Carabids, as well-known bioindicators, have been used to study the long term changes that have occurred in their communities in the Dinaric Alps. This study involved eight sites in the protected ...forests of the Risnjak National Park in the years 2015 and 2016 of which three were previously studied in 1990 and 1991. A total of 9, 521 individual ground beetles belonging to 17 genera and 33 species were collected. Species diversity and community composition, including percentages of species grouped according to their habitat preferences, body size, wing morphology, preferred moisture and temperature were used to compare the sites sampled in 1990 and 1991 and resampled in 2015 and 2016. Even though this study was carried out in protected forests within the National Park with minimal anthropogenic pressure and the fact that available climatic data didn't show any significant change in climate over the last 25 years, there was a reduction in the abundance of specialist species and increase in the spread of generalist species. Furthermore, the lower abundance of a mountain specialist and endemic species, Pterostichus variolatus, and the lack of mountain specialists Molops alpestris, Pterostichus unctulatus and Trechus croaticus in the catches indicate the importance of further monitoring of these mountain forest ecosystems and for a well-timed and appropriate conservation approach.
Spiders act as one of the major predators among arthropods in agroecosystems and are crucial to the control of pest densities. As they are almost exclusively predators, they have developed a number ...of hunting strategies, which have consequently impacted their complex trophic interactions. The development of molecular biology methods for environmental DNA analysis has made it easier to analyze such complex trophic networks. In order to ascertain the trophic interactions of spiders, a sampling of spider species was carried out in two olive groves in Zadar County, Croatia, under integrated and ecological pest management. To construct the trophic networks of spiders, we performed DNA metabarcoding. The combined general and spider-excluding primers were able to recognize prey from 12 distinct orders in the guts of the 57 spiders. According to our results, spiders have a complex trophic network that exhibits seasonal and site-specific variations. The results obtained from both sites having different pest management also confirmed that spiders consumed phytophagous insects in the highest ratio, including some important pests, in comparison to other prey and that management and guild type had an impact on the predation of phytophagous insects.
Carabids (Coleoptera: Carabidae) are abundant predators in ecosystems and serve as pest biocontrol in agroecosystems and forestry. Here we test the impact of thiamethoxam, among the most used ...neonicotinoids on the consumption rate, locomotion, metabolomics, and oxidative stress level measuring superoxide dismutase (SOD) activity in a predatory carabid,
Abax parallelus
(Duftschmid, 1812), after acute exposure in the laboratory trials, to get additional data that might link the use of pesticides and predation efficiency. Beetles were exposed to increasing concentrations of thiamethoxam by dipping method, and left to feed overnight prior to the assays. The results showed that individuals treated with higher concentrations of thiamethoxam (20 and 40 mg/L) consumed significantly less food per body weight and had a higher share of intoxicated and moribund individuals. The mass of consumed food per beetle body weight and observed locomotion did not differ significantly between control and groups treated with lower concentrations of thiamethoxam. There are significant differences in concentrations of some metabolites between treated and control individuals, primary in succinate and d-glucose, indicating a disruption in energy production. On the other hand, there is no statistically significant differences in SOD activity among the groups. To conclude, acute exposure to thiamethoxam can result in negative sub-lethal effects in predatory activity and energy budget, while the effects of long-term exposure to lower doses require further research, as well as field assessment on the predation efficiency after pesticide application.
The Mediterranean region has a high but unevenly studied level of invertebrate diversity. Genetic-based methods, such as DNA barcoding and metabarcoding, are proposed for biodiversity assessment; ...however, their application is not always straightforward. The current state of data available in genetic databases limits species identification, especially in the case of certain invertebrate groups. The aim of the study was (1) to assess the diversity of seven invertebrate groups, which are potential prey for predatory arthropods, in order to facilitate the analysis of the metabarcoding of trophic interactions and, thus, expand our knowledge on biocontrol potential, and (2) to estimate the representation of local species in BOLD and NCBI GenBank databases. The DNA barcoding results consisting of sequences for 269 specimens, collected in Zadar County, within Mediterranean part of Croatia, were used for species identification and species richness assessment through the comparison of our data with the data available in BOLD and NCBI databases, and by applying species delimitation methods. Previous barcode records enabled Lepidopteran, Hemipteran, Dipteran, and Hymenopteran species identification, while Collembolan and Oligochaetes species numbers were assessed using species delimitation. Our results showed that a high number of species were unique to the study area, especially in the case of Collembolans and Oligochaetes. We confirmed that the studied area is under-researched, which was particularly evident in taxonomically demanding groups, such as Collembolans and Oligochaetes, which are rich in rare endemic species.
Knowledge of patterns of genetic diversity in populations of threatened species is vital for their effective conservation. Rosalia longicorn (Rosalia alpina) is an endangered and strictly protected ...beetle. Despite a marked decline in part of its range, the beetle has recently expanded to the lowlands of Central Europe. To facilitate a better understanding of the species' biology, recent expansion and more effective conservation measures, we investigated patterns of genetic structure among 32 populations across Central and South‐east Europe. Eight microsatellite loci and a partial mitochondrial gene (cytochrome c oxidase subunit I) were used as markers. Both markers showed a significant decline in genetic diversity with latitude, suggesting a glacial refugium in north‐western Greece. The cluster analysis of the nuclear marker indicated the existence of two genetically distinct lineages meeting near the border between the Western and Eastern Carpathians. By contrast, one widespread mtDNA haplotype was dominant in most populations, leading to the assumption that a rapid expansion of a single lineage occurred across the study area. The genetic differentiation among populations from the north‐western part of the study area was, however, surprisingly low. They lacked any substructure and isolation‐by‐distance on a scale of up to 600 km. This result suggests a strong dispersal capacity of the species, as well as a lack of migration barriers throughout the study area. That the lowland populations are closely related to those from the nearby mountains indicates repeated colonization of the lowlands. Our results further suggest that R. alpina mostly lives in large, open populations. Large‐scale conservation measures need to be applied to allow for its continued existence.
Predatory carabid beetles are important for regulating prey abundance in terrestrial ecosystems. While surveys of carabid diet have revealed many insights into trophic interactions, the high species ...diversity and heterogeneous developmental stages of prey identified in the gut have made further advances difficult. In addition, the carabid gut contains partially digested and mainly soft tissue parts of the prey species, difficult to identify by traditional methods. Molecular gut content analysis (MGCA) avoids these disadvantages but to date has been limited primarily to revealing pest species in agricultural fields. Here we used MGCA to screen for the presence of Lepidoptera in carabid guts, in woodland ecosystems, in both Croatia and the UK. Data on carabids positive for Lepidoptera were compared with those from previous work on the same carabid assemblages, screened for earthworms, slugs, woodlice and springtails. In both locations, the prey group most frequently detected was earthworms, followed by slugs and Lepidoptera and then finally by woodlice and springtails. The composition of the diet changed with season, carabid sex, and carabid size. In both locations, Lepidoptera were the third most frequent prey, with 27% of carabids testing positive in Croatia and 20% in UK, suggesting that carabids could be significant predators of Lepidoptera in woodland ecosystems and may potentially play an important role in controlling moth pests.
The Mediterranean is characterised by high biodiversity and numerous endemic species. These species are not only present in natural habitats, but also inhabit areas under human influence, such as ...agricultural lands. In the biodiversity assessment of Mediterranean vineyards and olive orchards within Zadar County, in Croatia, we identified eight endemic species with Mediterranean distribution, six with a Balkan Peninsula distribution, four with Dinaric Alps distribution and three species rare and endangered in Europe. Alongside these species, we have recorded five new species for Croatian fauna, many of those identified by combining morphological characteristics and the DNA barcoding tool. Araneae and Coleoptera contributed the highest number of endemic species and groups with new record were the following: Coleoptera, Diptera and Araneae. Compared to other sites, an olive orchard with ecological pest management (EPM), surrounded by natural ecosystems, had the highest ratio of endemic and rare species. Our findings emphasise that agricultural lands in the Mediterranean can be habitats for endemic and rare species and that future biodiversity research of these habitats is highly important, to monitor potential biodiversity changes and motivate future species and ecosystem conservation.
Contamination pathways in complex food chains in soil ecosystems can be difficult to elucidate. Molecular analysis of predator gut content can, however, rapidly reveal previously unidentified trophic ...interactions between invertebrates and thereby uncover pathways of pollutant spread. Here, we measured concentrations of the toxic metals lead, cadmium and mercury in carabid beetle predators and their prey. Invertebrates were sampled at one control and four heavy metal‐polluted sites to reveal the impact of diet composition and seasonal variation in prey availability on metal burden in carabids and metal transfer pathways through forest ecosystems. This is the first report, to our knowledge, of carabid diet composition based on PCR analysis of gut contents at the forest community level, rather than in cultivated fields. Extensive screening using group‐ and species‐specific primers revealed that carabids ate primarily earthworms and slugs, as well as smaller numbers of woodlice and springtails. Metal concentrations in carabids correlated with seasonal changes in diet. Mercury accumulated in beetle predators more than in their slug prey. As earthworms, slugs and carabid beetles are the major prey of many birds and mammals, prey–predator transfer and associated toxicity are major risks at mercury‐contaminated sites. Carabids may be useful bioindicators for assessing the impact of pollutants on soil ecosystems, as long as species and seasonal factors are taken into account.
Fluctuating asymmetry (FA) is used in assessing the effect of environmental stress on the development stability of individuals by measuring small random deviations from perfect bilateral symmetry. ...Here, we checked for FA on two predatory carabid beetles, Pterostichus melas and Poecilus koyi, in order to evaluate species response to agricultural practices within Mediterranean agroecosystems, as well as FA as a method. The samples were collected in vineyards and olive groves, both under integrated pest management (IPM) and ecological pest management (EPM), and in pristine habitats in the Mediterranean region of Croatia. Geometric morphometrics (GMMs) were used to analyze the pronotum and abdomen shape variations and left–right asymmetries of each population. In respect to the FA measurements, analyzed species responded differently, with P. koyi displaying a lower intensity of FA than P. melas. On the other hand, P. melas beetles from vineyards showed a higher intensity of FA compared with populations from pristine habitats and olive groves. Accordingly, FA pointed out olive groves as potentially less adverse habitats to predatory carabids, keeping in mind the different levels of asymmetry between the two species. Our study singled out P.melas as a more suitable species for further research, in the effect that different agricultural practices can have their impact on non-target invertebrates analyzed by measuring the FA.
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