Morphology and distribution of antennal sensilla in five species of solitary bees (Hymenoptera, Apoidea).

Solitary bees play a crucial role in ecological systems, contributing to the pollination of crops and wild plants. All females are reproductive, and their habitat requirements include nesting sites, food resources and nesting materials. Although these activities require the ability to detect biotic and abiotic stimuli in the environment, the sensory system of these species is poorly studied. In this study, the antennal sensilla of five solitary bee species belonging to three Apoidea families were investigated using scanning electron microscopy. These included two species of stem-nesting bees, Ceratina cucurbitina (Rossi, 1792) (Apidae) and Osmia scutellaris (Morawitz, 1868) (Megachilidae), and three species of ground-nesting bees, Lasioglossum brevicorne (Schenck, 1870), Lasioglossum leucozonium (Schrank, 1781), and Lasioglossum villosulum (Kirby, 1802) (Halictidae). Thirteen different types of antennal sensilla were identified in females based on their morphological characteristics: sensilla trichodea (subtypes STI, II, III), chaetica (subtypes SchI, II), basiconica (subtypes SBI, II, III, IV), placodea, campaniformia, coeloconica, and ampullacea. Their functional role was discussed and morphology was compared among the species and within the antennal segments in each species. The results provide a baseline for further physiological and behavioural studies to determine the role of antennal sensilla in habitat selection, food search and nesting site selection.

Exploring the hidden riches: Recent remarkable faunistic records and range extensions in the bee fauna of Italy (Hymenoptera, Apoidea, Anthophila).

Background: The area sourrounding the Mediterranean basin is recognised as a major biodiversity hotspot for bees, and Italy is amongst the European countries with the highest bee species richness. Detailed knowledge of bee distribution is crucial for understanding bee biology and designing tailored conservation strategies, but is still insufficient in southern European countries, especially in Italy. New information: We report recent finds of 48 bee species that yield significant novelties for the Italian bee fauna. Eight species, namely Andrenaconfinis Stöckhert, Anthidiellumbreviusculum Pérez, Coelioxysalatus Foerster, Lasioglossumalgericolellum Strand, Megachilelapponica Thomson, Megachileopacifrons Pérez, Megachilesemicircularis auct. nec Zanden and Trachusaintegra Eversmann are reported as new for Italy. In addition, Andrenabinominata Smith, Andrenacompta Lepeletier, Colletesacutus Pérez, Lasioglossumstrictifrons Vachal, Rhodanthidiumsiculum Spinola and Rhodanthidiumsticticum Fabricius are newly recorded from mainland Italy, Osmiaheteracantha Pérez from Sardegna and Nomadaflavopicta Kirby from Sicilia. We also report significant range extensions for other bee species and recent records of species that had long gone unrecorded in Italy. The combination of morphology and DNA barcoding provided reliable identifications even for the most challenging specimens. As several of our records come from areas neglected by bee experts in the past, this study stands out as a key indicator of a bee faunistic richness still awaiting discovery and hopefully it will stimulate the interest of taxonomists and stakeholders in pursuing bee research in Italy in the near future.

Ecological and social factors influence interspecific pathogens occurrence among bees.

The interspecific transmission of pathogens can occur frequently in the environment. Among wild bees, the main spillover cases are caused by pathogens associated with Apis mellifera, whose colonies can act as reservoirs. Due to the limited availability of data in Italy, it is challenging to accurately assess the impact and implications of this phenomenon on the wild bee populations. In this study, a total of 3372 bees were sampled from 11 Italian regions within the BeeNet project, evaluating the prevalence and the abundance of the major honey bee pathogens (DWV, BQCV, ABPV, CBPV, KBV, Nosema ceranae, Ascosphaera apis, Crithidia mellificae, Lotmaria passim, Crithidia bombi). The 68.4% of samples were positive for at least one pathogen. DWV, BQCV, N. ceranae and CBPV showed the highest prevalence and abundance values, confirming them as the most prevalent pathogens spread in the environment. For these pathogens, Andrena, Bombus, Eucera and Seladonia showed the highest mean prevalence and abundance values. Generally, time trends showed a prevalence and abundance decrease from April to July. In order to predict the risk of infection among wild bees, statistical models were developed. A low influence of apiary density on pathogen occurrence was observed, while meteorological conditions and agricultural management showed a greater impact on pathogen persistence in the environment. Social and biological traits of wild bees also contributed to defining a higher risk of infection for bivoltine, communal, mining and oligolectic bees. Out of all the samples tested, 40.5% were co-infected with two or more pathogens. In some cases, individuals were simultaneously infected with up to five different pathogens. It is essential to increase knowledge about the transmission of pathogens among wild bees to understand dynamics, impact and effects on pollinator populations. Implementing concrete plans for the conservation of wild bee species is important to ensure the health of wild and human-managed bees within a One-Health perspective.

The new annotated checklist of the wild bees of Europe (Hymenoptera: Anthophila).

At a time when nature conservation has become essential to ensure the long-term sustainability of our environment, it is widely acknowledged that conservation actions must be implemented within a solid taxonomic framework. In preparation for the upcoming update of the IUCN Red List, we here update the European checklist of the wild bees (sensu the IUCN geographical framework). The original checklist, published in 2014, was revised for the first time in 2017. In the present revision, we add one genus, four subgenera and 67 species recently described, 40 species newly recorded since the latest revision (including two species that are not native to Europe), 26 species overlooked in the previous European checklists and 63 published synonymies. We provide original records for eight species previously unknown to the continent and, as original taxonomic acts, we provide three new synonyms, we consider two names as nomina nuda, ten names as nomina dubia, three as species inquirenda, synonymize three species and exclude 40 species from the previous checklist. Around a hundred other taxonomic changes and clarifications are also included and discussed. The present work revises the total number of genera for IUCN Europe to 77 and the total number of species to 2,138. In addition to specifying the taxonomic changes necessary to update the forthcoming Red List of European bees, we discuss the sampling and taxonomic biases that characterise research on the European bee fauna and highlight the growing importance of range expansions and species invasions.

A novel and non-invasive method for DNA extraction from dry bee specimens.

In recent years molecular techniques have been used on museum material as integrative support for classic taxonomy. This cumulative systematics approach is especially for rare or extinct specimens, and genetic analysis may be useful to discern information that is not possible to glean from live materials or morphology. To date, the extraction of DNA required at least a partial destruction of the specimens, which is not possible for all individuals, especially the types. In this study, we described a novel method to extract mitochondrial DNA (mtDNA) from pinned museum bee individuals to avoid any external morphological damage. This method was able to amplify the mtDNA Cytochrome C oxidase subunit I (COI) gene in bee samples collected up to 27 years ago. We tested the efficacy of this method on 72 preserved be specimens belonging to nine species among four families, it could be used on many museums' rare and/or extinct bee species because it does not provide external morphological damages. The method could be helpful for providing ecological, taxonomic, and phylogenetic information about specimens preserved in museum collections.

Occurrence of Honey Bee (Apis mellifera L.) Pathogens in Wild Pollinators in Northern Italy.

Diseases contribute to the decline of pollinator populations, which may be aggravated by the interspecific transmission of honey bee pests and pathogens. Flowers increase the risk of transmission, as they expose the pollinators to infections during the foraging activity. In this study, both the prevalence and abundance of 21 honey bee pathogens (11 viruses, 4 bacteria, 3 fungi, and 3 trypanosomatids) were assessed in the flower-visiting entomofauna sampled from March to September 2021 in seven sites in the two North-Italian regions, Emilia-Romagna and Piedmont. A total of 1,028 specimens were collected, identified, and analysed. Of the twenty-one pathogens that were searched for, only thirteen were detected. Altogether, the prevalence of the positive individuals reached 63.9%, with Nosema ceranae, deformed wing virus (DWV), and chronic bee paralysis virus (CBPV) as the most prevalent pathogens. In general, the pathogen abundance averaged 5.15 * 106 copies, with CBPV, N. ceranae, and black queen cell virus (BQCV) as the most abundant pathogens, with 8.63, 1.58, and 0.48 * 107 copies, respectively. All the detected viruses were found to be replicative. The sequence analysis indicated that the same genetic variant was circulating in a specific site or region, suggesting that interspecific transmission events among honey bees and wild pollinators are possible. Frequently, N. ceranae and DWV were found to co-infect the same individual. The circulation of honey bee pathogens in wild pollinators was never investigated before in Italy. Our study resulted in the unprecedented detection of 72 wild pollinator species as potential hosts of honey bee pathogens. Those results encourage the implementation of monitoring actions aiming to improve our understanding of the environmental implications of such interspecific transmission events, which is pivotal to embracing a One Health approach to pollinators' welfare.

Signals of adaptation to agricultural stress in the genomes of two European bumblebees.

Human-induced environmental impacts on wildlife are widespread, causing major biodiversity losses. One major threat is agricultural intensification, typically characterised by large areas of monoculture, mechanical tillage, and the use of agrochemicals. Intensification leads to the fragmentation and loss of natural habitats, native vegetation, and nesting and breeding sites. Understanding the adaptability of insects to these changing environmental conditions is critical to predicting their survival. Bumblebees, key pollinators of wild and cultivated plants, are used as model species to assess insect adaptation to anthropogenic stressors. We investigated the effects of agricultural pressures on two common European bumblebees, Bombus pascuorum and B. lapidarius. Restriction-site Associated DNA Sequencing was used to identify loci under selective pressure across agricultural-natural gradients over 97 locations in Europe. 191 unique loci in B. pascuorum and 260 in B. lapidarius were identified as under selective pressure, and associated with agricultural stressors. Further investigation suggested several candidate proteins including several neurodevelopment, muscle, and detoxification proteins, but these have yet to be validated. These results provide insights into agriculture as a stressor for bumblebees, and signal for conservation action in light of ongoing anthropogenic changes.

On the road: Anthropogenic factors drive the invasion risk of a wild solitary bee species.

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.

Beewatching: A Project for Monitoring Bees through Photos.

Bees play a key role in natural and agro-ecosystems and their diversity is worldwide threatened by anthropogenic causes. Despite this, there is little awareness of the existence of the numerous species of wild bees, and the common name "bee" is very often exclusively associated with Apis mellifera. Our aim was to create a citizen science project in Italy with the following objectives: (a) raising awareness of the importance and diversity of bees, (b) obtaining data on the biology, ecology and distribution of Italian species, and (c) launching the monitoring of alien bees. The first step of the project was to create a website platform with a section containing informative datasheets of the wild bee families and of the most common bee genera present in Italy, a form to send reports of observed bees and an interactive map with all citizen's reports. During the 2 years of the project 1086 reports were sent by 269 users, with 38 Apoidea genera reported on 190 plant genera; furthermore, 22 reports regarding the alien species Megachile sculpturalis arrived. The majority of bees (34 genera) were observed on spontaneous plants, including 115 genera native to Italy. Considering the increasing number of reports and data obtained in these first two years of the project, our objectives seem to be achieved. Future steps will be to outline the profile of beewatchers, to plan activities in a more targeted way, and also to start some sub-projects for conservation purposes.

Twenty New Records of Bees (Hymenoptera, Apoidea) for Sardinia (Italy).

In Sardinia, the second largest Mediterranean island, 316 species of bees are known. Here, for the first time, the following 20 taxa are reported: Colletes cunicularius (Linnaeus, 1761), and C. eous Morice, 1904 (Colletidae); Andrena humilis Imhoff, 1832, A. granulosa Pérez, 1902, A. cineraria (Linnaeus, 1758), A. pallitarsis Pérez, 1903, A. rugulosa Stöckhert, 1935, A. savignyi Spinola, 1838, and A. tenuistriata Pérez, 1895 (Andrenidae); Sphecodes reticulatus Thomson, 1870 (Halictidae); Lithurgus tibialis Morawitz, 1875, Chelostoma emarginatum (Nylander, 1856), Dioxys cinctus (Jurine, 1807), Coelioxys caudatus Spinola, 1838, C. obtusus Pérez, 1884, and Megachile ericetorum (Lepeletier, 1841) (Megachilidae); and Nomada melathoracica Imhoff, 1834, N. pulchra Arnold, 1888, Eucera proxima Morawitz, 1875 and Tetralonia malvae (Rossi, 1790) (Apidae). N. pulchra is reported for the first time in Italy.