Color polymorphism,development, and reproductive diapause of the multicolored Asian ladybird <Emphasis Type="Italic">Harmonia axyridis</Emphasis> (Pallas) (Coleoptera,Coccinellidae) females

Preimaginal development and maturation of females of two laboratory strains originated from two populations of the multicolored Asian ladybird Harmonia axyridis were investigated under laboratory conditions. Females of the autochthonous population from Irkutsk (Siberia) enter diapause under the short day conditions, whereas in females of the invasive population from Sochi (the Caucasus) photoperiodic induction of diapause is weak. The two populations also differ in the proportions of morphs: the population from Sochi is represented only by the morph succinea, whereas the population from Irkutsk is represented by the morphs succinea и axyridis with the predominance of the last one, which in our study was separated into two phenotypes, differed in the degree of melanization. Rearing of adults under the short day (12 h) conditions induced reproductive diapause in females of all the studied morphs and phenotypes of the Irkutsk population, whereas under the long day (18 h) conditions females of the morph succinea showed a slightly lower tendency to diapause. Evidently, the interpopulation differences in the responses regulating the seasonal cycle of the multicolored Asian ladybird are determined by genes that are not involved (or almost not involved) in the determination of the color polymorphism. The interpopulation differences in size and weight were quite substantial, whereas the differences between morphs and phenotypes were statistically significant in only some of our experiments. In combination with the literature data, these results suggest that the genes determining the color polymorphism in H. axyridis may have a pleiotropic effect on other traits including important eco-physiological parameters but this effect is relatively weak and manifests itself only against a particular genetic background and / or under particular environmental conditions.     

Genetic heterogeneity and adaptive strategies of the ladybird <Emphasis Type="Italic">Harmonia axyridis</Emphasis> Pall. (Coleoptera,Coccinellidae)

Analysis of microstatial variability of the phenetic composition of populations of the ladybird Harmonia axyridis Pall. is performed in Baikal region of the Primorskii krai. It is revealed that the phenetic composition of the Baikal H. axyridis population is significantly more labile than that in Primorie. In individual micropopulations the phenoimage is clarified due to a local increase in frequency of the morph succinea. Individual and family testing of H. axyridis individuals from the Primorie and Baikal populations is performed by the quantitative parameters affecting the adaptability-the larval and pupal survival at starvation, critical weight of pupation, the imago weight and fertility. At starvation of larvae of the IV instars for 3–4 days, only the morph succinea individuals from the Primorie population reached the imago stage. The oviposition value in these imagoes corresponded to the mean for the population (31.2 ± 1.06 eggs). The obtained result confirms the earlier expressed suggestion that the morph succinea is distinguished by a high ecologic plasticity. This morph is able to survive under conditions of the food deficit and is characterized by the intermediate, but stable reproduction.     

Seasonal phenotypic plasticity: wild ladybirds are darker at cold temperatures

Seasons vary in the average environmental conditions a species experiences, meaning that optimum strategies for concealment or feeding may also vary. Populations of the ladybird Harmonia axyridis contain both melanic and non-melanic forms and changes in allele frequency in some populations suggest that melanism may be advantageous in winter, but costly in summer. This could favour the evolution of phenotypic plasticity in colour pattern, as individuals which changed colour throughout the year would be able to maximise their fitness. We have previously shown in the laboratory that melanisation in the “non-melanic” morph of H. axyridis, f. succinea, is predominantly controlled by temperature during development. We now report that wild populations of H. axyridis f. succinea also conform to this principle: lower field temperatures during development produce individuals with more and larger spots. Furthermore, we have found that the critical period of development where temperature affects the level of melanisation covers the pupal and late larval stages, and melanisation increases with the length of time spent at cold temperature. We conclude it is likely that the temperature experienced during this period is used to predict the temperature encountered as an adult. This may allow individuals to produce the level of melanisation necessary to maintain activity levels at the temperatures encountered when they emerge. The long sensitive period seen in H. axyridis may be in order to avoid mismatches between melanisation and seasonal environment.     

The influence of density-dependent factors on larval development in native and invasive populations of <Emphasis Type="Italic">Harmonia axyridis</Emphasis> (Pall.) (Coleoptera,Coccinellidae)

Effects of the number of larvae per Petri dish (1, 5, and 10) on the preimaginal development of individuals of the native (Irkutsk, southern Siberia) and invasive (Sochi, the Northern Caucasus) populations of the multicolored Asian ladybird Harmonia axyridis were investigated in the laboratory. The experiments were conducted under short (12 h) and long (18 h) day conditions; the larvae were fed on the green peach aphid Myzus persicae or on the eggs of the grain moth Sitotroga cerealella. An increase in the number of larvae developed in one Petri dish resulted in a significant decrease in the rate of development in individuals from both populations which fed on aphids. Survival decreased with an increase in the number of larvae developed in one Petri dish fed on both prey species, but only in larvae from the invasive population of H. axyridis. The weight of emerging adults decreased with the number of larvae per dish in individuals from both study populations, but only when fed on aphids. These data suggest that the influence of density-dependent factors on the development of H. axyridis depends significantly on larval prey species. In addition, larvae from the invasive population have somewhat more aggressive interactions with competitors, this possibly having been one of the prerequisites for invasion.     

Genetic variation and population differentiation in Siberian fir Abies sibirica ledeb. inferred from allozyme markers

Genetic variation in 24 populations of Siberian fir Abies sibirica Ledeb. from the Urals, West Siberia, East Siberia, South Siberia, and the Baikal region were examined using allozyme markers. Three out of fifteen allozyme loci proved to be polymorphic. Heterozygosity H _e was 6.6–9.6%, which is substantially lower than that in other widely spread boreal conifers. Our results suggest that the Siberian fir populations are subdivided into four geographic groups: (1) the Baikal Lake group, (2) the Sayan and the Altai group, (3) the Middle and Southern Urals group, and (4) Subpolar and Northern Urals group. This pattern of geographic differentiation may be explained by the preservation of the Siberian fir during the last glacial maximum (18 000–22 000 years B.P.) in isolated refugia with subsequent recolonization of the present area. F _ST in the populations examined was 10.16%, which is comparable to the estimate for Larix sibirica (7.9%), a conifer species having a similar range and pattern of geographic population differentiation.     

Weak photoperiodic response facilitates the biological invasion of the harlequin ladybird Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae)

Photoperiodic regulation of reproductive diapause in two invasive and two native populations of Harmonia axyridis and in one native population of Harmonia yedoensis was investigated in laboratory at 20°C, five photoperiods (day length of 10, 12, 14, 16 and 18 h) and two diets: (i) eggs of the Angoumois grain moth Sitotroga cerealella and (ii) the green peach aphid, Myzus persicae. Laboratory strains originated from native populations of H. axyridis from Irkutsk province of Siberia and H. yedoensis from South Korea showed a strong photoperiodic response: under short photoperiods (10–14 h and 10–12 h for H. axyridis and H. yedoensis, correspondingly), all females which fed on eggs and most of those fed on aphids did not start to lay eggs during 40 days after emergence, while under long photoperiods, all females fed on aphids and most of those fed on eggs oviposited. The photoperiodic response of H. axyridis from South Korea was less strong: on the both diets, the range of the photoperiodic response (the difference in the proportion of ovipositing females between the treatments with long and short days) was ca 40%. In the European (Czech Republic) and in the Caucasian (Sochi region, Russia) invasive populations of H. axyridis, the photoperiodic response was very weak: the proportion of females that started oviposition (when fed on aphids) or at least reproductive maturation (when fed on eggs) during 40 days after emergence was close to 100%, independently of the photoperiodic conditions. Obviously, instead of a rapid micro‐evolutionary adaptation of the critical day length to a new climate, the invasive populations of the harlequin ladybird decrease their dependence on photoperiod and thus the weak photoperiodic response of SE Asian population of H. axyridis can be considered as a pre‐adaptation further developed during the invasion.     

The Influence of Diet and Population Density on Maturation of Females from Native and Invasive Populations of the Multicolored Asian Ladybird <Emphasis Type="Italic">Harmonia axyridis</Emphasis> (Pallas) (Coleoptera,Coccinellidae)

Population density can influence insect reproduction both directly and indirectly causing quantitative and qualitative changes in the feeding regime. We investigated the impact of diet and population density on reproductive maturation of females from native (Irkutsk) and invasive (Sochi) populations of the multicolored Asian ladybird Harmonia axyridis. During the study the beetles fed either on the green peach aphid, Myzus persicae, or on less suitable factitious food (eggs of the grain moth Sitotroga cerealella). Population density was determined by the number of females and males placed in a standard Petri dish. The experiments showed that feeding on the grain moth eggs (other conditions being equal) delayed maturation and increased the tendency to enter reproductive diapause in females from the native but not from the invasive population of H. axyridis. In addition, the preoviposition period increased with the number of females but decreased with the number of males in a dish, although these effects were observed only in individuals from the invasive population and their strength depended on the food of the beetles. Earlier we have demonstrated that the impact of the density-dependent factors on the larvae of the invasive population of H. axyridis was stronger than that on the larvae of the native population because the larvae of the invasive population have somewhat more aggressive interactions with competitors. In the present study, similar differences were revealed between females of these populations.     

Effects of temperature on the expression of elytral colour polymorphism in the ladybird beetle,Menochilus sexmaculatus (Coleoptera: Coccinellidae)

The ladybird beetle, Menochilus sexmaculatus (Fabricius), has a remarkable elytral colour polymorphism composed of black and red. In the present study, we investigated the effect of temperature on growth from the first instar larva to the pupal stage, as well as maternal morph types on the phenotypic expression of the elytral colour morph in a polymorphic population from Osaka, Japan. Female individuals of three different elytral colour morphs were collected from a wild population, and hatchlings from each female were divided into three groups, which were reared at three constant temperatures: 20 °C, 25 °C, and 30 °C. The phenotypic frequency of F₁ adults indicated that the elytral morph type was determined by genetic factors, but not by growth temperatures. Namely, type A (almost black morph) was the most abundant in F₁ from type A mothers (Male: 52.6%; Female: 32.3%); and types B (four small-dotted morph) and F (four medium-dotted morph) were the most abundant from type B (Male: 56.7%; Female: 53.3%) and type G (four larger-dotted morph) mothers (Male: 33.3%; Female: 31.3%), respectively. Therefore, the expression of elytral colour polymorphism in the Osaka, Japan population is likely to have a genetic basis contingent on parental morphs, rather than a phenotypic plasticity associated with growth temperatures.     

Loss of habitats,naturalness and species diversity in Eurasian forest landscapes

Man has exploited land and forests in Western and Central Europe longer and more intensively than in Northern Europe and further east in Eurasia. We estimated forest naturalness and modelled expected biodiversity loss in seven different landscapes (2500 km² each) in the Netherlands, Sweden, Finland, Poland, St. Petersburg (Western European Russia), Perm (Eastern European Russia), and Irkutsk (Central Siberia) across the distribution of Pinus sylvestris L. in Eurasia. Field inventories showed that the mean living tree volumes were relatively similar in the studied sites, but the volumes of dead wood differed greatly. In Irkutsk and Perm the volume of dead trees per ha was about 5–10 times larger than in Central and Western European regions. The studied forests were generally young in all regions except for Irkutsk, where about half of the study plots had trees older than 120 years. Signs of recent forest fires were found almost exclusively on Russian sites. According to Landsat satellite image-based land-cover classifications the amount of remaining forest habitat in the studied landscapes varied from 25% in the Netherlands to 93% in Irkutsk. Estimated by forest patch size and density of cut stumps, forests were also more fragmented and heavily managed in the western study landscapes compared to eastern ones. Based on species–area relationship functions, we calculated that the proportion of forest-dwelling species already extinct or expected to become extinct due to habitat loss ranges from 1–2% in Irkutsk to 13–24% in the Netherlands study landscape. For saproxylic species, which depend on dead wood, the extinction estimates were calculated based on remaining dead wood volume in the landscape. The modelled expected loss of saproxylic species ranged from 7–14% in Irkutsk to 35–58% in the Netherlands.     

Species composition and pattern of fish distribution in Siberia

At the end of the first half of the 20th century, 61 species and subspecies of fish, including one invader (bleak Alburnus alburnus) and 17 species—endemics of Baikal—were reported for Siberia (Berg, 1933, 1949). At the present time, in rivers, lakes, and reservoirs of Siberia, 96 fish species and subspecies are described, of which 80 are aboriginal and 16 are invaders; 33 species are endemics of Baikal. Each landscapegeographic zone of Siberia has its specific ichthyofauna: in rivers and lakes of the south of Siberia, species of boreal piedmont complex dominate; in water bodies of the steppe, forest-steppe, taiga, and southern parts of the forest-steppe zone boreal plain dominates; in the zone of tundra, arctic freshwater dominates; and in Baikal, the most part (35) of species belongs to the Baikal autochtonous complex. Most researchers, as before, distinguish in Siberia two ichthyogeographic sites—West Siberian and East Siberian—that enter the Arctic Province of the Circumpolar subregion of the Holarctic region. Baikal is considered in the rank of the suboblast of the Holarctic.     

The invasion history,distribution and colour pattern forms of the harlequin ladybird beetle Harmonia axyridis (Pall.) (Coleoptera,Coccinellidae) in Slovakia,Central Europe

The harlequin ladybird beetle Harmonia axyridis (Coleoptera, Coccinellidae) has invaded and established in Slovakia. Following unintentional introduction in 2008, the spread of the alien coccinellid was very fast. By the end of 2009, it was recorded across the whole country, and by the end of 2012 it was widely distributed and common in various habitats, particularly gardens, orchards and urban areas, where it was most frequent on trees. The rate of eastward spread was approximately 200 km year^-1, similar to the overall rate of spread in Europe. Between 2008 and 2012, the coccinellid was recorded in a total of 153 localities, in altitudes ranging from 98 to 1,250 m. Most records of this species were made in lowlands, hilly areas and valleys separating mountain ridges. However, it was only rarely documented in areas above 700 m a.s.l. The non-melanic colour form (f. succinea) was dominant along a longitudinal transect including eight urban areas across Slovakia, with the frequency of melanic forms (f. spectabilis and f. conspicua together) between 6.3 and 19.2% and a median equal to 10.5%. The invasion history and distribution of H. axyridis in Slovakia are discussed with regard to the time sequence of records, rate of spread, altitudinal distribution, anthropogenic dispersal, effective recording, proportion of melanic forms and other relevant aspects associated with the spread of this successful invader.     

Changes in the ranges of pasture ixodid ticks of the genus Ixodes Latr., 1795 (Parasitiformes, Ixodidae) in West Siberia

The distribution pattern of two tick species, Ixodes persulcatus and Ixodes pavlovskyi, in the plain part of West Siberia is analyzed. The exact northern range boundary of I. persulcatus in the Khanty-Mansi Autonomous Area is determined based on long-term data on the population density of adult and immature ticks (1960–2011). The shift of the southern boundary of the species range in West Siberia as related to anthropogenic transformation (reforestation measures, reduced or stopped sanitary forest cutting, road construction, etc.) is demonstrated. The specific traits of distribution of the taiga tick I. persulcatus in some localities of Southwest Siberia are analyzed. The modern state of the tick population in the areas co-inhabited by the two species is characterized. The possible reasons of changes in the structure of tick communities toward complete prevalence of I. pavlovskyi in recreational zones of Novosibirsk and Tomsk are discussed. The most significant changes in the distribution pattern of these two tick species in West Siberia seem to have occurred after 1990. During this period, the local stable populations of the taiga tick to the south of its main range in West Siberia (within Omsk and Novosibirsk provinces) were formed, the pattern of its distribution on the right bank of the Ob River (Novosibirsk Province) and in the Tom River valley (Tomsk Province) changed, whereas I. pavlovskyi became the dominant species.     

An addition to the myrmecofauna (Hymenoptera,Formicidae) of Baikalian Siberia

Four species, Formica cinerea Mayr, 1853, Lasius gebaueri Seifert, 1992, L. platythorax Seifert, 1991, and L. sabularum (Bondroit, 1918), are recorded in the myrmecofauna of Baikal Siberia for the first time. At the present time, the myrmecofauna of Baikal Siberia includes 65 species.     

Novel Data on the Taxonomic Diversity,Distribution, and Host Plants of Leafmining Moths of the Family Gracillariidae (Lepidoptera) in Siberia,Based on DNA Barcoding

The Gracillariidae fauna of Siberia, the region that occupies almost half of the territory of the Russian Federation, remains poorly studied. During a DNA barcoding study of Gracillariidae in Siberia, based on analysis of larvae and pupae collected from their leaf mines on woody plants, we identified 41 species. Three gracillariids were identified only to genus: Caloptilia sp. (host plant Prunus padus), Parornix sp. (Malus sp.), and Phyllonorycter sp. (Crataegus sp.), representing poorly studied or undescribed species. Six species are reported here for the first time for Siberia: Callisto insperatella (from Novosibirsk and Tomsk provinces), Caloptilia alnivorella (Buryatia), Phyllonorycter ermani (Irkutsk Province), Ph. lantanella (Novosibirsk Province), Ph. pumilae (Omsk and Irkutsk provinces), and Ph. viciae (Krasnoyarsk Territory). Parornix pfaffenzelleri, found in Khakassia, is reported as a species new to Russia. Other 15 gracillariid species previously known from Siberia were recorded in new administrative regions. The invasive lime leafminer Phyllonorycter issikii was first documented in Tomsk Province and Krasnoyarsk Territory in 2017 and 2018, respectively. Seven new gracillariid-host plant associations were found: Parectopa ononidis on Lupinaster pentaphyllus, Sauterina hofmanniella on Lathyrus gmelinii, Caloptilia stigmatella on Salix kochiana, Callisto insperatella on Prunus virginiana, Parornix scoticella on Amelanchier sp., Phyllonorycter ermani on Alnus alnobetula subsp. fruticosa, and Phyllonorycter viciae on Vicia unijuga. The Gracillariidae fauna of Siberia has 51% similarity with that of European Russia and only 38% similarity with that of the Russian Far East.

     

Graylings of Baikal Lake basin (Thymallus, Thymallidae): Diversity of forms and their taxonomic status

The morphological characters, molecular-genetic features, and patterns of the dorsal fin in different subspecies and forms of Arctic grayling Thymallus arcticus populating Lake Baikal and its tributaries, Irkutsk Reservoir, and Lake Khubsugul have been studied. Three groups are discernable. The first includes the white and black Baikal graylings T. a. baicalensis, as well as the western Siberian T. a. arcticus; the second group is represented by the Kosogol grayling T. a. nigrescens, and the third is composed of T. arcticus ssp. from the Yakchii lakes (the Verkhnyaya Angara basin) with a phenotype close to graylings populating the upper reaches of the Lena River. All of them are distinguished by some morphological characters, elements of the dorsal fin pattern, and by body coloration. The populations of black Baikal graylings are genetically uniform, and their distinctions from white Baikal graylings are insignificant, which agrees with the absence of a considerable divergence of these forms by a complex of meristic characters. It is assumed that in the black and white Baikal graylings the exchange by genetic information has either ceased quite recently, or persists, although, insignificantly. Some genetic remoteness of the west Siberian grayling from Irkutsk Reservoir and Nizhnyaya Tunguska, closely related to the Baikal grayling, is recorded. The formation of the Khubsugul subspecies is possibly a result of the contact of grayling populations during the rearrangements of the river system in the last glaciation period in the upper reaches of Yenisei and Selenga in Mongolia. The habitation in the Baikal system of the Upper Lena graylings indicates a connection between the Lena and Baikal basins in the past. The results of a multivariate analysis of meristic characters and the sequences of mitochondrial DNA confirm the conclusion made by Svetovidov (1931, 1936), concerning the absence of grounds to assign a species status to the Baikal forms.     

Paternity following multiple mating in ladybird <Emphasis Type="Italic">Harmonia axyridis</Emphasis>

We investigated factors which may determine realised paternity following multiple mating in a promiscuous ladybird Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), namely the mating order and ability of males of different morphs to fertilize females. In experiments using males of two colour morphs, we found that the first male had a reproductive advantage over the second male (sperm precedence P2 = 0.38). Males of the melanic morph spectabilis had a reproductive advantage over males of the semi-melanic morph axyridis (P2 = 0.35). Analysis of paternity using microsatellites applied to young larvae, which avoids possible differential mortality of progeny, confirmed the precedence of the first male and higher paternity rate of colour morphs that are more frequent in the wild. Hatchability of eggs increased from 65% after the first mating to 85% after the second mating delayed by five days. Average duration of mating was 157 min and did not differ between the first and second mating and between the colour morphs of males.     

Winter survival of Harmonia axyridis in The Netherlands

Since the establishment of Harmonia axyridis in Europe, populations of native ladybirds have decreased. Overwintering survival is one of the aspects of the biology of H. axyridis that may contribute to its firm establishment in and invasion of a new area. In this study winter survival of five wild H. axyridis populations was assessed under natural and semi-natural conditions, with a focus on the potential influence of location and orientation on winter survival.Overwintering survival of H. axyridis in the Netherlands is high: 70.8-88.2%. When overwintering at one central site, populations sampled at five locations showed statistically significant different mortality rates. Furthermore, winter survival of H. axyridis at the sample sites was higher when beetles were hibernating at the southwestern sides of buildings, where most aggregations of ladybirds were found. Survival was higher at sheltered sites compared to exposed sites.Harmonia axyridis has a comparable or higher overwintering survival than most common native ladybird species. A high overwintering survival results in a large post-hibernation population in spring, leading to a rapid population build-up. Thus, the high winter survival probably contributes to the success of the exotic H. axyridis.     

Diversity of cyanobacterial species and phylotypes in biofilms from the littoral zone of Lake Baikal

The majority of naturally occurring biofilms contain numerous microorganisms that have not yet been cultured. Additionally, there is little information available regarding the genetic structure and species diversity of these communities. Therefore, we characterised the species diversity, structure and metagenome of biofilms grown on stones and steel plates in the littoral zone of Lake Baikal (East Siberia, Russia) by applying three different approaches. First, light microscopy enabled identification of the species diversity of biofilm-forming cyanobacteria on different substrates with the dominance of Rivularia rufescens, Tolypothrix limbata, Chamaesiphon fuscus, Ch. subglobosus, and Heteroleibleinia pusilla. Additionally, scanning electron microscopy was used to show the spatial structure of biofilms. Finally, sequence analysis of 30,660 16S rRNA clones indicated a high diversity within the biofilm communities, with the majority of the microbes being closely related to Cyanobacteria (8–46% sequences), Proteobacteria (14–43%), and Bacteroidetes (10–41%). Rivularia sp., Pseudanabaena sp., and Chamaesiphon spp. were the dominant cyanobacterial phylotypes.     

农林复合系统中灌木篱墙对异色瓢虫种群分布的影响

以北京大兴农区农林复合系统为对象,围绕灌木篱墙(沙棘绿篱和杨树萌条带)上和麦田中的主要捕食性天敌——异色瓢虫对栖息地的选择趋向及灌木篱墙对异色瓢虫种群分布的影响进行了研究。结果表明:(1)小麦生长前期(返青期至抽穗期或扬花期)灌木篱墙上异色瓢虫种群密度是麦田的3.25—9.57倍,是异色瓢虫由越冬地向麦田过渡前的主要栖息地,是农林复合系统中异色瓢虫种群建立的"种库";(2)异色瓢虫对栖息生境有较强的选择性,明显趋向于蚜虫密集分布的生境,小麦生长前期趋向于灌木篱墙,小麦生后期(扬花期或灌浆期至完熟期)趋向于麦田,整个小麦生长期内异色瓢虫种群在不同生境斑块间存在明显的移动现象;(3)麦收后,邻近麦田的杨树萌条带上异色瓢虫种群密度相比于完熟期增加了42%,为异色瓢虫提供了重要的庇护场所。