Seasonality of first coitus in Northwestern Russia: the importance of location availability

&nbsp; The majority of studies addressing sexual behavior of adolescents were conducted in the USA, which has prevented generalizations to the countries which differ from the USA in social interactions, quality of life and sexual culture. Furthermore, the studies of sexual debut usually explore the role of time availability and supervision, while location availability in some countries may be more important than time availability. The questionnaires filled in by 262 Russian students demonstrated relatively early sexual debut (males: 16.4 years; females: 17.0 years) and strong summer peak of coital activity associated with frequent use of marginally suitable locations. Use of marginally suitable locations was much higher in small villages than in cities, at a younger age, and when sex was by desire rather than by love. These data suggest &lsquo;Location Availability Hypothesis&rsquo; partially competing with &lsquo;Summer Vacation Theory&rsquo;: in summer more sites, including marginally suitable locations, are available for adolescent sexual activity, and the use of these locations contributes to the summer peak in the onset of sexuality. </p

Critical evaluation of faunistic data: Three species of monotrysian moths (Eriocraniidae, Prodoxidae and Incurvariidae) erroneously reported from Russia

The published records of Eriocrania chrysolepidella Zeller, 1851, Incurvaria koerneriella (Zeller, 1839) and Lampronia aeneella (Heinemann, 1870) from Chuvash and Karelia Republics in Russia are based on misidentified specimens. This finding, along with earlier reports on the widespread occurrence of errors, even in the most authoritative works, calls for a critical approach to published data in order to stop sp reading and citing false information across future publications

Sources of variation in plant responses to belowground insect herbivory: a meta-analysis

Growing interest in belowground herbivory and the remarkable diversity of the accumulated information on this topic inspired us to quantitatively explore the variation in the outcomes of individual studies. We conducted a meta-analysis of 85 experimental studies reporting the effects of root-feeding insect herbivores (36 species) on plants (75 species). On average, belowground herbivory led to a 36.3% loss of root biomass, which was accompanied by a reduction in aboveground growth (-16.3%), photosynthesis (-11.7%) and reproduction (-15.5%). The effects of root herbivory on aboveground plant characteristics were significant in agricultural and biological control studies, but not in studies of natural systems. Experiments conducted in controlled environments yielded larger effects on plants than field experiments, and infestation experiments resulted in more severe effects than removal studies employing natural levels of herbivory. Simulated root herbivory led to greater aboveground growth reductions than similar root loss imposed by insect feeding. External root chewers caused stronger detrimental effects than sap feeders or root borers; specialist herbivores imposed milder adverse effects on plants than generalists. Woody plants suffered from root herbivory more than herbaceous plants, although root loss was similar in these two groups. Evergreen woody plants responded to root herbivory more strongly than deciduous woody plants, and grasses suffered from root herbivory more than herbs. Environmental factors such as drought, poor nutrient supply, among-plant competition, and aboveground herbivory increased the adverse effects of root damage on plants in an additive manner. In general, plant tolerance to root herbivores is lower than tolerance to defoliating aboveground herbivores

The costs and effectiveness of chemical defenses in herbivorous insects: a meta-analysis

The evolution of defensive traits and strategies depends on the intensity of selection imposed by natural enemies and on the fitness costs of defenses against these enemies. We tested several hypotheses about the evolution of chemical defenses in plant-feeding insects using a meta-analysis. We analyzed the effectiveness (in terms of prey survival; 159 publications) and costs (in terms of reduction in performance due to defense production; 33 publications) of chemical defenses in various prey-predator systems (140 herbivore species and 124 enemy species). The chemical defenses of insect herbivores, on average, were effective against generalist predators, were not effective against specialist predators and generalist parasitoids, and increased the risk of parasitism by specialist parasitoids. The defenses were more effective against vertebrate than against invertebrate predators and most effective against birds. Defensive compounds synthesized de novo and derived from the herbivore&#39;s food plants did not differ in the magnitude of their effects. Externalization of chemical defenses enhanced their effects on naive vertebrate predators but simultaneously increased the risk of parasitism. The defenses of specialist herbivores were more effective than those of generalists, mostly due to species that sequestered plant allelochemicals for their own defenses. Advertising of chemical defenses by warning display enhanced their effectiveness only against vertebrate predators. Aposematic colors and patterns were more effective warning signals than other types of conspicuous coloration against both experienced and naive vertebrate predators, suggesting that certain colors and/or patterns were more important than conspicuousness for both learning and innate avoidance. The meta-analysis did not reveal physiological costs of the production of chemical defenses across 22 herbivore species, although the results varied strongly with the method used to measure these costs. We conclude that the cost-benefit trade-offs driving the evolution of chemical defenses in herbivorous insects are affected by ecological costs (i.e., increased susceptibility to parasitoids) more than by costs in terms of resources. Still, a favorable cost-benefit ratio, i.e., great effects for a small expenditure, may partly explain the prevalence of chemical anti-predator defenses in insects.</p

Distribution records of aphids (Hemiptera: Phylloxeroidea, Aphidoidea) associated with main forest-forming trees in Northern Europe

Stekolshchikov, A. V. & Kozlov, M. V. 2012: Distribution records of aphids (Hemiptera: Phylloxeroidea, Aphidoidea) associated with main forest-forming trees in Northern Europe.-Entomol. Fennica 23: 206-214. We report records of 25 species of aphids collected from four species of woody plants (Pinus sylvestris, Picea abies, Betula pubescens and B. pendula) at 50 study sites in Northern Europe, located from 59 degrees to 70 degrees N and from 10 degrees to 60 degrees E. Critical evaluation of earlier publications demonstrated that in spite of the obvious limitations of our survey, the obtained information substantially contributed to the knowledge of the distribution of aphids in North European Russia, including Murmansk oblast (103 species recorded to date), Republic of Karelia (58 species), Arkhangelsk oblast (37 species), Vologda oblast (17 species) and Republic of Komi (29 species). We confirm the occurrence of Cinara nigritergi in Southern Karelia; Pineus cembrae, Cinara pilosa and Monaphis antennata are for the first time recorded in Norway

Can the use of landmarks improve the suitability of fluctuating asymmetry in plant leaves as an indicator of stress?

Fluctuating asymmetry (FA), defined as the random deviations from symmetry in morphological traits, has repeatedly been suggested as a handy indicator of genetic and environmental stress experienced by organisms during their development. However, the value of FA for applied ecological and environmental research is now questioned by a growing number of studies that have found no increases in FA under stress. We used geometric morphometrics to test the hypothesis that FA measures based on naturally defined landmarks are better suited for detection of deviations from leaf symmetry than are traditional measures of FA. We compared two sets of mountain birch (Betula pubescens ssp. czerepanovii) leaves, obtained from trees growing in industrially polluted natural populations and from experimentally stressed seedlings, by examining three measures of FA: 1) a traditional distance-based measure calculated from the width of the left and right halves of a leaf at the middle of the lamina (FA(width)), 2) a distance-based measure reflecting differences in vein length calculated from three landmarks (FA(veins)), and 3) a multivariate FA measure describing asymmetry in leaf shape based on five landmarks (FA(shapc)). These three FA measures were poorly (albeit positively) correlated with each other. The two distance-based measures reflected different parts of the multivariate measure FA(shape )which had the highest sensitivity for detection of deviations from leaf symmetry. FA(shape) was also the only FA measure that weakly confirmed the expected increase in FA under experimental stress, and particularly under stress caused by application of heavy metals. However, very high levels of within-individual variation in asymmetry remain to be explained, and even FA(shape )did not show the expected effects of.industrial pollution on leaf symmetry. We conclude that FA in birch leaves cannot be regarded as a reliable indicator of environmental stress, even when quantified using modern methods

Can Larvae of Forest Click Beetles (Coleoptera: Elateridae) Feed on Live Plant Roots?

Simple SummaryDetailed natural history information is still lacking for many species of soil-dwelling invertebrates. We asked whether the larvae (wireworms) of two click beetle species, which are most abundant in European boreal forests, feed on live roots of forest plants. The weight of root pieces of downy birch, Scots pine, Norway spruce and wavy hair-grass, offered to wireworms in a laboratory experiment, did not decrease, indicating that these larvae did not consume live root tissues. Therefore, Athous subfuscus and Dalopius marginatus should be excluded from the lists of forest pests damaging tree roots.The life histories of many soil-dwelling invertebrates remain poorly studied. The larvae of two click beetle species, Athous subfuscus and Dalopius marginatus, which are most abundant in European boreal forests, are both classified as omnivorous and are included in lists of root-damaging pests. Nevertheless, we are not aware of any direct proof of their ability (or inability) to consume plant roots. In this study, we asked whether these larvae actually feed on the roots of forest plants in the absence of other food sources. Live roots of boreal forest plants, including trees (Betula pubescens, Picea abies and Pinus sylvestris) and grass (Deschampsia flexuosa), were offered to click beetle larvae in a two-month microcosm experiment. The weight of roots placed in vials with the wireworms did not decrease, indicating that the larvae of these click beetle species did not feed on live roots, even in the absence of other food sources. This suggests that the feeding niches of A. subfuscus and D. marginatus larvae are narrower than previously thought and do not include live plant tissues. Therefore, these click beetle species should be excluded from the lists of forest pests damaging tree roots

Ontogenetic changes in insect herbivory in birch (Betula pubesecens): The importance of plant apparency

Several theories aim at predicting changes in the interactions between plants and herbivores over the lifetime of a plant. Hypotheses based on ontogenetic changes in resource allocation to plant defence and in plant apparency lead to partly opposing predictions regarding the differences in levels of herbivory between juvenile and mature plant individuals. We tested these predictions by measuring background foliar losses to insects in saplings and mature trees of downy birch (Betula pubescens) in ten sites along a latitudinal gradient from 60 degrees to 69 degrees N in boreal forests of Northern Europe. The percentage of consumed leaf area increased, and the variation in the levels of herbivory among plant individuals decreased, for tree sizes ranging from small saplings (2-12cm tall) to large saplings (13-80cm tall) and then to mature trees (3-18m tall). Small saplings had higher foliar quality for insects, as indicated by better performance of leafmining larvae of Eriocrania semipurpurella and by greater specific leaf area, compared with large saplings and mature trees. The average percentage of leaf area consumed from a damaged leaf, which reflects the inducibility of local defence responses to insect damage, did not vary among the birch size classes. The foliar losses to insects decreased nearly fivefold with an increase in latitude from 60 degrees to 69 degrees N, but the relative differences in these losses among the birch size classes were independent of latitude. Our findings fit well with the predictions based on a plant apparency hypothesis, but do not support predictions based on ontogenetic changes in resource allocation to plant antiherbivore defences. We conclude that the generally overlooked effects of apparency on plant damage by insects can explain, at least in some cases, the frequently observed lack of correspondence between the levels of plant defences and herbivory.A is available for this article

Photosynthetic Efficiency is Higher in Asymmetric Leaves than in Symmetric Leaves of the Same Plant

Symmetry pervades nature, but asymmetry is also rather common. Deviations from genetically programmed symmetry are usually associated with internal or external developmental disturbances and may therefore be related to imperfections in physiological processes. In this study, we test the hypotheses that the photosynthetic efficiency of individual leaves of a plant is negatively related to their asymmetry. We measured chlorophyll fluorescence in leaves of three woody species (Betula pubescens, Populus tremula and Salix caprea) in early and late summer in two localities situated ca. 1000 km apart, and we quantified the asymmetry of these leaves by a multivariate measure based on the relative positions of several landmarks. Contrary to our expectation, we found that the photochemical efficiency of photosystem II was positively correlated with leaf fluctuating asymmetry; this effect was weak but consistent across the studied plant species, localities and seasons. Our finding adds to limited evidence that within-plant variation in leaf asymmetry is associated with variation in leaf physiology. Irrespective of the underlying mechanisms, which remain unknown, the results suggest that trees may benefit even more from their asymmetric leaves, at least in terms of photosynthesis, than they do from their more symmetric leaves

Variation in defensive chemistry within a polyphagous Baikal population of Chrysomela lapponica (Coleoptera: Chrysomelidae): potential benefits in a multi-enemy world

Variation in anti-predator chemical defence is frequently observed in natural populations, but its adaptive significance remains debatable. Most populations of the chemically defended leaf beetle, Chrysomela lapponica, are specialized to their host plants, but some populations are polyphagous. We tested the hypothesis that the use of multiple host plants by a Baikal population of C. lapponica results in variation in the composition of its defensive secretions, leading to variation in defence effectiveness against different natural enemies. The secretions of larvae feeding on local host plants differed both in the origin of major components (sequestered or autogeneous) and in chemical profiles. This variation was at least partly associated with differences in the secondary chemistry among the five most abundant plant species used by this population. Larvae feeding on different hosts in nature suffered similar overall mortality from enemies, but the relative contributions of different enemy species (natural enemy profiles) varied among host plant species. Behavioural experiments with three predators and one parasitoid showed that this variation may result from idiosyncratic responses of the enemy species to the composition of the larval defences. These differences allow part of the polyphagous leaf beetle population to escape from the currently most abundant enemy on the host plant species that provides the best protection against this enemy. In this way, the within-population variability in chemical defence, associated with feeding on hosts differing in chemistry, can buffer prey populations against fluctuating pressures of specific enemies