In this note we report the first record of Borearctia menetriesii (Eversmann, 1846) (Erebidae: Arctiinae) larva on a native host plant, Aconitum rubicundum Fischer (Ranunculaceae). This aconite species is a close relative of A. lycoctonum, which is widespread across Eurasia, but has a scattered distribution in Fennoscandia. The majority of B. menetriesii localities are situated within the distribution range of A. lycoctonum and other aconite taxa, which are diverse and widespread in the Eastern Palaearctic. However, only two of the six westernmost B. menetriesii localities in Finland are in accordance with sporadic records of A. lycoctonum. Our record confirms that B. menetriesii is a polyphagous species like most other boreal Arctiinae. We have expanded the list of a few Lepidoptera species which can use Aconitum spp. as suitable host plants despite the fact that they are poisonous for insects because of high alkaloid content.

The Menetries’s tiger moth Borearctia menetriesii (Eversmann, 1846) (Erebidae: Arctiinae) is the most enigmatic representative among the Palaearctic arctiine moths. The biology of this large and colorful species is poorly known because of its extremely low abundance throughout its distribution range (Lappi et al. 2004; Dubatolov 2010; Bolotov et al. 2013). Only single specimens were found in the majority of known localities, and sometimes the records are separated from each other by many decades (Bolotov et al. 2013).

Krogerus (1944) experimentally identified three available host plants in Finland, including Taraxacum spp. (Asteraceae), Plantago ssp. (Plantaginaceae) and Polygonum ssp. (Polygonaceae). In a preliminary report on the food preference of the larvae, Saarenmaa (2014) lists 15 plant species which B. menetriesii larvae preferred or accepted during experiments, including Larix spp. (Pinaceae), Rubus chamaemorus L., R. idaeus L., R. saxatilis L. and Potentilla palustris (L.) Scop. (Rosaceae), Menyanthes trifoliata L. (Menyanthaceae), Rumex crispus L., Polygonum persicaria L. and P. lapathifolium L. (Polygonaceae), Plantago major L. (Plantaginaceae), Ribes rubrum L. (Grossulariaceae), Salix phylicifolia L. (Salicaceae), Taraxacum officinale Weber (Asteraceae), Vaccinium uliginosum L. (Ericaceae) and Viola riviniana Rchb. (Violaceae). He noted that the larch species might be a significant food plant over the majority of the B. menetriesii range. However, all those data are based exclusively on these laboratory experiments. There is the unique observation in natural habitat in Finland in June 1920 of a larva having climbed a spruce trunk (Krogerus 1944). Here we report the first record of a feeding larva on a native host plant in the Baikalo-Lensky State Nature Reserve, Eastern Siberia.

Locality: Eastern Siberia, the Baikal Lake Area, the Bolshoy Anay River terrace, 53°56'19"N, 107°24'35"E, ca 770 m alt., mixed coniferous taiga forest with herb-Equisetum-moss plant cover (locality description and photo: Suppl. material 1: Table S1, Fig. S1). A last instar larva of B. menetriesii was collected alive on Aconitum rubicundum Fischer (Ranunculaceae) 9.viii.2013 (Figs 1–3) and was placed in a cage that was taken to the Irkutsk city. In captivity, the larva had a daytime feeding activity and consumed only fresh A. rubicundum leaves which we had collected from the same locality as the larva. The leaves were completely eaten by 15.viii.2013. Unfortunately, we could not find any aconite species in the city surroundings. The larva did not accept Taraxacum spp. and Plantago spp. leaves which we placed in the cage and it was found dead on 22.viii.2013. An additional larva was captured dead in a pitfall trap at the same locality on 10.viii.2013. The collected larvae were 32–35 mm long.

Figure 1. 

The last instar larva of B. menetriesii on Aconitum rubicundum Fischer, Baikalo-Lensky Nature Reserve, 9.viii.2013 (photo: O. E. Berlov).

Figures 2–3. 

Aconitum rubicundum Fischer, the host plant of B. menetriesii, Baikalo-Lensky Nature Reserve. 2. An inflorescence, upstream of the Pravaya Kirenga River, 14.vii.2006 (photo: N.V. Stepantsova). 3. A leaf at the B. menetriesii locality, 9.viii.2013 (photo: O. E. Berlov).

The observed host plant, A. rubicundum, is distributed in Central and Eastern Siberia, and is closely related to the widespread Eurasian A. lycoctonum (Malyschev and Pechkova 1993) and might even represent its eastern subspecies (Ivanova 1978). These two species (or subspecies) were separated on minor diagnostic features, particularly the location and density of hairs on the stem and leaf blade; both have identical chromosome number (2n = 16) (Malyschev and Pechkova 1993). All Russian B. menetriesii localities are situated within the distribution range of A. lycoctonum and other aconite taxa, which are especially diverse and widespread in the Eastern Palaearctic, including 26 species in Siberia and 37 species in the Russian Far East (Jalas and Suominen 1989; Malyschev and Pechkova 1993; Kharkevich 1995; Bolotov et al. 2013). In boreal Russia, various aconite species are abundant in the plant cover of river valleys and humid alpine meadows (Peshkova 1985; Malyschev and Pechkova 1993; Kharkevich 1995) where B. menetriesii most frequently occurs (Bolotov et al. 2013). For example, A. lycoctonum is one of the dominant plant species in the B. menetriesii habitat in the Sotka River Valley, Arkhangelsk Region (Bolotov et al. 2013). However, A. lycoctonum has a scattered distribution in Finland (Jalas and Suominen 1989; Lampinen et al. 2014), and only two of the six Finnish B. menetriesii localities are near sites where this plant species was recorded (Suppl. material 1: Fig. 2S).

Aconite species have a strong insecticidal activity (Yuan et al. 2012) because of their high alkaloid content (Azimova and Yunusov 2013). Eighteen alkaloids were isolated from A. lycoctonum (Azimova and Yunusov 2013). A. rubicundum contains at least nine diterpenoid alkaloids (Nishanov et al. 1991).

The HOSTS database (Robinson et al. 2010) listed only 16 Lepidoptera species feeding on Aconitum spp. The majority of these species are polyphagous (12 of them), including Euproctis similis (Fuessly, 1775), a unique Erebidae representative. According to other sources (Vorbrodt and Müller-Rutz 1914; Freina and Witt 1987; Bellmann 2003), there are two Arctiinae species recorded on Aconitum spp., Arctia flavia (Fuessly, 1779) on A. lycoctonum ssp. vulparia (Rchb.) Nyman and Diaphora sordida (Hübner, 1803) on A. napellus Linnaeus.

Our record confirms that B. menetriesii is a polyphagous species like most other boreal Arctiinae (Dubatolov 1990), but additional experiments are needed for an appropriate evaluation of the role of Aconitum spp. as a host plant for European populations of B. menetriesii.

The authors are grateful to Dr. N.V. Stepantsova, a botanist of the Baikalo-Lensky Nature Reserve, for help in identification of A. rubicundum, and to Dr. A. Zilli, Dr. J. Rota and an anonymous reviewer for valuable comments on the manuscript.