Western Honey Bee Apis Mellifera Research Articles

Parasite-insecticide interactions: a case study of Nosema ceranae and fipronil synergy on honeybee

In ecosystems, a variety of biological, chemical and physical stressors may act in combination to induce illness in populations of living organisms. While recent surveys reported that parasite-insecticide interactions can synergistically and negatively affect honeybee survival, the importance of sequence in exposure to stressors has hardly received any attention. In this work, Western honeybees (Apis mellifera) were sequentially or simultaneously infected by the microsporidian parasite Nosema ceranae and chronically exposed to a sublethal dose of the insecticide fipronil, respectively chosen as biological and chemical stressors. Interestingly, every combination tested led to a synergistic effect on honeybee survival, with the most significant impacts when stressors were applied at the emergence of honeybees. Our study presents significant outcomes on beekeeping management but also points out the potential risks incurred by any living organism frequently exposed to both pathogens and insecticides in their habitat.

Further evidence of an oriental origin for Nosema ceranae (Microsporidia: Nosematidae)

Although Nosema ceranae was first isolated from the Asian honeybee (Apis cerana) in Asia and then subsequently recognized as a widespread gut parasite of the Western honeybee (Apis mellifera), its origins and primary host are yet to be accurately established. In this study we examined the possibility of an Asian origin for the parasite by looking for evidence of its ongoing spread out of Asia. To do this, we surveyed for the presence of N. ceranae in A. cerana and A. mellifera on isolated islands of the Solomon Islands (Pacific region), most of which were inhabited with A. mellifera that had been introduced from Australia and New Zealand at a time when N. ceranae was not present in either country, but on which some had also recently become inhabited with invasive A. cerana that originated from Asia with no prior history of contact with A. mellifera infected with N. ceranae. We also sought to verify previous findings that N. ceranae was widespread in Asian honeybees by surveying for its presence in isolated populations of the Asian honeybees, A. cerana, A. koschevnikovi, A. nigrocincta and A. florea. We obtained evidence that A. cerana introduced N. ceranae to A. mellifera in the Solomon Islands and also confirmed the widespread occurrence of the parasite in Asian honeybees, even reporting it for the first time in A. koschevnikovi from Borneo.Our findings provide further support for the hypothesis that N. ceranae has only recently emerged from Asia to become a parasite of A. mellifera.

Proteome analysis of Paenibacillus larvae reveals the existence of a putative S‐layer protein

Honey bee pathology has attracted much interest recently due to the problems with honey bee declines in many regions of the world. American Foulbrood (AFB) caused by Paenibacillus larvae is the most devastating bacterial brood disease of the Western honey bee (Apis mellifera) causing considerable economic losses to beekeepers worldwide. AFB outbreaks are mainly caused by two differentially virulent genotypes of P. larvae, P. larvae ERIC I and ERIC II. To better understand AFB pathogenesis and to complement already existing data from the genetic level we aimed at obtaining expression data from the protein level. We successfully developed a protocol for two-dimensional proteome analysis of P. larvae with subsequent mass-spectrometry based protein sequencing. Based on the obtained master protein maps of P. larvae genotypes ERIC I and II we identified the dominantly expressed cytosolic proteins of both genotypes, some of them presumably linked to pathogenesis and virulence. Comparing the master maps of both genotypes revealed differentially expressed proteins, i.e. a putative S-layer protein which is expressed by P. larvae ERIC II but absent from the proteome of P. larvae ERIC I. The implications of our findings for pathogenesis of AFB and virulence of P. larvae will be discussed.

Factors Affecting Pollinators and Pollination

While it has been known for at least a decade that the colony numbers of the managed pollinator, the Western honey bee Apis mellifera, was on the decline, pollinator problemwas not well publicized until the Colony Collapse Disorder (CCD) further ravaged the honey bee population in the United States [1]. In addition to honey bees, now it is known that bumble bees [2] and other pollinators [3] are also on the decline, perhaps due to combined effects of pesticide use and habitat destruction by Homo sapiens. While in the past the main focus has been on the honey bees, we felt that a special issue that includes other pollinators was warranted. Thus was born this special issue, highlighting various important challenges pollinators face.

Nosema apis and N. ceranae in western honeybee (Apis mellifera) - geographical distribution and current methods of diagnosis.

During the last two decades, along the wellknown microsporidian Nosema apis, a new species – N. ceranae – is continuously spreading across the world where the western honeybee (Apis mellifera) is kept and bred by both professionals and hobbyists. Recent studies revealed that this species which jumped host from the asian honeybee (Apis cerana) to the more common western honeybee is present at least in the two American continents, Europe, Asia and Australia. Although the traditional standard diagnosis method is by visually detecting the Nosema spp. microspores by light microscopy, this approach can’t make the difference between the two species. Thus, a much reliable, accurate and sensitive diagnosis method is by molecular techniques, like multiplex PCR, RFLP, Real Time qPCR or Microarray methods. These main molecular techniques are briefly presented as well, along with the differences between the two species at the amplified DNA fragments level

Csd alleles in the red dwarf honey bee (Apis florea, Hymenoptera: Apidae) show exceptionally high nucleotide diversity

Abstract The single locus complementary sex determination (sl-csd) gene is the primary gene determining the gender of honey bees (Apis spp.). While the csd gene has been well studied in the Western honey bee (Apis mellifera), and comparable data exist in both the Eastern honey bee (Apis cerana) and the giant honey bee (Apis dorsata), no studies have been conducted in the red dwarf honey bee, Apis florea. In this study we cloned the genomic region 3 of the A. florea csd gene from 60 workers, and identified 12 csd alleles. Analysis showed that similar to A. mellifera, region 3 of the csd gene contains a RS domain at the N terminal, a proline-rich domain at the C terminal, and a hypervariable region in the middle. However, the A. florea csd gene possessed a much higher level of nucleotide diversity, compared to A. mellifera, A. cerana and Apis dorsata. We also show that similar to the other three Apis species, in A. florea, nonsynonymous mutations in the csd gene are selectively favored in young alleles.

Apicystis bombi (Apicomplexa: Neogregarinorida) parasitizing Apis mellifera and Bombus terrestris (Hymenoptera: Apidae) in Argentina

The neogregarine Apicystis bombi is considered a low prevalence parasite of Bombus spp. Before our work it has only once been detected in one single specimen of the Western honeybee Apis mellifera. This contribution reports the presence of A. bombi parasitizing both A. mellifera and Bombus terrestris at a site in Northwestern Argentine Patagonia (Bariloche, close to the border with Chile) and analyses its possible absence in the Pampas region, the most important beekeeping region of the country. In Bariloche, prevalence of A. bombi in A. mellifera was 7.6% in 2009, and 13.6% in 2010, whereas in B. terrestris it was 12.1%. Infections were not detected in 302 bee hives periodically prospected along 3 years (almost 400 000 honeybee specimens) in the Pampas. Analysis with the probability program FreeCalc2 suggested a possible absence of A. bombi in this area. Because of high virulence showed in several species of Bombus in the Northern hemisphere, A. bombi should be closely monitored in A. mellifera and in native Bombus species or other Apidae.

Comparison of the energetic stress associated with experimental Nosema ceranae and Nosema apis infection of honeybees (Apis mellifera)

Nosema ceranae is a relatively new and widespread parasite of the western honeybee Apis mellifera that provokes a new form of nosemosis. In comparison to Nosema apis, which has been infecting the honeybee for much longer, N. ceranae seems to have co-evolved less with this host, causing a more virulent disease. Given that N. apis and N. ceranae are obligate intracellular microsporidian parasites, needing host energy to reproduce, energetic stress may be an important factor contributing to the increased virulence observed. Through feeding experiments on caged bees, we show that both mortality and sugar syrup consumption were higher in N. ceranae-infected bees than in N. apis-infected and control bees. The mortality and sugar syrup consumption are also higher in N. apis-infected bees than in controls, but are less than in N. ceranae-infected bees. With both microsporidia, mortality and sugar syrup consumption increased in function of the increasing spore counts administered for infection. The differences in energetic requirements between both Nosema spp. confirm that their metabolic patterns are not the same, which may depend critically on host-parasite interactions and, ultimately, on host pathology. The repercussions of this increased energetic stress may even explain the changes in host behavior due to starvation, lack of thermoregulatory capacity, or higher rates of trophallaxis, which might enhance transmission and bee death.

The microsporidian Nosema ceranae, the antibiotic Fumagilin-B®, and western honey bee (Apis mellifera) colony strength

Western honey bees (Apis mellifera) are under threat from a number of emerging pathogens, including the microsporidian Nosema ceranae historically of Asian honey bees (Apis cerana). Because of its recent detection, very little is known about the biology, pathology, and control of N. ceranae in western honey bees. Here we investigated effects of the antibiotic Fumagilin-B®, which is commonly used to control the historical Nosema parasite of western honey bees Nosema apis, on N. ceranae and effects of N. ceranae on colony strength (i.e., number of bees and amount of capped and uncapped brood, honey, and pollen) and colony mortality. Similar to our previous study, fall Fumagilin-B® treatment lowered, albeit weakly, N. ceranae intensity the following spring. However, N. ceranae was not associated with variation in colony strength measures or with higher colony winter mortality.

Colony Collapse Disorder in context

Although most of humanity relies upon foods that do not require animal pollination 1, production of 39 of the world's 57 most important monoculture crops still benefits from this ecosystem service 2. Western honey bees (Apis mellifera) are undoubtedly the single-most valuable animal pollinators to agriculture because they can be easily maintained and transported to pollinator-dependent crops. Yet, despite an almost 50% increase in world honey bee stocks over the last century, beekeepers have not kept pace with the >300% increase in pollinator-dependent crops 3. This has led to great uncertainty surrounding the recent large-scale die-offs of honey bees around the world, and has sparked enormous interest from both scientists and the general public. Although sharp regional declines in honey bee populations have occurred in the past, such as the so-called unexplainable “Isle of Wight” disease in the early 1900s 4, the magnitude and velocity of these recent declines are likely unprecedented. Often in the media (e.g. “Mobile phones responsible for disappearance of honey bee,” available at http://www.telegraph.co.uk/), and sometimes in the scientific literature (e.g. 5), these losses are inappropriately equated with “Colony Collapse Disorder” or CCD, which is characterized by the rapid disappearance of adult bees from colonies containing brood and food stores but lacking damaging levels of parasitic Varroa destructor mites or Nosema microsporidians 6. Although, we agree that CCD is indeed a significant cause for concern, we believe that it is imperative to appropriately place CCD within the greater context of other honey bee morbidities occurring worldwide. In many cases, these morbidities can be explained by known parasites or beekeeper management issues. One example is the devastation caused by beekeepers' inability to control V. destructor, which not only feeds on host haemolymph and weakens host immunity but also vectors a variety of viruses 7. In other cases, however, these morbidities are genuinely unexplainable, including those attributed to CCD sensu stricto 6. In recent winters, colony mortality in Europe has averaged ∼20% (ranging from 1.8 to 53% among countries), with starvation and parasites believed to be the main contributors (“Proceedings of the 4th COLOSS Conference, Zagreb, Croatia, 3-4 March 2009”, available at http://www.coloss.org/publications). Colony mortality during the 2006/2007, 2007/2008, and 2008/2009 winters in the US, the only country where CCD has been documented sensu stricto, was 32% 8, 36% 9, and 29% 10, respectively. During the winter of 2008/2009, ∼10% of the 2.3 million managed honey bee colonies in the US died with “CCD-like symptoms”, and US beekeepers self-diagnosed CCD as only the 8th most important contributor to colony mortality, behind starvation, queen-related issues, and parasites 10. The point is, honey bees die from many things. We must be careful to not synonymize CCD with all honey bee losses. There is a growing consensus that colony mortality is the product of multiple factors, both known and unknown, acting singly or in combination 11, 12. Considering the reliance that modern agriculture places on honey bees for pollination, coordinated efforts, such as those of CANPOLIN (Canadian Pollination Initiative, http://www.uoguelph.ca/canpolin), COLOSS (Prevention of Honeybee Colony Losses, http://www.coloss.org/), and the US Department of Agriculture's Areawide and Managed Pollinator CAP (Coordinated Agricultural Project) 13, are urgently needed to understand and mitigate these losses. The first step in these efforts should be to objectively discriminate among types of colony mortality occurring worldwide. This will permit a more informed and appropriate allocation of research efforts into CCD specifically and other causes of mortality in general.

Does Cry1Ac Bt-toxin impair development of worker larvae of Africanized honey bee?

The western honey bee (Apis mellifera L.) is a widespread pollinator species. The present study aimed to test if Africanized honey bee larvae are negatively affected by the ingestion of diet contaminated with the Bacillus thunringiensis toxin Cry1Ac, which is expressed in GM cotton plants. The toxin activity was confirmed in bioassays with the velvetbean caterpillar (Anticarsia gemmatalis), a soybean pest species susceptible to Cry1Ac. The honey bee larvae were subjected to ingestion of either pure larval diet (control), diluted larval diet (diluted control) or larval diet diluted in a Cry1Ac solution at a concentration compatible with the maximum possible field exposure. Although diluted diet slightly increased larval mortality, Cry1Ac ingestion did not affect survival, developmental time, and neither adult body mass nor size, indicating that GM plants are unlikely to significantly impair the development of honey bee larvae. The larval-rearing system reported here was suitable to assess the lethal and sub-lethal effects of GM expressed toxins against honey bee larvae.

Expression of Recombinant AccMRJP1 Protein from Royal Jelly of Chinese Honeybee in Pichia pastoris and Its Proliferation Activity in an Insect Cell Line

Major royal jelly protein 1 (MRJP1) is the most abundant member of the major royal jelly protein (MRJP) family of honeybee. Mature MRJP1 cDNA of the Chinese honeybee (Apis cerana cerana MRJP1, or AccMRJP1) was expressed in Pichia pastoris. SDS-PAGE showed that recombinant AccMRJP1 was identical in molecular weight to the glycosylated AmMRJP1 from the Western honeybee (Apis mellifera). Western blots probed with anti-AccMRJP1 antibody demonstrated that recombinant AccMRJP1 and soluble protein of the Western honeybee RJ (AmSPRJ) contained immunoreactive MRJP1. The 57 kDa protein in AmSPRJ contained an N-terminal amino sequence of N-I-L-R-G-E, which is identical to that previously characterized in AmMRJP1. The molecular weight of recombinant AccMRJP1 was decreased from 57 to 48 kDa after deglycosylation, indicating that AccMRJP1 was glycosylated. The recombinant AccMRJP1 significantly stimulated Tn-5B-4 cell growth, similar to AmSPRJ and fetal bovine serum, and affected cell shape and adhesion to the substrate.

Estimating the Density of Honeybee Colonies across Their Natural Range to Fill the Gap in Pollinator Decline Censuses

Although pollinator declines are a global biodiversity threat, the demography of the western honeybee (Apis mellifera) has not been considered by conservationists because it is biased by the activity of beekeepers. To fill this gap in pollinator decline censuses and to provide a broad picture of the current status of honeybees across their natural range, we used microsatellite genetic markers to estimate colony densities and genetic diversity at different locations in Europe, Africa, and central Asia that had different patterns of land use. Genetic diversity and colony densities were highest in South Africa and lowest in Northern Europe and were correlated with mean annual temperature. Confounding factors not related to climate, however, are also likely to influence genetic diversity and colony densities in honeybee populations. Land use showed a significantly negative influence over genetic diversity and the density of honeybee colonies over all sampling locations. In Europe honeybees sampled in nature reserves had genetic diversity and colony densities similar to those sampled in agricultural landscapes, which suggests that the former are not wild but may have come from managed hives. Other results also support this idea: putative wild bees were rare in our European samples, and the mean estimated density of honeybee colonies on the continent closely resembled the reported mean number of managed hives. Current densities of European honeybee populations are in the same range as those found in the adverse climatic conditions of the Kalahari and Saharan deserts, which suggests that beekeeping activities do not compensate for the loss of wild colonies. Our findings highlight the importance of reconsidering the conservation status of honeybees in Europe and of regarding beekeeping not only as a profitable business for producing honey, but also as an essential component of biodiversity conservation.

Brood-cell size has no influence on the population dynamics ofVarroa destructormites in the native western honey bee,Apis mellifera mellifera

The varroa mite (Varroa destructor) is an ectoparasite of the western honeybee Apis mellifera that reproduces in the brood cells. The mite will generally kill colonies unless treatment is given, and this almost universally involves the use of chemicals. This study was undertaken to examine the effect of small cell size on the reproductive success of the mite, as a method of non-chemical control in the Northern European honeybee Apis mellifera mellifera. Test colonies with alternating small and standard cell size brood combs were sampled over a three-month period and the population biology of the mites evaluated. To ensure high varroa infestation levels, all colonies were infested with mites from a host colony prior to commencement. A total of 2229 sealed cells were opened and the varroa mite families recorded. While small-sized cells were more likely to be infested than the standard cells, mite intensity and abundance were similar in both cell sizes. Consequently, there is no evidence that small-cell foundation would help to contain the growth of the mite population in honeybee colonies and hence its use as a control method would not be proposed.

Effects at Nearctic north-temperate latitudes of indoor versus outdoor overwintering on the microsporidium Nosema ceranae and western honey bees ( Apis mellifera)

In northern temperate climates, western honey bee ( Apis mellifera) colonies can be wintered outdoors exposed to ambient conditions, or indoors in a controlled setting. Because very little is known about how this affects the recently-detected microsporidium Nosema ceranae, we investigated effects of indoor versus outdoor overwintering on spring N. ceranae intensity (spores per bee), and on winter and spring colony mortality. For colonies medicated with Fumagilin-B® to control N. ceranae, overwintering treatment did not affect N. ceranae intensity, despite outdoor-wintered colonies having significantly greater mortality. These findings suggest that N. ceranae may not always pose the most significant threat to western honey bees, and that indoor-wintering may ensure that a greater number of colonies are available for honey production and pollination services during the summer.

Worker reproductive parasitism and drift in the western honeybee Apis mellifera

When a honeybee (Apis spp.) colony loses its queen and is unable to rear a new one, some of the workers activate their ovaries and produce eggs. When a colony has a queen (i.e., it is queenright) almost all worker-laid eggs are eaten, but when hopelessly queenless, the workers become more tolerant of worker-laid eggs and rear some of them to adult drones. This increased tolerance renders a queenless colony vulnerable to worker reproductive parasitism, wherein unrelated workers enter the colony and lay eggs. Here, we show that the proportion of unrelated (non-natal) workers significantly decreases after an Apis mellifera colony becomes queenless. The remaining non-natal workers are as likely to have activated ovaries as natal workers, yet they produce more eggs than natal workers, resulting in significantly higher reproductive success for non-natal workers. In a second experiment, we provided queenless and queenright workers with a choice to remain in their own colony or to join a queenless or queenright colony nearby. The experiment was set up such that worker movement was unlikely to be due to simple orientation errors. Very few workers joined another colony, and there was no preference for workers to drift into or out of queenless or queenright colonies, in accordance with the proportion of non-natal workers declining significantly after becoming queenless in the first experiment.

Morphotypes of Varroa destructor collected in Apis mellifera colonies from different geographic locations of Argentina

Parasites display considerable phenotypic plasticity in life-history traits such as, body size. Varroa destructor is an ectoparasitic mite of the western honey bee Apis mellifera. Several studies have reported that in V. destructor, there is a wide phenotypic plasticity within a population of mites. However, it is unknown if there are morphologic variations in V. destructor populations affecting different A. mellifera populations. A morphometric study of V. destructor populations was conducted to provide information concerned to the relationships among parasite populations found in different geographic locations from A. mellifera colonies of Argentina. The hypothesis tested was different morphotypes of V. destructor populations parasitizing different A. mellifera populations from Argentina exist. A discriminant analysis employing eight morphologic variables revealed that it is possible to differentiate morphotypes of mites in Argentina. However, the level of discrimination detected among mites population varied according to the grouping of mite's population. Possible causes explaining the morphometric variability in the V. destructor populations were discussed.

Deformed wing virus in western honey bees ( Apis mellifera) from Atlantic Canada and the first description of an overtly-infected emerging queen

Deformed wing virus (DWV) in western honey bees ( Apis mellifera) often remains asymptomatic in workers and drones, and symptoms have never been described from queens. However, intense infections linked to parasitism by the mite Varroa destructor can cause worker wing deformity and death within 67 h of emergence. Ten workers (eight with deformed wings and two with normal wings) and three drones (two with deformed wings and one with normal wings) from two colonies infected with V. destructor from Nova Scotia, Canada, and two newly-emerged queens (one with deformed wings and one with normal wings) from two colonies infected with V. destructor from Prince Edward Island, Canada, were genetically analyzed for DWV. We detected DWV in all workers and drones, regardless of wing morphology, but only in the deformed-winged queen. This is the first report of DWV from Atlantic Canada and the first detection of a symptomatic queen with DWV from anywhere.

Apis floreadrone flight: longevity and flight performance

Mating flight records are presented for males (drones) of the Asian dwarf honeybee species Apis florea. These include observations on longevity, mortality and inclusive flight records for a cohort of known-aged males. Averages for flight performance show the flights/lifetime to be 15.3 (± 11.8 SD); the number of flight days, 9.1 (± 6.5 SD) and a drone mating flight lasting ca. 31 min (± 9 min, 27 s SD). For a smaller group of known-aged males, for which complete daily flight performance was recorded for all days of flight, the mean summed flight time was 6 h 38 min (± 5 h 53 min SD). Longevity and mortality data show the average age for commencement of flight to be 5.6 days (± 1.3 SD) and the mean age for the final flight to be 15.6 days (± 9.2 SD), providing an average reproductive flight window of 10 days. These observations for A. florea male longevity and mortality are significantly shorter than those reported for the western honeybee (Apis mellifera L.) as observed in temperate climates of North America.

The association of multiple sap beetle species (Coleoptera: Nitidulidae) with western honey bee (Apis mellifera) colonies in North Africa.

The association of multiple sap beetle species (Coleoptera: Nitidulidae) with western honey bee (Apis mellifera) colonies in North Africa.