii) to record its distribution and use of host plants over the past 5-year period (2015-2020) and (iii) to test, though experimentation, the flying ability of the beetle.

Reproduction and current distribution
From 2015 to 2020, multiple excursions were undertaken across the Island of Cyprus to locate C. americana. In particular, we searched for larvae and mating adults, in order to confirm the presence and local breeding of the species. We also searched repeatedly and on an annual basis certain localities with a strong presence of the host plants, grown both in natural and cultivated (e.g. garden) conditions. In addition, we checked new localities to record the dispersal of the species at new sites. The excursions were undertaken throughout the 5-year period. Road edges with planted Rosmarinus officinalis were frequently checked, as well as every other locality where we noticed the presence of the host plants. Rosemary is a common, native and widely-grown species in Cyprus and is planted at road edges, in house gardens and in parks. Additionally, several previouslyrecorded host plant species are native to Cyprus and occur naturally in the environment; such localities were also examined.
In addition to site visits, we frequently checked for records of C. americana in online social media groups on the fauna of Cyprus (e.g. in Facebook) where photos of insects are posted for identification. These resources were examined at least once per month.

Flying ability experiment
To confirm the flying ability of C. americana, a small tree branch was attached on a piece of modelling clay in the middle of a metal bowl with 2 cm of water ( Figure 2J). We placed 10 adults of C. americana on the branch and the bowl was placed on a sunny outdoor place for 24 hours. This process was repeated four times in warm, outdoor conditions and the activity of the beetles was checked every 1 hour. During the third and fourth trial, the experiment was carried out by adding a Rosemary plant at 1 m distance from the bowl, to check if that triggers the beetles to fly. It should be noted that different individuals were used each time the experiment was carried out. Individuals used for the experiment were collected from Aglantzia and Strovolos, in Nicosia District. The dates the experiment was performed are the following: 8 Feb 2020, 10 May 2020, 12 Aug 2020 and 5 Oct 2020. We have also attempted to provoke and encourage individuals to fly in field conditions, at the localities that were found, by moving the beetles on non-host plants and rocks near host plants.
Additionally, we examined the wings of more than 20 specimens of both sexes to confirm if the species is brachypterous (i.e. if it has reduced wings).

Occurrence, reproduction, current distribution
The species Chrysolina americana was recorded at 31 localities in Cyprus, as shown on the map (Fig. 1). The records occurred in five host plants: Rosmarinus officinalis L., Lavandula stoechas L., Lavandula angustifolia Mill., Salvia fruticosa Mill. and Salvia officinalis L. (Fig. 2). From the recorded host plants, Rosmarinus officinalis, Lavandula stoechas and Salvia fruticosa are native to Cyprus. Additionally, Lavandula angustifolia is a naturalised species and grows naturally (Tsintidis et al. 2002). The host plants identification was performed by the authors, using the books of Christofides 2017 and Tsintidis et al. 2002. In controversial cases, a flora specialist was asked to advise and confirm the validity of the identification. Both larvae and adults were present simultaneously at the majority of the recorded localities. In many cases, adults were mating ( Fig. 2A and B). The localities, dates, coordinates, host plants and altitudes of the records are shown in Table 1. Records of the same areas are shown on Fig. 1  Regarding reports in social media, we found 12 cases where photos of the species had been posted in the Facebook group 'Biodiversity of Cyprus'. Some of these records were at the same or a nearby locality to our previous records. When needed, we contacted the people posting the records to ask about the location and the date in which the photos were taken. In the majority of these cases, we visited the recording area for confirmation.

Flying ability experiment of Chrysolina americana
Regarding the flying ability experiment, in all four replicates, some of the beetles fell in the water and were repositioned to the branch. No individual beetle was found outside the bowl or attempted to fly. On the third replicate, we left the beetles on the branch for 9 days. Most individuals (9 out of 10) eventually drowned in the water during the 6 day. The remaining individual stood on the branch for 9 days; see the red arrow in Fig. 2J. On the fourth replicate, three beetles remained alive on the branch for 15 days.
In the case of the field experiment, beetles were placed on high branches of bushes and we observed their behaviour for 1 hour. None of the beetles attempted to fly. In all cases, the beetles walked randomly on the branches or fell off when they felt threatened. Similarly, beetles placed on rocks near the host plants walked randomly, but none of them attempted to fly. We also noticed that the beetles opened their wings only in some cases, i.e. when they fell upside down and in the attempt to reposition themselves.
From the examination of the beetles' wings, the species seems to have normal length wings for flight and it is not brachypterous. Two specimens showing the wing are presented in Fig. 3.
th First records of the pest leaf beetle Chrysolina (Chrysolinopsis) americana ... Table 1 and colours indicating the chronological order in the legend since 2015; the first record at Strovolos is indicated with a red dot. Both the indoors and outdoors flying experiments cannot confirm that C. americana is able to fly, despite the wings' examination showing that the species is not brachypterous (Fig.  3); this finding is not in agreement with MacLeod (2002). Nevertheless, C. americana could be capable of flight. A definitive answer to the question of whether it can fly or not can be given in a future examination of its flight muscles. From previous studies on other leaf beetles, such as Galeruca tanaceti (Linnaeus, 1758) (Beenen 2005), it seemed that a part of the fresh population of specimens had well-developed flight muscles and the old (postsummer diapause) specimens did not. Beenen 2005) findings suggest that, although we used individual specimens from different seasonal periods across a year for our experiments, not all populations may include specimens capable of flight. Therefore, it remains to be determined in a future study whether this species can fly or not.

Locations of Chrysolina americana records, with numbers indicating the records in
Although we are not sure of the flying capabilities of the Rosemary beetle, it has evidently a very good dispersal ability as it has spread over almost all of Cyprus in a period of five years from the first record. We are certain that the beetle was not introduced to Cyprus with the Rosemary plant of the first recording because the particular plantation existed years before the beetle appeared and the diameter of the Rosemary trunk at the time of recording was larger than 4 cm, indicating a relatively old Rosemary plant. We do not know if our first record at Strovolos (March 2015) coincides with the original year of introduction of the species to the Island or whether it arrived at an earlier date. What we can confirm, however, is that the species was recorded 95 km away (in Chloraka) from the first recorded site, 5 years later (April 2020, see Table 1). Such fast dispersal ability is unexpected for a flightless species. Some possible explanations include the frequent transfer of host plants by people, which potentially helps spread the species on the Island of Cyprus. Considering that the Rosemary beetle cannot reach Cyprus by flight, we assume that it was imported with its host plants relatively recently. This assumption is supported by new records in many countries outside its natural distribution (Bieńkowski and Orlova-Bienkowskaja 2018).
It is interesting to note that C. americana has also recently been reported from Israel with the presumed first record being December 2014 (Friedman 2016), a few months before our first record. This species probably arrived in Israel from imported host plants as it was first found close to the main port of Haifa (Friedman 2016 2017). Keeping in mind that the commercially-grown aromatic plants are organically cultivated and are typically used in cooking, farmers can use pesticides as a last resort; alternatively, farmers can prevent damage by maintaining the appropriate conditions for the natural enemies of the species. Additionally, control of the beetle population can be achieved by removing the beetles and larvae manually, by hand-picking, net sweeping or by shaking the plants and collecting the beetles from the ground, which, however, implies additional labour hours and cost.
As a concluding note and given that the initiation of this study was a record first reported in social media, we would like to emphasise the important role of citizen science and, in particular, the participation and contribution of people using such networking platforms in recording wildlife. Although citizen science -the collection of data relating to the natural world by members of the general public -has been a part of observations of the natural world for a very long time, digital developments in the past decade or so have vastly expanded the potential for input from citizens into the study of biodiversity and associated impacts (Bonney et al. 2014). Chrysolina americana is not the only recorded species in Cyprus whose presence was first known through social media. Several species were recorded in Cyprus for the first time from people posting photographs on social media and were noticed by researchers. Most of them are in the process of preparation for publication and scientists are collaborating with interested social media users in collecting more information and records for these new findings.