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Population systems in which all three taxa of the Pelophylax esculentus complex coexist are rare and in Serbia can only be found along the Danube. Although several studies describe the diet in populations with only one taxon, there is a lack of data from mixed populations. We studied the diet in mixed populations of edible frogs at three sites for three years. We collected gut contents from 221 adult frogs using the stomach flushing method and identified 1,477 prey items. The diet consisted mainly of insects (88%). For all three taxa, the most frequently consumed prey groups were Hymenoptera (28%), Coleoptera (18%), Lepidoptera (17%) and Diptera (11%). Larger prey (in terms of length and volume) was mainly consumed by P. ridibundus, followed by P. esculentus. The smallest prey were mainly consumed by P. lessonae. However, P. ridibundus consumed fewer prey items than P. lessonae. No significant difference was found between the taxa in the staple diet, while there were differences in the less abundant prey categories, especially between P. ridibundus and P. lessonae. The narrowest trophic niche width was observed in P. lessonae, followed by P. esculentus, and the widest in P. ridibundus. Our results suggest that the diet of the three taxa is diverse and consists of a large number of invertebrate groups. However, the diet was locality-specific, with the dominance of different prey groups in different localities depending on habitat characteristics. These results confirm our expectation that the frogs of the Pelophylax esculentus complex follow an opportunistic foraging strategy, as predicted by optimal foraging theory. [ABSTRACT FROM AUTHOR]

There is a growing interest to document and better understand patterns and processes involved in nonnative bee introductions and subsequent colonisation of new areas worldwide. We studied the spread of the East Asian bee Megachile sculpturalis in Serbia and south-eastern Europe; the bee was earlier established in the USA (since 1994) and western Europe (since 2008). Its establishment in Serbia remained dubious throughout most of 2017–2019, following its first detection. We hereby report on its establishment and spreading, which were corroborated in 2019 under specific circumstances. Owing to an exceptionally poor blooming of Styphnolobium japonicum in 2019, we recorded a high activity density of M. sculpturalis concentrated on a scarce key food resource. We present a novel quantitative approach for an improved early detection of M. sculpturalis, based on the interplay between the bee local occurrence pattern and dynamics of key food-plant(s) availability. This approach seems particularly effective during the early-phase colonisation, at initially low population density of introduced bees. We address the importance of integration of the genuine plant usage patterns with context-specific bee assessment options in establishing effective monitoring. The improved understanding of M. sculpturalis local dynamics triggered the questions about possible origin(s) and modes of its dispersal east of the Alps. To explore the possible scenarios of M. sculpturalis introduction(s), we extended the study to a wider spatio-temporal context – the region of SE Europe (2015–2019). The two complementary study approaches (at local and regional scale) provided more comprehensive evidence of bee dispersal history and the detection patterns in varied recording contexts. Based on this two-scale approach, we suggest that a diffusive mode of M. sculpturalis introduction into Serbia now seems to be a more plausible scenario (than a long-distance jump). We argue that the integration of outcomes from the contrasting approaches (a systematic surveillance, based on plant resources and a broad-scale opportunistic recording) could be of great methodological relevance for the development of future monitoring protocols. [ABSTRACT FROM AUTHOR]

Understanding the movement pattern and ranging behavior of the Griffon vulture population in Serbia is of great importance for prioritizing conservation action. In 2011, an immature vulture was the first bird to be equipped with a satellite transmitter in Serbia. Our study aims to define the vulture's foraging areas, home ranges, core and basic areas, and to investigate movement patterns across different years and seasons by analyzing satellite telemetry data. We tracked the movements of the vulture for over three years and obtained satellite tracking data for 34 bird-months (1976 GPS fixes) between October 2011 and July 2014. We determined that the overall foraging area of the vulture across the entire study period was 11654.34 km2. The overall area used by the vulture was larger during spring and summer than during winter periods. Combined ranges across all years identified one basic area and its associated core area around the Uvac colony and nearby feeding site; we identified three core areas in its proximity. This study showed that areas of traditional stock-raising practices are important vulture foraging areas and that supplementary feeding sites have a vital role. Our maps can be used for future planning of vulture conservation measures. [ABSTRACT FROM AUTHOR]

The genus Diaeretellus is a small group of Aphidiinae wasps, comprising five species from the Palaearctic so far. All members of the genus are highly specialised to semi-aquatic habitats and aphid hosts and plants that occupy them. Because they have practically no economic importance as biocontrol agents, the biology of Diaeretellus species is still somewhat unknown. We describe a new species of this genus, Diaeretellus nymphaealis sp. nov., another member of aphid-parasitoid guilds from wetland habitats and the first species of the genus to be described from the Nearctic. Wetland habitats are under considerable anthropogenic pressure and as such require intensive conservation efforts. Placing the focus of conservation strategies on hyperdiverse entomofauna, instead of only charismatic megafauna, can have positive effects on their outcomes. [ABSTRACT FROM AUTHOR]

Simple Summary: The western honey bee, a pollinator species that is essential for modern agriculture and food production sustainability, is under various anthropogenic pressures. In the last few decades, these have led to serious worldwide problems concerning the health and stability of honey bee colonies. The importance of wild or feral honey bees has only recently been recognized, as these populations are crucial for research on the processes that enable their survival under such pressures. Here, we present a case of an unmanaged free-living population of honey bees that, unlike in other known studies, live in a highly populated urban environment. This extraordinarily dense feral honey bee population, which is not directly associated with managed apiaries, provided us with a large dataset of various life history parameters that will considerably fill in the knowledge gaps on unmanaged colonies. Furthermore, we want to underline the importance of citizen science in the data collection process and suggest it as a suitable approach to study feral honey bees in urban landscapes. We believe that highly populated urban landscapes can support and reinforce feral honey bees and that similar citizen science projects should be set up in other urban areas or other countries. It is assumed that wild honey bees have become largely extinct across Europe since the 1980s, following the introduction of exotic ectoparasitic mite (Varroa) and the associated spillover of various pathogens. However, several recent studies reported on unmanaged colonies that survived the Varroa mite infestation. Herewith, we present another case of unmanaged, free-living population of honey bees in SE Europe, a rare case of feral bees inhabiting a large and highly populated urban area: Belgrade, the capital of Serbia. We compiled a massive data-set derived from opportunistic citizen science (>1300 records) during the 2011–2017 period and investigated whether these honey bee colonies and the high incidence of swarms could be a result of a stable, self-sustaining feral population (i.e., not of regular inflow of swarms escaping from local managed apiaries), and discussed various explanations for its existence. We also present the possibilities and challenges associated with the detection and effective monitoring of feral/wild honey bees in urban settings, and the role of citizen science in such endeavors. Our results will underpin ongoing initiatives to better understand and support naturally selected resistance mechanisms against the Varroa mite, which should contribute to alleviating current threats and risks to global apiculture and food production security. [ABSTRACT FROM AUTHOR]

Most animals concentrate their movement into certain hours of the day depending on drivers such as photoperiod, ambient temperature, inter-or intraspecific competition, and predation risk. The main activity periods of many mammal species, especially in human-dominated landscapes, are commonly set at dusk, dawn, and during nighttime hours. Large carnivores, such as brown bears, often display great flexibility in diel movement patterns throughout their range, and even within populations, striking between individual differences in movement have been demonstrated. Here, we evaluated how seasonality and reproductive class affected diel movement patterns of brown bears of the Dinaric-Pindos and Carpathian bear populations in Serbia. We analyzed the movement distances and general probability of movement of 13 brown bears (8 males and 5 females) equipped with GPS collars and monitored over 1-3 years. Our analyses revealed that movement distances and probability of bear movement differed between seasons (mating versus hyperphagia) and reproductive classes. Adult males, solitary females, and subadult males showed a crepuscular movement pattern. Compared with other reproductive classes, females with offspring were moving significantly less during crepuscular hours and during the night, particularly during the mating season, suggesting temporal niche partitioning among different reproductive classes. Adult males, solitary females, and in particular subadult males traveled greater hourly distances during the mating season in May-June than the hyperphagia in July-October. Subadult males significantly decreased their movement from the mating season to hyperphagia, whereas females with offspring exhibited an opposite pattern with almost doubling their movement from the mating to hyperphagia season. Our results provide insights into how seasonality and reproductive class drive intrapopulation differences in movement distances and probability of movement in a recovering, to date little studied, brown bear population in southeastern Europe. [ABSTRACT FROM AUTHOR]

In this study we used molecular markers to characterize various populations of the Ephedrus persicae species group originating from different aphid hosts and different habitat types. Twelve different haplotypes were identified in 15 E. persicae specimens, and thus there were no shared haplotypes between specimens from different aphid hosts. All haplotypes were clustered in two distinct phylogenetic clades ('persicae 1' and 'persicae 2'), the average genetic distance between these two clades being 3.1%. Ephedrus persicae specimens from the 'persicae 1' clade parasitize leaf-curling aphids from Prunus and Malus orchards. Furthermore, there was significant differentiation of the 'persicae 2' clade into two distinct evolutionary groups, with a genetic distance of 2.5% between them. On the basis of the genetically isolated position of Ephedrus specimens associated with Brachyunguis tamaricis on Tamarix gallica (more than 5.7% genetic distance), we describe Ephedrus tamaricis sp. n. as an additional member of the E. percicae species group. Key for identification of parasitoids belonging to the E. persicae species group is provided. [ABSTRACT FROM AUTHOR]