Invasive Bee Research Articles

Engaging citizens to monitor pollinators through a nationwide BioBlitz: Lessons learned and challenges remaining after four years

Pollination is a key mutualistic interaction between animals and flowering plants, generating biodiversity and providing valuable ecosystem services. However, a pollination crisis occurs because anthropogenic disturbance affects pollinators and their habitats, risking biodiversity and food security. Also, the lack of evidence-based knowledge may worsen disturbance effects by delaying decision-making and conservation actions. Citizen science plays an important role in data gathering by engaging volunteers in obtaining such information. Here, we present the results of four years of pollinator occurrence data from a series of targeted BioBlitz events conducted each November from 2020 to 2023 in Chile. We obtained a total of 6327 records (identified to the species or genus level), corresponding to 569 species from 44 families, collected along the Chilean territory, a 10-fold increase compared to the pre-BioBlitz period (2016–2019). The most frequent species were the butterfly Vanessa carye, the invasive bees Bombus terrestris and Apis mellifera, and the native bumblebee Bombus dahlbomii. Despite inter-annual abundance fluctuations, species composition was similar over time. The most recorded families were Apidae, Syrphidade, Nymphalidae, and Buprestidae. This nationwide multi-year citizen science survey allowed us to collect an impressive dataset that would have been unattainable by scientists alone. Furthermore, we obtained valuable information for monitoring threatened (e.g., B. dahlbomii) or invasive species (e.g., B. terrestris) over space and time, aiding decision-making and conservation efforts. Engaging people in pollinator monitoring strengthens human-nature connections and fosters conservation attitudes.

Evidence of introduced honeybees (Apis mellifera) as pollen wasters in orchid pollination

Biological invasions threaten global biodiversity, altering landscapes, ecosystems, and mutualistic relationships like pollination. Orchids are one of the most threatened plant families, yet the impact of invasive bees on their reproduction remains poorly understood. We conduct a global literature survey on the incidence of invasive honeybees (Apis mellifera) on orchid pollination, followed by a study case on Australian orchids. Our literature survey shows that Apis mellifera is the primary alien bee visiting orchids worldwide. However, in most cases, introduced honeybees do not deposit orchid pollen. We also test the extent to which introduced honeybees affect orchid pollination using Diuris brumalis and D. magnifica. Diuris brumalis shows higher fruit set and pollination in habitats with both native and invasive bees compared to habitats with only introduced bees. Male and female reproductive success in D. magnifica increases with native bee abundance, while conversely pollinator efficiency decreases with honeybee abundance and rises with habitat size. Our results suggest that introduced honeybees are likely involved in pollen removal but do not effectively deposit orchid pollen, acting as pollen wasters. However, Apis mellifera may still contribute to pollination of Diuris where native bees no longer exist. Given the global occurrence of introduced honeybees, we warn that certain orchids may suffer from pollen depletion by these invaders, especially in altered habitats with compromised pollination communities.

Monitoring strategies during the establishment phase of Aethina tumida on Oahu, Hawaii

AbstractThe small hive beetle Aethina tumida (SHB) Murray,1867, is an invasive bee pest that is expanding its range across Latin America, parts of Australia and the Philippines, and is now established in two regions in Italy. However, despite multiple recent introductions, there is scant information about the dynamics of the initial stages of colonization of the SHB and this knowledge gap could impact management and quarantine strategies decisions for many countries. This note describes the monitoring strategies and the patterns of SHB establishment in a previously SHB‐free apiary on the island of Oahu, Hawaii in 2010–2011. The weekly hive inspections, conducted over a ten‐month period, showed that beetle prevalence increased slowly at the apiary level, and adult beetles were more commonly found (87.9%) inside the oil traps that were placed inside the hives between the outermost frames of the hive. There were relatively few “free roaming” beetles detected at this point and they were more often found on the side frames and underneath the cover of the hive, not on the floor of the hive. The results also suggest that in the early stages of colonization careful visual inspections of the frames of each colony had relatively low detection success when compared to oil traps. Our results support previous modelling studies that suggest the need to inspect a high proportion of colonies per apiary (>80%) to ensure a 5% detection rate during the initial stages of invasion.

Home-and-away comparisons of life history traits indicate enemy release and founder effects of the solitary bee, Megachile sculpturalis

Occurrences of introduced and invasive pollinators are increasing worldwide. To predict the potential impacts of exotic bees on native ecosystems we need to understand their ecological interactions. Life history traits are fundamental for understanding ecological interactions and often help to explain the spread of exotic species. We conducted home-and-away comparisons of life history traits of the first invasive bee in Europe, the sculptured resin bee Megachile sculpturalis Smith 1853. We compiled information on nest architecture, offspring, natural enemies, body size and phenology using published literature, museum specimen, data from citizen science initiatives, field observations and reared specimen. Megachile sculpturalis uses a broad variety of nesting materials for brood cell construction, including even plastic at the exotic range. Body size at warm temperate climate was similar in the native and exotic ranges, but phenology shifted forward by about one month (28.9 ± 3.3 SE days) in the exotic ranges. The abundance of natural enemies was similar between native and exotic ranges but specialist enemies were missing in the exotic ranges. These trait shifts may be explained by founder effects or ecological filtering. The comparison of life history traits in native and exotic ranges sheds light on the ecological-evolutionary process of this quickly spreading species and provides a better understanding of invasion processes in solitary bees.

Plant-pollinator interactions in the neotropics are affected by urbanization and the invasive bee Apis mellifera

Plant-pollinator interactions in the neotropics are affected by urbanization and the invasive bee Apis mellifera

Microbiota and pathogens in an invasive bee: Megachile sculpturalis from native and invaded regions.

The present study aimed to characterise the bacterial, fungal and parasite gut community of the invasive bee Megachile sculpturalis sampled from native (Japan) and invaded (USA and France) regions via 16S rRNA and ITS2 amplicon sequencing and PCR detection of bee microparasites. The bacterial and fungal gut microbiota communities in bees from invaded regions were highly similar and differed strongly from those obtained in Japan. Core amplicon sequence variants (ASVs) within each population represented environmental micro-organisms commonly present in bee-associated niches that likely provide beneficial functions to their host. Although the overall bacterial and fungal communities of the invasive M. sculpturalis in France and the co-foraging native bees Anthidium florentinum and Halictus scabiosae, were significantly different, five out of eight core ASVs were shared suggesting common environmental sources and potential transmission. None of the 46 M. sculpturalis bees analysed harboured known bee pathogens, while microparasite infections were common in A. florentinum, and rare in H. scabiosae. A common shift in the gut microbiota of M. sculpturalis in invaded regions as a response to changed environmental conditions, or a founder effect coupled to population re-establishment in the invaded regions may explain the observed microbial community profiles and the absence of parasites. While the role of pathogen pressure in shaping biological invasions is still debated, the absence of natural enemies may contribute to the invasion success of M. sculpturalis.

Small hive beetle (Aethina tumida) threat on the horizon

Beekeeping is an agricultural industry that deals with breeding bees, obtaining honey, wax, and other products. Bees are used for pollination of many types of crops to increase their harvest. Beekeeping products are also used in medicine, pharmacology, chemical, and food industries. One of the essential aspects of successful beekeeping development is ensuring sustainable epizootic well-being from infectious and invasive bee diseases in Ukraine. About 3 million bee colonies are owned by private farms and amateur beekeepers, which give approximately 50-60 thousand tons of commercial honey and 1.2–1.4 thousand tons of wax per year at the current stage of beekeeping development in Ukraine. Honey and bee products from Ukraine received 15 prestigious awards in various categories at the 77th National Honey Show, held in London among many countries in 2008. In recent years, there has been a constant increase in the threat of new little-known invasive and infectious diseases that pose a significant danger to beekeeping worldwide. The invasion of the small hive beetle Aethina tumida belongs to quarantine and hazardous invasive diseases, which have destroyed many bee colonies in several countries worldwide (USA, Canada, African countries, Australia, some European countries – Italy, and Portugal). There are no effective methods of preventing and controlling the small hive beetle. The only way to prevent the invasion of the small hive beetle in Ukraine is constant monitoring and control at the state border of the movement of bee packages and bee products, which may pose a threat to introducing this invasive species into Ukraine.

BeeNet: An End-To-End Deep Network For Bee Surveillance

Computer vision-based image classification plays a vital role in developing surveillance tools for measuring the biological behavior of bees and their disease detection. Native bees often face numerous environmental threats, ranging from invasive bees to numerous parasitic diseases, which affect not only the existing ecosystem but also the booming honey and wax industries. Numerous ML-based, pre-trained models showed potential in bee classification and monitoring tasks, but heavily curated data-set and closed-set models hinder their applicability in-field monitoring tasks. In this paper, we proposed a deep learning model to obtain improved levels of feature representations of eleven economically important bee species, fine-grained object (e.g. parasite, pollen) detection for bee-health monitoring and gradually progress to an end-to-end model to provide a solution for bee surveillance. Our model can extract learned feature representations from publicly available complex back-grounded images and propose similar usage on other domains through a qualitative analysis to learn appropriate defining features, Specifically for morphological classification. In particular, we utilize a variant of the transformer encoder-decoder architecture with the incorporation of extracted image features from a ResNet50 network. Our model obtained 92.45% classification accuracy on the bee species classification task and up to 99.18% on fine-grain object detection sub-tasks. Besides the classification task, our end-to-end model can detect varroa pests and pollen on bee images with 94.50% and 99.18% accuracies. Our model outperformed other existing models for bee surveillance or health monitoring tools. We also discussed the applicability of our BeenNet model in real-time settings. Overall, our end-to-end model has implications in both computer vision and biological computing tasks, such as visual feature extraction, in-domain classification, and sub-task identification. It will also serve as a baseline for future bee monitoring tools and a multi-modal model for disease detection.

Suitable areas for the invasion expansion of Xylocopa bees in South America

AbstractThe introduction of exotic species into native ecosystems can be a cause for concern when those species are invasive. Invasive species cause ecological problems and have socio‐cultural impacts on human health and the economy; for example, invasive bees may negatively impact their introduced ecosystem by spreading diseases or outcompeting native pollinators. Xylocopa spp. bees are diverse and distributed throughout the Neotropics. However, Xylocopa augusti (Lepeletier, 1841) and Xylocopa splendidula (Lepeletier, 1841) are not native to Mediterranean Chile. This study aimed to evaluate the invasive potential of these exotic species and predict the potential macroecological effects of their invasions. We also aimed to pinpoint possible distributions for these species throughout South America. We correlated biogeographic occurrence data with climatic variables for each species to model their potential distribution in both current and future scenarios. The models provide strong evidence that both species are changing their distributions: their ranges are expanding towards western South America, particularly Bolivia, Chile and Peru. We demonstrate an increase in niche overlap between these species and show there are new geographic areas vulnerable to the establishment of these invasive bees under current and future climate conditions. These data suggest that these bees may adapt their geographic distribution as the climate changes and pose a threat to native pollinators in new geographic areas.

Black-Banded Honey Bee, Sulawesian Honey Bee Apis nigrocincta Smith (Insecta: Hymenoptera: Apidae)

The Featured Creatures collection provides in-depth profiles of insects, nematodes, arachnids and other organisms relevant to Florida. These profiles are intended for the use of interested laypersons with some knowledge of biology as well as academic audiences. Apis nigrocincta Smith (1860) is a cavity-nesting honey bee native to the Philippines and Indonesia. The Florida Department of Agriculture and Consumer Services – Division of Plant Industry’s Apiary Inspection Section is actively screening for invasive honey bee species in an effort to eradicate unwanted pests. This bee is not currently considered a threat to Florida, but state researchers are actively screening honey bees of unknown origins using molecular markers to detect the presence of Apis nigrocincta.

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.

Non-Native Non-Apis Bees Are More Abundant on Non-Native Versus Native Flowering Woody Landscape Plants

Simple SummaryBees and other pollinators play a vital role in food production and natural ecosystems. Native bee populations are declining due in part to habitat loss. Individuals can help bees by landscaping with plants that provide pollen and nectar. Most information on bee-friendly plants concerns herbaceous ornamentals, but flowering trees and shrubs, too, can provide food for urban bees. Conservation organizations recommend landscaping mainly with native plants to support native bees, but some studies suggest that including some non-invasive non-native plants that bloom earlier or later than native plants can help support bees when resources from native plants are scarce. That strategy might backfire, however, if such plants disproportionately host invasive bee species. This study tested that hypothesis by identifying all non-native bees among 11,275 bees previously collected from 45 species of flowering woody plants across hundreds of urban sites. Besides the ubiquitous honey bee, six other non-native bee species comprised 2.9% of the total collection. Two alien species considered to have invasive tendencies by outcompeting native bees were more abundant on non-native plants. Planting their favored hosts might facilitate those bees’ spread in urban areas. Pros and cons of non-native woody landscape plants for urban bee conservation warrant further study.Urban ecosystems can support diverse communities of wild native bees. Because bloom times are conserved by geographic origin, incorporating some non-invasive non-native plants in urban landscapes can extend the flowering season and help support bees and other pollinators during periods when floral resources from native plants are limiting. A caveat, though, is the possibility that non-native plants might disproportionately host non-native, potentially invasive bee species. We tested that hypothesis by identifying all non-native bees among 11,275 total bees previously collected from 45 species of flowering woody landscape plants across 213 urban sites. Honey bees, Apis mellifera L., accounted for 22% of the total bees and 88.6% of the non-native bees in the collections. Six other non-native bee species, accounting for 2.86% of the total, were found on 16 non-native and 11 native woody plant species. Non-Apis non-native bees in total, and Osmia taurus Smith and Megachile sculpturalis (Smith), the two most abundant species, were significantly more abundant on non-native versus native plants. Planting of favored non-native hosts could potentially facilitate establishment and spread of non-Apis non-native bees in urban areas. Our host records may be useful for tracking those bees’ distribution in their introduced geographical ranges.

Invasive bumble bee disrupts a pollination mutualism over space and time

Invasive bumble bee disrupts a pollination mutualism over space and time

Serial Founder Effects Reduce Fitness at Range Edges and Slow Expansion Rate in an Invasive Bee

Serial Founder Effects Reduce Fitness at Range Edges and Slow Expansion Rate in an Invasive Bee

Reproductive Success of an Endangered Plant after Invasive Bees Supplant Native Pollinator Services

Arctomecon humilis (dwarf bear poppy) is an endangered gypsophile restricted to the St. George area in southern Utah, USA. Extirpation of the rare oligolectic bee Perdita meconis and decline of other native pollinators within the last 20 years has been largely attributed to the advent of invasive Africanized honeybees (AHBs), which have become the predominant pollinator for A. humilis. A three-year study was carried out to determine if reliance on AHBs had a negative effect on reproductive output. In the first year, pollen addition experiments were carried out in a small, isolated population to determine if pollinator scarcity or genetic factors affected reproductive output. In the subsequent two years, reproductive output studies were conducted across four populations. In all years, fruit set across study sites was exceptionally high. There was no consistent effect from flower number or interplant distance, which have historically been shown to have a significant impact on reproductive output prior to AHB arrival. The consequences and sustainability of this relatively young relationship between A. humilis and the AHB remain unclear. However, high reproductive success shows that the AHB is currently capable of adequately fulfilling pollinator services for A. humilis.

Exotic insect pollinators and native pollination systems

Insect pollinators have been relocated by humans for millennia and are, thus, among the world’s earliest intentional exotic introductions. The introduction of managed bees for crop pollination services remains, to this day, a common and growing practice worldwide and the number of different bee species that are used commercially is increasing. Being generalists and frequently social, these exotic species have the potential to have a wide range of impacts on native bees and plants. Thus, understanding the consequences of introduced species on native pollinator systems is a priority. We generated a global database and evaluated the impacts of the two main groups of invasive bees, Apis mellifera and Bombus spp., on their pollination services to native flora and impacts on native pollinators. In a meta-analysis, we found that per-visit pollination efficiency of exotic pollinators was, on average, 55% less efficient than native pollinators when visiting flowers of native species. In contrast to per-visit pollination efficiency, our meta-analysis showed that visitation frequency by exotic pollinators was, on average, 80% higher than native pollinators. The higher visitation frequency of exotic pollinators overcame deficiencies in pollen removal and transfer resulting in seed/fruit set levels similar to native pollinators. Also, evidence showed that exotic pollinators can displace native insect and bird pollinators. However, the direct effects of exotic insect pollinators on native pollination systems can be context dependent, ranging from mutualism to antagonism.

Ensemble Models Predict Invasive Bee Habitat Suitability Will Expand under Future Climate Scenarios in Hawai'i.

Simple SummaryClimate change exacerbates the threat of biological invasions by increasing climatically suitable regions for species to invade outside of their native range. Island ecosystems may be particularly sensitive to the synergistic effects of climate change and biological invasions. In Hawai’i there are 21 non-native bees that have the capacity to spread pathogens and compete for resources with native bees. We performed an ensemble of species distribution models (SDM) for eight non-native bee species (Hymenoptera: Anthophila) in Hawai’i to predict climatically suitable niches across current and future climate scenarios. We found a significant difference in habitat suitability between SDMs that were constructed with specimen records from their native and non-native (Hawai’i) range. Although SDMs predict expansion of suitable habitat into higher elevations under 2070 climate scenarios, species-rich areas are predicted to stay below 500 m elevation. Our models can inform decisions on the management of non-native bees in Hawai’i by assessing risk of invasion into new areas around the archipelago.Climate change is predicted to increase the risk of biological invasions by increasing the availability of climatically suitable regions for invasive species. Endemic species on oceanic islands are particularly sensitive to the impact of invasive species due to increased competition for shared resources and disease spread. In our study, we used an ensemble of species distribution models (SDM) to predict habitat suitability for invasive bees under current and future climate scenarios in Hawai’i. SDMs projected on the invasive range were better predicted by georeferenced records from the invasive range in comparison to invasive SDMs predicted by records from the native range. SDMs estimated that climatically suitable regions for the eight invasive bees explored in this study will expand by ~934.8% (±3.4% SE). Hotspots for the invasive bees are predicted to expand toward higher elevation regions, although suitable habitat is expected to only progress up to 500 m in elevation in 2070. Given our results, it is unlikely that invasive bees will interact directly with endemic bees found at >500 m in elevation in the future. Management and conservation plans for endemic bees may be improved by understanding how climate change may exacerbate negative interactions between invasive and endemic bee species.

Pairwise learning for predicting pollination interactions based on traits and phylogeny

Mutualistic bee–plant interaction networks are a vital part of terrestrial ecosystems. They frequently arise through co-evolutionary processes, which match the traits of both partners, facilitating their interaction. Insights in these interaction mechanisms are vital to be able to manage changing ecosystems. This entails the need for models to predict species interaction networks in general and pollination networks in particular.We show how kernel-based pairwise learning can predict bee–plant interactions based on the traits and the phylogeny of the plant and bee species. The traits and the phylogeny of the plant and bee species proved to be highly predictive. Although the traits were slightly more informative compared to the phylogeny, the best results were obtained by combining both the traits and the phylogeny in the model Notably, the model performance varied greatly depending on whether the goal was to pinpoint missing interactions in the network or to predict interactions for new bee species, new plant species, or both. This issue highlights the importance of proper stratification when fitting biological network prediction models. Our model, however, showed the capacity to generalize beyond the original dataset provided by FlorAbeilles. The model was validated by predicting potentially interacting plant species for the invasive bee species Megachile sculpturalis. Four out of the five plant species identified by the model could be validated based on literature.Our results indicate that pairwise learning has potential as a general method for supervised species interaction prediction. Caution should be taken to validate such models correctly.

Conservation insights from wild bee genetic studies: Geographic differences, susceptibility to inbreeding, and signs of local adaptation.

Conserving bees are critical both ecologically and economically. Genetic tools are valuable for monitoring these vital pollinators since tracking these small, fast‐flying insects by traditional means is difficult. By surveying the current state of the literature, this review discusses how recent advances in landscape genetic and genomic research are elucidating how wild bees respond to anthropogenic threats. Current literature suggests that there may be geographic differences in the vulnerability of bee species to landscape changes. Populations of temperate bee species are becoming more isolated and more genetically depauperate as their landscape becomes more fragmented, but tropical bee species appear unaffected. These differences may be an artifact of historical differences in land‐use, or it suggests that different management plans are needed for temperate and tropical bee species. Encouragingly, genetic studies on invasive bee species indicate that low levels of genetic diversity may not lead to rapid extinction in bees as once predicted. Additionally, next‐generation sequencing has given researchers the power to identify potential genes under selection, which are likely critical to species’ survival in their rapidly changing environment. While genetic studies provide insights into wild bee biology, more studies focusing on a greater phylogenetic and life‐history breadth of species are needed. Therefore, caution should be taken when making broad conservation decisions based on the currently few species examined.

Detection of Lotmaria passim, Crithidia mellificae and Replicative Forms of Deformed Wing Virus and Kashmir Bee Virus in the Small Hive Beetle (Aethina tumida).

Knowledge regarding the honey bee pathogens borne by invasive bee pests remains scarce. This investigation aimed to assess the presence in Aethina tumida (small hive beetle, SHB) adults of honey bee pathogens belonging to the following groups: (i) bacteria (Paenibacillus larvae and Melissococcus plutonius), (ii) trypanosomatids (Lotmaria passim and Crithidia mellificae), and (iii) viruses (black queen cell virus, Kashmir bee virus, deformed wing virus, slow paralysis virus, sacbrood virus, Israeli acute paralysis virus, acute bee paralysis virus, chronic bee paralysis virus). Specimens were collected from free-flying colonies in Gainesville (Florida, USA) in summer 2017. The results of the molecular analysis show the presence of L. passim, C. mellificae, and replicative forms of deformed wing virus (DWV) and Kashmir bee virus (KBV). Replicative forms of KBV have not previously been reported. These results support the hypothesis of pathogen spillover between managed honey bees and the SHB, and these dynamics require further investigation.