Colony Decline Research Articles

Complex dynamical behaviors of a honeybee-mite model in parameter plane

The honeybee has a significant impact on ecosystem stability, biodiversity conservation, and pollinating crops. However, during the past few years, there has been a sharp reduction in both the honeybee population and their colonies. It has been found that the parasitic mite Varroa destructor is responsible for the decline in honeybee colonies around the world, which in turn immensely affects the economic growth of a country. To investigate how the dynamics of a system is influenced by the growth of honeybees and the parasitism of mites, we study a nonlinear honeybee-mite population model in a discrete-time setup. We observe that an increase in the value of the queen’s egg-laying rate drives the system towards chaos. However, chaos can be controlled as well if the parasite attachment effect is increased. The intrinsic dynamical properties of the proposed system are investigated with the simultaneous variation of the queen’s egg-laying rate and the mite’s parasite attachment effect by constructing several largest Lyapunov exponent and isoperiodic diagrams. The investigation reveals the existence of several periodic structures in the quasiperiodic and chaotic regimes of the parameter plane, including Arnold tongues, saddle area, spring area, connected shrimp-shaped structure, and connected saddle area. We also find the appearance of a novel ‘jellyfish’-shaped periodic structure. One of the most fascinating findings of this study is the appearance of Arnold tongues along the inner boundary region of another Arnold tongue. In addition, this work also reveals different types of multistability, e.g., the coexistence of two, three, and even four attractors. What is more interesting is that the current analysis unveils the coexistence of five attractors as well, more specifically, four different periodic attractors coexist with the trivial fixed point attractor, which is quite rare in ecological systems. The structures of the basins of these coexisting attractors are either smooth or very complex in nature. Furthermore, the present study also discloses the fact that variation in the initial condition of the system can significantly change the appearance of the periodic structures in the parameter plane.

Sacbrood viruses and select Lake Sinai virus variants dominated Apis mellifera colonies symptomatic for European foulbrood.

European foulbrood (EFB) is a prevalent disease in the European honey bee (Apis mellifera) in the United States, which can lead to colony decline and collapse. The bacterial components of EFB are well-studied, but the diversity of viral infections within infected colonies has not been explored. In this study, we use meta-transcriptomics sequencing of 12 honey bee hives, symptomatic (+, n = 6) and asymptomatic (-, n = 6) for EFB, to investigate viral infection associated with the disease. We assembled 41 viral genomes, belonging to three families (Iflaviridae, Dicistroviridae, and Sinhaliviridae), all previously reported in honey bees, including Lake Sinai virus, deformed wing virus, sacbrood virus, Black queen cell virus, and Israeli acute paralysis virus. In colonies with severe EFB, we observed a higher occurrence of viral genomes (34 genomes) in contrast to fewer recovered from healthy colonies (seven genomes) and a complete absence of Dicistroviridae genomes.We observed specific Lake Sinai virus clades associated exclusively with EFB + or EFB - colonies, in addition to EFB-afflicted colonies that exhibited an increase in relative abundance of sacbrood viruses. Multivariate analyses highlighted that a combination of site and EFB disease status influenced RNA virome composition, while EFB status alone did not significantly impact it, presenting a challenge for comparisons between colonies kept in different yards. These findings contribute to the understanding of viral dynamics in honey bee colonies compromised by EFB and underscore the need for future investigations to consider viral composition when investigating EFB.IMPORTANCEThis study on the viromes of honey bee colonies affected by European foulbrood (EFB) sheds light on the dynamics of viral populations in bee colonies in the context of a prevalent bacterial brood disease. The identification of distinct Lake Sinai virus and sacbrood virus clades associated with colonies affected by severe EFB suggests a potential connection between viral composition and disease status, emphasizing the need for further investigation into the role of viruses during EFB infection. The observed increase in sacbrood viruses during EFB infection suggests a potential viral dysbiosis, with potential implications for honey bee brood health. These findings contribute valuable insights related to beekeeping practices, offering a foundation for future research aimed at understanding and mitigating the impact of bacterial and viral infection in commercial honey bee operations and the management of EFB.

A Hive Entrance System That Directs Honey Bees Inside or Outside a Greenhouse Reduced Colony Decline While Effectively Pollinating Zucchini Squash

Honey bee colonies rapidly decline when confined to greenhouses, increasing pollination rental costs as they need to be replaced frequently. We tested a hive system with entrances that can be manipulated to direct bees inside or outside greenhouses containing a zucchini crop. In one greenhouse, the bees could only forage inside for 15 days; in another, bees were directed to the inside from 5 to 9 a.m., after which they only foraged outside. This procedure was repeated two more times in each greenhouse with new hives. Data were collected on how the number of bee flower visits affected fruit production, the frequency of flower visits, and the amount of bee brood and food in the hives. Flowers visited by bees four times or more set more and larger fruit. The frequency of flower visits by bees from the hives confined to the greenhouse was reduced after eight days; it was not reduced in the greenhouse with bees that could forage outside. The bee brood area was reduced in the colonies that were confined to the greenhouse, while it was maintained in the semi-confined hives. The hives with controllable entrances proved effective for pollination, while causing less damage to the bees.

Colony performance of threenative bumblebee species from South China and association with their gut microbiome.

Bumblebees play an important ecological economic role as pollinators in nature and agriculture. For reasons of biosecurity, many countries promote the cultivation of native bumblebee species for crop pollination instead of importing "alien" species. In South China, a few bumblebee species are considered useful in this way, particularly, Bombus atripes, Bombus bicoloratus and Bombus breviceps. However, whether they are suitable for artificial rearing and forming healthy colonies for pollination, remains unknown. In this project, queens from the 3 native species of Guizhou Province were collected and colonies were started under standardized conditions. The colonies were scored based on 19 parameters, including the stage of colony development, number and weight of offspring, and diet consumed. The data revealed that B.breviceps had the best performance, produced more workers and consumed the smallest diet. Next, we performed 16S rDNA sequencing of the bacterial communities found in the guts of offspring workers, and then a correlation analysis between colony performance and gut bacteria was conducted. Here, B.breviceps showed the highest diversity in gut bacterial composition, dominated by the bacteria Gilliamella, Snodgrassella, Enterobacter, and Lactobacillus Firm5. The higher the abundance of Snodgrassella, the better the performance of the colony in the foundation stage, and later Lactobacillus Firm5, Apibacter and Bifidobacterium were beneficial during the stages of rapid growth and colony decline. Although we do not understand all of the interactions yet, these correlations explain why B.breviceps demonstrated better colony performance. Our data provide valuable information for breeding local Bombus species and will contribute to developing strong colonies for crop pollination.

Evaluating risks to seabirds on the urban–coastal interface: Modelling dog attacks on little penguin populations in Tasmania

Abstract Tasmania (including offshore islands) has the largest breeding population of little penguins (Eudyptula minor) in Australia, but coastal development around nesting areas has led to habitat loss, often resulting in smaller, fragmented colonies. Colonies have also been subject to predation by introduced domestic species. This study assessed whether historical levels of domestic dog predation could threaten the viability of penguin populations. Data collected since the 1980s detailing little penguin kills by domestic dogs were used to inform the extent of individual mortality events. The potential impact of dog attacks on the viability of little penguin colonies of the sizes typically found on mainland Tasmania was explored using an age‐based population model. Simulation was conducted over decadal timescales to assess the impact of attacks at varying frequencies and intensities on small (100 birds), medium (300 birds) and large (500 birds) colonies that were stable, growing or decreasing. Results suggested that frequent and intense dog attacks markedly increased the probability of colony decline, regardless of colony size. Even large, growing penguin colonies were at risk of decline. The risk of extinction was <10% for medium and large stable colonies if no more than 15–25 penguins were killed per attack and there were no more than 20 attacks per 50 years. For small‐sized colonies, the risk of extinction was <10% if fewer than 10 attacks occurred per 50‐year period and no more than 15 birds were killed per attack. Importantly, results suggested that for small colonies especially, even low levels of predator attack could lead to colony collapse in 10–15 years. For large colonies that were already decreasing, the average time to extinction was markedly increased with additional mortalities from dogs, highlighting the need for ongoing management measures that reduce or eliminate dog attacks to help conserve this iconic species.

Airborne imagery does not preclude detectability issues in estimating bird colony size

Aerial images obtained by drones are increasingly used for ecological research such as wildlife monitoring. Yet detectability issues resulting from animal activity or visibility are rarely considered, although these may lead to biased population size and trend estimates. In this study, we investigated detectability in a census of Malagasy pond heron Ardeola idae colonies on the island of Mayotte. We conducted repeated drone flights over breeding colonies in mangrove habitats during two breeding seasons. We then identified individuals and nests in the images and fitted closed capture-recapture models on nest-detection histories. We observed seasonal variation in the relative abundance of individuals, and intra-daily variation in the relative abundance of individuals—especially immature birds—affecting the availability of nests for detection. The detection probability of nests estimated by capture–recapture varied between 0.58 and 0.74 depending on flyover days and decreased 25% from early to late morning. A simulation showed that three flyovers are necessary to detect a 5–6% decline in colonies of 50 to 200 nests. These results indicate that the detectability of nests of forest-canopy breeding species from airborne imagery can vary over space and time; we recommend the use of capture-recapture methods to control for this bias.

Beekeeping role in enhancing food security and environmental public health

This conceptual article delves into the intricate relationship between public health and environmental health, using the underutilisation of beekeeping in the United States as a case study. The concept of food security, established after the 1996 World Food Summit, encompasses pillars of availability, accessibility, utilization, and stability. This thorough framework creates the foundation for comprehending the crucial aspects of food security and prepares the reader for a careful examination of the implications presented by the US honeybee colonies’ decline. The decline in honeybee colonies in the United States poses a significant threat to food production. Loss of honeybee colonies and the lack of attention to apiculture have far-reaching consequences for public and environmental health. This article explores the often-overlooked intersection of food security and beekeeping, recognizing the intricate dependencies between pollinators and crop sustainability. Honeybees, crucial pollinators for essential food crops, offer not only ecological benefits but also socio-economic opportunities. The article also highlights beekeeping’s diverse contributions, such as enhanced pollination, increased crop yields, ecosystem health, and climate change resilience. Despite the evident benefits of beekeeping for food security and the nutritional richness of bee products, commercial beekeeping in the USA is monopolised by a mere 1.4% of beekeepers. The 1.4% commercial beekeepers control 89.7% of country colonies, an indication of the huge neglect of apiculture. This neglect led to an alarming 48.2% loss of honeybee colonies between April 2022 and April 2023. This unprecedented decline, often overlooked, highlights a deficiency in attention and strategic planning within agriculture, underscoring broader implications for public and environmental health in the United States. This article introduces a theoretical framework incorporating ecological systems, social ecology, system theory, resource-based views, livelihood diversification, and sustainability, emphasizing their role in understanding and improving food security through beekeeping.

Early-Life Sublethal Thiacloprid Exposure to Honey Bee Larvae: Enduring Effects on Adult Bee Cognitive Abilities.

Honey bees have significant ecological and economic value as important pollinators, but they are continuously exposed to various environmental stressors, including insecticides, which can impair their health and cause colony decline. (1) Background: Cognitive abilities are vital for the functional maintenance of honey bees; however, it remains unknown if chronic, low-dose exposure to thiacloprid during the larval stage impairs the cognitive abilities of emerged adult honey bees. (2) Methods: To explore this question, honey bee larvae were fed 0, 0.5, and 1.0 mg/L thiacloprid during their developmental phase. Then, the cognitive (i.e., olfactory learning and memory) abilities of adult honey bees were quantified to assess the delayed impacts of early-stage thiacloprid exposure on adult honey bee cognition. Neural apoptosis and transcriptomic level were also evaluated to explore the neurological mechanisms underlying these effects. (3) Results: Our results revealed that chronic larval exposure to sublethal thiacloprid impaired the learning and memory abilities of adult honey bees by inducing neuronal apoptosis and transcriptomic alterations. (4) Conclusions: We highlighted a previously unknown impairment caused by thiacloprid in honey bees.

Identification of Floral Resources Used by the Stingless Bee Melipona beecheii for Honey Production in Different Regions of the State of Campeche, Mexico

The stingless bee Melipona beecheii is experiencing colony decline due to floral resource scarcity caused by deforestation. A study was conducted to identify the floral resources used by M. beecheii using honey samples collected in four regions of the state of Campeche, Mexico. A melissopalynological analysis of sixteen collected honey samples identified 69 plant species from 24 families, and established that Fabaceae was the main plant family visited. Based on botanical origin, seven samples were classified as monofloral and nine as multifloral. The predominant species were Bursera simaruba, Lonchocarpus longistylus, Piscidia piscipula, Senna pallida and Senna racemosa. Shannon diversity index values (2.06–2.55) indicated moderate diversity in floral resources and Simpson diversity index values (0.82–0.89) indicated a moderate dominance of plant species in the studied regions. The results suggest M. beecheii is polylectic with some degree of specialization. The plant species identified as predominant in the studied honey samples are candidates for use in strategies intended to conserve the food resources used by M. beecheii on the Yucatan Peninsula.

Establishment and Application of CRISPR-Cas12a-Based Recombinase Polymerase Amplification and a Lateral Flow Dipstick and Fluorescence for the Detection and Distinction of Deformed Wing Virus Types A and B.

Deformed wing virus (DWV) is one of the important pathogens of the honey bee (Apis mellifera), which consists of three master variants: types A, B, and C. Among them, DWV types A (DWV-A) and B (DWV-B) are the most prevalent variants in honey bee colonies and have been linked to colony decline. DWV-A and DWV-B have different virulence, but it is difficult to distinguish them via traditional methods. In this study, we established a visual detection assay for DWV-A and DWV-B using recombinase polymerase amplification (RPA) and a lateral flow dipstick (LFD) coupled with the clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein (Cas) 12a fluorescence system (RPA-CRISPR-Cas12a-LFD). The limit of detection of this system was ~6.5 × 100 and 6.2 × 101 copies/μL for DWV-A and DWV-B, respectively. The assays were specific and non-cross-reactive against other bee viruses, and the results could be visualized within 1 h. The assays were validated by extracting cDNA from 36 clinical samples of bees that were suspected to be infected with DWV. The findings were consistent with those of traditional reverse transcription-quantitative polymerase chain reaction, and the RPA-CRISPR-Cas12a assay showed the specific, sensitive, simple, and appropriate detection of DWV-A and DWV-B. This method can facilitate the visual and qualitative detection of DWV-A and DWV-B as well as the monitoring of different subtypes, thereby providing potentially better control and preventing current and future DWV outbreaks.

Exploring viral infections in honey bee colonies: insights from a metagenomic study in southern Brazil.

The decline in honey bee colonies in different parts of the world in recent years is due to different reasons, such as agricultural practices, climate changes, the use of chemical insecticides, and pests and diseases. Viral infections are one of the main causes leading to honey bee population declines, which have a major economic impact due to honey production and pollination. To investigate the presence of viruses in bees in southern Brazil, we used a metagenomic approach to sequence adults' samples of concentrated extracts from Apis mellifera collected in fifteen apiaries of six municipalities in the Rio Grande do Sul state, Brazil, between 2016 and 2017. High-throughput sequencing (HTS) of these samples resulted in the identification of eight previously known viruses (Apis rhabdovirus 1 (ARV-1), Acute bee paralysis virus (ABPV), Aphid lethal paralysis virus (ALPV), Black queen cell virus (BQCV), Bee Macula-like virus (BeeMLV), Deformed wing virus (DWV), Lake Sinai Virus NE (LSV), and Varroa destructor virus 3 (VDV-3)) and a thogotovirus isolate. This thogotovirus shares high amino acid identities in five of the six segments with Varroa orthomyxovirus 1, VOV-1 (98.36 to 99.34% identity). In contrast, segment 4, which codes for the main glycoprotein (GP), has no identity with VOV-1, as observed for the other segments, but shares an amino acid identity of 34-38% with other glycoproteins of viruses from the Orthomyxoviridae family. In addition, the putative thogotovirus GP also shows amino acid identities ranging from 33 to 41% with the major glycoprotein (GP64) of insect viruses of the Baculoviridae family. To our knowledge, this is the second report of a thogotovirus found in bees and given this information, this thogotovirus isolate was tentatively named Apis thogotovirus 1 (ATHOV-1). The detection of multiple viruses in bees is important to better understand the complex interactions between viruses and their hosts. By understanding these interactions, better strategies for managing viral infections in bees and protecting their populations can be developed.

Causes of honeybee colony decline in south Ethiopia

The purpose of this study was to identify the major causes of colony decline in the Gedeo Zone, South Ethiopia. Three districts, namely, Yirga Cheffe, Wonago, and Dilla Zuria, were purposefully selected based on beekeeping potential. A cross-sectional survey was conducted to collect data from 135 beekeepers and 15 key informants using a semi-structured questionnaire, focus group discussion, and personal observation of apiary sites. The results revealed two main causes of colony declines in the Gedeo zone: colony management-related factors and natural factors. Seventy percent of beekeepers lack the practical skills to perform hive inspection; 47% do not feed their colonies; 45% spray pesticides and insecticides near their apiaries; and 82% fail to control swarming. As a result, 87% of sampled beekeepers have experienced frequent colony absconding. The trends of colony decline showed an increase from 2008 to 2020 in the highlands and from 2008 to 2017 in the midlands and lowlands, respectively. The number of households facing colony declines increased in all agro-ecologies from 2008 to 2020. Pests and predators, like wax moths, and small hive beetles were take the first rank followed by ants, the inherent behavior of honeybees, a shortage of flora, and the presence of poisonous plants were the top five challenges among natural factors, respectively. Therefore, we strongly recommend educating beekeepers on scientific methods of colony management and planting bee flora. Laboratory diagnostics are required to identify bee diseases.

Insights into varroa mite (Varroa destructor) infestation levels in local honeybee (Apis mellifera) colonies of Ethiopia

AbstractThe varroa mite (Varroa destructor) is the most economically important parasitic pest of honey bees (Apis mellifera) that causes global colony decline and loss. Since its first detection in Ethiopia in 2010, little is known about the current infestation levels and contributing factors to the mite's distribution across the country. In this study, we conducted a large‐scale assessment of varroa prevalence and infestation levels in managed colonies across three potential beekeeping regions of Ethiopia; Oromia, Amhara and Southern Nations, Nationalities and Peoples Region (SNNPR). A total of 360 samples from 39 apiaries were collected following standard protocols and the mite prevalence and infestation levels were determined using the established method of varroa research. Overall, 89% of sampled colonies were infested by the mite, with varying prevalence rates across the regions: 95.8% in Oromia, 85.2% in Amhara and 71.9% in SNNPR, indicating the widespread nature of the parasite throughout the country. The varroa infestation levels were lower in local hives (2.6 ± 5.9) than in frame hives (5.0 ± 0.9), and significantly higher in brood bees (5.6 ± 0.8) than in adult bees (1.93 ± 0.17) (p < 0.001). Possible factors contributing to the varied mite prevalence and infestation levels in the country include differences in agro‐ecology, beekeeping practices, host age preference and the nature of bee hives. Therefore, our study provides insights into the current status of varroa prevalence and associated factors across regions in Ethiopia. Further investigation is required to explore the probable impact of the parasite on the health and productivity of local honey bees, in order to design future monitoring strategies.

Contribución sobre los hábitos alimenticios y nuevos registros de Mirothrips arbiter Cavalleri, Souza, Prezoto y Mound, 2013 (Thysanoptera: Phlaeothripidae) en nidos de avispas Polistes Latreille, 1802 (Hymenoptera: Vespidae)

New host wasps attacked by Mirothrips arbiter (Thysanoptera: Phlaeothripidae) are recorded and their possible feeding on fungi and mites in colonies of Polistes melanosoma and Polistes ferreri is evaluated. No predation events on mites or fungal ingestion were observed, indicating that these thrips only use wasp eggs as food. Thrips do not parasitize wasps’ bodies, they only live at the expense of their colonies, where they find food and shelter. However, as these insects feed on the immature stages of the wasps, it is possible that they cause or accelerate colony decline. Given this, we can say that the ecological relationship between thrips and social wasps is that of social parasitism, that is, thrips are parasites of wasps colonies, they depend directly on them for their survival and cause damage to them. From our findings, the number of host wasp species of this thrips rose to five, all belonging to the Polistinae subfamily.

Seasonal differences in Varroa destructor population growth in western honey bee (Apis mellifera) colonies

Varroa destructor is a major threat for apiculture worldwide. A successful approach to control this parasite must include the application of effective treatments at the correct time. To understand the effect that treatment timing has on Varroa populations at different seasons, we conducted an experiment using a dataset comprising two separate field trials over multiple years, both trials containing four apiary sites composed of 20 honey bee colonies across an area representative of north central Florida environments. Before the start of the season, colonies were treated with two acaricides simultaneously to bring the Varroa populations to ∼0.25 mites/100 bees. Following treatment, we monitored the mite populations monthly via alcohol washes. Our results show that the temporal efficacy of Varroa treatments varies across seasons. We observed that it takes about 4–5 months after treatment in winter and spring for mite populations to return to the standard economical threshold (3 mites/100 bees). Nevertheless, there is a steeper increase in mite populations (<3 months to exceed the economic threshold) after treating colonies in summer and fall. The level of infestation that leads to colony collapse and the rate of colony decline also varied by season. To our knowledge, this is the first study evaluating seasonal effects on Varroa population growth and the first model of Varroa population growth in Florida, USA. Our results serve as a foundation for Varroa treatment models, aiding beekeepers in the future as a part of a holistic approach to control this devastating honey bee parasite.

Evaluating the Impact of Commonly Used Pesticides on Honeybees (Apis mellifera) in North Gonder of Amhara Region, Ethiopia.

Global honeybee losses and colony decline are becoming continuous threat to the apicultural industry, as well as, for food security and environmental stability. Although the putative causes are still unclear, extensive exposure of bees to pesticides could be the possible factor for worldwide colony losses. This study was aimed at evaluating the impact of nine commonly used pesticide incidents on adult worker honeybees (A. mellifera) under the laboratory condition, in North Gonder of Amhara region, Ethiopia. Feeding test, contact test, and fumigation tests were carried out for each pesticide following the standard procedures, and each pesticide toxicity was compared to the standard toxic chemical, dimethoate 40% EC (positive control), and to 50% honey solution (negative control). The results revealed that all the tested pesticides caused significant deaths of the experimental bees (P < 0.05) in all the tests when compared to the negative control. Diazinon 60% EC, endosulfan 35% EC, and malathion 50% EC were appeared highly toxic causing 100% mortality of bees, while chlorsulfuron 75% WG killed 90% of the experimental bees as tested via feeding. On the other hand, agro-2, 4-D and its mixture with glycel 41% EC are moderately toxic, and mancozeb 80% WP and glycel 41% EC were slightly toxic to honeybees as compared to the positive control (dimethoate 40% EC). Suddenly, diazinon 60% EC and malathion 50% EC triggered 100% mortality of bees, while endosulfan 35% EC and chlorsulfuron 75% WG caused 63.63% and 90.82% of bee mortality, respectively, when evaluated via contact test. The fumigation test also showed that chlorsulfuron 75% WG, diazinon 60% EC, and endosulfan 35% EC caused 100%, 86.7%, and 65.6% mortality rate of bees. Our result also highlighted that tested LD50 of all pesticide incidents were significantly lower than the manufacturer-based LD50. This shows that local honeybees A. m. jemenetica are extremely sensitive to commonly used agricultural pesticides, which may affect the colony level due to the intensive application of these pesticides in Ethiopia.

Ecological threat caused by malathion and its chiral metabolite in a honey bee-rape system: Stereoselective exposure risk and the mechanism revealed by proteome

Honey bees play an important role in the ecological environment. Regrettably, a decline in honey bee colonies caused by chemical insecticides has occurred throughout the world. Potential stereoselective toxicity of chiral insecticides may be a hidden source of danger to bee colonies. In this study, the stereoselective exposure risk and mechanism of malathion and its chiral metabolite malaoxon were investigated. The absolute configurations were identified using an electron circular dichroism (ECD) model. Ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used for chiral separation. In pollen, the initial residues of malathion and malaoxon enantiomers were 3571–3619 and 397–402 μg/kg, respectively, and R-malathion degraded relatively slowly. The oral LD50 values of R-malathion and S-malathion were 0.187 and 0.912 μg/bee with 5 times difference, respectively, and the malaoxon values were 0.633 and 0.766 μg/bee. The Pollen Hazard Quotient (PHQ) was used to evaluate exposure risk. R-malathion showed a higher risk. An analysis of the proteome, including Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and subcellular localization, indicated that energy metabolism and neurotransmitter transport were the main affected pathways. Our results provide a new scheme for the evaluation of the stereoselective exposure risk of chiral pesticides to honey bees.

Economic Benefits of Using Essential Oils in Food Stimulation Administrated to Bee Colonies

Bees are the most important pollinators of agricultural plants. The decline of bee colonies is caused by a multitude of factors of which diseases, pesticides, and climate change seem to be the most important. Losses can be huge when several factors act together. In recent years, there has been a growing interest in the use of alternative sources such as medicinal plants in the form of extracts or essential oils. The purpose of our research was to evaluate the economic efficiency of the use of essential oils of basil (Ocimum basilicum), cinnamon (Cinnamomum veruum), clove (Syzgium aromaticum), juniper (Juniperus communis L.), oregano (Oreganum vulgare), mint (Mentha piperita), rosemary (Rosmarius officinalis), and thyme (Thymus vulgaris L.) in the additional feeding of bee colonies in the spring. Ninety colonies of Apis mellifera bees were used, which were additionally fed with sugar syrup and one of the essential oils. Our results showed strong positive correlations between the total number of germs in the gut of worker bees and the number of brood cells when using the essential oil of oregano (Oreganum vulgare) (R2 = 0.786) and thyme (Thymus vulgaris L.) (R2 = 0.729), and between the total number of germs and the yield of honey obtained at the first harvest in the case of the essential oil of basil (Ocimum basilicum) (R2 = 1), mint (Mentha piperita) (R2 = 0.718), oregano (Oreganum vulgare) (R2 = 0.621), and Thyme (Thymus vulgaris L) (R2 = 0.859). The best profit from the sale of honey was obtained in the case of the use of essential oils of mint, oregano, thyme, and basil, in a range of EUR 139.16–144.73/bee colony.

Imidacloprid Pesticide Causes Unexpectedly Severe Bioelement Deficiencies and Imbalance in Honey Bees Even at Sublethal Doses.

Pesticides impair honeybee health in many ways. Imidacloprid (IMD) is a pesticide used worldwide. No information exists on how IMD impact the bees' body bioelement balance, which is essential for bee health. We hypothesized that IMD disturbs this balance and fed the bees (in field conditions) with diets containing 0 ppb (control), 5 ppb (sublethal considered field-relevant), and 200 ppb (adverse) doses of IMD. IMD severely reduced the levels of K, Na, Ca, and Mg (electrolytic) and of Fe, Mo, Mn, Co, Cu, Ni, Se, and Zn, while those of Sn, V, and Cr (enzymatic) were increased. Levels of P, S, Ti, Al, Li, and Sr were also decreased, while only the B content (physiologically essential) was increased. The increase in Tl, Pb, and As levels (toxic) was alarming. Generally, IMD, even in sublethal doses, unexpectedly led to severe bioelement malnutrition in 69% of bioelements and to a stoichiometric mismatch in the remaining ones. This points to the IMD-dependent bioelement disturbance as another, yet unaccounted for, essential metabolic element which can interfere with apian health. Consequently, there is a need for developing methods of bioelement supplementation of the honey bee diet for better preventing bee colony decline and protecting apian health status when faced with pesticides.

Different effects of pesticides on transcripts of the endocrine regulation and energy metabolism in honeybee foragers from different colonies

Honeybees are important pollinators of many crops and contribute to biological biodiversity. For years, a decline in bee populations has been observed in certain areas. This decline in honeybees is accompanied by a decrease in pollinator services. One factor contributing to the decline of bee colonies is the exposure to pesticides. Pesticide exposure of bees, among other effects, can negatively affect orientation, memory, immune system function and gene expression. Among the altered expressed genes are transcripts of endocrine regulation and oxidative phosphorylation. Endocrine regulation plays an important role in the development of nurse bees into foragers and oxidative phosphorylation is involved in energy metabolism. Most of these transcriptional changes were investigated using mixed aged honeybees derived from the same colony. Experiments using nurse bees or foragers of the same age but from different colonies are rare. In the present study, effects of the two pesticides chlorpyrifos and pyraclostrobin on the expression of transcripts linked to endocrine regulation and oxidative phosphorylation in foragers of the same age from three different colonies are investigated to fill this gap. These two pesticides were selected because negative effects at sublethal concentrations on bees are known and because they are found in pollen and nectar of crops and wild plants. For this purpose, 20–22 days old foragers of three different colonies were exposed to different sublethal concentrations of the selected fungicides for 24 h, followed by analysis of the expression of buffy, vitellogenin, hbg-3, ilp-1, mrjp1, 2 and 3, cox5a, cox5b and cox17. Some significant changes in gene expression of both endocrine regulation transcripts and oxidative phosphorylation were shown. Furthermore, it became clear that forager bees from different colonies react differently. This is especially important in relation to the risk analysis of pesticides. In addition, it could be shown that the expression of hbg-3 in the brain of bees is a robust marker to distinguish nurse bees from foragers at the molecular biological level. In summary, this study clearly shows that pesticides, which are often detected in pollen and nectar, display negative effects at sublethal concentrations on bees and that it is important to use bees from different colonies for risk assessment of pesticides.