Adriana Correa-Benítez

Varroa destructor is the main culprit for the death and reduced populations of overwintered honey bee (Apis mellifera) colonies in Ontario, Canada

The relative effect of parasite levels, bee population size, and food reserves on winter mortality and post winter populations of honey bee colonies was estimated. More than 400 colonies were monitored throughout three seasons in Ontario, Canada. Most of the colonies were infested with varroa mites during the fall (75.7%), but only 27.9% and 6.1% tested positive to nosema disease and tracheal mites, respectively. Winter colony mortality was 27.2%, and when examined as a fraction of all morbidity factors, fall varroa mite infestations were the leading cause of colony mortality (associated to > 85% of colony deaths), followed by fall bee populations and food reserves. Varroa-infested colonies, with weak populations and low food reserves in the fall, significantly decreased spring colony populations, whereas varroa infestations and Nosema infections in the spring, significantly decreased bee populations by early summer. Overall, results suggest that varroa mites could be the main culprit for the death and reduced populations of overwintered honey bee colonies in northern climates.ZusammenfassungDer relative Effekt des Befallsgrades, der Volksstärke und der Futtervorräte auf die Überwinterungsverluste und die Auswinterungstärke von Honigbienenvölkern wurde abgeschätzt. Über 400 Bienenvölker in sechs verschiedenen Regionen in Ontario, Kanada, wurden im Herbst, Frühjahr und im Frühsommer kontrolliert. Die meisten Völker waren im Herbst mit Varroamilben befallen (75,7 %), aber nur 6,1 % and 27,2 % der Völker wurden positiv auf Tracheenmilben bzw. Nosemose getestet. Die Wintermortalität lag bei 27,2 %, wobei die überlebenden Völker etwa die Hälfte ihrer Bienen und Futtervorräte verloren hatten. Während der Varroabefall über den Winter abnahm, stieg der Nosemabefall um das 317-fache auf mehr als 3,1 Millionen Sporen pro Biene im Frühjahr an (Tab. I). Allerdings wurden keine Unterschiede im Nosemabefall zwischen zusammengebrochenen und überlebenden Bienenvölkern gefunden. Bienenvölker, die während des Winters eingegangen waren, hatten signifikant weniger Bienen und Futtervorräte sowie einen höheren Milbenbefall im vorherigen Herbst als überlebende Völker (P < 0, 001; Tab. II). Bei den Mortalitätsraten gab es Unterschiede zwischen den sechs Regionen: Die drei Regionen mit der höchsten Mortalitätsrate waren signifikant stärker mit Varroamilben befallen als die drei Regionen mit den geringsten Verlusten (P < 0, 0001). Wenn man die einzelnen Faktoren bzgl. ihrer Bedeutung für die Winterverluste beurteilt, so waren die meisten Völkerverluste mit dem Varroabefall korreliert (> 85 %), gefolgt von der Bienenpopulation (> 69 %) und den Futtervorräten (> 67 %; Ta b. III). Die Futtervorräte und die Bienenpopulation im Herbst waren signifikant positiv korreliert mit der Anzahl an bienenbesetzten Waben im Frühjahr, während der Varroabefall mit dieser Variablen negativ korreliert war (P < 0, 0001). Auch zwischen der Bienenpopulation im Frühsommer und der Anzahl an bienenbesetzten Waben im Frühjahr gab es signifikant positive Korrelationen (P < 0, 001). Der Frühjahrsbefall mit Varroamilben und der Nosemabefall waren dagegen negativ korreliert mit der Bienenpopulation im Sommer (P < 0, 001).Insgesamt zeigen die Ergebnisse, dass Varroamilben große und negative Auswirkungen auf die Überlebensrate von überwinternden Bienenvölkern haben. Darüber hinaus könnte eine Kombination von Varroabefall, Nosemabefall und schwachen Völkern die Frühjahrsentwicklung von Bienenvölkern in nördlichen Klimazonen signifikant beeinträchtigen. Diese Ergebnisse betonen die Bedeutung einer geringen Varroapopulation im Herbst verbunden mit der Einwinterung von gut gefütterten und starken Bienenvölkern.

Nosema ceranae has parasitized Africanized honey bees in Mexico since at least 2004

Ernesto Guzman-Novoa, Mollah Md Hamiduzzaman, Miguel E Arechavaleta-Velasco, Gun Koleoglu, Pegah Valizadeh and Adriana Correa-Benitez School of Environmental Sciences, University of Guelph, 50 Stone Road East, Guelph, Ontario, N1G 2W1, Canada. Centro Nacional de Investigacion en Fisiologia y Mejoramiento Animal, INIFAP, km 1 Carretera a Colon, Ajuchitlan, Qro. Mexico. Departamento de Produccion Animal: Abejas, FMVZ, UNAM, Cd. Univ., Mexico DF 04510, Mexico.

Length of life, age at first foraging and foraging life of Africanized and European honey bee (Apis mellifera) workers, during conditions of resource abundance

SUMMARY This study was conducted to analyse the length of life, the age at which bees began to forage, and the foraging life of European and Africanized worker honey bees (Apis mellifera) during conditions of resource abundance. Newly emerged worker bees were identified with coloured paint or numbered plastic tags on their thorax, and were co-fostered in common colonies of European, Africanized or unrelated bee origin to infer if the variation found was due to genetic or environmental effects. Both European and Africanized bees varied significantly in their length of life, within a range of 19.9 to 25.9 days, but there was no clear and consistent difference for this trait between the two types of bees. Hive and colony environment influenced the length of life of both bee types. Bees lived longer in colonies with Africanized environment. These results suggest that genetic effects influence the length of life of workers bees to a lesser degree than do environmental effects. The age at which bees began foraging affected both the length of life and the foraging life of the experimental workers. Bees that started to forage late in life lived longer than those that started early. Additionally, bees that initiated foraging activities at a younger age had a longer foraging life. The strongest correlation was between length of life and foraging life (ρ = 0.66), indicating that bees that lived longer also had a longer foraging life. Bees with the longest foraging lives were those that began to forage early in life and that also lived as long or longer than average bees. European bees had longer foraging lives than Africanized bees. The implications of these results on the life-history strategies of Africanized and European bees are discussed.

Differential responses of Africanized and European honey bees (Apis mellifera) to viral replication following mechanical transmission or Varroa destructor parasitism.

For the first time, adults and brood of Africanized and European honey bees (Apis mellifera) were compared for relative virus levels over 48 h following Varroa destructor parasitism or injection of V. destructor homogenate. Rates of increase of deformed wing virus (DWV) for Africanized versus European bees were temporarily lowered for 12h with parasitism and sustainably lowered over the entire experiment (48 h) with homogenate injection in adults. The rates were also temporarily lowered for 24h with parasitism but were not affected by homogenate injection in brood. Rates of increase of black queen cell virus (BQCV) for Africanized versus European bees were similar with parasitism but sustainably lowered over the entire experiment with homogenate injection in adults and were similar for parasitism and homogenate injection in brood. Analyses of sac brood bee virus and Israeli acute paralysis virus were limited as detection did not occur after both homogenate injection and parasitism treatment, or levels were not significantly higher than those following control buffer injection. Lower rates of replication of DWV and BQCV in Africanized bees shows that they may have greater viral resistance, at least early after treatment.

Nosema ceranae is an old resident of honey bee (Apis mellifera) colonies in Mexico, causing infection levels of one million spores per bee or higher during summer and fall

This study was conducted to identify Nosema spp. and to determine their infection levels in honey bee (Apis mellifera) samples collected in Mexico in 1995-1996. Samples of historical surveys from different countries are of particular interest to support or challenge the hypothesis that the microsporidium Nosema ceranae is a new parasite of A. mellifera that has recently dispersed across the world. We demonstrate that N. ceranae has parasitized honey bees in Mexico since at least 1995 and that the infection levels of this parasite during summer and fall, exceed the threshold at which treatment of honey bee colonies is recommended.

First detection of honey bee viruses in stingless bees in North America

Here, we report the first molecular detection of two honey bee viruses (deformed wing virus (DWV) and black queen cell virus (BQCV)) in stingless bees of the genus Scaptotrigona. This is the first molecular report of the presence of DWV and BQCV in stingless bees in North America and the first in S. mexicana.

First detection of four viruses in honey bee (Apis mellifera) workers with and without deformed wings and Varroa destructor in Mexico

Summary Little information exists in Mexico about the presence of viral diseases in honey bee (Apis mellifera) colonies and their association with Varroa destructor mites. Here we report the first investigation using molecular techniques, of honey bees and varroa mites tested for viruses in Mexico. Samples of varroa mites, worker pupae, and adult bees were collected from five colonies, four of which had a high proportion of workers with deformed wings. Varroa mite infestation rates were determined in worker brood and in adult bees. Samples were analysed by reverse transcription-PCR (RT-PCR) for sacbrood virus (SBV), deformed wing virus (DWV), acute bee paralysis virus (ABPV), Israeli acute paralysis virus (IAPV), chronic bee paralysis virus (CBPV) and Kashmir bee virus (KBV). Of the six viruses surveyed, four were found in adult bees (DWV, IAPV, ABPV and SBV), two in worker brood (DWV and IAPV) and two in varroa mites (DWV and IAPV). Only KBV and CBPV were not detected. This is the first molecular detection of these four viruses infecting honey bees and varroa mites in Mexico. The association of these viruses with V. destructor is discussed.

Varroa destructor (Mesostigmata: Varroidae) Parasitism and Climate Differentially Influence the Prevalence, Levels, and Overt Infections of Deformed Wing Virus in Honey Bees (Hymenoptera: Apidae)

The prevalence and loads of deformed wing virus (DWV) between honey bee (Apis mellifera L.) colonies from a tropical and a temperate environment were compared. The interaction between these environments and the mite Varroa destructor in relation to DWV prevalence, levels, and overt infections, was also analyzed. V. destructor rates were determined, and samples of mites, adult bees, brood parasitized with varroa mites and brood not infested by mites were analyzed. DWV was detected in 100% of the mites and its prevalence and loads in honey bees were significantly higher in colonies from the temperate climate than in colonies from the tropical climate. Significant interactions were found between climate and type of sample, with the highest levels of DWV found in varroa-parasitized brood from temperate climate colonies. Additionally, overt infections were observed only in the temperate climate. Varroa parasitism and DWV loads in bees from colonies with overt infections were significantly higher than in bees from colonies with covert infections. These results suggest that interactions between climate, V. destructor, and possibly other factors, may play a significant role in the prevalence and levels of DWV in honey bee colonies, as well as in the development of overt infections. Several hypotheses are discussed to explain these results.

Analysis of volatile components from Melipona beecheii geopropolis from Southeast Mexico by headspace solid-phase microextraction

A head space solid-phase microextraction method combined with gas chromatography–mass spectrometry was developed and optimised to extract and analyse volatile compounds of Melipona beecheii geopropolis. Seventy-three constituents were identified using this technique in the sample of geopropolis collected. The main compounds detected include β-fenchene (14.53–15.45%), styrene (8.72–9.98%), benzaldehyde (7.44–7.82%) and the most relevant volatile components presents at high level in the geopropolis were terpenoids (58.17%).

A scientific note on the first detection of black queen cell virus in honey bees ( Apis mellifera ) in Mexico

Honey bees / Apis mellifera / black queen cell virus / Mexico Honey bees (Apis mellifera L.) are infected by a variety of viruses of worldwide distribution (Allen and Ball 1996; Ellis and Munn 2005). Some of them, including deformed wing virus (DWV), acute bee paralysis virus (ABPV), chronic bee paralysis virus (CBPV), Kashmir bee virus, and Israeli acute paralysis virus (IAPV) have been associated with cases of bee mortality (Berthoud et al. 2010; Gen-ersch and Aubert 2010). Thus, an increasing number of studies are being conducted to find out whether viruses are responsible for the massive loss of colonies recently experienced in many countries. Mexico is a major honey producer, but despite its beekeeping importance, not much information exists for this country about the presence of viral diseases in honey bees. Of the more than 20 viruses known to infect the honey bee, the only viruses so far reported from bees collected in Mexico are CBPV (Bailey 1967), and more recently sacbrood virus, ABPV, DWV, and IAPV (Guzman-Novoa et al. 2012). Here, we report for the first time, the presence in Mexico of the black queen cell virus (BQCV). Samples of worker pupae were collected in RNA Later (Invitrogen Canada, Burlington, Ontario, Canada) from five colonies kept by the Ministry of the Environment in Tlalpan, Distrito Federal, Mexico for different studies. It was noticed that some of the samples had a darker color than the typical white pearl color of healthy brood. Thus, they were tested for the presence of BQCV using reverse transcription polymerase chain reaction (Total RNA was extracted from 12 samples collected from five colonies (at least two samples per colony) by homogenizing five pupae per sample as per Chen et al. (2000); all pupae showed a dark color. All items that were used for macerating bees or mites, or extracting RNA, were thoroughly washed and then auto-claved prior to these procedures. The homoge-nates were extracted twice with chloroform and the RNA was precipitated using LiCl as described by Sambrook et al. (1989). The amount of total RNA extracted was determined with a spectrophotometer (Nanovue GE Healthcare; Cambridge, UK). For cDNA synthesis, 2 μg of total RNA was reverse-transcribed using Oligo (dT) and M-MuLV RT with the RevertAid TM H Minus First Strand cDNA Synthesis Kit (Fermentas Life Sciences; Burlington, Ontario, Canada), following the instructions of the manufacturer. The primer sequences used to detect the BQCV …