Range shifts are among the most conspicuous effects of global warming. Marked changes in distribution are recorded both for highly mobile species of insects, which are capable of flight, and wing-dimorphic species with predominantly short-winged individuals. One of these species is the bush-cricket Metrioptera roeselii, which occasionally produces long-winged individuals. However, there is little known about the locomotory behaviour of wing-dimorphic insects. Yet to be able to predict potential range shifts it is necessary to know the dispersal potential of macropters. Therefore, an experiment was conducted in which individually marked M. roeselii were released at four sites. Different movement parameters, such as daily movement, activity radius, dispersal range, net displacement and crowding rate, were calculated. The statistical analyses showed that the movement of long-winged and short-winged individuals did not differ, but the percentage of individuals that were not seen again was twice as high for long-winged bush-crickets. These results suggest that most of the long-winged individuals that were seen again did not fly; i.e., they had the same basic mobility as the short-winged individuals. However, the comparatively low number of long-winged individuals that were seen again suggests that at least some macropters are long-distance dispersers, which is relevant for the dispersal process. The comparison of sexes showed that males were significantly more mobile than females. This sex-specific locomotory behaviour in M. roeselii might depend on a complex series of social interactions and physiological conditions. and Dominik Poniatowski, Thomas Fartmann.
Rove beetles (Staphylinidae) are used to explore the forces that shaped the terrestrial fauna on Læsø, a young ca. 3000 year old Danish oceanic island located in the Kattegat strait between mainland Denmark and Sweden. We compile a detailed list of species of rove beetles for Læsø (328 species) and the surrounding Danish and Swedish regions (altogether 1075 species), which includes a standardized inventory of their body sizes, and the habitat and microhabitat preference of each species. The composition of the fauna on Læsø and adjacent mainland regions points to North-Eastern Jutland as the main source of the rove beetles on Læsø. Although large beetles are more active and likely to disperse than small beetles, there is no bias towards large species on the island indicating that the sea separating Læsø from the mainland has not been a barrier for rove beetle dispersal. The statistical analysis of the habitat and microhabitat preferences of the species of the entire system studied has shown that Læsø, compared to the mainland areas, is distinctly more dominated by ecological generalists, especially by species adapted to ephemeral, temporary humid microhabitats. Presumably, the mosaic of mostly dry open habitats available on Læsø filters for species, that are able to populate these suboptimal habitats via patches of humid but ephemeral microhabitats. A comprehensive eco-faunistic dataset for the Staphylinidae compiled for this study is the first modern account of the rove beetle fauna on the Danish island of Læsø., Aslak K. Hansen, Mathias J. Justesen, Sebastian Kepfer-Rojas, David B. Byriel, Jan Pedersen, Alexey Solodovnikov., and Obsahuje bibliografii
The Tisza River Basin is an important area as it is a green corridor in which there are highly endangered habitats and a high level of biodiversity. The patterns in the species richness of invertebrates and the environmental conditions affecting these patterns are poorly studied in the grassy habitats in the lower reaches of the Tisza River Basin. The present study focuses on the effects of flooding, habitat and landscape features on the species richness of orthopterans at 24 grassland sites in two different landscapes. The relations between the explanatory variables and the pattern of diversity of orthopterans with different life-history traits were studied, using ordination and Generalized Linear Mixed Models. Although the influential factors for the different trait groups differed, we suggest that landscape features are the most important in shaping orthopteran assemblages, whereas habitat characteristics and flooding have comparatively little effect. Habitat characteristics affected only the non-xerophilous and Ensifera species and only the species richness of non-xerophilous orthopterans in flooded and non-flooded sites differed. We emphasize that even in countries where there are still considerable areas of high value natural grasslands, such as Hungary, non-protected meadows, linear grassy habitats (dikes, ditch banks, road verges, etc.) need more attention and should be given higher priority in the conservation of invertebrates., Attila Torma, Miklós Bozsó., and Obsahuje bibliografii
Macroptery is common in many species of Orthoptera, but the causes are still discussed. Besides the assumption that macroptery is genetically determined, there is evidence that wing dimorphism is induced by environmental factors, particularly population density. However, most of the research is on pest species. In contrast, knowledge of wing dimorphism in species that occur at low population densites is still poor. Our study aims to test how density actually affects macroptery. As model organisms we chose two bush-cricket species of the genus Metrioptera (Ensifera: Tettigoniidae): While long-winged M. roeselii (Hagenbach, 1822) occur regularly, macropterous M. brachyptera (Linnaeus, 1761) are rare and are never observed outside their mating habitat. Nymphs of populations from the range core of both species (340 individuals each) were reared in groups of three and six individuals per 500 cm3 box, and individually. Our analyses revealed that development of macropters was mainly affected by the initial rearing densities. Compared with those reared individually the number of macropters was significantly higher among individuals reared at medium and high densities. The percentage of macropterous individuals was about twice as high in M. brachyptera as in M. roeselii, and the development of macropters significantly differed between the two species. These findings lead to the conclusion that macropterism is mainly influenced by density stress in both bush-crickets. Genetically determined wing dimorphism is unlikely, otherwise the observed high numbers of long-winged individuals of M. brachyptera, which are very rare under natural conditions, would never have developed in the laboratory. Macropterous M. brachyptera may rarely be found in the field, but we argue that this is due to low natural densities and, accordingly, to rare exposure to density stress.
A novel method was used to study dispersal in the spruce bark beetle, Ips typographus (L.), under epidemic conditions (rapidly increasing population density) in the Šumava National Park. Infested spruce logs were coated with a fine fluorescent powder and the passively marked emerging beetles were captured in pheromone baited traps located at various distances from these logs. The number of marked beetles captured decreased exponentially with increasing distance from the release point. The sex ratio of the bark beetles was more female biased the further they were recaptured from the logs, being 57% and 60% at distances of up to 50 and 100 m, respectively. The maximum distance flown by a marked beetle recorded in this experiment was 1094 m. A model fitted to the data on dispersal indicates that 10% of the spruce bark beetles dispersed over distances of 55 m and 4 m in spring (overwintered parental generation) and summer (first filial generation), respectively. Differences between spring and summer swarming are briefly discussed., Petr Doležal, Jan Okrouhlík, Markéta Davídková., and Obsahuje bibliografii
The gallmidge Aphidoletes aphidimyza is used commercially to control aphids infesting greenhouse crops such as sweet pepper and tomato. In this study we investigated several different ways of improving its use as a biocontrol agent. In the laboratory there was a very strong relation between the availability of spider's webs and successful mating. When mated in cages containing spider's webs a greater proportion of the females were mated and the females laid more eggs compared to the females in cages without spider's webs. As adults emerging from cocoons can crawl up through 15 cm of vermiculite it is possible to transport and release them from bottles, which can be placed open in a greenhouse instead of having to spread the material around the plants. Dispersal of adults from the bottles was measured by placing sentinel plants around a single release point. Eggs of the gallmidge were found on plants at distances up to 45 m from the release point. Intraguild predation of the eggs of the gallmidge by the mites Amblyseius degenerans and Amblyseius cucumeris was also assessed.
House mice are believed to be, unlike rats, only reluctant swimmers. If water is a barrier to mouse dispersal water bodies and streams can have a substantial impact on the genetic structure of populations. Previous studies revealed influence of rivers on the position and structure of the European hybrid zone between two house mouse subspecies, Mus musculus musculus and M. m. domesticus. In this study, we used a simple motivation experiment to test the disposition of both wild and inbred mice representing the subspecies to overcome a water barrier. As the more dispersing sex, males were chosen for the experiment. Mice were tested under two air/water temperature regimes, 20 °C and 10 °C. Contrary to a common belief tested animals entered water rather easily, often even engaging in repeated swimming. We found significant differences in scored behavioural parameters between the subspecies. Under the 20 °C regime, both wild and inbred domesticus males entered and crossed the water earlier and more often swam even when satiated. Strikingly, under the 10 °C regime, the results were rather equivocal but with the opposite tendencies, with musculus males being more willing to swim. We discuss implications of these findings for the hybrid zone dynamics.
1. Flight activity in zygopterans is generally restricted to short-range movements associated with foraging, reproductive activity and escape. Indeed, previous studies have suggested that Calopteryx species, including C. splendens, are relatively sedentary species, with a low tendency for long distance movements.
2. Recent observations suggest that C. splendens is expanding its northern range in the UK; in the northeast the species is now well established in Northumberland and, in the northwest, has recently spread into south-west Scotland. The current study aimed to investigate the mobility and dispersal tendency of C. splendens in a well-established breeding population in NE England.
3. A mark-release-recapture study was carried out on a population of C. splendens along a section of the River Wharfe, West Yorkshire, UK. 831 adult C. splendens were marked uniquely for individual identification in order to monitor the day-to-day, and overall, distance and direction of movement for each individual. Of these 381 were recaptured at least once.
4. The majority of males (85%) and females (88%) moved a distance of 100 m or less and only five of the recaptured individuals (1.3%) moved a minimum distance in excess of 500 m. Although the median distance moved by males was greater than that for females, this was not significant. In addition, there was no significant difference in the number of either males or females moving upstream as opposed to downstream.
5. The results are compared with those from other studies on calopterygid movement. Although most individual C. splendens stay within a suggested home range of approximately 300 m, clearly individuals have the potential to cover relatively long distances, and it is these latter movements that play a fundamental role in increasing the range of the species.
Dispersal of the sevenspotted lady beetle, Coccinella septempunctata, was measured in a series of mark-release-recapture experiments in Utah alfalfa. In three experiments, samples were taken in a radial pattern around the release point. Released beetles for the most part left the 0.36 ha (68 m diameter) sample area within 24 hours, and their average residence time in the sample area was calculated as 12, 6 and 1.6 h in the three experiments, respectively. The spatial distribution of beetles around the point of release could be described with normal distributions whose variance increased linearly in time with 3.8, 1.1 and 0.34 m2 per hour. In three additional field experiments the departure of marked beetles was compared between sugar-sprayed plots and control plots. Residence time was 20-30% longer in sugar-sprayed plots than in control plots, with mean residences of 5.3, 3.6, and 2.9 h in the sugar-sprayed plots in the three experiments, respectively, and means of 4.4, 2.7, and 2.4 h in the control plots. The density of unmarked beetles rose by a factor of 10-20 in the sugar sprayed plots during the first 4 to 6 hours following early morning spraying of sugar. This rapid and substantial increase in density cannot be explained by the slightly longer residence time in sugar-sprayed plots. We hypothesize that the aggregation in sugar-sprayed plots is mostly due to greatly increased immigration into those plots, in response to volatiles produced by the plant-pest-predator assembly.
The Eurasian otter is one of the most endangered mammals in Italy and its distribution is now restricted in two isolated portions in southern Italy. However, in recent times, this species has shown a tendency to expand its range, especially northwards. It is therefore important to identify suitable areas on the border of its expansion range where the species can establish and disperse, so that these areas can be targeted for conservation actions. To this aim, the distribution, quality and connectivity of habitats of seven river catchments located in the northern portion of the current otter range in Italy were assessed. Catchments included both rivers where the otter currently occurs and where it is likely to expand in the short-medium term. An expert-based Habitat Suitability (HS) model was developed and validated using otter presence-absence data based on standard field surveys. Fine scale riverbank land cover, extra-riparian coarse scale land cover, altitude, bank slope, and human disturbance were considered as the main factors in the HS model. These variables were available or newly created in the form of digital maps (layers) and the HS model was built by sequentially filtering these layers. Connectivity was assessed within and between river basins through landscape algorithms by taking into account variables that could influence otter dispersal.Tthe results indicated that the seven rivers considered are heterogeneous both in terms of habitat suitability and in terms of connectivity. Among these, one river in particular (the river Volturno), where otters are currently present, showed one of the largest extensions of suitable habitats and the best connectivity both within the river and between the river and the neighbouring catchments, suggesting that this river could play a strategic role in the survival and expansion of otters in the surrounding areas.