Honey Bee Survival Research Articles

Chronic Exposure to Polystyrene Microplastic Fragments Has No Effect on Honey Bee Survival, but Reduces Feeding Rate and Body Weight

Microplastics (MPs), in the form of fragments and fibers, were recently found in honey samples collected in Ecuador as well as in honey bees collected from Denmark and China. However, little is known about how MPs impact bee health. To fill this knowledge gap, we investigated the potential toxicity of irregularly shaped polystyrene (PS)-MP fragments on honey bee health. In the first experiment of its kind with honey bees, we chronically exposed bees with a well-established gut microbiome to small (27 ± 17 µm) or large (93 ± 25 µm) PS-MP fragments at varying concentrations (1, 10, 100 µg mL-1) for 14 days. Bee mortality, food consumption, and body weight were all studied. We found that chronic exposure to PS-MP fragments has no effect on honey bee survival, but reduced the feeding rate and body weight, particularly at 10 µg PS-MP fragments per mL, which may have long-term consequences for honey bee health. The findings of this study could assist in the risk assessment of MPs on pollinator health.

Evaluating the Efficacy of Common Treatments Used for Vairimorpha (Nosema) spp. Control

Vairimorpha (formerly Nosema) apis and V. ceranae are microsporidian pathogens that are of concern for managed honey bee colonies. Multiple treatments have been proposed to be effective in reducing the prevalence and intensity of Vairimorpha spp. infections. Here, we test the efficacy of these products in one lab-based experiment and three field experiments. In the lab experiment, we found no reductions in Vairimorpha spp. prevalence (proportion of individuals infected with Vairimorpha spp.) or intensity (number of Vairimorpha spp. spores per individual), but we did find a decrease in honey bee survival after treatment with Fumagilin-B, Honey-B-Healthy®, and Nozevit Plus. The first field experiment showed increased Vairimorpha spp. intensity in colonies treated with Fumagilin-B and HiveAlive® compared to a negative control (sucrose syrup alone). The second field experiment showed a weak reduction in Vairimorpha spp. intensity after 3 weeks post treatment with Fumagilin-B compared to Nozevit. However, Vairimorpha spp. intensity returned to levels comparable to those of other treatment groups after 5 weeks post treatment and remained similar to those of other groups for the duration of the experiment. The final field trial showed no positive or negative effects of treatment with Fumagilin-B or Nosevit on Vairimorpha spp. prevalence or intensity. These findings raise questions regarding the efficacy of the products currently being used by beekeepers to control Vairimorpha spp. We argue that the observed reduction of Vairimorpha spp. is more likely relevant to the phenology of spore prevalence and intensity in honey bee colonies than to chemical treatment.

Insights into the effects of sublethal doses of pesticides glufosinate-ammonium and sulfoxaflor on honey bee health

Insect pollinators are threatened worldwide, being the exposure to multiple pesticides one of the most important stressor. The herbicide Glyphosate and the insecticide Imidacloprid are among the most used pesticides worldwide, although different studies evidenced their detrimental effects on non-target organisms. The emergence of glyphosate-resistant weeds and the recent ban of imidacloprid in Europe due to safety concerns, has prompted their replacement by new molecules, such as glufosinate-ammonium (GA) and sulfoxaflor (S). GA is a broad-spectrum and non-selective herbicide that inhibits a key enzyme in the metabolism of nitrogen, causing accumulation of lethal levels of ammonia; while sulfoxaflor is an agonist at insect nicotinic acetylcholine receptors (nAChRs) and generates excitatory responses including tremors, paralysis and mortality. Although those molecules are being increasingly used for crop protection, little is known about their effects on non-target organisms. In this study we assessed the impact of chronic and acute exposure to sublethal doses of GA and S on honey bee gut microbiota, immunity and survival. We found GA significantly reduced the number of gut bacteria, and decreased the expression of glucose oxidase, a marker of social immunity. On the other hand, S significantly increased the number of gut bacteria altering the microbiota composition, decreased the expression of lysozyme and increased the expression of hymenoptaecin. These alterations in gut microbiota and immunocompetence may lead to an increased susceptibility to pathogens. Finally, both pesticides shortened honey bee survival and increased the risk of death. Those results evidence the negative impact of GA and S on honey bees, even at single exposition to a low dose, and provide useful information to the understanding of pollinators decline.

The Active Site of the Enzyme 10-Formyl-THFDH in the Honey Bee Apis mellifera-A Key Player in Formic Acid Detoxification.

Honey bees are important managed pollinators that fulfill important ecological and economic functions. In recent decades, the obligate ectoparasite Varroa destructor severely affected the survival of honey bees, as it weakened them by different means. A common treatment against V. destructor is formic acid fumigation, which has been used for decades by beekeepers across the world. This treatment is known to be effective, but many beekeepers report adverse effects of formic acid on bees, which include damage to the brood, worker bee mortality, and queen loss. Little is known about the molecular mechanisms of formic acid detoxification in honey bees. Recently, we reported upregulation of the bee enzyme, 10-formyl-THFDH, under formic acid fumigation. Here, the active site of this enzyme is characterized by an interdisciplinary approach combining homology modeling and protein mutagenesis. In addition, the limitations of the 3D protein structure prediction program AlphaFold2 are shown in regard to docking studies. This study provides a more thorough understanding of the molecular detoxification mechanisms of formic acid in Apis mellifera.

Apilactobacillus kunkeei Alleviated Toxicity of Acetamiprid in Honeybee.

Nowadays, colony collapse disorder extensively affects honeybees. Insecticides, including acetamiprid, are considered as critical factors. As prevalent probiotics, we speculated that supplementation with lactic acid bacteria (LAB) could alleviate acetamiprid-induced health injuries in honeybees. Apilactobacillus kunkeei was isolated from beebread; it significantly increased the survival of honeybees under acetamiprid exportation (from 84% to 92%). Based on 16S rRNA pyrosequencing, information on the intestinal bacteria of honeybees was acquired. The results showed that supplementation with A. kunkeei significantly increased survival and decreased pollen consumption by honeybees under acetamiprid exportation. Under acetamiprid exportation, some opportunistic and pathogenic bacteria invaded the intestinal regions. Subsequently, the community richness and diversity of symbiotic microbiota were decreased. The community structure of intestinal bacteria was changed and differentiated. However, with the supplementation of A. kunkeei, the community richness and community diversity of symbiotic microbiota showed an upward trend, and the community structure was stabilized. Our results showed that A. kunkeei alleviated acetamiprid-induced symbiotic microbiota dysregulation and mortality in honeybees. This demonstrates the importance of symbiotic microbiota in honeybees and supports the application of Apilactobacillus kunkeei as probiotics in beekeeping.

Impact of nutritional and sanitary management on Apis mellifera colony dynamics and pathogen loads

Aim of study: The aim of this study was to assess the impact of the mite control strategies combined with nutritional management on honey bee colony dynamics and survival during winter, the following spring, and summer. Area of study: Santa Fe province in central Argentina. Material and methods: We set two apiaries with 40 colonies each and fed one apiary with high fructose corn syrup (HFCS) and the other with sucrose syrup (SS). Within each apiary, we treated half the colonies against Varroa mites and half of these treated colonies also received a pollen patty. The other half of the colonies remained untreated and did not received pollen patties. All colonies were sampled for Varroa infestation level, Nosema ceranae abundance and colony strength seven times during a year (from summer 2016 to autumn 2017). We computed autumn mite invasion and colony losses at each sampling time. Main results: Colonies fed with HFCS had more brood cells during the study that those fed with SS and treated colonies had fewer adult bees and Varroa infestation than untreated colonies. No significant effect of the protein supplementation was observed on any of the response variables. , SS colonies from all groups had significantly more mites drop counts than HFCS colonies. Research highlights: Considering that a reduced frequency of application is desirable, our results suggested that nutrition management could enhance chemical treatment effectiveness since honey bees might profit from improved nutrition. However, a better understanding of the nutritional requirements of the colonies under field conditions is needed.

The impact of smoke and fogged/vaporized thyme oil on honey bee (Apis mellifera) survival and behavior in vitro

Essential oils, such as thyme oil, are natural chemicals used to treat Varroa destructor infestations in western honey bee (Apis mellifera L.) colonies. We compared the effects of thyme oil/mineral oil mixtures delivered with an insect fogger or vaporizer to those of smoke from a smoker on the mortality and behavior of adult honey bees (Apis mellifera). Thyme oil delivered by fogging significantly increased caged bee mortality over that of the controls. The behaviors of thyme oil-treated bees in the observation hives were somewhat similar to those of the control bees exposed to smoke.

Selected Biochemical Markers Change after Oral Administration of Pesticide Mixtures in Honey Bees.

The honey bee is an important pollinator. In the environment, it can be exposed to many harmful factors, such as pesticides. Nowadays, attention is paid to evaluating the potentially harmful effects of these substances. This study aimed to evaluate the effect of worst-case environmental concentrations of pesticide mixtures on honey bee survival and selected physiological markers (the activity of ALT, AST, ALP, and GGTP, and the concentration of albumin, creatinine, urea, and uric acid). Pesticides of three different groups (insecticide—acetamiprid, herbicide—glyphosate, and fungicide—tebuconazole) and their mixtures were resolved in 50% (w/v) sucrose solution and given to bees ad libitum. After 24 h, hemolymph was collected. All mixtures caused higher mortality than single pesticides. Pesticides in mixtures caused disturbances in biochemical markers, and in some cases the interaction between pesticides was synergistic. The mixtures had individual effects on physiology, and the results were sensitive to changes in proportions.

Impact of Imunit® insecticide on survival and detoxification enzymes activity of adult worker honey bee (Apis mellifera L.)

آلفاسایپرمترین+تفلوبنزورون (ایمونیت®) حشره‌کشی است که توسط سازمان حفظ نباتات ایران برای کنترل کرم میوه‌خوار (Helicoverpa armigera Hübner) در مزارع گوجه‌فرنگی توصیه می‌شود. در این پژوهش، تأثیر ایمونیت® روی نرخ بقای حشرات بالغ زنبورعسل کارگر (Apis mellifera L.) در شرایط آزمایشگاهی بررسی شد. زنبورهای تازه‌متولدشده (با سن کمتر از 24 ساعت) و چراگر (با سن بیشتر از 21 روز) به سه روش تماس با باقی‌مانده، گوارشی، و پاششی با دُز توصیه‌شدۀ مزرعه-ای این حشره‌کش تیمار شدند. همچنین، اثرات زیرکشندگی ایمونیت® روی فعالیت ویژه برخی از آنزیم‌های سم‌زُدا از قبیل آلفا-استراز، بتا-استراز، و گلوتاتیون اس-ترانسفراز مورد مطالعه قرار گرفت. آزمایش‌های زیست‌سنجی نشان داد که سمیت ایمونیت® با توجه به سن زنبور و روش استفاده از حشره‌کش فرق داشت. به استثنای روش پاششی، زنبورهای چراگر در مقایسه با زنبورهای تازه‌متولدشده از حساسیت بیشتری به این حشره‌کش برخوردار بودند. سمیت تماس با باقی‌مانده و پاششی ایمونیت® روی زنبورهای تازه‌متولدشده در مقایسه با سمیت گوارشی آن به طور معنی‌داری بیشتر بود، در حالی که زنبورهای چراگر بیشترین حساسیت را پس از تماس با باقی‌مانده این حشره‌کش نشان دادند. فعالیت آنزیم‌های سم‌زُدا نیز با توجه سن زنبورها و روش قرارگیری در معرض ایمونیت® تغییر پیدا کرد. به طور کلی، یافته‌های ما بیانگر پتانسیل بالای ایمونیت® برای ایجاد مسمومیت در زنبورعسل می‌باشد.

Impact of Imunit® insecticide on survival and detoxification enzymes activity of adult worker honey bee (Apis mellifera L.)

آلفاسایپرمترین+تفلوبنزورون (ایمونیت®) حشره‌کشی است که توسط سازمان حفظ نباتات ایران برای کنترل کرم میوه‌خوار (Helicoverpa armigera Hübner) در مزارع گوجه‌فرنگی توصیه می‌شود. در این پژوهش، تأثیر ایمونیت® روی نرخ بقای حشرات بالغ زنبورعسل کارگر (Apis mellifera L.) در شرایط آزمایشگاهی بررسی شد. زنبورهای تازه‌متولدشده (با سن کمتر از 24 ساعت) و چراگر (با سن بیشتر از 21 روز) به سه روش تماس با باقی‌مانده، گوارشی، و پاششی با دُز توصیه‌شدۀ مزرعه-ای این حشره‌کش تیمار شدند. همچنین، اثرات زیرکشندگی ایمونیت® روی فعالیت ویژه برخی از آنزیم‌های سم‌زُدا از قبیل آلفا-استراز، بتا-استراز، و گلوتاتیون اس-ترانسفراز مورد مطالعه قرار گرفت. آزمایش‌های زیست‌سنجی نشان داد که سمیت ایمونیت® با توجه به سن زنبور و روش استفاده از حشره‌کش فرق داشت. به استثنای روش پاششی، زنبورهای چراگر در مقایسه با زنبورهای تازه‌متولدشده از حساسیت بیشتری به این حشره‌کش برخوردار بودند. سمیت تماس با باقی‌مانده و پاششی ایمونیت® روی زنبورهای تازه‌متولدشده در مقایسه با سمیت گوارشی آن به طور معنی‌داری بیشتر بود، در حالی که زنبورهای چراگر بیشترین حساسیت را پس از تماس با باقی‌مانده این حشره‌کش نشان دادند. فعالیت آنزیم‌های سم‌زُدا نیز با توجه سن زنبورها و روش قرارگیری در معرض ایمونیت® تغییر پیدا کرد. به طور کلی، یافته‌های ما بیانگر پتانسیل بالای ایمونیت® برای ایجاد مسمومیت در زنبورعسل می‌باشد.

Bees under interactive stressors: the novel insecticides flupyradifurone and sulfoxaflor along with the fungicide azoxystrobin disrupt the gut microbiota of honey bees and increase opportunistic bacterial pathogens

The gut microbiome plays an important role in bee health and disease. But it can be disrupted by pesticides and in-hive chemicals, putting honey bee health in danger. We used a controlled and fully crossed laboratory experimental design to test the effects of a 10-day period of chronic exposure to field-realistic sublethal concentrations of two nicotinic acetylcholine receptor agonist insecticides (nACHRs), namely flupyradifurone (FPF) and sulfoxaflor (Sulf), and a fungicide, azoxystrobin (Azoxy), individually and in combination, on the survival of individual honey bee workers and the composition of their gut microbiota (fungal and bacterial diversity). Metabarcoding was used to examine the gut microbiota on days 0, 5, and 10 of pesticide exposure to determine how the microbial response varies over time; to do so, the fungal ITS2 fragment and the V4 region of the bacterial 16S rRNA were targeted. We found that FPF has a negative impact on honey bee survival, but interactive (additive or synergistic) effects between either insecticide and the fungicide on honey bee survival were not statistically significant. Pesticide treatments significantly impacted the microbial community composition. The fungicide Azoxy substantially reduced the Shannon diversity of fungi after chronic exposure for 10 days. The relative abundance of the top 10 genera of the bee gut microbiota was also differentially affected by the fungicide, insecticides, and fungicide-insecticide combinations. Gut microbiota dysbiosis was associated with an increase in the relative abundance of opportunistic pathogens such as Serratia spp. (e.g. S. marcescens), which can have devastating consequences for host health such as increased susceptibility to infection and reduced lifespan. Our findings raise concerns about the long-term impact of novel nACHR insecticides, particularly FPF, on pollinator health and recommend a novel methodology for a refined risk assessment that includes the potential effects of agrochemicals on the gut microbiome of bees.

BeeGUTS-A Toxicokinetic-Toxicodynamic Model for the Interpretation and Integration of Acute and Chronic Honey Bee Tests.

Understanding the survival of honey bees after pesticide exposure is key for environmental risk assessment. Currently, effects on adult honey bees are assessed by Organisation for Economic Co‐operation and Development standardized guidelines, such as the acute and chronic oral exposure and acute contact exposure tests. The three different tests are interpreted individually, without consideration that the same compound is investigated in the same species, which should allow for an integrative assessment. In the present study we developed, calibrated, and validated a toxicokinetic–toxicodynamic model with 17 existing data sets on acute and chronic effects for honey bees. The model is based on the generalized unified threshold model for survival (GUTS), which is able to integrate the different exposure regimes, taking into account the physiology of the honey bee: the BeeGUTS model. The model is able to accurately describe the effects over time for all three exposure routes combined within one consistent framework. The model can also be used as a validity check for toxicity values used in honey bee risk assessment and to conduct effect assessments for real‐life exposure scenarios. This new integrative approach, moving from single‐point estimates of toxicity and exposure to a holistic link between exposure and effect, will allow for a higher confidence of honey bee toxicity assessment in the future. Environ Toxicol Chem 2022;41:2193–2201. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Best practices for instrumenting honey bees

Honey bees are vital pollinators and can be used to monitor the landscape. Consequently, interest in mounting technologies onto bees to track foraging behaviors is increasing. The barrier to entry is steep, in part because the methodology for fastening tags to bees, and the success rates, are often missing from publications. We tested six factors suspected to influence the presence and tag retention rates of nurse honey bees after their introduction to hives, and followed bees until foraging age. We also compared reintroducing foragers to their maternal colony using the best method for nurse bees to releasing them in front of their maternal hive and allowing them to fly back unaided. Nurses were most likely to be present in the hive with their tag still attached when introduced using an introduction cage at night. Glue type was important, but may further be influenced by tag material. Foragers were most likely to be present with a tag attached if released in front of their colony. Preparation and introduction techniques influence the likelihood of tagged honey bee survival and of the tags remaining attached, which should be considered when executing honey bee tagging and tracking experiments.

Activating transcription factor 2 (AccATF2) regulates tolerance to oxidative stress in Apis cerana cerana

Activating transcription factor 2 (ATF2), a basic leucine zipper (bZIP) transcription factor, plays a crucial role in immune and DNA damage response in mammals. However, the function of ATF2 in insects remains unknown. Here, we isolated the ATF2 gene from Apis cerana cerana (AccATF2) and found that AccATF2 was a main regulator of the honeybee response to oxidative stress. Our results showed that AccATF2 was highly expressed in the head, thorax and integument. AccATF2 was expressed throughout the development period of honeybees, and the highest AccATF2 transcript level was noted in brown-eyed pupae, indicating its indispensable roles in honeybee survival. Antioxidant function analysis showed that AccATF2 expression was markedly induced in response to oxidative stress caused by various environmental stresses. AccATF2 overexpression substantially enhanced the tolerance to oxidative stress of Escherichia coli cells compared with control cells. AccATF2 knockdown significantly increased the production of malondialdehyde (MDA), the transcription of antioxidant genes and the activity of antioxidant enzymes in honeybees, suggesting that AccATF2 knockdown resulted in oxidative damage to honeybees. Moreover, AccATF2 knockdown decreased honeybee resistance to oxidative stress caused by high temperature. Overall, AccATF2 plays an important role in maintaining redox homeostasis and protecting honeybees from oxidative stress caused by various environmental stimuli. Our discoveries add to a growing understanding of how honeybees cope with various adverse environmental conditions to ensure their survival.

Macronutrient balance has opposing effects on cognition and survival in honey bees

Abstract Malnutrition in vertebrates, including humans, is known to affect brain development. Protein deprivation in the early stages of life dramatically impairs cognitive abilities. In insects, dietary protein deficiency influences several physiological and behavioural traits, but it is unknown how protein to carbohydrate (P:C) ratio simultaneously affects survival and cognitive performance. We used the geometric framework approach to examine the effects of P:C ratio in the diet of newly emerged honey bees on their survival, sucrose sensitivity, and learning and memory by conditioning of the proboscis extension response. The P:C ratio in the diet did not affect sucrose sensitivity, whereas it affected lifespan and cognition differently. While lifespan peaked at P:C ratio of 1:19, learning and short‐term memory peaked at P:C ratios of 1:9 and 1:4. Protein deprivation slightly reduced bee lifespan but highly impaired learning and short‐term memory. On the other hand, an excess of protein dramatically reduced bee lifespan with lesser effects on learning and short‐term memory. Bees were only able to form an early long‐term memory when they had been eating a protein diet (P:C ratio of 1:9) during 24 hr before the test, regardless of the diet eaten previously. Our study shows that nutrition affects honey bee cognitive abilities, but that these effects, unlike in vertebrates, can be quickly reversed with an appropriate diet. Read the free Plain Language Summary for this article on the Journal blog.

Comparison of Two Diagnostic Techniques for the Apis mellifera Varroatosis: Strengths, Weaknesses and Impact on the Honeybee Health.

Simple SummaryVarroa destructor is the main parasite affecting the health of adult honey bees and their larval forms. This mite negatively influences beekeeping income, as it can cause a decrease in yields and the loss of entire colonies of an apiary. To control this parasite, it is essential to establish the level of infestation through a precise diagnosis. In this work, two techniques used for the diagnosis of V. destructor on a bee sample were compared: the sugar roll test and CO2 injection. Both techniques were evaluated with the Varroa EasyCheck tool. This device is particularly versatile because it allows you to choose between different diagnostic techniques. The results of a comparison show that the sugar roll technique is cheaper and results in greater diagnostic accuracy. Both methods do not have a major impact on the health and welfare of bees compared to the alcohol washing method, which results in the death of the test sample. This study is of particular practical value, as it guides beekeepers in choosing the technique to use in a crucial practice for breeding, which is diagnosis.Varroa destructor is the most dangerous pest that poses a threat to honey bee survival. In recent years, increasingly worrying phenomena of drug resistance have occurred to various active ingredients of pharmaceutical formulations used to control this parasitosis. Determining the level of infestation is essential to preventing the inappropriate use and abuse of veterinary medicines, and to choose the most appropriate time for treatment. This comparative study investigates the sensitivity and diagnostic accuracy of two field techniques for diagnosing V. destructor infestations in hives. The EasyCheck device (Véto-pharma) was used in two of its application modes, namely, the sugar roll test and carbon dioxide (CO2) injection. The experiments were conducted on 15 samples of 300 bees each taken from the same frame and checked for the presence of mites using standard and modified field techniques in both uncaged and caged queen hive conditions. The results demonstrate that the sugar roll technique is significantly more effective and safer than CO2 injection, allowing for a higher accuracy in diagnosing a V. destructor infestation. Furthermore, the evaluation of mites present on bees in brood block conditions has proven to be particularly reliable. Considering the number of mites on the filter of the device as an additional step helps to implement the diagnostic accuracy of the CO2 injection technique, however, not achieving the efficacy results of the sugar roll.

Revisión de los efectos contaminantes del glifosato y su posible correlato con procesos de metalurgia extractiva

A review of the contaminating effects of glyphosate and their possible correlation with an extractive metallurgy process was carried out. For such comparison, copper recovery by pyrometallurgy was chosen because the hazardous substances formed (SO2, As4O6) propagate in air and water. Next, those aspects of glyphosate that determine its sanitary tolerance were discussed: carcinogenic risk to humans and maximum concentration in drinking water. As a remarkable fact, it is mentioned that at least one of the constituents of the commercial herbicide formulations has greater toxicity in relation to the active principle. Various issues regarding the glyphosate transport through the subsoil unsaturated zone in an agricultural basin in Argentina were analyzed. According to the compiled references, the inhalation-ingestion of large amounts of the herbicide is required to affect health. This statement would not explain why children exposed to glyphosate, among other pesticides, suffered genetic damage. It was found that the survival of honey bees is threatened by the presence of the herbicide in their diet. Germany, Luxembourg and Austria banned the use of glyphosate in their territories, invoking different arguments. Finally, it was noted that when adverse effects of the herbicide are reported, the work is refuted almost immediately.

The impact of tobacco (Nicotiana tabacum) farming on the survival of honeybees (Apis mellifera) in Nyamakate Communal Area, northern Zimbabwe

ABSTRACT The impact of tobacco (Nicotiana tabacum) farming on the survival of honeybees (Apis mellifera) was investigated through the documentation of mortality of honeybees, the number of trees cut and planted, and agrochemicals used in tobacco farming in Nyamakate Communal Area, Hurungwe District, northern Zimbabwe. The study was conducted in the wet season, i.e. between December 2017 and March 2018 using a stratified random sampling design to sample tobacco farmers and apiculturists. Honeybee mortalities across five sampled villages were significantly different (Kruskal–Wallis χ2 test = 74.54, df = 4, p < 0.05). The survey recorded 14 different agrochemicals that tobacco farmers used in tobacco farming, although the local regulator banned five of them in the 2018 and 2019 agriculture season. All five villages recorded an estimated 5,220 indigenous trees that were cut to cure tobacco whereas 483 Eucalyptus trees were planted as part of ongoing reforestation efforts in the district within the study period. It was concluded that tobacco farming negatively impacts honeybees through reduced forage and nesting sites (resulting from deforestation) and increased mortalities from the use of toxic agro-chemicals. There is a need for legislative alignment to ensure effective law enforcement on compliance. Government and partners need to encourage tobacco farmers to plant fast-growing indigenous trees for afforestation and adopt modern technology such as the use of solar-powered tobacco curing barns.

Decreased Mite Reproduction to Select Varroa destructor (Acari: Varroidae) Resistant Honey Bees (Hymenoptera: Apidae): Limitations and Potential Methodological Improvements.

The invasive parasitic mite, Varroa destructor (Anderson and Trueman), is the major biotic threat to the survival of European honey bees, Apis mellifera L. To improve colony survival against V. destructor, the selection of resistant lineages against this parasite is considered a sustainable solution. Among selected traits, mite fertility and fecundity, often referred to as suppressed mite reproduction are increasingly used in breeding programmes. However, the current literature leaves some gaps in the assessment of the effectiveness of selecting these traits toward achieving resistance. In the population studied here, we show a low repeatability and reproducibility of mite fertility and fecundity phenotypes, as well as a low correlation of these traits with infestation rates of colonies. Phenotyping reliability could neither be improved by increasing the number of worker brood cells screened, nor by screening drone brood, which is highly attractive for the parasite and available early in the season, theoretically allowing a reduction of generation time and thus an acceleration of genetic progress in selected lineages. Our results provide an evaluation of the potential and limitations of selecting on decreased mite reproduction traits to obtain V. destructor-resistant honeybee colonies. To allow for a more precise implementation of such selection and output reporting, we propose a refined nomenclature by introducing the terms of decreased mite reproduction and reduced mite reproduction, depending on the extent of mite reproduction targeted. We also highlight the importance of ensuring accurate phenotyping ahead of initiating long-lasting selection programmes.

A Detoxification Enzyme for Apis mellifera Newly Characterized by Recombinant Expression: 10-Formyl Tetrahydrofolate Dehydrogenase.

Honeybees are important managed pollinators that perform important ecological and economic functions. In recent decades, the obligate ectoparasite Varroa destructor severely affected survival of honeybees as it either feeds on hemolymph and fat bodies or acts as a vector for viruses. A common treatment against the varroa mite is formic acid, which has been used for many years by beekeepers. This treatment is known to be effective, but the therapeutic index is very narrow. Many beekeepers report negative effects of formic acid on bees, which include damage to brood, worker bee mortality, and queen loss. Little is yet known about the molecular mechanisms of formic acid detoxification in honeybees. Our previous study shows the upregulation of predicted 10-formyl tetrahydrofolate dehydrogenase (10-FTHFDH) transcripts in honeybees exposed to formic acid. Here, the predicted honeybee-specific 10-FTHFDH is recombinantly expressed, and its hydrolase and dehydrogenase activities are investigated. As a result, the enzyme shows similar dehydrogenase activity in comparison to known 10-FTHFDHs. This study provides further knowledge to better understand the detoxification mechanisms of formic acid in Apis mellifera.