Decline Of Bee Colonies Research Articles

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.

Characterisation of thymol effects on RDL receptors from the bee parasite Varroa destructor

A major contributor to bee colony decline is infestation with its most devastating pest, the mite Varroa destructor. To control these mites, thymol is often used, although how it achieves this is not understood. One well-documented action of thymol is to modulate GABA-activated ion channels, which includes insect RDL receptors, a known insecticidal target. Here we have cloned two Varroa RDL subunits, one of which is similar to the canonical RDL subunit, while the other has some differences in M4, and, to a lesser extent, M2 and its binding site loops. Expression of this unusual RDL receptor in Xenopus oocytes reveals GABA-activated receptors, with an EC50 of 56 μM. In contrast to canonical RDL receptors, thymol does not enhance GABA-elicited responses in this receptor, and concentration response curves reveal a decrease in GABA Imax in its presence; this decrease is not seen when similar data are obtained from Apis RDL receptors. We conclude that an M2 T6′M substitution is primarily responsible for the different thymol effects, and suggest that understanding how and where thymol acts could assist in the design of novel bee-friendly miticides.

Impact of Neonicotinoid Insecticides on the Foraging Activity of Indian Honey Bee, Apiscerana indica (Fab.) in the Cotton Ecosystem

Indian honey bees are the important managed pollinators of several agricultural and horticultural crops in India. At present, bee colony decline is the biggest crisis amongbeekeepers. The use of neonicotinoid insecticides is considered the prime factor, and they were found to cause a direct impact on bees by mortality and indirectly impair the foraging behavior of bees. Hence, the study aimed to assess the impact of neonicotinoids on the foraging activity of Indian honey bees. The neonicotinoids viz., imidacloprid 17.8 SL, clothianidin 50 WDG, thiamethoxam 25 WG, and thiacloprid 21.7 SC, along with organophosphate dimethoate 30 EC (chemical check) and control (no spray) were sprayed at field recommended doses on cotton crop. Foraging activity of the bees,viz.,incoming foragers with nectar and pollen load and outgoing foragers were counted at the hive entrance during the morning (09.00-11.00), afternoon (13.00-15.00), and evening (16.00-18.00) hours of the day. The data were recorded at pre-treatment count and posttreatment count on different day intervals viz., 1DAS, 3DAS, 7DAS, and 15DAS. The mean number of incoming nectar, pollen foragers, and outgoing foragers were recorded to be maximum in control than neonicotinoid-treated plots. Hence, the reduction in foraging activity may lead to areduction in the food storage area and brood area ultimately lesseningthe overall colony growth. It’s always better to avoid spraying cotton crop during the flowering period using neonicotinoids to dodge the residues even though cotton is not a food crop; meanwhile, it will safeguard the pollinators.

A scientific note of pest-insects associated with stingless bee hive Melipona eburnea in the Ecuadorian Amazon Region

Bees are the primary pollinators in nature. However, climate change, excessive use of fertilizers and invasive species have caused the decline of bee colonies. Therefore, this study aimed to analyze the presence of pests in colonies of Melipona eburnea. For this, the colonies of M. eburnea were examined during the honey extraction process. We found 4 different pests associated with the physical conditions of colonies and the fragile defense of the bees against the invaders. In conclusion, this report of the presence of pests is to alert researchers and meliponicultures to prevent the decline of stingless bees.

Beekeeping Production System, Challenges, and Opportunities in Selected Districts of South Wollo Zone, Amhara, Ethiopia

The study was conducted in Tehulederie, Kalu, and Dessie Zuria districts of South Wollo Zone, Amhara, Ethiopia, to assess the current beekeeping production system with available opportunities and challenges facing the beekeeping subsector. The districts were purposively selected based on potential and accessibility and then stratified into lowland, midland, and highland. In total, 135 beekeepers, of which 126 were males and 9 were females, were interviewed using a pretested semistructured questionnaire. The result revealed that beekeeping is actively practiced by the community regardless of age and sex. Three beekeeping production systems, that is, traditional, transitional, and movable frame hive, have been identified, accounting for 80%, 4%, and 16%, respectively. More than 80% of total bee colonies are managed being placed in the backyard. Besides, the study indicated that about 79% of the beekeepers keep bees primarily for income generation and home consumption. According to this study, the average bee colony holding size is 5.13 per a beekeeper. Also, this study identified that the swarm catching method is the major source of bee colony accounting for more than 45% to start beekeeping and 76% to increase existing colony number. Bee colony decline, absconding and swarming, honeybee pests and predators, and lack of training and extension were identified as major beekeeping challenges in the study areas. This study identified the beekeeping production system, opportunities, and challenges of the study areas and has significantly contributed to our knowledge and identified lack of extension and training as intervention areas. Therefore, practical beekeeping training and extension should get primary emphasis to combat the existing challenges.

Microplastic Polystyrene Ingestion Promotes the Susceptibility of Honeybee to Viral Infection

Microplastics (MPs) are an emerging threat to ecological conservation and biodiversity; however, little is known of the types and possible impacts of MPs in pollinators. To examine whether MPs were present in honeybees, we analyzed the honeybee samples collected in fields from six provinces in China. Four types MPs were identified in honeybee including polystyrene (PS) by Raman spectroscopic analysis, and these plastic polymers were detected in 66.7% bee samples. Then, we assessed the physical and biological impacts of PS of three sizes (0.5, 5, and 50 μm) on bees for 21 days. Next, we measured how the presence of PS affected the Israeli acute paralysis virus proliferation, a small RNA virus associated with bee colony decline. Experimental evidence showed that a large mass of PS was ingested and accumulated within the midgut and enhanced the susceptibility of bees to viral infection. Not only histological analysis showed that PS, especially 0.5 μm PS, damaged the midgut tissue and was subsequently transferred to the hemolymph, trachea, and Malpighian tubules, but also qPCR and transcriptomic results indicated that genes correlated with membrane lipid metabolism, immune response, detoxification, and the respiratory system were significantly regulated after PS ingestion. Our results highlight neglected MP contamination to the bees, a pollination ecosystem stressed by the anthropogenic pollution, and have implications for human health via ingestion of bee products.

Enzymatic responses in the head and midgut of Africanized Apis mellifera contaminated with a sublethal concentration of thiamethoxam

The increasing use of insecticides, promoted by the intensification of agriculture, has raised concerns about their influence on the decline of bee colonies, which play a fundamental role in pollination. Thus, it is fundamental to elucidate the effects of insecticides on bees. This study investigated the damage caused by a sublethal concentration of thiamethoxam - TMX (0.0227 ng/μL of feed) in the head and midgut of Africanized Apis mellifera, by analyzing the enzymatic biomarkers, oxidative stress, and occurrence of lipid peroxidation. The data showed that the insecticide increased acetylcholinesterase activity (AChE) and glutathione-S-transferase (GST), whereas carboxylesterase (CaE3) activity decreased in the heads. Our results indicate that the antioxidant enzymes were less active in the head because only glutathione peroxidase (GPX) showed alterations. In the midgut, there were no alkaline phosphatase (ALP) or superoxide dismutase (SOD) responses and a decrease in the activity of CaE was observed. Otherwise, there was an increase in GPX, and the TBARS (thiobarbituric acid reactive substances) assay also showed differences in the midgut. The TBARS (thiobarbituric acid reactive substances) assay also showed differences in the midgut. The results showed enzymes such as CaE3, GST, AChE, ALP, SOD, and GPX, as well as the TBARS assay, are useful biomarkers on bees. They may be used in combination as a promising tool for characterizing bee exposure to insecticides.

Genetic variability and phylogenetic analysis among strains of deformed wing virus infesting honey bees and other organisms.

Various viruses can infect honey bees, but deformed wing virus (DWV) is considered the most dangerous virus to them and has role in the sudden decline of bee colonies. This virus has different strains; however, there are no available studies to compare the characteristics of these strains utilizing bioinformatics. In this study, 27 strains of deformed wing virus were analyzed based on their sequences and their genetic relationships. Also, some primers were designed and tested to identify their ability to separate DWV strains. The percentages range from 28.99% to 29.63%, 22.28% to 22.78%, 15.73% to 16.28%, and 31.71% to 32.86% for nucleotides A, G, C, and T, respectively in all strains. The numbers of polymorphic sites as well as nucleotide diversity were highly similar in all strains. Statistical analyses generally showed the absence of high variations between sequences. Also, the phylogenetic tree classified strains into three groups. The network between strains of each group was established and discussed based on their geographical locations. Two groups contained strains from USA and Europe while one group contained strains from Asia. Rapid variations and mutations in the sequences of DWV were suggested. Notably, genetic studies on DWV are lacking in some geographical regions. The variations between strains detected in honey bees and other organisms were discussed. Four primers were designed and tested beside two reference primers. One of the designed primers showed the best results in binding with all DWV strains except one.

Lotmaria Passim As Third Parasite Gastrointestinal Tract of Honey Bees Living in Tree Trunk

Abstract Honey bees (Apis mellifera L.) inhabiting trees in forests are not managed by humans or treated for pathogens; therefore, many researchers and beekeepers believe that viral, bacterial, and parasitic diseases may lead to their decline. The aim of the study was to evaluate the prevalence of L. passim and Nosema spp. in feral colonies by real-time PCR. This study was performed on twenty-six samples of honey bees inhabiting tree trunks in north-eastern Poland. One sample consisted of sixty worker bee abdomens collected from hollow trees. Honey bees were sampled only from naturally colonized sites. Amplicons of the three evaluated pathogens were detected in twenty of the twenty-six tested samples. A significant correlation was observed between infection with three pathogens (N. apis, N. ceranae, L. passim) (r = 0.84) compared to infection with only two pathogens (N. apis and N. ceranae) (r = 0.49). N. ceranae was the predominant pathogen, but infections with various severity caused by L. passim were also noted in fourteen of the twenty-six tested samples. In view of the general scarcity of epidemiological data concerning coinfections with Nosema spp. and L. passim in honey bees in tree trunks in other countries, further research is needed to confirm the effect of concurrent pathogenic infections on the decline of bee colonies.

Interactions Between Thiamethoxam and Deformed Wing Virus Can Drastically Impair Flight Behavior of Honey Bees.

Exposure to multiple stress factors is believed to contribute to honey bee colony decline. However, little is known about how co-exposure to stress factors can alter the survival and behavior of free-living honey bees in colony conditions. We therefore studied the potential interaction between a neonicotinoid pesticide, thiamethoxam, and a highly prevalent honey bee pathogen, Deformed wing virus (DWV). For this purpose, tagged bees were exposed to DWV by feeding or injection, and/or to field-relevant doses of thiamethoxam, then left in colonies equipped with optical bee counters to monitor flight activity. DWV loads and the expression of immune genes were quantified. A reduction in vitellogenin expression level was observed in DWV-injected bees and was associated with precocious onset of foraging. Combined exposure to DWV and thiamethoxam did not result in higher DWV loads compared to bees only exposed to DWV, but induced precocious foraging, increased the risk of not returning to the hive after the first flight, and decreased survival when compared to single stress exposures. We therefore provided the first evidence for deleterious interactions between DWV and thiamethoxam in natural conditions.

A Reverse Genetics System for the Israeli Acute Paralysis Virus and Chronic Bee Paralysis Virus.

Honey bee viruses are associated with honey bee colony decline. Israeli acute paralysis virus (IAPV) is considered to have a strong impact on honey bee survival. Phylogenetic analysis of the viral genomes from several regions of the world showed that various IAPV lineages had substantial differences in virulence. Chronic bee paralysis virus (CBPV), another important honey bee virus, can induce two significantly different symptoms. However, the infection characteristics and pathogenesis of IAPV and CBPV have not been completely elucidated. Here, we constructed infectious clones of IAPV and CBPV using a universal vector to provide a basis for studying their replication and pathogenesis. Infectious IAPV and CBPV were rescued from molecular clones of IAPV and CBPV genomes, respectively, that induced typical paralysis symptoms. The replication levels and expression proteins of IAPV and CBPV in progeny virus production were confirmed by qPCR and Western blot. Our results will allow further dissection of the role of each gene in the context of viral infection while helping to study viral pathogenesis and develop antiviral drugs using reverse genetics systems.

Electron Paramagnetic Resonance Imaging of Melanin in Honey Bee

Honey bees play a crucial role in the nature by pollinating wild flowers. Over the past years, there has been an increasing concern regarding the honey bee colony decline. Pesticides or environmental effects targeting the biochemistry of insect chitin and cuticle coating may be in part responsible for honey bee pathologies. We here propose the use of electron paramagnetic resonance imaging (EPRI) as a tool to image the melanin-chitin complexes as part of the exoskeleton of the honey bee. EPRI at 9.65 GHz was applied on intact freeze-dried bees. The imaging data were collected on the melanin peak. High-resolution images revealed that this compound is extensively distributed in the periphery of the animal, data consistent with the localization in the cuticle of the bee. While EPR of melanin has been so far explored in the context of melanoma characterization, it may offer new opportunities in research on honey bees and other insects.

Improved Pollination Efficiency and Reduced Honey Bee Colony Decline in Greenhouses by Allowing Access to the Outside During Part of the Day

Although honey bees are efficient pollinators of many crops cultivated in greenhouses, it is difficult to maintain colony strength and consequently pollination efficiency. Many bees die under greenhouse conditions and the colonies rapidly weaken. We examined the effect of adaptations to the hive entrance that allowed control of whether and when bees had access to the outside environment to see how it would affect pollination efficiency and colony condition in greenhouses with flowering cucumber (Cucumis sativus) plants in comparison with colonies that remained constantly inside the greenhouse, previously left in a dark environment or not. We recorded the type and period of visitation to the cucumber flowers, numbers of honey bees entering and leaving the two entrance hives and the effect of this type of management on the quantity of brood and food. Fiveframe Langstroth “nucleus” colonies were equipped with two 30 square centimeter entrances and two 3.0 cm diameter circular openings. Allowing the bees to make visits outside the greenhouse in early morning with redirection of bees into the greenhouse at 8.30 a.m. did not reduce visitation to cucumber flowers in the greenhouse. Maintaining colonies in the greenhouse reduced brood area and food stores. These losses were significantly reduced in colonies that had access outside the greenhouse during the early morning. Another advantage of alternating access to the inside and the outside of the greenhouse was that there was less possibility of interactions between bees and people working on the crop, and also pesticides application could be made without directly affecting foraging bees.

The reduced brood nursing by mite-infested honey bees depends on their accelerated behavioral maturation

The parasitic mite Varroa destructor is regarded as the most important parasite of honey bees and plays a fundamental role in the decline of bee colonies observed in the last decade in the Northern hemisphere. Parasitization has a number of detrimental effects on bees, including reduced nursing, which can have important impacts on colony balance.In this work we investigated at the individual level the causes of this abnormal behavior and found that the reduced nursing activity in mite-infested workers is associated with impaired learning performance and a series of physiological traits that are typical of foragers, including reduced response to brood pheromone, limited development of hypopharyngeal glands and higher juvenile hormone titre in the haemolymph. Altogether our data confirm the premature transition to foraging already postulated based on previous genomics studies, from a physiological point of view.

Scientific note on the first report of Varroa destructor in Cameroon

Honey bee colony decline in major parts of the world represents a severe risk to global food and nutritional security (Potts et al., 2010). This trend has been attributed to a plethora of biotic, a...

Identifying The Species, Effects And Seasonal Dynamics Of Honeybee Varroa Mites: A Newly Emerging Parasite To Ethiopian Honeybee

The loss of bee colonies in recent years is a global phenomenon and Ethiopia is not exceptional. No single cause has been identified for the lose interactions of biotic and abiotic factors are speculated for the global bee colony decline.

In vitro effects of thiamethoxam on larvae of Africanized honey bee Apis mellifera (Hymenoptera: Apidae)

Several investigations have revealed the toxic effects that neonicotinoids can have on Apis mellifera, while few studies have evaluated the impact of these insecticides can have on the larval stage of the honeybee. From the lethal concentration (LC50) of thiamethoxam for the larvae of the Africanized honeybee, we evaluated the sublethal effects of this insecticide on morphology of the brain. After determine the LC50 (14.34ng/μL of diet) of thiamethoxam, larvae were exposed to a sublethal concentration of thiamethoxam equivalent to 1.43ng/μL by acute and subchronic exposure. Morphological and immunocytochemistry analysis of the brains of the exposed bees, showed condensed cells and early cell death in the optic lobes. Additional dose-related effects were observed on larval development. Our results show that the sublethal concentrations of thiamethoxam tested are toxic to Africanized honeybees larvae and can modulate the development and consequently could affect the maintenance and survival of the colony. These results represent the first assessment of the effects of thiamethoxam in Africanized honeybee larvae and should contribute to studies on honey bee colony decline.

Abscisic acid enhances the immune response in Apis mellifera and contributes to the colony fitness

The primary food of adult honey bees (Apis mellifera) is honey prepared by bees from nectar, provided by plants in order to stimulate the bee’s pollination service. Nectar consists of carbohydrates, amino acids and water, as well as other minor compounds whose proportion varies among plant species and whose biological implications in the honey bee physiology require intense research. Several environmental stressors are causing the decline of bee colonies, and thereby, we tried to connect the nutritional quality of bee’s diet with the strength of the bee’s immune system. The phytohormone abscisic acid (ABA) is present in nectar, honey and adult honey bees. It has been demonstrated that ABA stimulates innate immune defences in animal cells. However, the influence of ABA on A. mellifera’s health and fitness is unknown. Here, we show that honey bees fed with an ABA supplement in field experiments resulted in (i) the appearance of ABA in larvae and adult bees, (ii) enhanced haemocyte response to non-self recognition, (iii) improved wound healing and granulocyte and plasmatocyte activation and (iv) maximum adult bee population after the winter and increased pesticide tolerance. The results indicate that the naturally occurring compound ABA has a positive influence in honey bee immunity. ABA emerges as a potent booster of immune defence in A. mellifera and may be useful in addressing the colony losses threatening apiculture and pollination service worldwide.