Consequesnces of asymmetric competition between resident and invasive defoliators: a novel empirically based modelling approach

Invasive species can have profound effects on a resident community via indirect interactions among community members. While long periodic cycles in population dynamics can make the experimental observation of the indirect effects difficult, modelling the possible effects on an evolutionary time scale may provide the much needed information on the potential threats of the invasive species on the ecosystem. Using empirical data from a recent invasion in northernmost Fennoscandia, we applied adaptive dynamics theory and modelled the long term consequences of the invasion by the winter moth into the resident community. Specifically, we investigated the outcome of the observed short-term asymmetric preferences of generalist predators and specialist parasitoids on the long term population dynamics of the invasive winter moth and resident autumnal moth sharing these natural enemies. Our results indicate that coexistence after the invasion is possible. However, the outcome of the indirect interaction on the population dynamics of the moth species was variable and the dynamics might not be persistent on an evolutionary time scale. In addition, the indirect interactions between the two moth species via shared natural enemies were able to cause asynchrony in the population cycles corresponding to field observations from previous sympatric outbreak areas. Therefore, the invasion may cause drastic changes in the resident community, for example by prolonging outbreak periods of birch-feeding moths, increasing the average population densities of the moths or, alternatively, leading to extinction of the resident moth species or to equilibrium densities of the two, formerly cyclic, herbivores

Microgastrinae (Hymenoptera: Braconidae) parasitizing Epirrita autumnata (Lepidoptera: Geometridae) larvae in Fennoscandia with description of Cotesia autumnatae Shaw, sp. n.

The microgastrine subset of hymenopteran parasitoids of the geometrid Epirrita autumnata is investigated in Fennoscandia. Ecology, including population dynamics, of the moth has been intensively studied in northern and mountainous Finland, Norway and Sweden. Recently supported hypotheses about the causes of its cyclic population dynamics stress the role of parasitoids, while the parasitoid complex with some 15 species is insufficiently known. The complex includes four solitarymicrogastrine species, Protapanteles anchisiades (Nixon), P. immunis (Wesmael), Cotesia salebrosa (Marshall) and C. autumnatae Shaw, sp. n. Here, we provide detailed figures for the latter, which is morphologically close to C. jucunda (Marshall), and describe the species as new to science. We also providemore general habitus figures of the other three species, as well as an identification key for the four species, aiming to aid recognition of these species by ecologists dealingwithmicrogastrine parasitoids of E. autumnata and their alternative geometrid hosts

Birds help plants: a meta-analysis of top-down trophic cascades caused by avian predators

The tritrophic interactions between plants, herbivores and avian predators are complex and prone to trophic cascades. We conducted a meta-analysis of original articles that have studied birds as predators of invertebrate herbivores, to compare top-down trophic cascades with different plant responses from different environments and climatic areas. Our search found 29 suitable articles, with a total of 81 separate experimental study set-ups. The meta-analysis revealed that plants benefited from the presence of birds. A significant reduction was observed in the level of leaf damage and plant mortality. The presence of birds also positively affected the amount of plant biomass, whereas effects on plant growth were negligible. There were no differences in the effects between agricultural and natural environments. Similarly, plants performed better in all climatic areas (tropical, temperate and boreal) when birds were present. Moreover, both mature plants and saplings gained benefits from the presence of birds. Our results show that birds cause top-down trophic cascades and thus they play an integral role in ecosystems

A Preliminary Discussion of the Kinematics of BHB and RR Lyrae Stars near the North Galactic Pole

The radial velocity dispersion of 67 RR Lyrae variable and blue horizontal branch (BHB) stars that are more than 4 kpc above the galactic plane at the North Galactic Pole is 110 km/sec and shows no trend with Z (the height above the galactic plane). Nine stars with Z < 4 kpc show a smaller velocity dispersion (40 +/-9 km/sec) as is to be expected if they mostly belong to a population with a flatter distribution. Both RR Lyrae stars and BHB stars show evidence of stream motion; the most significant is in fields RR2 and RR3 where 24 stars in the range 4.0 < Z < 11.0 kpc have a mean radial velocity of -59 +/- 16 km/sec. Three halo stars in field RR 2 appear to be part of a moving group with a common radial velocity of -90 km/sec. The streaming phenomenon therefore occurs over a range of spatial scales. The BHB and RR Lyrae stars in our sample both have a similar range of metallicity (-1.2 < [Fe/H] < -2.2). Proper motions of BHB stars in fields SA 57 (NGP) and the Anticenter field (RR 7) (both of which lie close to the meridional plane of the Galaxy) show that the stars that have Z 4 kpc have a Galactic V motion that is < -200 km/sec and which is characteristic of the halo. Thus the stars that have a flatter distribution are really halo stars and not members of the metal-weak thick-disk.Comment: Accepted for publication in the March 1996 AJ. 15 pages, AASTeX V4.0 latex format (including figures), 2 eps figures, 2 separate AASTeX V4.0 latex table

Territory Choice of Pied Flycatchers is Not Based on Induced Cues of Herbivore Damaged Trees

Passerine birds use a variety of indirect cues to make territory location decisions. These birds can also distinguish herbivore-damaged plants from undamaged ones during foraging, even when they cannot see the herbivorous larvae or damaged leaves. To test the possibility that also the territory choice of passerines is affected by herbivore-induced plant cues, we established territories with and without indirect cues of herbivore presence for migratory pied flycatchers (Ficedula hypoleuca) at the time of their arrival. Half of the territories had folivorous moth larvae hidden inside mesh bags to defoliate small trees (Betula spp.) and half had only empty mesh bags on trees. Hidden herbivory on the trees did not affect the mean date of territory choice by either male or female birds. Nonetheless, there was a trend that females, but not males, chose the territories in the same order in two consecutive years. Thus, it seems that pied flycatchers do not use indirect cues of larval presence as a basis for their choice of territory, but possibly some more general environmental cues.</p

Foraging preference of barnacle geese on endophytic tall and red fescues

Many grasses (Poaceae) have symbiotic fungal endophytes, which affect livestock by producing unpalatable or harmful secondary compounds. Less is known about the repelling effects of fungal endophytes on avian grazers despite potential wildlife management implications. Herbivorous goose (Branta spp.) species may become a nuisance in recreational use areas via fecal littering. Planting these areas with grasses that avian grazers avoid may help mitigate this damage. In 2016, we studied the foraging preference of the barnacle geese (B. leucopsis) with endophytic (E+) or endophyte-free (E-) red fescue (Festuca rubra) and/or tall fescue (Schedonorus phoenix) in 2 sites in Finland that had a history of nuisance geese damage. In the high grazing pressure site, we planted both grass species, while in the low grazing pressure site only tall fescue was used. Geese preference was measured as the percentage of the area grazed, the height of the residual grass grazed, and the number of fecal droppings in the grass plots. Geese foraging did not differ between E- and E+ grasses, but red fescues were preferred over tall fescues. This supports previous findings that tall fescues or other coarse species could reduce the attractiveness of recreational areas to geese

The investigation of absolute proper motions of the XPM Catalogue

The XPM-1.0 is the regular version of the XPM catalogue. In comparison with XPM the astrometric catalogue of about 280 millions stars covering entire sky from -90 to +90 degrees in declination and in the magnitude range 10^m<B<22^m is something improved. The general procedure steps were followed as for XPM, but some of them are now performed on a more sophisticated level. The XPM-1.0 catalogue contains star positions, proper motions, 2MASS and USNO photometry of about 280 millions of the sources. We present some investigations of the absolute proper motions of XPM-1.0 catalogue and also the important information for the users of the catalogue. Unlike previous version, the XPM-1.0 contains the proper motions over the whole sky without gaps. In the fields, which cover the zone of avoidance or which contain less than of 25 galaxies a quasi absolute calibration was performed. The proper motion errors are varying from 3 to 10 mas/yr, depending on a specific field. The zero-point of the absolute proper motion frame (the absolute calibration) was specified with more than 1 million galaxies from 2MASS and USNO-A2.0. The mean formal error of absolute calibration is less than 1 mas/yr.Comment: 11 pages, 9 figures, accepte

Astrometric Control of the Inertiality of the Hipparcos Catalog

Based on the most complete list of the results of an individual comparison of the proper motions for stars of various programs common to the Hipparcos catalog, each of which is an independent realization of the inertial reference frame with regard to stellar proper motions, we redetermined the vector $\omega$ of residual rotation of the ICRS system relative to the extragalactic reference frame. The equatorial components of this vector were found to be the following: $\omega_x = +0.04\pm 0.15$ mas yr$^{-1}$, $\omega_y = +0.18\pm 0.12$ mas yr$^{-1}$, and $\omega_z = -0.35\pm 0.09$ mas yr$^{-1}$.Comment: 8 pages, 1 figur

Northern geometrid forest pests (Lepidoptera: Geometridae) hatch at lower temperatures than their southern conspecifics: Implications of climate change

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 degrees 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