Colony Decline Research Articles

Silencing the Honey Bee (Apis mellifera) Naked Cuticle Gene (nkd) Improves Host Immune Function and Reduces Nosema ceranae Infections.

Given the critical role of honey bees in the pollination of agricultural crops, it is urgent to develop strategies to prevent the colony decline induced by the infection of parasites/pathogens. Targeting parasites and pathogens directly by RNAi has been proven to be useful for controlling infections in honey bees, but little is known about the disease impacts of RNAi silencing of host factors. Here, we demonstrate that knocking down the honey bee immune repressor-encoding nkd gene can suppress the reproduction of N. ceranae and improve the overall health of honey bees, which highlights the potential role of host-derived and RNAi-based therapeutics in controlling the infections in honey bees. The information obtained from this study will have positive implications for honey bee disease management practices.

Short communication: Survival of honey bees (Apis mellifera) infected with Crithidia mellificae (Langridge and McGhee: ATCC® 30254™) in the presence of Nosema ceranae

Crithidia mellificae, a trypanosomatid parasite of Apis mellifera, has been proposed to be one of the pathogens responsible for the serious honey bee colony losses produced worldwide in the last decade, either alone or in association with Nosema ceranae. Since this pathogenic effect contradicts the results of the experimental infections originally performed by Langridge and McGhee nearly 40 years ago, we investigated the potential linkage of this protozoan with colony decline under laboratory conditions. Nosema-free and trypanosomatid-free honey bees from three different colonies were experimentally infected with fresh C. mellificae spheroid forms (reference strain ATCC30254), with N. ceranae fresh spores and with both parasites at the same time. Replicate cages were kept at 27 °C and used to analyse survival. C. mellificae spheroid forms did not reduce significantly the survival of the worker bees (64.5% at 30 days post-infection vs. 77.8% for the uninfected bees used as controls; differences were non statistically significant) under these experimental conditions. In contrast, the cages infected with N. ceranae exhibited higher rates of mortality from the 20th day post-infection onwards, irrespective of the presence of C. mellificae, suggesting that the spheroid forms of the latter have no pathological effect on A. mellifera.

Nitenpyram degradation in finished drinking water.

Neonicotinoid pesticides and their metabolites have been indicated as contributing factors in the decline of honey bee colonies. A thorough understanding of neonicotinoid toxicity requires knowledge of their metabolites and environmental breakdown products. This work investigated the rapid degradation of the neonicotinoid nitenpyram in finished drinking water. Nitenpyram reaction products were characterized using liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/QTOFMS). A software algorithm that compared degraded and control samples was utilized to facilitate efficient data reduction. Fragmentation pathways for six reaction products and nitenpyram were proposed using predictive software and manual product ion analysis. This study showed that nitenpyram degradation in unpreserved finished drinking water was likely the result of oxidation, hydrolysis and reaction with Cl2 . Structures for six nitenpyram reaction products were proposed that suggest the C9/C11 olefin as the key reactive site. Similarities between the identified nitenpyram reaction products and imidacloprid metabolites highlight the importance of this study, as the toxicity of neonicotinoids to pollinators has been linked to their metabolites. Based on the proposed reaction mechanisms, the identified nitenpyram reaction products in finished drinking water could also be present in the environment and water treatment facilities. As such, identifying these degradation products will aid in evaluating the environmental impact of neonicotinoid pesticides. Copyright © 2016 John Wiley & Sons, Ltd.

Causes of mortality of Polistes nimpha colonies.

We studied populations of the eusocial paper wasps Polistes nimpha from 2012 to 2014, near Poznań, Poland, to identify the causes of mortality and to analyze changes in the number of active nests during the breeding season (from May to September). Results of the 3-year study showed that the major cause of P. nimpha mortality (51.9 %) in the study areas was the activity of mammals, probably foxes and wild boars. The second major cause of wasp death was ant predation (12 %). Only 11 of the 308 nests (3.6 %) demonstrated a natural colony decline, following the emergence of reproductives.

Disease dynamics of honeybees with Varroa destructor as parasite and virus vector

The worldwide decline in honeybee colonies during the past 50 years has often been linked to the spread of the parasitic mite Varroa destructor and its interaction with certain honeybee viruses carried by Varroa mites. In this paper, we propose a honeybee-mite-virus model that incorporates (1) parasitic interactions between honeybees and the Varroa mites; (2) five virus transmission terms between honeybees and mites at different stages of Varroa mites: from honeybees to honeybees, from adult honeybees to the phoretic mites, from brood to the reproductive mites, from the reproductive mites to brood, and from adult honeybees to the phoretic mites; and (3) Allee effects in the honeybee population generated by its internal organization such as division of labor. We provide completed local and global analysis for the full system and its subsystems. Our analytical and numerical results allow us have a better understanding of the synergistic effects of parasitism and virus infections on honeybee population dynamics and its persistence. Interesting findings from our work include: (a) due to Allee effects experienced by the honeybee population, initial conditions are essential for the survival of the colony. (b) Low adult honeybees to brood ratios have destabilizing effects on the system which generate fluctuating dynamics that lead to a catastrophic event where both honeybees and mites suddenly become extinct. This catastrophic event could be potentially linked to Colony Collapse Disorder (CCD) of honeybee colonies. (c) Virus infections may have stabilizing effects on the system, and parasitic mites could make disease more persistent. Our model illustrates how the synergy between the parasitic mites and virus infections consequently generates rich dynamics including multiple attractors where all species can coexist or go extinct depending on initial conditions. Our findings may provide important insights on honeybee viruses and parasites and how to best control them.

Longings for Manila: Projections of Imperialism and Decline in the Poems of J. Slauerhoff

The Dutch poet Jan Jacob Slauerhoff (1898–1936) featured Manila in three poems written in the late 1920s. These poems present the city as the decaying remnant of a deceased empire. Manila appears as a memory site of Spain’s bygone world dominance, resonates with the discourse of the “decline of the West,” and bears parallels to an image of a decaying Dutch empire. The city functions as a screen against which cultural images derived from the author’s personal European context are projected: cultural pessimism and colonial decline. Keywords: Slauerhoff • cultural pessimism • culture and imperialism • Manila literature • poetry

Multiple Virus Infections and the Characteristics of Chronic Bee Paralysis Virus in Diseased Honey Bees (Apis Mellifera L.) in China

Abstract China has the largest number of managed honey bee colonies globally, but there is currently no data on viral infection in diseased A. mellifera L. colonies in China. In particular, there is a lack of data on chronic bee paralysis virus (CBPV) in Chinese honey bee colonies. Consequently, the present study investigated the occurrence and frequency of several widespread honey bee viruses in diseased Chinese apiaries, and we used the reverse transcription-polymerase chain reaction (RT-PCR) assay. Described was the relationship between the presence of CBPV and diseased colonies (with at least one of the following symptoms: depopulation, paralysis, dark body colorings and hairless, or a mass of dead bees on the ground surrounding the beehives). Phylogenetic analyses of CBPV were employed. The prevalence of multiple infections of honey bee viruses in diseased Chinese apiaries was 100%, and the prevalence of infections with even five and six viruses were higher than expected. The incidence of CBPV in diseased colonies was significantly higher than that in apparently healthy colonies in Chinese A. mellifera aparies, and CBPV isolates from China can be separated into Chinese-Japanese clade 1 and 2. The results indicate that beekeeping in China may be threatened by colony decline due to the high prevalence of multiple viruses with CBPV.

Lost colonies found in a data mine: Global honey trade but not pests or pesticides as a major cause of regional honeybee colony declines

Recent losses of honeybee (Apis mellifera) colonies have been linked to several non-exclusive factors; such as pests, parasites, pesticides (e.g., neonicotinoids) and other toxins. Whereas these losses pose a threat to apiculture, the number of globally managed colonies appeared to be less affected because beekeepers replace lost colonies. From a socioeconomic and ecological perspective the number of managed colonies is arguably more relevant when addressing the issue of apiculture and pollination services provided by honeybees. We here use the FAO data base to dissect the interactions between the global honey market and the number of colonies. Global scale analyses do not show a general colony decline. Whereas Western Europe and the US show suffer colony declines, other regions show considerable increase. We could not find any link between the colony dynamics and the occurrence of specific pathogens or the use of pesticides. In contrast, changes in the political and socioeconomic system show strong effects on apiculture. In addition, many countries show a tight negative correlation between honey import and the number of managed colonies. For some countries, the amount of honey produced per colony is highly positively correlated with the amount of honey imports, and we cannot exclude large scale relabeling of imported to nationally produced honey. It is very clear that honey trade is a dominating factor for the number of managed colonies since countries with a strong import and export ratio are those suffering most strongly from colony declines.

Modeling Honey Bee Populations.

Eusocial honey bee populations (Apis mellifera) employ an age stratification organization of egg, larvae, pupae, hive bees and foraging bees. Understanding the recent decline in honey bee colonies hinges on understanding the factors that impact each of these different age castes. We first perform an analysis of steady state bee populations given mortality rates within each bee caste and find that the honey bee colony is highly susceptible to hive and pupae mortality rates. Subsequently, we study transient bee population dynamics by building upon the modeling foundation established by Schmickl and Crailsheim and Khoury et al. Our transient model based on differential equations accounts for the effects of pheromones in slowing the maturation of hive bees to foraging bees, the increased mortality of larvae in the absence of sufficient hive bees, and the effects of food scarcity. We also conduct sensitivity studies and show the effects of parameter variations on the colony population.

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.

Honey bee workers that are pollen stressed as larvae become poor foragers and waggle dancers as adults.

The negative effects on adult behavior of juvenile undernourishment are well documented in vertebrates, but relatively poorly understood in invertebrates. We examined the effects of larval nutritional stress on the foraging and recruitment behavior of an economically important model invertebrate, the honey bee (Apis mellifera). Pollen, which supplies essential nutrients to developing workers, can become limited in colonies because of seasonal dearths, loss of foraging habitat, or intensive management. However, the functional consequences of being reared by pollen-stressed nestmates remain unclear, despite growing concern that poor nutrition interacts with other stressors to exacerbate colony decline. We manipulated nurse bees’ access to pollen and then assessed differences in weight, longevity, foraging activity, and waggle-dance behavior of the workers that they reared (who were co-fostered as adults). Pollen stress during larval development had far-reaching physical and behavioral effects on adult workers. Workers reared in pollen-stressed colonies were lighter and shorter lived than nestmates reared with adequate access to pollen. Proportionally fewer stressed workers were observed foraging and those who did forage started foraging sooner, foraged for fewer days, and were more likely to die after only a single day of foraging. Pollen-stressed workers were also less likely to waggle dance than their unstressed counterparts and, if they danced, the information they conveyed about the location of food was less precise. These performance deficits may escalate if long-term pollen limitation prevents stressed foragers from providing sufficiently for developing workers. Furthermore, the effects of brief pollen shortages reported here mirror the effects of other environmental stressors that limit worker access to nutrients, suggesting the likelihood of their synergistic interaction. Honey bees often experience the level of stress that we created, thus our findings underscore the importance of adequate nutrition for supporting worker performance and their potential contribution to colony productivity and quality pollination services.

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.

Loss of the ability to generate large burst-forming unit-like megakaryocytic colonies from thawed cord blood in semisolid cultures after short term suspension culture.

Total colony-forming cells from thawed cord blood units (CBUs) include megakaryocytic colony-forming units (CFU-Mks), which survive the freezing process. The aim of this study was to evaluate whether different megakaryocytic progenitors from unseparated CBUs survive the freezing process and a short-term liquid culture. Thawed samples of CBUs were cultured in liquid medium. During the cultures, serial samples were drawn to assess the growth of different megakaryocytic progenitors in a semisolid collagen medium with identical cytokines as in the liquid medium. Megakaryocytic cells were detected using immunohistochemistry and flow cytometry. In suspension culture, the megakaryocytic progenitors almost completely lost the ability to generate large (burst-forming unit-like, BFU-like) megakaryocytic colonies in semisolid cultures (large colonies, median count per chamber d0: 7.25 vs. d7: 1.5; P < 0.0001), whereas the number of small colonies (median count per chamber d0: 7.25 vs. d7: 16.0; P = 0.0505) peaked at day seven. Further 7-day culture in suspension resulted in the decline of small colonies as well (d7: 16.0 vs. d14: 5.75; P = 0.0088). Total CFU-Mk count declined from 23.3 (range 12.5-34.0) at d0 to 7.25 (range 1.0-13.5) at d14 (P < 0.0001). Immediately post-thaw, CBUs possess an ability to generate large BFU-like megakaryocytic colonies, whereas the colonies were not detectable in most CBUs in semisolid culture after a short suspension culture. Small CFU-Mks were observed throughout the cultures. It may be that the BFU-Mk colonies matured and acquired CFU-Mk behaviour.

한국도시의 형태변화 모델

This study aims to develop a model that would explain the morphological transformation and development pattern of the Korean cities. To do so, it proposes HanJoo, a hypothetical city that would experimentally characterize the development process of formation, growth and decline of small and medium-sized cities. HanJoo focuses particularly on functional relationship with the adjacent cities in regional setting, locational orientation and topographical condition of the city site, and morphological characteristics and structural shift of the city growth characterized by a set of four-staged development phases: (1) walled town (675-1890); (2) town expansion via modern grid blocks (1890-1945); (3) industrial district and the company town linked by inter-city highway (1946-1994); (4) new community development and massive suburban growth (1995-present). The findings expect to be useful for improving the understanding the Korean cities particularly whose city layout and locational features in the formative stage, their transformation in the Japanese colonial period, growth and decline mechanism in modern and contemporary settings have not theoretically identified.

Honeybee immunity and colony losses

The decline of honeybee colonies and their eventual collapse is a widespread phenomenon in the Northern hemisphere of the globe, which severely limits the beekeeping industry. This dramatic event is associated with an enhanced impact of parasites and pathogens on honeybees, which is indicative of reduced immunocompetence. The parasitic mite Varroa destructor and the vectored viral pathogens appear to play a key-role in the induction of this complex syndrome. In particular, the Deformed Wing Virus (DWV) is widespread and is now considered, along with Varroa, one of the major causes of bee colony losses. Several lines of evidence indicate that this mite/DWV association severely affects the immune system of honeybees and makes them more sensitive to the action of other stress factors. The molecular mechanisms underpinning these complex interactions are currently being investigated and the emerging information has allowed the development of a new functional model, describing how different stress factors may synergistically concur in the induction of bee immune alteration and health decline. This provides a new logical framework in which to interpret the proposed multifactorial origin of bee colony losses and sets the stage for a more comprehensive and integrated analysis of the effect that multiple stress agents may have on honeybees.

Bee Health in Apiaries in the Paraíba Valley, São Paulo State, Southeast Brazil

Bee health is a growing global concern due to phenomena with as yet undefined causes, such as the sudden population decline of colonies that has been observed in apiaries in many countries, recently including Brazil. The main objective of this study was to assess the presence and/or prevalence of pathogens that afflict Africanized Apis mellifera bees in the Paraiba Valley region of Sao Paulo state, Brazil. Three sampling periods were established: period 1 – August and September 2009 (winter/start of spring); period 2 – December 2009 and January 2010 (summer); and period 3 – April and May 2010 (autumn). Different types of samples were collected from the brood chamber, besides foragers at the entrance of the hive, in order to evaluate the presence and prevalence of Paenibacillus larvae, Varroa destructor and Nosema sp. The results indicated that the intensity of infection by Nosema ceranae and infestation rates of V. destructor in the hives are low, with no detection of P. larvae spores in the samples analyzed. The prevalence of N. ceranae and V. destructor was high, at respective values of 85.2 and 95.7%. These results demonstrate that although mites and microsporidia are widespread in the region’s colonies, the Africanized bees are apparently tolerant of these parasites. However, the mechanisms related to defense against pathogens are not completely clear and monitoring and prophylactic measures are essential to maintain the health of bee colonies.

So near and yet so far: harmonic radar reveals reduced homing ability of Nosema infected honeybees.

Pathogens may gain a fitness advantage through manipulation of the behaviour of their hosts. Likewise, host behavioural changes can be a defence mechanism, counteracting the impact of pathogens on host fitness. We apply harmonic radar technology to characterize the impact of an emerging pathogen - Nosema ceranae (Microsporidia) - on honeybee (Apis mellifera) flight and orientation performance in the field. Honeybees are the most important commercial pollinators. Emerging diseases have been proposed to play a prominent role in colony decline, partly through sub-lethal behavioural manipulation of their hosts. We found that homing success was significantly reduced in diseased (65.8%) versus healthy foragers (92.5%). Although lost bees had significantly reduced continuous flight times and prolonged resting times, other flight characteristics and navigational abilities showed no significant difference between infected and non-infected bees. Our results suggest that infected bees express normal flight characteristics but are constrained in their homing ability, potentially compromising the colony by reducing its resource inputs, but also counteracting the intra-colony spread of infection. We provide the first high-resolution analysis of sub-lethal effects of an emerging disease on insect flight behaviour. The potential causes and the implications for both host and parasite are discussed.

Grappling with the Past: Wrestling and Performative Identity in Kenya

This article explores the decline of indigenous forms of wrestling under colonial rule in Kenya as well as contemporary attempts to revive the sport. Highlighting the role the colonial and post-colonial state played in marginalising ‘traditional' sports reveals a long history of hierarchical control of sport in Kenya. Local responses to this top-down approach also show how cultural lobbies and grass-roots organisations have tried to preserve, reinvent and market the sport as a moral symbol of masculine ethnic pride and cultural identity amidst a sometimes tense political landscape. With the current historiography of sport in Africa heavily imbalanced in favour of studies that highlight the adaptation of European sports within the continent, this article also serves as an initial examination of the historical roots and colonial decline of indigenous sporting traditions in Kenya.

The effects of an abnormal decrease in temperature on the Eastern Pacific reef-building coral Pocillopora verrucosa

Coral bleaching events are associated with abnormal increases in temperature, such as those produced during El Nino. Recently, a breakdown in the coral–dinoflagellate (genus Symbiodinium) endosymbiosis has been documented in corals exposed to anomalously cold-water temperatures associated with La Nina events. Given the ecological significance of such events, as well as the threat of global climate change, surprisingly little is known about the physiological response of corals to cold stress. This study evaluated some physiological effects of continuous temperature decline in colonies of the eastern Pacific reef-building coral Pocillopora verrucosa. Twenty days of incubation at 18.5–19.0 °C resulted in a substantial decrease in holobiont lipid and Chla content, as well as an increase in Symbiodinium density. These observations suggest a combination of symbiont acclimation due to the temperature decline and reallocation of carbon toward algal growth as opposed to translocation to the host coral. With a decreased availability of symbiont-derived carbon, the coral likely catabolized storage lipids in order to survive the stress event. Despite this stress and some tissue necrosis, no mortality was noted and corals recovered quickly when returned to the ambient temperature. As these results are in marked contrast to similar studies investigating elevated temperature on this coral from this same location, Pocillopora in the Mexican Central Pacific may be more prone to long-term damage and mortality during periods of ocean warming as opposed to ocean cooling.

The Road to Pollinator Health

Agricultural production is a balancing act. On one side is sustainable production of food and biobased products for a growing population. On the other is protecting our natural resources and the environment. The global decline of the honey bee, a major domestic pollinator of many crops, exemplifies how complex the factors are that contribute to maintaining this balance. Overall bee colony decline, including loss from colony collapse disorder (CCD), poses a serious challenge to agricultural research worldwide. The causes are still not definitive, but stress from pesticides may be a factor. This spring, the European Commission temporarily restricted the use of three neonicotinoid pesticides for specific applications (pending more research). Last year, the U.S. Environmental Protection Agency (EPA) and U.S. Department of Agriculture (USDA) formed a bee health task force to take an even broader look at the pollinator crisis, with a plan to collect interagency input and develop a federal Pollinator Roadmap before the end of 2013.