THE EPIDEMIOLOGY AND CONTROL OF NOSEMA DISEASE OF THE HONEY-BEE

The proportion of honey-bees infected with Nosema apis (Zander) declines in summer as the old infected bees die, for they cease to transmit their infection to the newly emerged individuals during the flying season. N. apis spores survive the summer on combs contaminated with infected faeces during the preceding winter. Although bees clean the combs during the summer, all infected material is not removed, and even well-used brood comb, which has been repeatedly cleaned by bees, can carry infection. Only a few bees may contract infection in the autumn from these faeces, but they join the winter cluster and initiate the next outbreak of the disease. Transferring a colony on to clean comb early in the spring or summer removes the source of the disease, and it then disappears when all the old infected bees die.
Old broodless comb can be sterilized quite simply by fumigation for a few days with the vapours of formalin or glacial acetic acid. Acetic acid is preferable, because it does not poison any honey or pollen in the combs. Formaldehyde can safely be used only with empty combs.
The autumn is the best time for treating colonies chemotherapeutically, because the combs are then cleanest and the few bees which are infected can be cured during the winter. The drug can be incorporated in the syrup normally fed to colonies in autumn, and there is no risk of seriously contaminating subsequent honey crops. However, such treatment cannot eliminate the disease because sufficient spores remain on the combs for the disease to start again when the drug supplied in the winter stores is exhausted.     

Honey bees (Apis mellifera) reared in brood combs containing high levels of pesticide residues exhibit increased susceptibility to Nosema (Microsporidia) infection

Nosema ceranae and pesticide exposure can contribute to honey bee health decline. Bees reared from brood comb containing high or low levels of pesticide residues were placed in two common colony environments. One colony was inoculated weekly with N. ceranae spores in sugar syrup and the other colony received sugar syrup only. Worker honey bees were sampled weekly from the treatment and control colonies and analyzed for Nosema spore levels. Regardless of the colony environment (spores+syrup added or syrup only added), a higher proportion of bees reared from the high pesticide residue brood comb became infected with N. ceranae, and at a younger age, compared to those reared in low residue brood combs. These data suggest that developmental exposure to pesticides in brood comb increases the susceptibility of bees to N. ceranae infection.     

The provision of supplementary food to hive bees

Sucrose syrup is less satisfactory than honey as a winter and spring food for bees: a mixture of approximately equal parts of honey and syrup is of almost the same value as honey alone.
Feeding confined to early autumn induced the strongest spring development of colonies; syrup feeding in the spring may retard colony development, and food supplied at this time is apparently wasted. Feeding with syrup and pollen is advantageous only when a colony is lacking in stores of carbohydrate and protein.
A total of four British Standard brood combs full of pollen provides sufficient protein for a colony on B.S. equipment from autumn until April: the best results were obtained by providing colonies on eleven B.S. combs, in early autumn, with 35-40 lb. of honey, or honey and concentrated sucrose syrup, and four brood combs full of pollen.     

Old comb for nesting site recognition by <Emphasis Type="Italic">Apis dorsata?</Emphasis> Field experiments in China

The Asian giant honey bee, Apis dorsata, often conducts seasonal, long-distance migrations in southern China, between a preferred tree (having more than one nest) and alternate sites. Although worker bees cannot make a round-trip journey, colonies re-utilize preferred trees after an absence of several months. We performed comb experiments in which bases and all abandoned combs were entirely scraped off trees and their sites covered with plastic, or comb was moved to trees of the same species. Swarms of giant honey bees investigated trees where combs were removed and continued to nest on the same trees. In contrast, placing combs in nets on previously used trees, or on nearby trees of the same species, did not attract more swarms. The same number of colonies that left them returned to previously occupied trees. Our findings suggest that direct olfactory or sensory contact with old comb bases might regulate nest establishment, but individual trees, lacking normal visual or chemical cues of old nests, are relocated using behavioral devices that remain to be elucidated. Received 12 February 2007; revised 5 June 2007; accepted 13 September 2007.     

Sub-lethal effects of pesticide residues in brood comb on worker honey bee (Apis mellifera) development and longevity

Background

Numerous surveys reveal high levels of pesticide residue contamination in honey bee comb. We conducted studies to examine possible direct and indirect effects of pesticide exposure from contaminated brood comb on developing worker bees and adult worker lifespan.

Methodology/Principal Findings

Worker bees were reared in brood comb containing high levels of known pesticide residues (treatment) or in relatively uncontaminated brood comb (control). Delayed development was observed in bees reared in treatment combs containing high levels of pesticides particularly in the early stages (day 4 and 8) of worker bee development. Adult longevity was reduced by 4 days in bees exposed to pesticide residues in contaminated brood comb during development. Pesticide residue migration from comb containing high pesticide residues caused contamination of control comb after multiple brood cycles and provided insight on how quickly residues move through wax. Higher brood mortality and delayed adult emergence occurred after multiple brood cycles in contaminated control combs. In contrast, survivability increased in bees reared in treatment comb after multiple brood cycles when pesticide residues had been reduced in treatment combs due to residue migration into uncontaminated control combs, supporting comb replacement efforts. Chemical analysis after the experiment confirmed the migration of pesticide residues from treatment combs into previously uncontaminated control comb.

Conclusions/Significance

This study is the first to demonstrate sub-lethal effects on worker honey bees from pesticide residue exposure from contaminated brood comb. Sub-lethal effects, including delayed larval development and adult emergence or shortened adult longevity, can have indirect effects on the colony such as premature shifts in hive roles and foraging activity. In addition, longer development time for bees may provide a reproductive advantage for parasitic Varroa destructor mites. The impact of delayed development in bees on Varroa mite fecundity should be examined further.     

Comparative reproduction of <Emphasis Type="Italic">Varroa destructor</Emphasis> in different types of Russian and Italian honey bee combs

Earlier studies showed that Russian honey bees support slow growth of varroa mite population. We studied whether or not comb type influenced varroa reproduction in both Russian and Italian honey bees, and whether Russian bees produced comb which inhibited varroa reproduction. The major differences found in this study concerned honey bee type. Overall, the Russian honey bees had lower (2.44 ± 0.18%) levels of varroa infestation than Italian honey bees (7.20 ± 0.60%). This decreased infestation resulted in part from a reduced number of viable female offspring per foundress in the Russian (0.85 ± 0.04 female) compared to the Italian (1.23 ± 0.04 females) honey bee colonies. In addition, there was an effect by the comb built by the Russian honey bee colonies that reduced varroa reproduction. When comparing combs having Russian or Italian colony origins, Russian honey bee colonies had more non-reproducing foundress mites and fewer viable female offspring in Russian honey bee comb. This difference did not occur in Italian colonies. The age of comb in this study had mixed effects. Older comb produced similar responses for six of the seven varroa infestation parameters measured. In colonies of Italian honey bees, the older comb (2001 dark) had fewer (1.13 ± 0.07 females) viable female offspring per foundress than were found in the 2002 new (1.21 ± 0.06 females) and 1980s new (1.36 ± 0.08 females) combs. This difference did not occur with Russian honey bee colonies where the number of viable female offspring was low in all three types of combs. This study suggests that honey bee type largely influences growth of varroa mite population in a colony.     

Orientation of comb building by honeybees

Summary Upon entering a new home site a honeybee swarm is faced with the task of organizing the building activities of thousands of component bees so that several straight and parallel vertically oriented combs can be quickly and efficiently built. As a part of this organization process it is necessary for the bees to select and agree upon a planar orientation for the new combs.This paper presents evidence that memory of a previously used comb direction influences the building of the new set of combs. Swarms which have recently moved into bait-hives (empty boxes placed in trees to attract feral swarms) tend to maintain the previously used comb direction when removed and forced to build new combs, whereas swarms which have occupied the bait-hives for a longer period (over 9 days) do not.Recent swarms predictably alter their comb building direction within the influence of an applied earthstrength magnetic field, indicating that honey bees are able to use the earth's magnetic field as a reference at the commencement of comb construction in a new hive.     

Acceptance by Honey Bee Guards of Non‐Nestmates is not Increased by Treatment with Nestmate Odours

Honey bee, Apis mellifera, entrance guards use chemical cues to discriminate nestmates from non‐nestmates. Previous research has shown that when wax combs are reciprocally swapped between two colonies, guards become more accepting of workers from the swap partner. However, when combs were transferred only one way, guards in the comb‐receiver colony became more accepting of bees from the comb‐donor colony, but not vice versa. Hence, the increased acceptance of non‐nestmates caused by reciprocal comb swapping was not because of introduced bees acquiring odours from the transferred combs, which was surprising because comb wax was known to affect the odour of bees. In the current experiment, we caused workers to acquire either nestmate or non‐nestmate odours by holding them for 15 min in a tube, which had previously held nestmates or non‐nestmates and then measured their acceptance by entrance guards of nestmate or non‐nestmate hives. When transferred workers had acquired odours of non‐nestmates, acceptance by their own colony’s guards significantly decreased to 66% from 91%. Conversely, the acceptance of non‐nestmates that had acquired odours of the guards’ own nestmates was unchanged, 25% vs. 25%. These results show that when equivalent changes in the odour of introduced bees are made, guards are more sensitive to changes that cause nestmates to acquire non‐nestmate odours than vice versa. These results are also a likely explanation for the earlier and surprising results from the unidirectional comb swap experiment ( Couvillon et al. 2007 ). We make a hypothesis for the underlying mechanism in terms of a multidimensional recognition cue space.     

An experiment on comb orientation by honey bees (Hymenoptera: Apidae) in traditional hives

The orientation of combs in traditional beehives is extremely important for obtaining a marketable honey product. However, the factors that could determine comb orientation in traditional hives and the possibilities of inducing honey bees, Apis mellifera (L.), to construct more desirable combs have not been investigated. The goal of this experiment was to determine whether guide marks in traditional hives can induce bees to build combs of a desired orientation. Thirty-two traditional hives of uniform dimensions were used in the experiment. In 24 hives, ridges were formed on the inner surfaces of the hives with fermented mud to obtain different orientations, circular, horizontal, and spiral, with eight replicates of each treatment. In the remaining eight control hives, the inner surface was left smooth. Thirty-two well-established honey bee colonies from other traditional hives were transferred to the prepared hives. The colonies were randomly assigned to the four treatment groups. The manner of comb construction in the donor and experimental hives was recorded. The results showed that 22 (91.66%) of the 24 colonies in the treated groups built combs along the ridges provided, whereas only 2 (8.33%) did not. Comb orientation was strongly associated with the type of guide marks provided. Moreover, of the 18 colonies that randomly fell to patterns different from those of their previous nests, 17 (94.4%) followed the guide marks provided, irrespective of the comb orientation type in their previous nest. Thus, comb orientation appears to be governed by the inner surface pattern of the nest cavity. The results suggest that even in fixed-comb hives, honey bees can be guided to build combs with orientations suitable to honey harvesting, without affecting the colonies.     

The influence of brood comb cell size on the reproductive behavior of the ectoparasitic mite Varroa destructor in Africanized honey bee colonies

Africanized honey bees (Apis mellifera, Hymenoptera: Apidae) in Brazil are tolerant of infestations with the exotic ectoparasitic mite, Varroa destructor (Mesostigmata: Varroidae), while the European honey bees used in apiculture throughout most of the world are severely affected. Africanized honey bees are normally kept in hives with both naturally built small width brood cells and with brood cells made from European-sized foundation, yet we know that comb cell size has an effect on varroa reproductive behavior. Three types (sizes) of brood combs were placed in each of six Africanized honey bee colonies: new (self-built) Africanized comb, new Italian comb (that the bees made from Italian-sized commercial foundation), and new Carniolan comb (built naturally by Carniolan bees). About 100 cells of each type were analyzed in each colony. The Africanized comb cells were significantly smaller in (inner) width (4.84 mm) than the European-sized comb cells (5.16 and 5.27 mm for Italian and Carniolan cells, respectively). The brood cell infestation rates (percentage cells infested) were significantly higher in the Carniolan-sized comb cells (19.3%) than in the Italian and Africanized cells (13.9 and 10.3%, respectively). The Carniolan-sized cells also had a significantly larger number of invading adult female mites per 100 brood cells (24.4) than did the Italian-sized cells (17.7) and the natural-sized Africanized worker brood cells (15.6). European-sized worker brood cells were always more infested than the Africanized worker brood cells in the same colony. There was a highly significant correlation (P<0.01) between cell width and the rate of infestation with varroa in four of the six colonies. The small width comb cells produced by Africanized honey bees may have a role in the ability of these bees to tolerate infestations by Varroa destructor, furthermore it appears that natural-sized comb cells are superior to over-sized comb cells for disease resistance.     

Colony founding and initial nest design of honey bees, Apis mellifera L

Thirty-two colonies of bees with varying populations were established in 1·2-m³ boxes for 24 days. At the end of this time, the bees were killed, and the comb structure, design, and placement were examined to obtain information about the initiation of bee nests. The analysis of variance of three dimensions of the comb (height, width, and length) showed no statistical differences when all thirty-two colonies were considered as a group.Comb built by queenless bees differed from any described in the literature. We think it is comb characteristically built by queenless bees that is neither worker nor drone in size but intermediate.The occurrence of multiple clusters building comb with and without queen in the same box is recorded but unexplained at present.An explanation is offered for the curl appearing in the lower edges of straight combs.     

Hierarchy of Attractants for Honey Bee Swarms

Chemical signals influence the selection of potential nest cavities by honey bee reproductive swarms. Attractants for swarms include the odors of old dark honey bee brood combs, odors from noncomb hive materials and propolis, and Nasonov pheromone, the odor released from the Nasonov glands of worker bees. Based on crossover and choice test experiments, swarms were shown to prefer, among otherwise identical cavities, those cavities containing Nasonov pheromone over cavities with only comb or other hive odors, cavities containing old comb over those with only noncomb odors or propolis, and cavities containing noncomb odors or propolis over those without bee or hive odor. Synergy between odors was not observed; that is, comb and/or noncomb hive odors did not enhance the attractiveness of Nasonov pheromone. The data support a model based on a hierarchy of olfactory attractants used by honey bee swarms, in order of highest to lowest: Nasonov pheromone, comb odor, noncomb and propolis odors, and, finally, absence of bee- or hive-produced odor.     

Adaptive spatial biases in nectar deposition in the nests of honey bees

Honey bees store their large supply of honey at the top and, to a lesser extent, along the edges of their nests. Whether this pattern is the result of preferences for where nectar is deposited is unclear. Camazine, in a path breaking study of pattern formation, found evidence that workers deposit nectar at random, while Free and Williams in an earlier study found evidence that bees prefer to deposit nectar into particular types of comb. Here we reexamine this question. We tested three hypotheses, all of which posit that bees have adaptive biases which allow them to deposit nectar directly into the most useful locations. We found that bees have preferences for depositing nectar into cells at the top of the nest, into old vs. new comb, and into interior facing comb vs. comb facing the exterior environment. These preferences may ensure that nectar is placed directly into those regions where it will ultimately be stored. They may also result in an optimal pattern of comb usage with respect to brood rearing. This work, along with the results of previous studies, suggests that comb usage patterns may reflect competing selective pressures and be more complicated than previously thought. Received 17 May 2007; revised 15 June 2007; accepted 3 July 2007.     

The behaviour of wasps (Vespula germanica L. andV. Vulgaris L.) when foraging

Summary While foraging on dead adult and pupal honeybees, individual wasps showed little conformity in the order in which they dismembered their prey; they attempted to take as large loads as possible and preferred abdomens and thoraces to heads.Although wasps always removed some of the appendages from thoraces, especially the hind and middle legs, the presence of these appendages did not encourage foraging or facilitate recognition of the prey.Pupae were preferred to newly emerged bees, and newly emerged bees to old bees, probably because of the difference in hardness of the cuticle. Whereas wasps learnt to divide adult bodies at the neck and waist, they showed considerable adaptability when dismembering pupae and when confronted with unusual situations. Although individuals tended to become conditioned to collecting one type of prey, some changed from collecting adults to collecting pupae.Wasps could easily be enticed away from meat by offering sugar syrup, but the change from syrup to meat was much more difficult, although it happened occasionally.Some wasps attempted to defend a supply of food against other would-be collectors. Despite their wariness of each other, wasps were attracted to the sight of others at a food source. The frequency with which a wasp continues to visit a site that has ceased to yield food depends on its previous foraging experience there.     

Ultra-violet reflectance of male and female red grouse, Lagopus lagopus scoticus, sexual ornaments reflect nematode parasite intensity

In many birds, females prefer males with the biggest or brightest sexual ornaments, which might reflect a higher phenotypic quality, such as fewer parasites. Unlike humans, most birds detect near-ultraviolet (UV) light, and UV signals can play an important role in sexual signalling and mate choice. Using a spectrophotometer, we analysed the colour of red grouse Lagopus lagopus scoticus sexual ornaments (their combs). We first show that combs reflect both in the red (600–700 nm) and UV (300–400 nm) part of the spectrum. Second, we investigated whether comb size and colour, and UV reflectance in particular, reflected an aspect of individual quality: the intensity of infection by a main nematode parasite, the caecal threadworm Trichostrongylus tenuis . We first analysed comb size and colour variation, and parasite intensity variation, in relation to sex and age. Males had bigger and redder combs than females, but UV brightness was greater for female than for male combs. Comb colour also differed between age groups, with young birds of both sexes showing brighter UV than old birds. Young grouse also had fewer T. tenuis worms than old grouse. We further tested whether intensity of infection could be predicted from comb characteristics (size and colour) in male and female red grouse. We found that parasite intensity was not significantly related to comb size or red brightness, but fewer worms were predicted from brighter UV in combs, in both males and females. The results indicate that UV reflectance of combs have a quality revealing function and might play an important role in grouse mate choice: UV brightness of combs could enable both male and female red grouse to assess the parasite loads of a potential mate.     

The queen in relation to wax secretion and comb building in honeybees

Summary The role of the queen in relation to wax secretion and comb building in honeybees was analyzed with respect to queen status (mated, virgin and dead queens and queenlessness), and pheromones of the head and abdominal tergite of queens. Worker variables considered were colony size, percentage of bees bearing wax scales, wax scale weight, and weight of constructed combs.The amount of wax recovered from festoon bees and the percentage of festoon bees bearing wax were independent of queen status, the pheromones of queens and access to the queen. Colonies with full access to freely moving mated queens always constructed significantly more comb than those headed by virgin or dead queens as well as all permutations of caged and division board queens whose mandibular glands and/or abdominal tergite glands were operative or not.Despite pheromonal similarity of virgin queens to mated ones, colonies headed by virgin queens constructed as little comb as did queenless colonies. The bouquets of the mandibular glands did not differ significantly among queens nor was the amount of comb constructed correlated with pheromonal bouquet. Comb building is greatest among colonies having full access to freely moving queens but the stimulus for such building is not attributable to the 90DA, 9HDA and 10HDA components of the queen's mandibular gland secretions.     

In vivo Responses of Honey Bee Midgut Proteases to Two Protease Inhibitors from Potato

Potato protease inhibitors, POT-1 and POT-2, were fed to newly emerged adult honey bees in cages at different doses in either sugar syrup (0.2 or 0.01% w:v) or pollen food (1 or 0.2% w:w). In vivo activities of three digestive endopeptidases (trypsin, chymotrypsin and elastase) and one exopeptidase (leucine aminopeptidase; LAP) were measured after 3 or 8days' exposure of bees to inhibitor. Enzyme activities were significantly lower at day 8 than at day 3, except for elastase, which did not change. POT-2 significantly reduced the activity of all endopeptidases at both timepoints, regardless of the dose level or the medium in which the inhibitor was administered. POT-1 acted in a similar manner, except that 0.01% POT-1 in syrup had no effect on bees. There was no consistent trend in changes in LAP activity. Bees fed either inhibitor at 1% in pollen or at 0.2% in syrup had significantly reduced lifespans, with the effect of the pollen treatment being greater than the syrup treatment. The survival of bees fed POT-1 or POT-2 at 0.2% in pollen or 0.01% in syrup did not differ from the controls.     

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.     

培菌白蚁菌圃微生物降解木质纤维素的研究进展

白蚁及其共生微生物协同降解植物细胞壁的机理一直被世界各国科学家所关注。培菌白蚁作为高等白蚁,相比低等食木白蚁具有更多样化的食性,其利用外共生系统“菌圃”,对多种植物材料进行处理。本文综述了菌圃微生物降解木质纤维素的研究进展,以期为深入研究菌圃中木质纤维素降解过程及其机制,并挖掘利用菌圃降解木质纤维素的能力及仿生模拟菌圃开发新的生物质利用系统提供参考。培 菌白蚁在其巢内利用由植物材料修建的多孔海绵状结构——“菌圃”来培养共生真菌鸡枞菌Termitomyces spp.,形成了独特的木质纤维素食物降解和消化策略,使木质纤维素在培菌白蚁及其共生微生物协同作用下被逐步降解。幼年工蚁取食菌圃上的共生真菌菌丝组成的小白球和老年工蚁觅得食物并排出粪便堆积到菌圃上成为上层菌圃。这一过程中,被幼年工蚁取食的共生真菌释放木质素降解酶对包裹在植物多糖外部的木质素屏障进行解聚。菌圃微生物(包括共生真菌)对解聚的木质素基团进一步降解,将多糖长链或主链剪切成短链,使菌圃基质自下而上被逐步降解。最后下层的老熟菌圃被老年工蚁取食,其中肠的内源酶系及后肠微生物将这些短链进一步剪切和利用。因此,蚁巢菌圃及其微生物是培菌白蚁高效转化利用木质纤维素的基础。化学层面的研究表明,菌圃能够实现对植物次生物质解毒和植 物纤维化学结构解构。对共生真菌相关酶系的研究显示可能其在菌圃的植物纤维化学结构和植物次生物质的降解中发挥了作用,但不同属共生真菌间其效率和具体功能不尽相同。而菌圃中的细菌是否发挥了作用和哪些细菌类群发挥了作用等仍有待进一步的研究。相比于低等食木白蚁利用其后肠共生微生物降解木质纤维素,培菌白蚁利用菌圃降解木质纤维素具有非厌氧和能处理多种类型食物两大优势,仿生模拟菌圃降解木质纤维素的机制对林地表面枯枝落叶的资源化利用具有重要意义。     

Use of flax oil to influence honey bee nestmate recognition

Fatty acids, normally found in comb wax, have a strong influence on nestmate recognition in honey bees, Apis mellifera L. Previous work has shown that bees from different colonies, when treated with 16- or 18-carbon fatty acids, such as oleic, linoleic, or linolenic acids, are much less likely to fight than bees from two colonies when only one of the two is treated. Previous work also shows that the influence of comb wax on recognition has practical applications; transfer of empty comb between colonies, before merger of those colonies, reduces fighting among workers within the merged colony. Flax oil contains many of the same fatty acids as beeswax. Here, we tested the hypothesis that treatment of individual bees with flax oil affects nestmate recognition; the results proved to be consistent with this hypothesis and showed that treated bees from different colonies were less likely to fight than untreated bees. These results suggest that flax oil may be useful in facilitating colony mergers.