A survey of jumping plant-lice (Hemiptera: Psylloidea) overwintering on conifers in Hungary

Some jumping plant-lice species are economically important due to their capacity as vectors of phyto-pathogenic bacteria, for example phytoplasmas. Previous studies have identified 80 jumping plant-louse species from Hungary; however, little is known about their occurrence during winter. To extend our knowledge of overwintering sites of jumping plant-lice in Hungary, we sampled them from conifers in various regions of the country. One of our main objectives was to find Cacopsylla pruni (Scopoli, 1763), the vector of ‘ Candidatus Phytoplasma prunorum ’ during winter. The period of this study extended from 2014 to 2020 in the winter months. Insects were collected at 18 sampling sites from Borsod-Abaúj-Zemplén county to Somogy county, located at Alsótekeres, Balatonvi-lágos, Boldogk ő váralja, Budakeszi, Feny ő f ő , Gyöngyöspata, Kecskemét, Martonvásár, Mátra Mountain, Nagykovácsi, Nagyszakácsi, Páty, Piliscsaba, Somogytúr, Soroksár, Sóskút and Verpelét. A total of 1,600 jumping plant-louse specimens belonging to 20 species and three families (Psyllidae, Aphalaridae and Triozidae) were collected and identified during the study. In the case of plum psyllid ( C. pruni ) four shelter sites


INTRODUCTION
Jumping plant-lice (Hemiptera, Psylloidea) are small plant sap sucking insects, feeding mainly on woody plants and leaves of herbaceous plants and shrubs. Adults of many jumping plantlouse species migrate from host plants to conifers as shelter plants for overwintering ( Cermák and Lauterer, 2008;Hodkinson, 2009;Gallinger and Gross, 2018). After egg hatching larvae go through five instars to adults. Jumping plant-lice typically feed on a single host plant species (monophagous) or on a few related ones (oligophagous) (Ossiannilsson, 1992). Amongst these insects many species are multivoltine (mostly in tropical to warm temperate regions), while others exhibit univoltine or bivoltine life cycles (Brambila and Hodges, 2008).
Jumping plant-lice include about 4,000 described species so far (Burckhardt and Queiroz, 2020). Some species cause serious economic losses to crop plants (Hodkinson, 2009), either by phloem feeding and honeydew production or indirectly by transmission of phytopathogenic agents like phytoplasmas. For example, the 16SrX or apple proliferation group phytoplasmas are transmitted exclusively by jumping plant-lice from the genus Cacopsylla (Jarausch et al., 2019). These pathogens cause serious damage on several fruit trees in Europe and North America (Tedeschi et al., 2002;Frisinghelli et al., 2000;Carraro et al., 1998;Grbic, 1974;Mergenthaler et al., 2017).
To date, 80 species of Psylloidea have been reported from Hungary (Kontschán et al., 2020). In most cases jumping plant-louse species were collected from their host plants (e. g. Ripka, 2010;Kontschán et al., 2021;Ripka et al., 2018;Ripka and Csóka, 2016;Ripka, 2012). Although Kontschán and Ripka (2019) collected jumping plant-lice also from their winter shelter plants, little is known about the overwintering sites of most jumping plant-louse species in Hungary. Therefore, the objective of this study was to survey coniferous trees during winter for evidence of jumping plant-lice. A better understanding of the Hungarian jumping plant-lice populations provides greater knowledge about their biology, distribution and abundance.

MATERIAL AND METHODS
Jumping plant-lice were collected from conifers in winter months from 2014 to 2020 from 18 different localities in Hungary including the oldest pine stand in Hungary (Fenyőfő) ( Fig. 1 and Table 1).
One of our aims was to determine overwintering sites of Cacopsylla pruni (Scopoli, 1763) as no data are currently available for Hungary. Insect captures were carried out in various pure and mixed coniferous forests. Because there are very few coniferous forests in our country, insects were also collected from forestry nurseries, botanical gardens and individual conifer trees. A diverse range of habitats was sampled with different altitudes and vegetation types.
Insects were collected with an insect net attached to a five-meter telescopic handle or with a garden leaf suction machine equipped with a flexible suction pipe attached to a spliced bamboo rod that can be adjusted to the height of trees (up to 10 m in height). Collected material was preserved in 70% ethanol. Species identification was carried out under an Olympus SZ40 stereomicroscope according to Ossiannilsson (1992), and Hodkinson and White (1979), and their classification/nomenclature was performed according to Burckhardt et al. (2021). Table 2, a total of 1,600 jumping plant-louse specimens belonging to 20 species and three families (Psyllidae, Aphalaridae and Triozidae) were collected and identified during the study.
Special attention was paid to the plum psyllid (C. pruni) that was found in Mátra Mountain, Gyöngyöspata, Nagyszakácsi and in the Budakeszi arboretum on Norway spruce and Douglas fir.
In this study we recorded 20 out of the 80 jumping plant-louse species reported from Hungary. The new and the previously reported overwintering sites are shown in Fig. 1. One species, Trioza neglecta is known as a non-native species in Hungary (Lauterer and Jani cek, 1990;Kontschán et al., 2020).
Although C. melanoneura was reported to overwinter at Kék in Hungary (Kontschán and Ripka, 2019), we found it at ten new localities. Four overwintering sites of C. pruni, the vector of 'Candidatus Phytoplasma prunorum' were identified: Mátra Mountain, Budakeszi arboretum, Gyöngyöspata and Nagyszakácsi.
We also found 14 new overwintering sites of T. urtice which was previously known only from Budapest, Martonvásár and Kék (Kontschán and Ripka, 2019).
The overwintering sites of jumping plant-lice are relatively poorly studied in Hungary, and collection data provided in this work includes additional information about the overwintering sites of jumping plant-louse species in Hungary, which broadens our knowledge of the regional jumping plant-lice fauna.