2024

Jump to: 2023, 2022, 2021

9 pages, 508 KiB

Open AccessArticle

Micronutrient Deficiency May Be Associated with the Onset of Chalkbrood Disease in Honey Bees

by Ratko Pavlović, Robert Brodschneider, Walter Goessler, Ljubiša Stanisavljević, Zoran Vujčić and Nenad M. Zarić

Insects 2024, 15(4), 269; https://doi.org/10.3390/insects15040269 - 12 Apr 2024

Viewed by 503

Abstract

Chalkbrood is a disease of honey bee brood caused by the fungal parasite Ascosphaera apis. Many factors such as genetics, temperature, humidity and nutrition influence the appearance of clinical symptoms. Poor nutrition impairs the immune system, which favors the manifestation of symptoms [...] Read more.

Chalkbrood is a disease of honey bee brood caused by the fungal parasite Ascosphaera apis. Many factors such as genetics, temperature, humidity and nutrition influence the appearance of clinical symptoms. Poor nutrition impairs the immune system, which favors the manifestation of symptoms of many honey bee diseases. However, a direct link between dietary ingredients and the symptoms of chalkbrood disease has not yet been established. We show here that the elemental composition of chalkbrood mummies and healthy larvae from the same infected hives differ, as well as that mummies differ from larvae from healthy hives. Chalkbrood mummies had the highest concentration of macroelements such as Na, Mg, P, S, K and Ca and some microelements such as Rb and Sn, and at the same time the lowest concentration of B, As, Sr, Ag, Cd, Sb, Ba and Pb. Larvae from infected hives contained less Pb, Ba, Cs, Sb, Cd, Sr, As, Zn, Cu, Ni, Co, Mn, Cr, V and Al in contrast to healthy larvae from a disease-free apiary. This is the first study to demonstrate such differences, suggesting that an infection alters the larval nutrition or that nutrition is a predisposition for the outbreak of a chalkbrood infection. Though, based on results obtained from a case study, rather than from a controlled experiment, our findings stress the differences in elements of healthy versus diseased honey bee larvae. Full article

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15 pages, 1041 KiB

Open AccessArticle

Effects of Disinfectants on Bacterium Paenibacillus larvae in Laboratory Conditions

by Ivana Tlak Gajger, Zlatko Tomljanović, Franco Mutinelli, Anna Granato and Josipa Vlainić

Insects 2024, 15(4), 268; https://doi.org/10.3390/insects15040268 - 12 Apr 2024

Viewed by 318

Abstract

American foulbrood is an infectious disease of the honeybee brood that causes multiple types of damage to beekeeping. The causative agent of the disease is the bacterium Paenibacillus larvae, which forms resistant infective spores and is viable for decades. After the eradication [...] Read more.

American foulbrood is an infectious disease of the honeybee brood that causes multiple types of damage to beekeeping. The causative agent of the disease is the bacterium Paenibacillus larvae, which forms resistant infective spores and is viable for decades. After the eradication measures have been implemented, in cases of clinically visible disease, it is necessary to conduct effective final disinfections of equipment and tools. This study aimed to determine the effect of ten commercially available and commonly used disinfectants on certified strains of P. larvae under laboratory conditions, as well as to compare the obtained results among individual genotypes of P. larvae. Selected products were tested by determining the zone of inhibition using an agar diffusion test, a suspension test for viable bacteria, a surface disinfectant test, and a sporicidal effect in the suspension test. Incidin OxyFoam S and Sekusept Aktiv are both effective against all examined genotypes of P. larvae. Despadac and Despadac Secure have a bactericidal effect, but their sporocidal effect is not as satisfactory as that of Genox. Genoll does not exhibit a sporicidal effect, and Ecocide S at 1%, Bee protect H forte, and Bee protect F did not exhibit a satisfactory sporocidal effect. Additionally, EM^® PROBIOTIC FOR BEES did not exhibit any bactericidal effect. The effective application of control measures and proper application of final disinfection can reduce the reoccurrence of visible clinical signs of disease, whereas methods of early diagnosis can significantly reduce the incidence of the disease. Full article

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2023

Jump to: 2024, 2022, 2021

11 pages, 1373 KiB

Open AccessArticle

Honey vs. Mite—A Trade-Off Strategy by Applying Summer Brood Interruption for Varroa destructor Control in the Mediterranean Region

by Marin Kovačić, Aleksandar Uzunov, Ivana Tlak Gajger, Marco Pietropaoli, Victoria Soroker, Noureddine Adjlane, Valerija Benko, Leonidas Charistos, Raffaele Dall’Olio, Giovanni Formato, Fani Hatjina, Valeria Malagnini, Fabrizio Freda, Asaf Otmi, Zlatko Puškadija, Claudio Villar and Ralph Büchler

Insects 2023, 14(9), 751; https://doi.org/10.3390/insects14090751 - 07 Sep 2023

Viewed by 2489

Abstract

In this study, we investigated the effect of queen caging on honey bee colonies’ post-treatment development and the optimal timing of method application on honey production during the main summer nectar flow. We conducted the study in nine apiaries (N = 9) across [...] Read more.

In this study, we investigated the effect of queen caging on honey bee colonies’ post-treatment development and the optimal timing of method application on honey production during the main summer nectar flow. We conducted the study in nine apiaries (N = 9) across six Mediterranean countries, with a total of 178 colonies. The colonies were divided into three test groups: QC1, QC2, and C. The QC1 group involved queens caged for a total of 28 days before the expected harvesting day. In the QC2 group, queens were caged for 28 days, but only 14 days before the expected harvesting day. The C group consisted of queens that were not caged, and the colonies received common local treatments. In both the QC1 and QC2 groups, the colonies were treated with a 4.2% oxalic acid (OA) solution by trickling after the queen release. Our findings revealed no significant adverse effects (p > 0.05) on colony strength at the end of the study resulting from queen caging. However, significantly lower amounts of honey were extracted from the QC1 group compared to both the QC2 group (p = 0.001) and the C group (p = 0.009). Although there were no initial differences in Varroa destructor infestation between the groups, ten weeks later, a significantly higher infestation was detected in the C group compared to both the QC1 group (p < 0.01) and the QC2 group (p = 0.003). Overall, our study demonstrates that queen caging, in combination with the use of OA, is an effective treatment for controlling V. destructor. However, the timing of caging plays a crucial role in honey production outcomes. Full article

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15 pages, 2201 KiB

Open AccessArticle

Intraspecific Variability in Proteomic Profiles and Biological Activities of the Honey Bee Hemolymph

by Salma A. Elfar, Iman M. Bahgat, Mohamed A. Shebl, Mathieu Lihoreau and Mohamed M. Tawfik

Insects 2023, 14(4), 365; https://doi.org/10.3390/insects14040365 - 06 Apr 2023

Cited by 1 | Viewed by 1565

Abstract

Pollinator declines have raised major concerns for the maintenance of biodiversity and food security, calling for a better understanding of environmental factors that affect their health. Here we used hemolymph analysis to monitor the health status of Western honey bees Apis mellifera. [...] Read more.

Pollinator declines have raised major concerns for the maintenance of biodiversity and food security, calling for a better understanding of environmental factors that affect their health. Here we used hemolymph analysis to monitor the health status of Western honey bees Apis mellifera. We evaluated the intraspecific proteomic variations and key biological activities of the hemolymph of bees collected from four Egyptian localities characterized by different food diversities and abundances. Overall, the lowest protein concentrations and the weakest biological activities (cytotoxicity, antimicrobial and antioxidant properties) were recorded in the hemolymph of bees artificially fed sucrose solution and no pollen. By contrast, the highest protein concentrations and biological activities were recorded in bees that had the opportunity to feed on various natural resources. While future studies should expand comparisons to honey bee populations exposed to more different diets and localities, our results suggest hemolymph samples can be used as reliable indicators of bee nutrition. Full article

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2022

Jump to: 2024, 2023, 2021

13 pages, 1450 KiB

Open AccessArticle

Interaction between Thiamethoxam and Deformed Wing Virus Type A on Wing Characteristics and Expression of Immune and Apoptosis Genes in Apis mellifera

by Patcharin Phokasem, Wannapha Mookhploy, Sasiprapa Krongdang, Chainarong Sinpoo and Panuwan Chantawannakul

Insects 2022, 13(6), 515; https://doi.org/10.3390/insects13060515 - 31 May 2022

Cited by 1 | Viewed by 2142

Abstract

Honey bees are economically important insects for crop pollination. They play a significant role as pollinators of wild plants and agricultural crops and produce economical products, such as honey, royal jelly, wax, pollen, propolis, and venom. Despite their ecological and economical importance, the [...] Read more.

Honey bees are economically important insects for crop pollination. They play a significant role as pollinators of wild plants and agricultural crops and produce economical products, such as honey, royal jelly, wax, pollen, propolis, and venom. Despite their ecological and economical importance, the global honey bee population is in decline due to factors including pathogens, parasites, intensive agriculture, and pesticides. Moreover, these factors may be interlinked and exacerbate the loss of honey bees. This study aimed to investigate the interaction between a pesticide, thiamethoxam, and deformed wing virus type A (DWV-A) to honey bees and the effects on survival rate, wing characteristics, and expression of immune and apoptosis genes in Apis mellifera. We described the potential interaction between thiamethoxam and DWV-A on honey bee wing characteristics, DWV-A loads, and the expressions of immune (defensin, abaecin, and hymenoptaecin) and apoptosis genes (buffy, apaf1, caspase3-like, caspase8-like, and caspase9-like). Honey bee larvae were fed with three different thiamethoxam doses (0.001, 1.4, and 14.3 ng/µL of the diet). Then, thiamethoxam-treated white-eyed pupae were injected with 10⁷ copy numbers/honey bee of the DWV-A genome. The interaction between thiamethoxam and DWV-A caused a high mortality rate, crippled wings in newly emerged adult honey bees (100%), and resulted in induced expression of hymenoptaecin gene compared to the control group, while downregulation of caspase8-like, caspase9-like genes compared to the DWV injection group. Therefore, the potential interaction between thiamethoxam and DWV-A might have a deleterious effect on honey bee lifespan. The results from this study could be used as a tool to combat DWV-A infection and mitigate pesticide usage to alleviate the decrease in the honey bee population. Full article

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20 pages, 1444 KiB

Open AccessArticle

Effects of Thiamethoxam-Dressed Oilseed Rape Seeds and Nosema ceranae on Colonies of Apis mellifera iberiensis, L. under Field Conditions of Central Spain. Is Hormesis Playing a Role?

by Elena Alonso-Prados, Amelia Virginia González-Porto, Carlos García-Villarubia, José Antonio López-Pérez, Silvia Valverde, José Bernal, Raquel Martín-Hernández and Mariano Higes

Insects 2022, 13(4), 371; https://doi.org/10.3390/insects13040371 - 09 Apr 2022

Cited by 3 | Viewed by 2405

Abstract

To study the influence of thiamethoxam exposure on colony strength and pathogen prevalence, an apiary (5 colonies) was placed in front of a plot sown with winter oilseed rape (wOSR), just before the flowering phase. Before sowing, the seeds were treated with an [...] Read more.

To study the influence of thiamethoxam exposure on colony strength and pathogen prevalence, an apiary (5 colonies) was placed in front of a plot sown with winter oilseed rape (wOSR), just before the flowering phase. Before sowing, the seeds were treated with an equivalent application of 18 g thiamethoxam/ha. For comparison, a second apiary (5 colonies) was located in front of a separate 750 m plot sown with untreated wOSR. Dead foragers at the entrance of hives were assessed every 2–3 days throughout the exposure period, while the colony strength (number of combs covered with adult honey bees and brood) and pathogens were monitored each month until the following spring. Foraging on the wOSR crop was confirmed by melissopalynology determination of the corbicular pollen collected periodically, while the chemical analysis showed that exposure to thiamethoxam was mainly through nectar. There was an increase in the accumulation of dead bees in the apiary exposed to thiamethoxam relating with the control, which was coped with an increment of bee brood surface and adult bee population. However, we did not find statistically significant differences between apiaries (α = 0.05) in terms of the evolution of pathogens. We discuss these results under hormesis perspective. Full article

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17 pages, 1681 KiB

Open AccessArticle

Sensitivity of Buff-Tailed Bumblebee (Bombus terrestris L.) to Insecticides with Different Mode of Action

by Guillermo Cabezas and Gema P. Farinós

Insects 2022, 13(2), 184; https://doi.org/10.3390/insects13020184 - 10 Feb 2022

Cited by 2 | Viewed by 2223

Abstract

Systemic insecticides are recognized as one of the drivers of the worldwide bee decline as they are exposed to them through multiple pathways. Specifically, neonicotinoids, some of which are banned for outdoor use in the European Union (EU), have been pointed out as [...] Read more.

Systemic insecticides are recognized as one of the drivers of the worldwide bee decline as they are exposed to them through multiple pathways. Specifically, neonicotinoids, some of which are banned for outdoor use in the European Union (EU), have been pointed out as a major cause of bee collapse. Thus, farmers have had to look for alternatives for pest control and use known insecticides or new substances reportedly less harmful to bees. We evaluated the oral acute toxicity of six insecticides (three of them systemic: imidacloprid, thiacloprid and sulfoxaflor) with four different modes of action on buff-tailed bumblebee workers (Bombus terrestris): two banned neonicotinoids (imidacloprid, thiacloprid), two pyrethroids (deltamethrin, esfenvalerate), one sulfoximine (sulfoxaflor) and a microbial insecticide based on Bacillus thuringiensis toxins, present in genetically modified (Bt) maize. The microbial insecticide only caused mortality to bumblebee workers at extremely high concentrations, so it is expected that Bt maize does not pose a risk to them. The toxicity of the other five insecticides on bumblebees was, from highest to lowest: imidacloprid, sulfoxaflor, deltamethrin, esfenvalerate and thiacloprid. This outcome suggests that certain insecticides in use are more toxic to B. terrestris than some banned neonicotinoids. Further chronic toxicity studies, under realistic conditions, are necessary for a proper risk assessment. Full article

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2021

Jump to: 2024, 2023, 2022

9 pages, 267 KiB

Open AccessArticle

Translocation of Tebuconazole between Bee Matrices and Its Potential Threat on Honey Bee (Apis mellifera Linnaeus) Queens

by Risto Raimets, Sigmar Naudi, Marika Mänd, Vadims Bartkevičs, Guy Smagghe and Reet Karise

Insects 2022, 13(1), 45; https://doi.org/10.3390/insects13010045 - 31 Dec 2021

Cited by 6 | Viewed by 4201

Abstract

Various pesticide residues can be found in different bee colony components. The queen larvae of honey bee (Apis mellifera L.) receive non-contaminated food from nurse bees. However, there is little knowledge about how pesticide residues affect developing bees. Additionally, little is known [...] Read more.

Various pesticide residues can be found in different bee colony components. The queen larvae of honey bee (Apis mellifera L.) receive non-contaminated food from nurse bees. However, there is little knowledge about how pesticide residues affect developing bees. Additionally, little is known about the migration of lipophilic pesticides between bee matrices. While wax, royal jelly (RJ), and bee larvae are chemically distinct, they all contain lipids and we expected the lipophilic fungicide tebuconazole to be absorbed by different contacting materials. Our aim was to analyze the translocation of tebuconazole residues from queen cell wax to RJ, queen larvae, and newly emerged queens and to evaluate its potential risk to queens. We demonstrated the potential for the migration of tebuconazole from wax to RJ, with a strong dilution effect from the original contamination source. No residues were detected in queen bee larvae and newly emerged queens, indicating that the migration of tebuconazole probably did not directly endanger the queen bee, but there was some risk that tebuconazole might still affect the homeostasis of developing bees. Full article

20 pages, 2281 KiB

Open AccessArticle

Reliability of Morphological and PCR Methods for the Official Diagnosis of Aethina tumida (Coleoptera: Nitidulidae): A European Inter-Laboratory Comparison

by Stéphanie Franco, Nicolas Cougoule, Amandine Tison, Aurélie Del Cont, Cristina Gastaldi, ILC Consortium and Véronique Duquesne

Insects 2022, 13(1), 33; https://doi.org/10.3390/insects13010033 - 28 Dec 2021

Cited by 3 | Viewed by 1876

Abstract

The Small Hive Beetle (Aethina tumida Murray, 1867) is an invasive scavenger of honeybees. Originally endemic in sub-Saharan Africa, it is regulated internationally in order to preserve the areas still free from this species. To ensure the reliability of official diagnoses in [...] Read more.

The Small Hive Beetle (Aethina tumida Murray, 1867) is an invasive scavenger of honeybees. Originally endemic in sub-Saharan Africa, it is regulated internationally in order to preserve the areas still free from this species. To ensure the reliability of official diagnoses in case of introduction, an inter-laboratory comparison was organised on the identification of A. tumida by morphology and real-time PCR. Twenty-two National Reference Laboratories in Europe participated in the study and analysed 12 samples with adult coleopterans and insect larvae. The performance of the laboratories was evaluated in terms of sensitivity and specificity. Sensitivity was satisfactory for all the participants and both types of methods, thus fully meeting the diagnostic challenge of confirming all truly positive cases as positive. Two participants encountered specificity problems. For one, the anomaly was minor whereas, for the other, the issues concerned a larger number of results, especially real-time PCR, which probably were related to inexperience with this technique. The comparison demonstrated the reliability of official diagnosis, including the entire analytical process of A. tumida identification: from the first step of the analysis to the expression of opinions. The performed diagnostic tools, in parallel with field surveillance, are essential to managing A. tumida introduction. Full article

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19 pages, 6188 KiB

Open AccessArticle

Suitable Areas for Apiculture Expansion Determined by Antioxidant Power, Chemical Profiles, and Pesticide Residues in Caldcluvia paniculata Honey and Beeswax Samples

by Enrique Mejías, Carlos Gómez and Tatiana Garrido

Insects 2022, 13(1), 31; https://doi.org/10.3390/insects13010031 - 28 Dec 2021

Cited by 2 | Viewed by 1830

Abstract

Forty-two samples of Tiaca Honey (Caldcluvia paniculata) obtained from beehives belonging to 14 apiaries (three honey samples per apiary) were collected at the end of January near Osorno (40°34′ S, 73°8′ W), Puyehue (40°40′ S, 72°37′ W) and Frutillar 41°7′ S, [...] Read more.

Forty-two samples of Tiaca Honey (Caldcluvia paniculata) obtained from beehives belonging to 14 apiaries (three honey samples per apiary) were collected at the end of January near Osorno (40°34′ S, 73°8′ W), Puyehue (40°40′ S, 72°37′ W) and Frutillar 41°7′ S, 72°59′ W) covering an area of 1240 km². They presented the highest phenol contents (0.36 mg gallic acid equivalent/kg) and antioxidant power (1.27 mM equivalent of Fe⁺²/g of sample), and were among the highest for antiradical activity. Phenol contents and antioxidant power (r = 0.72, p-value < 0.01) and total phenol contents and antiradical activity (r = 0.69; p-value < 0.01) displayed linear correlations. Only two beeswax samples showed residues of the pesticide fenhexamid. The respective sites (Purranque [40°55′ S, 73°10′ W] and Coligual [40°49′ S, 72°54′ W]) were the only areas located near active farms. Additionally, the m/z value 163.1091 was found as an element to identify honeys. Data were used to construct a mapped suitability index ranking for pesticide-free areas with high biological quality. The provided chemical profiles will aid local beekeepers in obtaining international certifications, particularly for the EU market. In turn, the constructed maps indicate suitable areas for apiculture expansion, while differentiated pesticide detection in honey and beeswax requires further comparative research. Full article

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17 pages, 6475 KiB

Open AccessArticle

Unprecedented Density and Persistence of Feral Honey Bees in Urban Environments of a Large SE-European City (Belgrade, Serbia)

by Jovana Bila Dubaić, Slađan Simonović, Milan Plećaš, Ljubiša Stanisavljević, Slobodan Davidović, Marija Tanasković and Aleksandar Ćetković

Insects 2021, 12(12), 1127; https://doi.org/10.3390/insects12121127 - 16 Dec 2021

Cited by 14 | Viewed by 5621

Abstract

It is assumed that wild honey bees have become largely extinct across Europe since the 1980s, following the introduction of exotic ectoparasitic mite (Varroa) and the associated spillover of various pathogens. However, several recent studies reported on unmanaged colonies that survived [...] Read more.

It is assumed that wild honey bees have become largely extinct across Europe since the 1980s, following the introduction of exotic ectoparasitic mite (Varroa) and the associated spillover of various pathogens. However, several recent studies reported on unmanaged colonies that survived the Varroa mite infestation. Herewith, we present another case of unmanaged, free-living population of honey bees in SE Europe, a rare case of feral bees inhabiting a large and highly populated urban area: Belgrade, the capital of Serbia. We compiled a massive data-set derived from opportunistic citizen science (>1300 records) during the 2011–2017 period and investigated whether these honey bee colonies and the high incidence of swarms could be a result of a stable, self-sustaining feral population (i.e., not of regular inflow of swarms escaping from local managed apiaries), and discussed various explanations for its existence. We also present the possibilities and challenges associated with the detection and effective monitoring of feral/wild honey bees in urban settings, and the role of citizen science in such endeavors. Our results will underpin ongoing initiatives to better understand and support naturally selected resistance mechanisms against the Varroa mite, which should contribute to alleviating current threats and risks to global apiculture and food production security. Full article

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15 pages, 3102 KiB

Open AccessArticle

Screening of Honey Bee Pathogens in the Czech Republic and Their Prevalence in Various Habitats

by Petr Mráz, Marian Hýbl, Marek Kopecký, Andrea Bohatá, Irena Hoštičková, Jan Šipoš, Kateřina Vočadlová and Vladislav Čurn

Insects 2021, 12(12), 1051; https://doi.org/10.3390/insects12121051 - 24 Nov 2021

Cited by 11 | Viewed by 2718

Abstract

Western honey bee (Apis mellifera) is one of the most important pollinators in the world. Thus, a recent honey bee health decline and frequent honey bee mass losses have drawn attention and concern. Honey bee fitness is primarily reduced by pathogens, [...] Read more.

Western honey bee (Apis mellifera) is one of the most important pollinators in the world. Thus, a recent honey bee health decline and frequent honey bee mass losses have drawn attention and concern. Honey bee fitness is primarily reduced by pathogens, parasites, and viral load, exposure to pesticides and their residues, and inadequate nutrition from both the quality and amount of food resources. This study evaluated the prevalence of the most common honey bee pathogens and viruses in different habitats across the Czech Republic. The agroecosystems, urban ecosystems, and national park were chosen for sampling from 250 colonies in 50 apiaries. Surprisingly, the most prevalent honey bee pathogens belong to the family Trypanosomatidae including Lotmaria passim and Crithidia mellificae. As expected, the most prevalent viruses were DWV, followed by ABPV. Additionally, the occurrence of DWV-B and DWV-C were correlated with honey bee colony mortality. From the habitat point of view, most pathogens occurred in the town habitat, less in the agroecosystem and least in the national park. The opposite trend was observed in the occurrence of viruses. However, the prevalence of viruses was not affected by habitat. Full article

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12 pages, 705 KiB

Open AccessArticle

Evaluating the Efficacy of 30 Different Essential Oils against Varroa destructor and Honey Bee Workers (Apis mellifera)

by Marian Hýbl, Andrea Bohatá, Iva Rádsetoulalová, Marek Kopecký, Irena Hoštičková, Alena Vaníčková and Petr Mráz

Insects 2021, 12(11), 1045; https://doi.org/10.3390/insects12111045 - 21 Nov 2021

Cited by 20 | Viewed by 5098

Abstract

Essential oils and their components are generally known for their acaricidal effects and are used as an alternative to control the population of the Varroa destructor instead of synthetic acaricides. However, for many essential oils, the exact acaricidal effect against Varroa mites, as [...] Read more.

Essential oils and their components are generally known for their acaricidal effects and are used as an alternative to control the population of the Varroa destructor instead of synthetic acaricides. However, for many essential oils, the exact acaricidal effect against Varroa mites, as well as the effect against honey bees, is not known. In this study, 30 different essential oils were screened by using a glass-vial residual bioassay. Essential oils showing varroacidal efficacy > 70% were tested by the complete exposure assay. A total of five bees and five mites were placed in the Petri dishes in five replications for each concentration of essential oil. Mite and bee mortality rates were assessed after 4, 24, 48, and 72 h. The LC₅₀ values and selectivity ratio (SR) were calculated. For essential oils with the best selectivity ratio, their main components were detected and quantified by GC-MS/MS. The results suggest that the most suitable oils are peppermint and manuka (SR > 9), followed by oregano, litsea (SR > 5), carrot, and cinnamon (SR > 4). Additionally, these oils showed a trend of the increased value of selective ratio over time. All these oils seem to be better than thymol (SR < 3.2), which is commonly used in beekeeping practice. However, the possible use of these essential oils has yet to be verified in beekeeping practice. Full article

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18 pages, 2159 KiB

Open AccessArticle

Novel TaqMan PCR Assay for the Quantification of Paenibacillus larvae Spores in Bee-Related Samples

by Darja Kušar, Bojan Papić, Urška Zajc, Irena Zdovc, Majda Golob, Lucija Žvokelj, Tanja Knific, Jana Avberšek, Matjaž Ocepek and Metka Pislak Ocepek

Insects 2021, 12(11), 1034; https://doi.org/10.3390/insects12111034 - 17 Nov 2021

Cited by 7 | Viewed by 2429

Abstract

Paenibacillus larvae is the causative agent of American foulbrood (AFB), a devastating disease of honeybees. P. larvae spore counts in bee-related samples correlate with the presence of AFB symptoms and may, therefore, be used to identify at-risk colonies. Here, we constructed a TaqMan-based [...] Read more.

Paenibacillus larvae is the causative agent of American foulbrood (AFB), a devastating disease of honeybees. P. larvae spore counts in bee-related samples correlate with the presence of AFB symptoms and may, therefore, be used to identify at-risk colonies. Here, we constructed a TaqMan-based real-time PCR (qPCR) assay targeting a single-copy chromosomal metalloproteinase gene for reliable quantification of P. larvae. The assay was calibrated using digital PCR (dPCR) to allow absolute quantification of P. larvae spores in honey and hive debris samples. The limits of detection and quantification were 8 and 58 spores/g for honey and 188 and 707 spores/mL for hive debris, respectively. To assess the association between AFB clinical symptoms and spore counts, we quantified spores in honey and hive debris samples originating from honeybee colonies with known severity of clinical symptoms. Spore counts in AFB-positive colonies were significantly higher than those in asymptomatic colonies but did not differ significantly with regard to the severity of clinical symptoms. For honey, the average spore germination rate was 0.52% (range = 0.04–6.05%), indicating poor and inconsistent in vitro germination. The newly developed qPCR assay allows reliable detection and quantification of P. larvae in honey and hive debris samples but can also be extended to other sample types. Full article

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11 pages, 7538 KiB

Open AccessArticle

Effectiveness of Different Soft Acaricides against Honey Bee Ectoparasitic Mite Varroa destructor (Acari: Varroidae)

by Ziyad Abdul Qadir, Atif Idrees, Rashid Mahmood, Ghulam Sarwar, Muhammad Abu Bakar, Saboor Ahmad, Muhammad Mohsin Raza and Jun Li

Insects 2021, 12(11), 1032; https://doi.org/10.3390/insects12111032 - 17 Nov 2021

Cited by 20 | Viewed by 5890

Abstract

Honey bees (Apis mellifera) are essential for their products—honey, royal jelly, pollen, propolis and beeswax. They are also indispensable because they support ecosystems with their pollination services. However, the production and functions of honey bees are hindered by the arthropod pest [...] Read more.

Honey bees (Apis mellifera) are essential for their products—honey, royal jelly, pollen, propolis and beeswax. They are also indispensable because they support ecosystems with their pollination services. However, the production and functions of honey bees are hindered by the arthropod pest Varroa destructor, which attacks bees through its feeding activities. Efforts to control varroa mites have been made through the development of various synthetic pesticide groups, but have had limited success because the mites developed resistance and some of these pesticides are harmful to bees. Branded pesticides are rarely used in Pakistan, as beekeepers utilize acaricides from unknown sources. There is a need to create awareness of available naturally occurring acaricides that may serve as an alternative to synthetic acaricides. Although some naturally occurring compounds are considered toxic to the environment, the soft acaricides oxalic acid, thymol, and formic acid 65% are usually safe for honey bee colonies and beekeepers, when handled appropriately. The current study investigated the effectiveness of formic acid (10, 15, and 20 mL/hive), oxalic acid (4.2, 3.2, and 2.1%/hive), and thymol (6, 4, and 2 g/hive) in controlling mite infestation. The results indicated that all treatments significantly reduced the mite population (p < 0.05). The average efficacies of oxalic acid at 3.2% (94.84% ± 0.34) and 4.2% (92.68% ± 0.37) were significantly higher than those of the other treatments. The lowest efficacy was recorded in formic acid 65% at 10 mL (54.13%). Overall, the results indicated that soft acaricides—such as oxalic acid at 3.2% and 4.2% concentrations—are very effective at controlling varroa mites and can be used in broodless conditions without side effects. Full article

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15 pages, 12950 KiB

Open AccessArticle

Bumble Bee Foraged Pollen Analyses in Spring Time in Southern Estonia Shows Abundant Food Sources

by Anna Bontšutšnaja, Reet Karise, Marika Mänd and Guy Smagghe

Insects 2021, 12(10), 922; https://doi.org/10.3390/insects12100922 - 09 Oct 2021

Cited by 2 | Viewed by 2432

Abstract

Agricultural landscapes usually provide higher quantities of single-source food, which are noticeably lacking in diversity and might thus have low nutrient value for bumble bee colony development. Here, in this study, we analysed the pollen foraging preferences over a large territory of a [...] Read more.

Agricultural landscapes usually provide higher quantities of single-source food, which are noticeably lacking in diversity and might thus have low nutrient value for bumble bee colony development. Here, in this study, we analysed the pollen foraging preferences over a large territory of a heterogeneous agricultural landscape: southern Estonia. We aimed to assess the botanical diversity of bumble bee food plants in the spring time there. We looked for preferences for some food plants or signs of food shortage that could be associated with any particular landscape features. For this purpose, we took Bombus terrestris commercial hives to the landscape, performed microscopy analyses and improved the results with the innovative DNA metabarcoding technique to determine the botanical origin of bumble bee-collected pollen. We found high variability of forage plants with no strong relationship with any particular landscape features. Based on the low number of plant species in single flights, we deduce that the availability of main forage plants is sufficient indicating rich forage availabilities. Despite specific limitations, we saw strong correlations between microscopy and DNA metabarcoding data usable for quantification analyses. As a conclusion, we saw that the spring-time vegetation in southern Estonia can support bumble bee colony development regardless of the detailed landscape structure. The absence of clearly dominating food preference by the tested generalist bumble bee species B. terrestris makes us suggest that other bumble bee species, at least food generalists, should also find plenty of forage in their early development phase. Full article

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14 pages, 1385 KiB

Open AccessArticle

Effects of Agaricus bisporus Mushroom Extract on Honey Bees Infected with Nosema ceranae

by Uros Glavinic, Milan Rajkovic, Jovana Vunduk, Branislav Vejnovic, Jevrosima Stevanovic, Ivanka Milenkovic and Zoran Stanimirovic

Insects 2021, 12(10), 915; https://doi.org/10.3390/insects12100915 - 07 Oct 2021

Cited by 16 | Viewed by 2680

Abstract

Agaricus bisporus water crude extract was tested on honey bees for the first time. The first part of the cage experiment was set for selecting one concentration of the A. bisporus extract. Concentration of 200 µg/g was further tested in the second part [...] Read more.

Agaricus bisporus water crude extract was tested on honey bees for the first time. The first part of the cage experiment was set for selecting one concentration of the A. bisporus extract. Concentration of 200 µg/g was further tested in the second part of the experiment where bee survival and food consumption were monitored together with Nosema infection level and expression of five genes (abaecin, hymenoptaecin, defensin, apidaecin, and vitellogenin) that were evaluated in bees sampled on days 7 and 15. Survival rate of Nosema-infected bees was significantly greater in groups fed with A. bisporus-enriched syrup compared to those fed with a pure sucrose syrup. Besides, the anti-Nosema effect of A. bisporus extract was greatest when applied from the third day which coincides with the time of infection with N. ceranae. Daily food consumption did not differ between the groups indicating good acceptability and palatability of the extract. A. bisporus extract showed a stimulative effect on four out of five monitored genes. Both anti-Nosema and nutrigenomic effects of A. bisporus extract were observed when supplementation started at the moment of N. ceranae infection or preventively (before or simultaneously with the infection). Full article

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15 pages, 737 KiB

Open AccessArticle

A Multi-Scale Model of Disease Transfer in Honey Bee Colonies

by Matthew Betti and Karalyne Shaw

Insects 2021, 12(8), 700; https://doi.org/10.3390/insects12080700 - 04 Aug 2021

Cited by 2 | Viewed by 2815

Abstract

Inter-colony disease transfer poses a serious hurdle to successfully managing healthy honeybee colonies. In this study, we build a multi-scale model of two interacting honey bee colonies. The model considers the effects of forager and drone drift, guarding behaviour, and resource robbing of [...] Read more.

Inter-colony disease transfer poses a serious hurdle to successfully managing healthy honeybee colonies. In this study, we build a multi-scale model of two interacting honey bee colonies. The model considers the effects of forager and drone drift, guarding behaviour, and resource robbing of dying colonies on the spread of disease between colonies. Our results show that when drifting is high, disease can spread rapidly between colonies, that guarding behaviour needs to be particularly efficient to be effective, and that for dense apiaries drifting is of greater concern than robbing. We show that while disease can put an individual colony at greater risk, drifting can help less the burden of disease in a colony. We posit some evolutionary questions that come from this study that can be addressed with this model. Full article

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15 pages, 4450 KiB

Open AccessArticle

Japanese Honeybees (Apis cerana japonica Radoszkowski, 1877) May Be Resilient to Land Use Change

by Philip Donkersley, Lucy Covell and Takahiro Ota

Insects 2021, 12(8), 685; https://doi.org/10.3390/insects12080685 - 30 Jul 2021

Cited by 2 | Viewed by 3289

Abstract

Pollinators are being threatened globally by urbanisation and agricultural intensification, driven by a growing human population. Understanding these impacts on landscapes and pollinators is critical to ensuring a robust pollination system. Remote sensing data on land use attributes have previously linked honeybee nutrition [...] Read more.

Pollinators are being threatened globally by urbanisation and agricultural intensification, driven by a growing human population. Understanding these impacts on landscapes and pollinators is critical to ensuring a robust pollination system. Remote sensing data on land use attributes have previously linked honeybee nutrition to land use in the Western Honeybee (Apis mellifera L.). Here, we instead focus on the less commonly studied Apis cerana japonica—the Japanese Honeybee. Our study presents preliminary data comparing forage (honey and pollen) with land use across a rural-urban gradient from 22 sites in Kyushu, southern Japan. Honey samples were collected from hives between June 2018 and August 2019. Pollen were collected and biotyped from hives in urban and rural locations (n = 4). Previous studies of honey show substantial variation in monosaccharide content. Our analysis of A. cerana japonica honey found very little variation in glucose and fructose (which accounted for 97% of monosaccharides), despite substantial differences in surrounding forage composition. As expected, we observed temporal variation in pollen foraged by A. cerana japonica, likely dependent on flowering phenology. These preliminary results suggest that the forage and nutrition of A. cerana japonica may not be negatively affected by urban land use. This highlights the need for further comparative studies between A. cerana japonica and A. mellifera as it could suggest a resilience in pollinators foraging in their native range. Full article

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10 pages, 861 KiB

Open AccessCommunication

Changes in Lithium Levels in Bees and Their Products Following Anti-Varroa Treatment

by Éva Kolics, Zsófi Sajtos, Kinga Mátyás, Kinga Szepesi, Izabella Solti, Gyöngyi Németh, János Taller, Edina Baranyai, András Specziár and Balázs Kolics

Insects 2021, 12(7), 579; https://doi.org/10.3390/insects12070579 - 25 Jun 2021

Cited by 11 | Viewed by 3491

Abstract

The biggest threat to beekeeping is varroosis caused by the mite Varroa destructor. Chemicals available to treat this fatal disease may present problems of resistance or inconsistent efficacy. Recently, lithium chloride has appeared as a potential alternative. To date, the amount of [...] Read more.

The biggest threat to beekeeping is varroosis caused by the mite Varroa destructor. Chemicals available to treat this fatal disease may present problems of resistance or inconsistent efficacy. Recently, lithium chloride has appeared as a potential alternative. To date, the amount of residue lithium treatments may leave in honeybee products is poorly understood. Honeybees were fed with 25 mM lithiated sugar syrup, which was used in earlier studies. The accumulation and elimination of the lithium were monitored in bees and their products for 22 days. Lithium concentration increased in the entire body of the bees to day 4 post-treatment and then recovered rapidly to the control level. Lithium exposure was found to affect uncapped honey in the short term (<16 days), but ripe (capped) honey measured at the end of the trial remained affected. On the other hand, lithium treatment left beeswax lithium-free. Based on these data, we propose that comprehensive research on harvested honey is needed to decide on the veterinary use of lithium. Full article

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12 pages, 1355 KiB

Open AccessArticle

Polyphenols as Food Supplement Improved Food Consumption and Longevity of Honey Bees (Apis mellifera) Intoxicated by Pesticide Thiacloprid

by Marian Hýbl, Petr Mráz, Jan Šipoš, Irena Hoštičková, Andrea Bohatá, Vladislav Čurn and Tomáš Kopec

Insects 2021, 12(7), 572; https://doi.org/10.3390/insects12070572 - 23 Jun 2021

Cited by 15 | Viewed by 2269

Abstract

Malnutrition is one of the main problems related to the global mass collapse of honey bee colonies, because in honey bees, malnutrition is associated with deterioration of the immune system and increased pesticide susceptibility. Another important cause of mass bee colonies losses is [...] Read more.

Malnutrition is one of the main problems related to the global mass collapse of honey bee colonies, because in honey bees, malnutrition is associated with deterioration of the immune system and increased pesticide susceptibility. Another important cause of mass bee colonies losses is the use of pesticides. Therefore, the goal of this study was to verify the influence of polyphenols on longevity, food consumption, and cytochrome P450 gene expression in worker bees intoxicated by thiacloprid. The tests were carried out in vitro under artificial conditions (caged bees). A conclusively lower mortality rate and, in parallel, a higher average food intake, were observed in intoxicated bees treated using a mixture of phenolic acids and flavonoids compared to untreated intoxicated bees. This was probably caused by increased detoxification capacity caused by increased expression level of genes encoding the cytochrome P450 enzyme in the bees. Therefore, the addition of polyphenols into bee nutrition is probably able to positively affect the detoxification capacity of bees, which is often reduced by the impact of malnutrition resulting from degradation of the environment and common beekeeping management. Full article

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