Vol 10, No 4 (2019)

The hybrid origin of the Bidens × decipiens species, which was earlier ascribed to the North American alien species B. connata, was confirmed by analyzing the nucleotide sequences of the ITS nuclear site. The name “B. connata” is indicated as invalid for a taxon that does not grow in North America. Earlier, we tested the hypothesis of hybrid origin of B. × decipiens using ISSR analysis and revealed that B. × decipiens can be considered as a complex of hybrids and backcrosses of B. cernua and B. frondosa. Analysis of the Internal transcribed spacer (ITS) and the trnL-trnF intergenic spacer confirmed the hybrid origin of this taxon and made it possible to establish that B. cernua is the maternal species and B. frondosa with a high probability is the paternal species of the taxon.

Zooplankton was studied in August 2015–2017 in eight reservoirs of the Volga River, in an unregulated part of the river between the cities of Volgograd and Astrakhan, and in three reservoirs of the Kama River. The Ponto-Caspian species were recorded in the Volga River downstream of the city of Kazan (south of 55°32′ N) and in the Kama River from the mouth to the upper reaches of the Kama Reservoir (59°20′ N). Six alien species (Heterocope caspia, Calanipeda aquaedulcis, Eurytemora caspica, Cornigerius maeoticus maeoticus, Cercopagis pengoi, and Podonevadne trigona ovum) were recorded in the Volga reservoirs and three species (Heterocope caspia, Eurytemora caspica, and Cercopagis pengoi) were recorded in the Kama reservoirs. It was found first time that copepods Heterocope caspia and Eurytemora caspica spread and naturalized in the areas of all three Kama reservoirs (within the distance of 1000 km from the Volga River); the cladoceran Cercopagis pengoi formed a disrupted range with a group of habitats in the mouth part of the Kama River (55°12′–55°26′ N) and north near the city of Perm (57°53′–58°26′ N). The boundary of the ranges of Calanipeda aquaedulcis, Cornigerius maeoticus, and Cercopagis pengoi shifted 300–400 km to the north in the Volga River and 300 km in the Kama River; they occupied almost all area of the Kuibyshev Reservoir except for the upper reaches of its Volga part. The range expansion of the cladoceran Podonevadne trigona ovum was not observed; this species was found only in the Volgograd Reservoir (46°18′ N). It was revealed that by 2017 the Mediterranean copepod Calanipeda aquaedulcis had become common (occurrence in more than 90% of samples), locally numerous in the Volga River from the city of Astrakhan (52° N) to the mouth of the Kama River (55°12′ N) and in the Kama River from the mouth to the upper reaches of the Kama part of the Kuibyshev Reservoir (55°24′ N). It is revealed that a new species Eurytemora caspica (described in 2013), but not E. affinis (as it was believed earlier), lives in the Volga and Kama rivers. The prospects of the further spread of Ponto-Caspian species up the Volga and Kama rivers and their role in the zooplankton in water bodies are discussed.

The results of the herbological analyses of the seed lots of Sinapis alba and Phacelia tanacetifolia received in the trading networks of Tomsk oblast are presented. The species composition of weedy plants which are able to spread by speirochory is revealed. A high degree of weed infestation of green manure seeds, including diaspores of invasive and potentially invasive species (as well as quarantine plants), has been recorded. In seed lots of Sinapis alba and Phacelia tanacetifolia supplied to Tomsk oblast in 2017–2018 from the European part of Russia and the Siberian Federal District, diaspores of 58 weed species were found, among which nine species are invasive, including one quarantine species (Acroptilon repens). Along with a large diversity of weed species, a high total contamination (from 340 to 86 500 pcs/kg) of green manure seeds, including the most harmful weeds, is noted. For example, diaspores of seven weed species recognized as dangerous and one species which is especially dangerous for products of plant origin were present in the studied samples of Sinapis alba and Phacelia tanacetifolia. A large threat is also posed by the contamination of the studied green manure seeds by weeds with a pronounced dormant period, the seeds of which replenish the soil bank of agrocenoses, ensuring their contamination for many years to come. To ensure the agricultural safety of the region, strict control of the contamination of imported seed lots, their culling, and preventing the sale of heavily contaminated seed lots are necessary.

New data on the structure of seedlings, juvenile, immature, virginal, and generative individuals of invasive species Ambrosia artemisiifolia L. and A. trifida L. and the time of their transition to different age stages in Moscow and Moscow oblast have been obtained. These data can help in recognition of plants at different stages of their ontogenesis in nature and in their timely control. It has been shown that both species have a high germination rate; however, the pace of development differs, which affects the time of flowering and fruit ripening. For A. artemisiifolia, the duration of the growing season in Moscow and Moscow oblast is not enough to form mature seeds, while A. trifida in these conditions sets high-grade fruits and seeds with high germination capacity. The main propagation path of A. artemisiifolia fruits from the southern regions to the north is the railways. Seed drift of A. trifida is mainly associated with wheeled transport and transport and processing of grain. It has been suggested that A. trifida can potentially be a rather dangerous plant for the northeastern regions of Central Russia as an invasive species, which in the case of massive introduction of diaspores can occupy large areas in disturbed and natural communities and form stable self-renewing populations. The northward movement of A. artemisiifolia is more problematic. However, in consideration of wide adaptive potential of the species, including the shortening of development cycle and the formation of early maturing and female forms, it can be concluded that naturalization of the species in the northeastern regions of Russia is also possible.

Invasive species have to overcome the biotic resistance of the environment for successful distribution in the secondary range; this resistance can be effectively made by unspecialized phytophages. We carried out a series of laboratory experiments on studying the ability of generalist phytophages, such as terrestrial mollusks, to feed on invasive goldenrod species (Solidago canadensis L. and S. gigantea Aiton). A significant number of terrestrial mollusks of six species were found on the stems and leaves of goldenrods; however, the results of laboratory experiments have shown that most of them cannot consume this plant as food, and Fruticicola fruticum (O.F. Müller) (Bradybaenidae) and Deroceras sp. (Agriolimacidae) do not choose goldenrod when there are other alternatives, although they can potentially feed on goldenrod. Therefore, snails and slugs in natural populations have a negligible effect on the vital activity of S. canadensis and S. gigantea and cannot suppress the expansion of these species.