Aleksandar Cetkovic

The social wasps of the family Vespidae are among the better studied groups of Hymenoptera, but the distribution patterns of most representatives are not adequately studied in many regions.

In the framework of the comprehensive biogeographical survey of the social wasp fauna of the Balkan Peninsula, southern Pannonian Plane, and some adjacent regions, an extensive review of the European distribution of Vespa orientalis L. is presented. It is based on the critical assessment of the complete literature faunistic data and the examination of the available specimens from various sources (totalling about 130
specimens in 10 different collections).

Within the two principal range areas of V. orientalis distribution in Europe (the Balkans and the southern Apennine Peninsula with Maltese Islands, respectively), it is now formally recorded from almost all countries within this region (except for the European Turkey); the paper includes the first formally published data for the territory of the current Yugoslavia (Serbia and Montenegro). All the exact collecting localities in the treated area are mapped. Various controversies about the previously established range of this species are discussed and rectified accordingly: within this, the existing records for Slovenia, Romania and Bulgaria are now formally disputed, on various grounds (although the presence of V. orientalis in Bulgaria is considered quite likely). Several noteworthy facts about its complex and dynamic distribution pattern in Europe are established, including the true position and the characteristics of its northwestern range periphery, and particularly, the fluctuation of the established range during the seventh decade of the 20'h century; the complete retreat of the Oriental hornet is documented for all territories along its previous northern limit - Dalmatia (Croatia), Herzegovina (B&H), Montenegro (S&M) and Macedonia (FYR).

Finally, ecological affinities of V. oriental is are discussed with respect to the relevant aspects of the recorded distribution patterns and possible/presumed dispersal routes.

Citizen science, a practice of public participation in scientific projects, is popular in Western countries, however, it is still a relatively novel approach in Southeast Europe. In this region, citizen science can be a useful tool for increasing the understanding of alien species. One such species is the sculptured resin bee, Megachile sculpturalis, a putatively invasive alien pollinator native to East Asia. It was introduced to France in 2008, from where it quickly spread across West and Central Europe. However, our knowledge of its eastern distribution is scarce since it is based mostly on isolated findings. We combined citizen science and data extraction from online sources (e.g., naturalist’s databases and social media) covering 6 years, and 3 years of targeted floral resource monitoring in the search for M. sculpturalis across regions of southeastern Europe. We collected presence data and information on M. sculpturalis abundances across an urban-rural gradient from eight count...

Megachile sculpturalis is the first non-native bee species established in Europe, originating from E-Asia. Since early detections in SW-Europe (2008–2010) its spreading resulted in a range currently spanning nearly 2,800 km x 1,100 km across the southern and central Europe. In SE-Europe establishment was confirmed since 2015 in NE-Hungary, followed by detection in N-Serbia (2017), and wider spreading across the eastern Pannonian Plain (2018–2019); eventually it was detected in NW-Bosnia & Herzegovina (2020). Accordingly, the repeated calls for monitoring of M. sculpturalis spread were voiced, aiming to address its potential invasiveness, but mostly lacking a more specific assessment protocol. A 'working concept' for a comprehensive monitoring of M. sculpturalis was proposed within the survey conducted in Belgrade (Serbia) during 2017–2019, based on quantitative assessment of bee population trends in relation to focal plant resources. There was a need to improve and broaden t...

Complex biotic networks of invaders and their new environments pose immense challenges for researchers aiming to predict current and future occupancy of introduced species. This might be especially true for invasive bees, as they enter novel trophic interactions. Little attention has been paid to solitary, invasive wild bees, despite their increasing recognition as a potential global threat to biodiversity. Here, we present the first comprehensive species distribution modelling approach targeting the invasive bee Megachile sculpturalis, which is currently undergoing parallel range expansion in North America and Europe. While the species has largely colonised the most highly suitable areas of North America over the past decades, its invasion of Europe seems to be in its early stages. We showed that its current distribution is largely explained by anthropogenic factors, suggesting that its spread is facilitated by road and maritime traffic, largely beyond its intrinsic dispersal ability. Our results suggest that M. sculpturalis is likely to be negatively affected by future climate change in North America, while in Europe the potential suitable areas at-risk of invasion remain equally large. Based on our study, we emphasise the role of expert knowledge for evaluation of ecologically meaningful variables implemented and interpreted for species distribution modelling. We strongly recommend that the monitoring of this and other invasive pollinator species should be prioritised in areas identified as at-risk, alongside development of effective management strategies.

Original information on aphidiine braconids attacking aphids feeding on Solanaceae (i.e., Capsicum annuum L., Lycium europaeum L., Lycopersicon esculentum Miller, Solanum spp.) and Cucurbitaceae (i.e., Citrullus vulgaris Schrad., Cucumis spp., Cucurbita pepo L.) plants in southeastern Europe is presented. A total of 13 species are keyed and illustrated with scanning electron micrographs, microscope micrographs and line drawings. The aphidiines presented in this work have been identified from nine aphid taxa. Two hundred four aphidiine-aphid-plant associations are presented, 176 of which are new. The results are discussed in relation to over-all parasitoid-aphid-plant associations in the area.

There is a growing interest to document and better understand patterns and processes involved in non-native 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 partic...

This paper presents the first report on ensign wasp fauna in two central Balkan countries, Serbia and Montenegro. We established the presence of three species  (out of five recorded in Europe): Brachygaster minutus , Prosevania fuscipes and Zeuxevania splendidula , the last based on an old literature report. We briefly discuss the patterns of their distribution and occurrence, in relation to their specific bionomy and the collecting techniques applied.

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 de...

ABSTRACTHuman land use threatens global biodiversity and compromises multiple ecosystem functions critical to food production. Whether crop yield-related ecosystem services can be maintained by few abundant species or rely on high richness remains unclear. Using a global database from 89 crop systems, we partition the relative importance of abundance and species richness for pollination, biological pest control and final yields in the context of on-going land-use change. Pollinator and enemy richness directly supported ecosystem services independent of abundance. Up to 50% of the negative effects of landscape simplification on ecosystem services was due to richness losses of service-providing organisms, with negative consequences for crop yields. Maintaining the biodiversity of ecosystem service providers is therefore vital to sustain the flow of key agroecosystem benefits to society.

Range expansions of naturally spreading species are crucial for understanding how species interact with the environment and build their niche. Here, we studied the bumblebeeBombus haematurusKriechbaumer, 1870, a species historically distributed in the eastern Mediterranean area which has very recently started expanding northwards into Central Europe. After updating the global distribution of this species, we investigated if niche shifts took place during this range expansion between colonized and historical areas. In addition, we have explored which climatic factors have favoured the natural range expansion of the species. Our results indicated thatBombus haematurushas colonized large territories in 7 European countries outside the historical area in the period from the 1980s to 2018, a natural expansion over an area that equals the 20% of the historical distribution. In addition, this bumblebee performs generalism in flower visitation and habitat use, although a preference for fore...

The publication „Biodiversity of the Stara Planina Mt. in Serbia – Results of the Project: “Trans-Boundary Cooperation Through the Management of Shared Natural Resources” represents only a small part of the results accumulated during the activities on a very complex project 1 „Promotion of Networks and Exchanges in the Countries of South-Eastern Europe“that was realised in scope of the REReP2 Programme No. 4.3.23. The Project was developed in scope of the „Immediate Project Priorities for the Implementation of the Regional Environmental Reconstruction Programme –REReP“, accepted at the meeting of the ministers of environmental protection of the countries of south-eastern Europe in March 2000. In keeping with the general REReP policy, the basic task of the Project 4.3.23 was to strengthen and develop the contact and cooperation between countries and people in scope of environmental protection and biodiversity conservation, with the aim to build the civil society, peace, and stability...

A regional survey of the complex tritrophic associations (parasitoid-aphid-plant) of aphid parasitoids (Hymenoptera: Braconidae: Aphidiinae) was carried out to determine and explore the patterns of those associations in various types of environments. Here, we present trophic relationship patterns of the five aphid parasitoid species in crop and noncrop habitats in southeastern Europe, and we contrast them in a regional (Mediterranean [MED] versus continental [CNT]) context. In total, 79 aphid host taxa were identified in this survey. Forty-two of these were recorded from noncrop plants only, 21 from crop plants only, and 18 were present on both types of plants. This means that approximately 74% of all the parasitoid-aphid trophic interactions that support the persistence of the five selected parasitoids are entirely (54%) or partially (20%) associated with noncrop plants. The correspondence of parasitoid-aphid combinations among habitat/region combinations is very high and specific. Our results suggest that Mediterranean and continental regions are clearly distinguished by a contrasting pattern of trophic interactions in crop habitats, whereas the noncrop habitats contribute in lesser degree to these differences. For the crop/noncrop breakdown, the number of nonspecific interactions was larger than expected in crop habitats, whereas in noncrop habitats the abundance of partially specific and specific interactions was larger. The analysis of variance for the regional and habitat distribution of mean aphid host number per parasitoid was highly significant. When both regions were analyzed separately, the parasitoid/crop design showed significant parasitoid effects as well as interactions, whereas the habitat effect was not significant for the Mediterranean region and highly so for the continental region. This highly complex pattern suggests that the mean number of parasitized aphid species is not distributed among parasitoids, regions, and habitats in a similar manner. Even with these complexities taken into account, the overall trend is that noncrop habitats support more parasitoid-aphid combinations and more so in the continental than in Mediterranean regions, although not always statistically significant. As mentioned, large number of noncrop aphid hosts, especially for Lysiphlebus fabarum (Marshall), Praon volucre (Haliday) and Aphidius colemani Viereck, can significantly enhance the population buildup for these important parasitoids around agroecosystems. These facts can be important in biological aphid pest control in the region. Although not easily quantified, the overall positive effects of larger parasitoid diversity in noncrop habitats are undoubtedly related to the distribution and structure of noncrop habitat patches in agroecosystems at a landscape scale.

A new endemic aphid parasitoid species, Aphidius persicus sp. n., parasitic on Uroleucon chondrillae (Nevsky) in Iran and Iraq, is described. The identities of the new species and other co‐existing species of Aphidius are discussed. In the parasitoid association with Uroleucon aphids, A. persicus sp. n. probably replaces Aphidius funebris Mackauer in the studied area. The latter species is a common member of the parasitoid guild on Uroleucon species in the Western Palaearctic and Western Mediterranean.

The idea that noncrop habitat enhances pest control and represents a win-win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and so...