Heracleum mantegazzianum is one of the most invasive species in the Czech flora. The present study describes its flowering phenology and assess the effectiveness of protandry in preventing selfing in this self-compatible species, describes the timing of flowering in a heavily invaded area of Slavkovský les (Czech Republic) and estimates fruit set in a large sample of plants, which provides reliable data on the often exaggerated fecundity of this species. The study of flowering phenology revealed that protandry is always effective only within individual flowers, where male and female flowering phases are completely separated. In contrast, anther dehiscence in some flowers can occasionally overlap with stigma receptivity in other flowers in the same umbel, providing an opportunity for geitonogamous (i.e. between-flower) selfing. Nevertheless, the potential for selfing in H. mantegazzianum is determined mainly by an overlap in the male and female flowering phases between umbels on the same plant; at least a short overlap between some umbels was observed in 99% of the plants at the Slavkovský les. Although the degree of protandry in H. mantegazzianum favours outcrossing, the opportunity to self may be of crucial importance for an invasive plant, especially if a single plant colonizes a new location. At Slavkovský les, flowering started within one week (from 20 to 27 June 2002) at all 10 sites. The duration of flowering of an individual plantwas on average 36 days,with maximum of 60 days, and increased significantly with the number of umbels on a plant. In the second half of August, the majority of the fruits were ripe and had started to be shed. The beginning of flowering of a plant was significantly negatively correlated with the number of umbels it had – the earlier a plant started to flower the more umbels it had produced. A significant negative relationship was also found between basal diameter and beginning of flowering; plants with large basal diameters started to flower earlier. An average plant at Slavkovský les produced 20,671 fruits. Of these, 44.6% were produced by the terminal umbel, 29.3% by secondary umbels on satellites, 22.6% by secondary umbels on branches and only 3.5% by tertiary umbels. The estimated fruit number of the most fecund plant was 46,470 – compared to an average plant, the proportional contribution of tertiary umbels increased relative to the primary umbel. This study revealed a significant positive relationship between fecundity and plant basal diameter. Although the results of this study indicate that the fecundity of this species is often overestimated in the literature, the number of fruits produced by H. mantegazzianum provides this invasive species with an enormous reproductive capacity.
The effect of larval body size of Epirrita autumnata (Lepidoptera, Geometridae) on the risk of parasitism was studied in a field experiment. The experiment involved three pairwise exposures of different larval instars to parasitoids. Three hymenopteran species were responsible for most of the parasitism. Parasitism risk was found to be host-instar independent. This result was consistent across parasitoid species and experiments. The results suggest that host use by larval parasitoids cannot constrain selection for larger body size in E. autumnata. However, high mortality due to parasitism may select for a short developmental period (the slow-growth/high-mortality hypothesis), and smaller body sizes as a by-product. A strong selective effect of parasitism on the timing of larval development in E. autumnata is also unlikely. The larger was the host, the larger was the adult size of the parasitoid and the shorter its development time (for one species). We suggest that the lack of a preference-performance linkage in the system studied may be related to the time stress associated with the short phenological window of host vulnerability.
Mean annual first arrival dates (FAD) of 45 migratory bird species recorded in Moravia (Czech Republic, c. 49º N) in 109 spring seasons between 1881 and 2007 were correlated with the preceding winter (December to March) North Atlantic Oscillation (NAO) index. The arrival of birds occurred significantly earlier following high NAO winter index values (those result in spring warmer than normal in central Europe) in all short-distance migratory species with a European or North African winter range, whereas the arrival timing did not correlate significantly with the seasonal NAO index in long-distance migrants having sub-Saharan winter range. When the values of Pearson coefficient between NAO and FAD were correlated with the migration distance of all 45 bird species, the correlation was remarkable and significant (p<0.001): r = 0.848 for the distance to central locations of winter range, and r = 0.822 for the northern limits of the wintering area. The migration distance was thus responsible for 68–72 % of variation in the regression of birds’ arrival on NAO winter index in central Europe. The data are robust (this is the longest avian phenological record analyzed for correlation with NAO in Europe), and indicate different mechanisms that govern timing between short-distance and long-distance migrants in their departure from wintering areas.
1_The maritime pine bast scale, Matsucoccus feytaudi Ducasse (Hemiptera: Matsucoccidae), occurs in the western part of the Mediterranean basin and is a sap sucking insect that feeds only on maritime pine (Pinus pinaster Aiton). It causes damage in SE France and Italy, where it was accidentally introduced. In Spain information is scarce and, moreover, almost nothing is known about the predators of this species. This study was designed to determine the seasonal trends in abundance of M. feytaudi and its major predators, which might help to improve the biological control of this pest in other areas. Natural P. pinaster stands in the Valencian Community (Spain) were surveyed in 2004. In addition, the seasonal trends in abundance of M. feytaudi and its natural enemies were monitored in three stands over a period of three years (2002, 2005 and 2006). The monitoring was carried by wrapping sticky tapes around tree trunks and using delta traps baited with sexual pheromone. The maritime pine bast scale was detected in all the stands surveyed. At almost all the sites surveyed, three species of predators were captured: Elatophilus nigricornis Zetterstedt (Hemiptera: Anthocoridae), Hemerobius stigma Stephens (Neuroptera: Hemerobiidae) and Malachiomimus pectinatus (Kiesenwetter) (Coleoptera: Malachiidae). The presence of M. pectinatus is noteworthy as this is the first record of this species as a possible predator of M. feytaudi. The results show that M. feytaudi, although differing in its phenology depending on the location, is univoltine in the study area. The prepupae, pupae and adults of M. feytaudi appeared between December and March in colder areas and between October and February in warmer areas. E. nigricornis nymphs are important predators of M. feytaudi, and were abundant when the scale insect (crawlers, prepupae, pupae, male and female adults) was present., 2_The flight period of E. nigricornis and the hemerobiid H. stigma ranged from May to October. However, these flight patterns did not correlate with the presence of the different stages of the bast scale (crawlers, prepupae, pupae, male and female adults) on the surface of tree trunks. The presence of M. pectinatus in large numbers in some stands suggests it might be an important natural regulator, which helps to keep M. feytaudi populations at low densities in the areas of Spain studied. This malachiid shows a strong kairomonal attraction to the sexual pheromone of M. feytaudi and its flight activity is significantly correlated with the presence of crawlers of bast scale., Eugenia Rodrigo ... [et al.]., and Obsahuje seznam literatury
Climate change may facilitate shifts in the ranges and the spread of insect pests, but a warming climate may also affect herbivorous insects adversely if it disrupts the locally adapted synchrony between the phenology of insects and that of their host plant. The ability of a pest species to colonize new areas depends on its ability to adjust the timing of phenological events in its life cycle, particularly at high latitudes where there is marked seasonality in temperature and day length. Here we incubated eggs of three species of geometrid moth, Epirrita autumnata, Operophtera brumata and Erannis defoliaria from different geographical populations (E. autumnata and O. brumata from Northern Finland, E. autumnata and E. defoliaria from Southern Finland and all three species from Germany) in a climate chamber at a constant temperature to determine the relative importance of geographic origin in the timing of egg hatch measured in terms of cumulative temperature sums (degree days above 5°C, DD5); i.e. the relative importance of local adaptation versus phenotypic plasticity in the timing of egg hatch. In all three species, eggs from northern populations required a significantly lower temperature sum for hatching than eggs from southern populations, but the differences between them in temperature sum requirements varied considerably among species, with the differences being largest for the earliest hatching and northernmost species, E. autumnata, and smallest for the southern, late-hatching E. defoliaria. In addition, the difference in hatch timing between the E. autumnata eggs from Southern Finland and Germany was many times greater than the difference between the two Finnish populations of E. autumnata, despite the fact that the geographical distances between these populations is similar. We discuss how these differences in hatching time may be explained by the differences in hatch-budburst synchrony and its importance for different moth species and populations. We also briefly reflect on the significance of photoperiod, which is not affected by climate change. It is a controller that works parallel or in addition to temperature sum both for egg hatch in moths and bud burst of their host plants., Julia Fält-Nardmann, Tero Klemola, Mechthild Roth, Kai Ruohomäki, Kari Saikkonen., and Obsahuje bibliografii
Insects experience important selection pressures from their parasitoids, which affect both their population dynamics and their evolutionary responses. The interaction between the egg parasitoid Oomyzus galerucivorus Graham (Hymenoptera: Eulophidae) and its chrysomelid host Galeruca tanaceti L. (Coleoptera: Galerucinae) was investigated with the particular aim determining whether the chrysomelid host can escape its parasitoid by ovipositing late in the year as early as September. Although the leaf beetle and its parasitoid emerge in April, G. tanaceti starts to oviposit after spending the summer in reproductive diapause. The objective was to determine, whether the small parasitic wasp can parasitise its host's eggs even at the end of its host's reproductive season in December, when temperatures are low. Beetle oviposition, parasitism rates and temperatures were measured on three comparable mesoxerophytic grassland sites over the coarse of a season. Beetle oviposition, but not parasitism, was significantly positively dependent on temperature. Rate of oviposition decreased over the oviposition period with decrease in temperature. In contrast, after a lag phase of 1-2 weeks at the beginning of the oviposition period in September beetle egg clutches were parasitised at a constant rate until the end of the season in December. Host eggs were parasitised even at mean daily temperatures of 0-6°C. Thus the tansy leaf beetle does not escape from egg parasitism by ovipositing late in the season in central Germany.
The univoltine leaf miner Chromatomyia fuscula Zetterstedt is a Scandinavian cereal pest. We wanted to compare the phenology of C. fuscula in southern Norway with that of its most important natural enemies: 15 parasitoids of the families Eulophidae and Pteromalidae (Hymenoptera: Chalcidoidea). The use of two Malaise traps in an organically-grown spring barley field and its boundary through 6 seasons (1992-1997) also allowed us to compare these two habitats and to observe the effect of harvesting on the parasitoid activity without interference from pesticides. C. fuscula overwinters as an adult and oviposits in May/June. Few specimens of the next generation, emerging in the crop, were caught in the boundary traps, suggesting the fly hibernates elsewhere. In contrast, the F1 generation of the parasitoids was caught in considerable amounts both in the crop and boundary. The abundance of parasitoids was highest in July/August; in the crop it usually started decreasing well before harvesting; in the boundary it peaked two weeks or more after harvesting. The results suggest that many parasitoids (especially females) move from the crop to the boundary (or beyond) before harvesting. In both habitats parasitoid species richness usually increased until harvesting, and thereafter decreased. The pooled parasitoid female proportion was 0.36; in crop and boundary it was 0.30 and 0.66, respectively, and the majority of species had a higher proportion of females in the boundary than in the crop. The phenology of two of the most common parasitoids is presented: The pupal parasitoid Cyrtogaster vulgaris Walker (Pteromalidae) had a high activity in the boundary, also very early (females only) and late (both sexes) in the season. The larval parasitoid Diglyphus begini (Ashmead) (Eulophidae) was less active early and late in the season, and had a much smaller boundary activity than C. vulgaris. Both sexes were present throughout the season. The annual sex ratio of D. begini was density dependent, being highly male biased in the two years with highest catches. In C. vulgaris neither density nor habitat explained the sex ratio. D. begini probably overwinters inside the mine as a preadult, having one generation on C. fuscula in the crop and another one in an alternate host away from the habitats sampled here. C. vulgaris overwinters as fertilized females in the border habitat.
The effects of photoperiod on pre-imaginal development and reproductive maturation of adult females of the multicolored Asian lady beetle, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), were investigated at 20°C and at photoperiods from 10L : 14D to 18L : 6D. Experiments were conducted on a laboratory strain that originated from the Russian Far East. Larvae and adults were fed on the green peach aphid Myzus persicae. Under short day conditions the pre-imaginal development was faster than under long day conditions. The acceleration of pre-imaginal development occurred when day length was shorter than 16 h and the threshold day length was ca 14 h. The rate of reproductive maturation of adult females, in contrast, was twice as high under long day conditions, with the threshold between 14L : 10D and 12L : 12D, although even under short day conditions ca 10% of the females show a tendency to mature more quickly. This difference between the thresholds of these two photoperiodic reactions indicates they are relatively independent of one another. and Sergey Ya. Reznik, Nina P. Vaghina.
Plants’ abilities to function are difficult to evaluate directly in the field. Therefore, a number of attempts have been made to determine easily measurable surrogates – plant functional traits (PFTs). In particular, the value of PFTs as tools for predicting vegetation responses to management (i.e., grazing and mowing) is the focus of a large number of studies. However, recent studies using PFTs to predict the effect of pasture management in different regions did not give consistent predictions for the same set of PFTs. This lead to the suggestion that more specific traits better suited for a specific region be used in the future. We consider the identification of the most adaptative traits for surviving grazing and mowing in different biomes an important goal. Using temperate grasslands in Europe as an example, we show that (i) plant height, often considered as the best predictor of species response to grassland management, is coupled with other more relevant functional traits, and that (ii) clonal traits have important, often neglected functions in the response of species to grassland management. We conclude that single traits cannot be the only basis for predicting vegetation changes under pasture management and, therefore, a functional analysis of the trade-off between key traits is needed.
Ecosystem photosynthetic characteristics are of utmost importance for the estimation of regional carbon budget, but such characteristics are not well understood in alpine regions. We collected CO2 flux data measured by eddy covariance technique over an alpine dwarf shrubland on the Qinghai-Tibetan Plateau during years 2003-2010; and we quantified the temporal patterns of ecosystem apparent quantum yield (a), saturated photosynthetic rate (Pmax), and ecosystem dark respiration (RDe). Results showed that the strong seasonality of a and RDe was driven mainly by air temperature (Ta), whereas that of Pmax was much more determined by leaf area index rather than abiotic factors. Diurnal thermal fluctuation inhibited significantly the daytime photosynthetic capacity. Stepwise regression revealed that the seasonal deviations of a, Pmax, and RDe were significantly controlled by Ta. The annual a was regulated mainly by annual growing season Ta, which indicated that the response of ecosystem a was instant. The annual variations of Pmax correlated positively with soil temperature 5 cm below ground (Ts) of the annual nongrowing season and those of RDe related negatively with the annual nongrowing season precipitation. We suggested that a lagged response regulated the annual Pmax and the annual RDe. Annual deviations of a and RDe were both significantly controlled by annual Ts, and those of Pmax were marginally determined by annual PPFD. Thus, the future warming scenario, especially significant for nongrowing seasonal warming in the Qinghai-Tibetan Plateau, would favor ecosystem photosynthetic capacity in the alpine dwarf shrubland., H. Q. Li, F. W. Zhang, Y. N. LI, G. M. Cao, L. Zhao, X. Q. Zhao., and Obsahuje bibliografii