Effects of time, temperature, and honey on Nosema apis (Microsporidia: Nosematidae), a parasite of the honeybee, Apis mellifera (Hymenoptera: Apidae).

Newly emerged adult bees were fed with Nosema apis spores subjected to various treatments, and their longevity, proportions of bees infected, and spores per bee recorded. Spores lost viability after 1, 3, or 6 months in active manuka or multifloral honey, after 3 days in multifloral honey, and after 21 days in water or sugar syrup at 33 degrees C. Air-dried spores lost viability after 3 or 5 days at 40 degrees, 45 degrees, or 49 degrees C. Increasing numbers of bees became infected with increasing doses of spores, regardless of their subsequent food (active manuka honey, thyme honey, or sugar syrup). Final spore loads were similar among bees receiving the same food, regardless of dose. Bees fed with either honey had lighter infections than those fed with syrup, but this may have been due to reductions in their longevity. Bees fed with manuka honey were significantly shorter lived, whether infected or not.     

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.     

Microsatellite loci for euglossine bees (Hymenoptera: Apidae)

The Neotropical Euglossini (Hymenoptera: Apidae) are important pollinators of many flowering plants, particularly orchids. Lack of highly polymorphic genetic markers for euglossine species has limited the study of their social organization and inbreeding. We therefore developed microsatellite markers for two species, Eulaema nigrita (11 loci) and Euglossa cordata (nine loci), most of which were highly polymorphic in the source species and in a range of related euglossine bees.     

Allozyme variation in bumble bees (Hymenoptera: Apidae)

Allozyme variation at an average of 37.3 loci was assessed in queens of 16 Bombus and 2 Psithyrus bumble bee species from North America. The mean expected heterozygosity (H) for the Bombus species was 0.008 +/- 0.006 (95% confidence limits) and that for the Psithyrus was 0.007 +/- 0.007. These levels are significantly lower than found in other Hymenoptera but are comparable to those found in previous studies of bumble bees based on far fewer loci. Neutral mutation and random genetic drift can account for the observed variation, but this implies a very small effective population size for species of bumble bees.     

American foulbrood and African honey bees (Hymenoptera: Apidae)

We have taken samples of honey from individual beekeepers (N = 64), and of domestic (N = 35) and imported honey (N = 15) retailed in supermarkets in several sub-Saharan countries and cultivated these samples for Paenibacillus larvae subsp. larvae Heyndrickx et al. causing American foulbrood in honey bee colonies. The results are compared with samples of similar backgrounds and treated the same way but collected in Sweden (N = 35). No P. larvae subsp. larvae spores were found in any honey produced in Africa south of the Sahara although honey imported into this region frequently contains the pathogen. Swedish honey frequently contains P. larvae subsp. larvae spores although the general level of visibly infected bee colonies is low (roughly 0.5%). The results suggest that large parts of Africa may be free from American foulbrood. Behavioral studies (hygienic behavior) on Apis mellifera subsp. scutellata Lepeletier in Zimbabwe suggest that hygienic behavior of African bees could influence the apparent low level, or even absence of American foulbrood in large parts of Africa.     

Application of a modified selection index for honey bees (Hymenoptera: Apidae)

Nine different genetic families of honey bees (Apis mellifera L.) were compared using summed z-scores (phenotypic values) and a modified selection index (Imod). Imod values incorporated both the phenotypic scores of the different traits and the economic weightings of these traits, as determined by a survey of commercial Ontario beekeepers. Largely because of the high weight all beekeepers place on honey production, a distinct difference between line rankings based on phenotypic scores and Imod scores was apparent, thereby emphasizing the need to properly weight the traits being evaluated to select bee stocks most valuable for beekeepers. Furthermore, when beekeepers who made >10% of their income from queen and nucleus colony sales assigned relative values to the traits used in the Imod calculations, the results differed from those based on weightings assigned by honey producers. Our results underscore the difficulties the North American beekeeping industry must overcome to devise effective methods of evaluating colonies for breeding purposes.     

Africanized honey bees (Hymenoptera: Apidae) have a greater fidelity to sunflowers than European bees

A study of sunflower, Helianthus annuus L., pollen collection by Africanized and European honey bees, Apis mellifera L., was conducted in a hybrid seed production field in Argentina. Africanized honey bees collected significantly larger proportions of sunflower pollen than did European honey bees. The result suggests that Africanized bees would be more efficient for commercial sunflower seed production.     

Phylogenetic divergence of the Australian allodapine bees (Hymenoptera: Apidae)

Allodapine bees are most diverse in Africa but are distributed throughout the Old World tropical and Austral regions. They are considered useful for studies into the evolution of social behaviour since they exhibit the full range of social organisation from solitary to highly eusocial (sensu; ). Five genera are found in Australia, namely Braunsapis, Exoneurella, Exoneura, Brevineura, and Inquilina. Sociality and life histories are well documented for the exoneurine genera (review in ) and Inquilina is an obligate social parasite of species of Exoneura (). In this paper, maximum parsimony and maximum likelihood methods using molecular sequence data from two mitochondrial gene regions (cyt b and COI) and a single nuclear gene region (EF-1alpha) are used to reconstruct phylogenetic relationships of the Australian allodapine genera. Results suggest that the exoneurine group (Brevineura, Exoneurella, and Exoneura+Inquilina) diverged very rapidly and are monophyletic to the exclusion of other (primarily African) allodapine genera. A clade containing Australian species of Braunsapis is also monophyletic to the exclusion of African congeners. Braunsapis is not phylogenetically close to, and is a more derived group than the exoneurine group and probably came to occupy the Australian plate via a later dispersal through the southern Asian region. It is unclear at this point how the exoneurine group came to occupy the Australian plate and possible scenarios are discussed.     

Managing honey bees (Hymenoptera: Apidae) for greenhouse tomato pollination

Although commercially reared colonies of bumble bees (Bombus sp.) are the primary pollinator world-wide for greenhouse tomatoes (Lycopersicon esculentum Mill.) previous research indicates that honey bees (Apis mellifera L.) might be a feasible alternative or supplement to bumble bee pollination. However, management methods for honey bee greenhouse tomato pollination scarcely have been explored. We 1) tested the effect of initial amounts of brood on colony population size and flight activity in screened greenhouses during the winter, and 2) compared foraging from colonies with brood used within screened and unscreened greenhouses during the summer. Brood rearing was maintained at low levels in both brood and no-brood colonies after 21 d during the winter, and emerging honey bees from both treatments had significantly lower weights than bees from outdoor colonies. Honey bee flight activity throughout the day and over the 21 d in the greenhouse was not influenced by initial brood level. In our summer experiment, brood production in screened greenhouses neared zero after 21 d but higher levels of brood were reared in unscreened greenhouses with access to outside forage. Flower visitation measured throughout the day and over the 21 d the colonies were in the greenhouse was not influenced by screening treatment. An economic analysis indicated that managing honey bees for greenhouse tomato pollination would be financially viable for both beekeepers and growers. We conclude that honey bees can be successfully managed for greenhouse tomato pollination in both screened and unscreened greenhouses if the foraging force is maintained by replacing colonies every 3 wk.     

Brood pheromone regulates foraging activity of honey bees (Hymenoptera: Apidae)

Brood pheromone modulated the foraging behavior of commercial honey bee, Apis mellifera L., colonies pollinating a 10-ha market garden of cucumber, Cucurbita pepo L., and zucchini, Cucumis saticus L., in Texas in late autumn. Six colonies were randomly selected to receive 2000 larval equivalents of brood pheromone and six received a blank control. The ratio of pollen to nonpollen foragers entering colonies was significantly greater in pheromone-treated colonies 1 h after treatment. Pheromone-treated foragers returned with pollen load weights that were significantly heavier than controls. Pollen returned by pheromone-treated foragers was 43% more likely to originate from the target crop. Number of pollen grains washed from the bodies of nonpollen foragers from pheromone-treated colonies was significantly greater than controls and the pollen was 54% more likely to originate from the target crop. Increasing the foraging stimulus environment with brood pheromone increased colony-level foraging and individual forager efforts. Brood pheromone is a promising technology for increasing the pollination activity and efficiency of commercial honey bee colonies.     

Bombus folsomi and the origin of Philippine bumble bees (Hymenoptera: Apidae)

Abstract The type female of Bombus folsomi (Frison) is redescribed and synomymized with B.ephippiatus Say. It is concluded that the putative type locality of B.folsomi , Mt Kinabalu in Borneo, is in error and that the genus appears to be absent from Borneo. This lends support to the hypothesis that bumble bees immigrated to the Philippines by an unusual northern route through Taiwan. More rigorous testing of this idea will require further cladistic analysis of the genus Bombus .     

Diversity and distribution of orchid bees (Hymenoptera: Apidae) with a revised checklist of species

The aim of this study was to investigate the diversity and distribution patterns of orchid bees (Euglossina). Cluster and correlation analyses were applied to data extracted from 28 orchid-bee surveys throughout the Neotropical Region. The 28 sampling sites were grouped in three main biogeographic areas that roughly correspond to the Amazonian Basin, the Atlantic Forest and Central America. These three regions, as well as subregions within each of them, correspond approximately to biogeographic components identified through phylogeny-based analyses for other bees and organisms. The Amazonian Forest as a whole has the richest fauna and the highest levels of endemism. The Atlantic Forest, on the other hand, showed the poorest fauna and the lowest levels of endemism. However, a major neotropical biome, in which orchid bees are known to occur, has not been sampled yet, the savanna-like cerrado. At least 30% of the species are endemic to each biome. An updated checklist of the species of Euglossina is provided.     

Nonrandom visitation of brood cells by worker honey bees (Hymenoptera: Apidae)

The visitation pattern by worker honey bees to cells in the brood nest was monitored on an artificially created brood pattern consisting of about one-fourth brood cells evenly distributed among empty cells. The majority (63 %) of the observed workers selectively entered larval cells. In contrast, some workers avoided egg cells when presented a choice of egg vs empty cells. The results suggest that larvae produce a general signal indicating their presence to worker bees. Eggs also seem to produce a signal, which is perceived to be different from the one from larvae.     

Prevalence of Nosema sp. (Microsporidia: Nosematidae) during an outbreak of the jack pine budworm in Ontario

Microsporidia are believed to play little or no role in outbreaks of the jack pine budworm, Choristoneura pinuspinus Freeman (Lepidoptrera: Tortricidae), because the short duration (2–4 years) of those outbreaks may not permit significant build-up of the pathogen. We conducted the first survey of Nosema sp. (Microsporidia: Nosematidae) over the course of a recent jack pine budworm outbreak in Ontario. Between 2004 and 2010 the outbreak defoliated a cumulative total of 1.78 million ha. Microscopic examination of ∼15,000 overwintering larvae collected over 6 years in sites with densities of 3 larvae per branch or more revealed widespread occurrence of Nosema at generally high infection intensities. The pathogen was present in 69.5% of the 518 plots that were monitored. Prevalence of infection was generally low (below 40% in 84% of plots with infected larvae) but reached high levels (80–95%) locally and increased rapidly in most infestations within 1–2 years of onset. We hypothesize that the habit of early-instar larvae to feed on developing male flowers (pollen cones) after spring emergence is critical in allowing rapid build-up of Nosema by increasing efficiency of horizontal transmission (higher density of both infected larvae and egested spores). Nosema infection may contribute to the complexity of jack pine budworm outbreak patterns by affecting egg recruitment and early-instar survival at the stand level in concert with known effects of budworm-induced reductions in pollen cone production on those processes.     

Lipid distribution in salivary glands of larvae and adult bees (Hymenoptera: Apidae)

Cytochemical studies were carried out to establish lipid distribution in the salivary glands of larvae and adult bees, using the imidazole buffer technique. In the duct cells of the larval salivary gland, the reaction was positive in the epicuticle and negative in the glandular lumen. The absence of smooth endoplasmic reticulum and the presence of lipids in the intercellular space suggest that lipids absorbed from the haemolymph could be used in the constitution of the epicuticle, after having been conveyed through the epithelium. In adult workers (new-emerged, nurse and forager workers), the head salivary glands presented a positive reaction in the secretion in glandular lumen, identifying its lipidic nature.     

Transfers ofVarroa mites from newly emerged bees: Preferences for age- and function-specific adult bees (Hymenoptera: Apidae)

Movements of the parasitic honey bee mite,Varroa jacobsoni (Oud.) were monitored in several assays as they moved among adult host honey bees,Apis mellifera. We examined the propensity of mites to leave their hosts and to move onto new bee hosts. We also examined their preference for bees of different age and hive function. Mites were standardized by selecting mites from newly emerged worker bees (NEWs). In closed jars, 50% ofVarroa left NEWs irreversibly when no physical path was present for the mites to return to the NEWs; about 90% of mites left newly emerged drones in identical assays. In petri dish arenas, mites were rarely seen off NEW hosts when monitored at 15-min intervals for 4 h; this was the case for single NEWs with one mite (NEWs+) and when a NEW+ and a NEW− (no mites) were placed together in a petri dish. When a NEW+ was held with either a nurse beeor a pollen forager, 25% of the mites moved to the older bees. When both a nurseand a pollen forager were placed in a petri dish with a NEW+, about 50% of the mites transferred to older bees; nurse bees received about 80% of these mites, whereas pollen foragers received significantly fewer mites (about 20%,P < 0.05). Most mite transfers occurred during the first 30 min after combining NEWs+ and test bees. When NEWs+ were combined with bees of known ages, rather than function, mites transferred more often to young bees than to older bees (1- and 5-day-old bees vs. 25-day-old bees,P < 0.05; 1-day-old vs. 13- and 25-day-old bees;P < 0.05). No differences in proportions of transferring mites were seen when the range of bee ages was ≤ 8 days (P > 0.05), implying that the factors mediating the mites’ adult-host preference change gradually with bee age. A possible chemical basis for host choice byVarroa is indicated by their greater propensity to move onto freezer-killed nurse bees than onto freezer-killed pollen foragers (P < 0.05) and by their lower movement onto heat-treated bees than onto control bees (P < 0.05). Bee age, hive function, and directional changes in cuticular chemistry are all correlated. Movements of newly emerged mites in relation to these variables may provide insights into their reproductive success inApis mellifera colonies.     

Host-seeking behaviour of tracheal mites (Acari: Tarsonemidae) on honey bees (Hymenoptera: Apidae)

The behaviour of the endoparasitic tracheal mite, Acarapis woodi (Rennie) on honey bees (Apis mellifera L.) is a challenge to observe because of its small size. Through a microscope, we videotaped this mite's movement on young bees, dead bees and bees exposed to vegetable oil. Previous studies have shown that solid vegetable oil decreases mite infestations in a bee colony. We hypothesized that the oil alters mite behaviour to the detriment of the parasite, thus helping to safeguard the host. Habitat-seeking behaviour, identified as necessary for mites to locate a new host environment, was disrupted on both dead and oil-treated bees. Questing behaviour, which is associated with transfer between hosts, increased significantly on the dead and oily bees. The behaviours of mites were significantly different between all three treatments (x ²=494.96, p<0.001 on dead bees and x ²=851.11, p<0.001 on oily bees). Both questing and seeking behaviours were significantly different on each of the thoracic treatments (F _2,66=7.88, p<0.001 and F _2,66=21.28, p<0.001) and mite questing behaviour was not altered between males and females on live or oily bees (F _1,22=0.25, p<0.62), but habitat seeking was (F _1,22=7.42, p<0.012). The male questing and habitat-seeking behaviours were observed. We conclude that oil-treated bees gained protection from habitat-seeking mites because the normal behaviour of the mites seeking an oviposition site is interrupted.