In: D. Marčić, M. Glavendekić, P. Nicot (Eds.) Proceedings of the 7th Congress on Plant Protection. Plant Protection Society of Serbia, IOBC-EPRS, IOBC-WPRS, Belgrade, 2015, pp. 247 - 253 COLOUR AND SEX RATIOS IN DIFFERENT bOX TREE MOTH (Cydalima perspectalis) POPULATIONS Katalin Tuba, Géza Kelemen and Miklós Molnár University of West-Hungary Institute of Silviculture and Forest Protection H-9401 Sopron Pf. 132 [email protected] Abstract The box tree moth, Cydalima perspectalis (Walker 1859), is native to East Asia and has recently been introduced in Europe. It was first recorded in South Germany in 2007. This alien moth has been causing severe damage to topiary box tree, hedges and plants in parks, gardens, cemeteries and nurseries as well as to native populations of the box-tree (Buxus spp.) in Europe. The larvae feed on leaves but they can also attack the bark. The affected bushes die after repeated infestations. The box tree moth is a polymorph species. Our aim was to investigate the sex ratio and this polymorphism regarding the appearance of the colours in the case of the sexes. To reach these goals to use of both field and laboratory techniques were required. The number and distribution of morphs were studied in different ways. 1) Light trap data were analysed in 2013 and 2014. 2) The data received from EDDMapS were also gathered and grouped to estimate the colour and sex ratios. 3) More than 100 larvae or pupae were collected from different sites in 2013-2014. These specimens were reared under laboratory conditions. The adults were examined and classified. 4) Last but not least we also gained genetic data from crossings. Three colour morphs were divided in the Hungarian C. perspectalis populations. The white morphs with brown band on the exterior margin only and white ones with brown band both on the exterior and interior margins were observed to start almost flying together. The dark ones fly the latest and the shortest time. The first generation flies for a short time while the third one flies for the longest time. The number of males is usually higher in the population than the number of females. Our results show that the ratio of the three morphotypes varied in different habitats. It seems that the white morph appears first during the course of spread. The crossings resulted in a special ratio among the morphs. Keywords: alien species, morphotypes, distribution Introduction its spread is the isotherm -16 °C in winter. So it might spread across most of Europe, except for North Fenno- The box tree moth is a relatively new alien species Scandinavia, northern Scotland and high mountain in Europe. It is native to East Asia (Inoue et al., 1982). regions, where the accumulated temperatures are not Its native range here is determined by the occurrence enough to allow the completion of an entire generation of its hosts and the climatic conditions. The limit of a year (Nacambo et al., 2013). 247 Cydalima perspectalis was first detected in south- 1968) and Phigalia pilosaria (Lees, 1974), Allophyes western Germany in Europe in 2007, but it had oxyacanthae (Steward, 1977), and Simyra albovenosa presumably arrived in Germany a bit earlier because (Vakkari, 1980). The increase in the proportion of the infection observed was very high and extended dark Biston betularius morphotype appears to be a (Billen, 2007; Krüger, 2008; Leuthardt et al., 2010). phenomenon for which no explanation has yet been Soon it was recorded in Switzerland (Leuthardt et al., presented in the scientific literature. Bishop and Cook 2010). The box tree moth was found in the Netherlands (1980) say:”The reason is not obvious”. The melanic (Muus et al., 2009) in 2007; in France (Feldtrauer et phenotype is inherited as autosomal dominants (Grant, al., 2009), in Britain (Mitchell, 2009), in Liechtenstein 2004). Two melanic alleles are present regarding (Slamka, 2010) in 2008; in Austria (Rodeland, 2009) Phigalia pedaria moth but also occur at combined in 2009; in Belgium (Casteels et al. 2011, De Prins & frequencies of 2-18% in rural areas across the British Steeman, 2011), in Italy (Biondi, 2010), in Slovenia (Jež, Isles (Lees 1971). Steward (1977) says that selective 2012), in Hungary (Sáfián & Horváth, 2011), in the predation could be a major factor in the variation of Czech Republic (Šumpich, 2011), in Romania (Székely melanic frequencies of Diurnea fagella and Allophyes et al., 2011), in Turkey (Hizal et al., 2012) in 2011; in oxyacanthae. The uniform black and the patterned Slovakia (Pastorális et al., 2013) and in Croatia (Koren intermediate form of Simyra albovenosa are controlled & Črne, 2012), in Sochi in 2012; in Denmark in 2013 by separate loci. The dark one is completely dominant (Rennwald, 2015). to pale and epistatic to intermediate, and the patterned Main hosts of the box tree moth are different one is partially dominant to pale. The intensity of the boxwood species in Europe (CABI, 2013). C. whitish to yellowish background colouration is affected perspectalis larvae have been observed as causing feeding by the developing strategy. Non-diapausing moths are damage by chewing the leaves and tree-bark of these paler than diapausing (Vakkari, 1980). plants. Complete defoliation causes the mortality of the damaged boxwood (Albert & Lehneis 2012; Kenis et al. 2013; Leuthardt & Baur 2013; Nacambo et al. Material AnD Methods 2013).There are two Buxus species, which are native to Europe: B. sempervirens and B. balearica (Di Domenico The number and distribution of morphs were observed et al., 2012). However, in Asia, other reported hosts in different ways. include Ilex purpurea, Euonymus japonicas, Euonymus alatus, Pachysandra terminalis and Murraya paniculata 1) Light trap data were analysed from the beginning of (Korycinska & Eyre, 2011; Wang, 2008). The natural May until the end of October 2013 and 2014. The light populations of Buxus are seriously threatened by C. trap was situated in Sopron where the first C. perspectalis perspectalis (Kenis et al. 2013). Cultivated boxwood was caught in Hungary in 2011. The different sexes and plants in parks, cemeteries and gardens are also colours were separated each day. damaged by this pest under urban conditions. 2) Photos of the moth received from EDDMapS were There are several species that have morphotypes. also gathered and grouped to estimate the ratios of the The morphological differences can appear in different colours and sexes. EDDMapS is an Early Detection and developmental stages. The causes of these phenomena Distribution Mapping System, which has been operated originate under different conditions. Two sympatric by Bugwood Network since 2008. Our institute has colour morphs of Zeiraphera diniana were described adopted this system and adjusted to the Hungarian that are distinguishable only during the final larval conditions. Spreading data of C. perspectalis have been stage; the dark one is found mainly on Larix decidua collected with this system in Hungary since March 2012. and the orange-yellow morph occurs on Pinus cembra 3) One hundred larvae were collected in Gyöngyösfalu (Bovey & Maksymov, 1959). Larvae of Zeiraphera and Sopron in May 2013, and one hundred pupae diniana were raised continuously or at least during their were gathered in Kőszeg and Pápa, Hungary in June latter larval stage at 10 °C were darker than larvae reared 2014. These specimens were reared under laboratory at 18 °C (Baltensweiler, 1977). Nutritional stress causes conditions (20 °C, 16L:8D photoperiod). The larvae an increase in frequency of intermediate morphotypes were fed with leaves of boxwood. The adults were in subsequent generations (Day & Baltensweiler, 1972). examined and classified based on colour and sex. Two or more morphs may be recognised e.g. in the 4) Last but not least we also gained data from crossings. cases of Odontopera bidentata (Kettlewe, 1959; 1973), This survey was carried out in a period of two years. Four Biston betularius (Clarke & Sheppard 1964; Lees, pairs of the moth were placed in a 40x25x25 cm box, and 248 they were fed with a mixed solution of honey and water. on the exterior and interior margins (of the forewing) The larvae hatched were placed into a 0.5 l plastic box. The (hereafter white with brown margin) and 3) the melanic rearing method was similar to that in the case of larvae (greyish-brown) form. and pupae (3). Regarding this examination the white with brown band on the exterior margin only and the 1) Light trap data white with brown band both on the exterior and interior The catches of the light trap show similarity in margins morphs were handled together, because it was not colours and between years. The number of females was possible to do proper crossings among the three morphs a slightly higher than the number of males. Considering neither next to high number of population in same time. the females the melanic form occurred in the highest ratio, while the white with brown margin form was the most frequent among the males (Tab. 1). Results The flight periods of the three colour morphs were variable but partly overlapping. The white and white In Hungary, three colour morphs were observed. 1) with brown margin morphotypes have a bit longer flight The white with brown band on the exterior margin only periods. 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