Thermal properties of hornet colonies: thermography of individual hornets and their nests and the role of the pupal silk in thermoregulation.

The present study focused on temperature assessments within a hornet nest. The measurements encompassed adult hornets, brood combs and the various stages of brood, and involved a thermographic method. Body parts of adult hornets were found to vary in their temperature, with the thorax eliciting the highest temperature and the abdomen the lowest. Similarly, there were thermal variances between larvae at instars 4-5, light-colored pupae and dark pupae. The measurements were made at day and night (when the entire population was present in the nest) on nests containing thousands of individuals at various ages. Most of the pupae measured during October were hornet drones. The usual air temperature between the (subterranean) combs was 28.7 degrees C, while the outside (ground level) temperature was 23.5 degrees C. The paper discusses the creation of heat by hornets, the thermoregulation throughout night and day, both by the hornets proper as well as by their products (comb and silk). Also discussed is the intra-nest conversion of one form of energy to another, as heat to electric current or vice versa.     

Process of comb division of reused nests in the Australian paper waspRopalidia plebeiana (Hymenoptera,Vespidae)

Summary InRopalidia plebeiana, combs made in the previous year are often reused by foundresses in the following spring and structurally divided into subnests by them. Close observations of the comb dividing process revealed that: 1) combs that had multiple brood areas (areas where cells had eggs) were frequently divided into subnests, while those with single brood areas were never divided; 2) groups of foundresses each occupied a particular brood area even before comb division started; and 3) frequency with which a foundress practiced comb cutting was independent of her social status or oviposition frequency. These observations suggest that the initial grouping of foundresses that colonize an old nest leads to subsequent comb division, rather than the major egg layers cutting combs to safeguard their oviposition territories from their rivals.     

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.     

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.     

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.     

Evaluation of drone brood removal for management of Varroa destructor (Acari: Varroidae) in colonies of Apis mellifera (Hymenoptera: Apidae) in the northeastern United States

The efficacy of drone brood removal for the management of Varroa destructor Anderson & Trueman in colonies of the honey bee, A. mellifera L., was evaluated. Colonies were treated with CheckMite+ in the fall of 2002. The following spring, quantities of bees and brood were equalized, but colonies were not retreated. The brood nest of each colony consisted of 18 full-depth worker combs and two full-depth drone combs. Each worker comb had <12.9 cm2 of drone cells. Standard management practices were used throughout the season. Colonies were randomly assigned to one of two groups. In the control group, drone combs remained in place throughout the season. In the treatment group, drone combs were removed on 16 June, 16 July, 16 August, and 16 September and replaced with empty drone combs (16 June) or with drone combs removed on the previous replacement date. In the early fall, the average mite-to-bee ratio in the control group was significantly greater than the corresponding ratio in the treatment group. Drone brood removal did not adversely affect colony health as measured by the size of the worker population or by honey production. Fall worker populations were similar in the two groups. Honey production in treatment colonies was greater than or similar to production in control colonies. These data demonstrate that drone brood removal can serve as a valuable component in an integrated pest management program for V. destructor and may reduce the need for other treatments on a colony-by-colony basis.     

Honeybee Colony Thermoregulation – Regulatory Mechanisms and Contribution of Individuals in Dependence on Age,Location and Thermal Stress

Honeybee larvae and pupae are extremely stenothermic, i.e. they strongly depend on accurate regulation of brood nest temperature for proper development (33–36°C). Here we study the mechanisms of social thermoregulation of honeybee colonies under changing environmental temperatures concerning the contribution of individuals to colony temperature homeostasis. Beside migration activity within the nest, the main active process is “endothermy on demand” of adults. An increase of cold stress (cooling of the colony) increases the intensity of heat production with thoracic flight muscles and the number of endothermic individuals, especially in the brood nest. As endothermy means hard work for bees, this eases much burden of nestmates which can stay ectothermic. Concerning the active reaction to cold stress by endothermy, age polyethism is reduced to only two physiologically predetermined task divisions, 0 to ∼2 days and older. Endothermic heat production is the job of bees older than about two days. They are all similarly engaged in active heat production both in intensity and frequency. Their active heat production has an important reinforcement effect on passive heat production of the many ectothermic bees and of the brood. Ectothermy is most frequent in young bees (<∼2 days) both outside and inside of brood nest cells. We suggest young bees visit warm brood nest cells not only to clean them but also to speed up flight muscle development for proper endothermy and foraging later in their life. Young bees inside brood nest cells mostly receive heat from the surrounding cell wall during cold stress, whereas older bees predominantly transfer heat from the thorax to the cell wall. Endothermic bees regulate brood comb temperature more accurately than local air temperature. They apply the heat as close to the brood as possible: workers heating cells from within have a higher probability of endothermy than those on the comb surface. The findings show that thermal homeostasis of honeybee colonies is achieved by a combination of active and passive processes. The differential individual endothermic and behavioral reactions sum up to an integrated action of the honeybee colony as a superorganism.     

Parental investment of male two-spotted goby, Gobiusculus flavescens (Fabricius)

The trade-off between parental care and feeding was studied in the male two-spotted goby (Gobiusculus flavescens F.). Two temperatures, 8.5 degrees C and 13.0 degrees C, were used, with five replicates at each temperature, in order to determine whether temperature influenced parental behaviour. In each replicate, two males and four females were introduced to an aquarium, where the males chose between two nests and courted the females. In each replicate, one male spawned. After spawning, the males guarded the eggs until hatching. The guarding males' behaviour was recorded with a video camera twice a day (15 min each time), once before and once after they were fed. The male's condition (c-factor) was calculated at the start of the experiment and after egg hatching. The eggs were spawned in an artificial nest (half of a PVC tube), and attached to the nest in a single layer. The areas with eggs (representing brood size) were marked after spawning and the fry counted after hatching (which was used to calculate area hatched). Numbers of prey eaten (plankton) and number of aggressive encounters between the guarding male and the other fishes were recorded. Time spent in the nest and time used on fertilisation, fanning and cleaning were estimated and related to egg age, brood size, hatching success, temperature and food availability (no food or food).The results showed that feeding (expected to influence future reproduction) decreased and parental expenditure (current reproduction) increased, as the eggs developed (became closer to independence). Parental expenditure was significantly higher at 13.0 degrees C than at 8.5 degrees C, presumably due to higher oxygen demands by the eggs, and a greater risk of egg-infections. The c-factor of the males guarding eggs decreased over time, in contrast to the non-guarding males' c-factor. Guarding males' aggressiveness decreased as the eggs got older, but increased just before hatching. A possible explanation for this could be the decreasing intrusion by the non-guarding male and females caused by high aggressive behaviour by the guarding male early in the brood cycle. The exploitation of the nest (percentage of total nest area covered by eggs) seemed to determine the amount of parental expenditure and loss of condition, while brood size (area of eggs) had no effect.     

Comb Wax Salvage by the Red Dwarf Honeybee, <Emphasis Type="Italic">Apis florea</Emphasis> F.

Cannibalizing wax from a deserted nest and reusing it in construction of a new nest is only known for absconding colonies of red dwarf honeybee, Apis florea. We tested whether A. florea would preferentially choose to salvage wax from their own, original natal comb over that of other conspecific combs (test 1) and whether they would salvage wax from comb facsimiles of A. florea combs (test 2) fashioned from the combs of A. cerana, A. dorsata, and A. mellifera. In test 1, preferences for natal comb were significantly greater than for non-natal combs. In test 2, no wax was collected from heterospecific combs. It is evident that wax discrimination is context-dependent and that there is considerable genetic variation for the wax-salvaging trait.     

Scaling in nests of a social wasp: a property of the social group

The numbers of brood cells in nests built by founding swarms of the Neotropical social wasp Polybia occidentalis closely correlate with the numbers of wasps in the swarms. We analyzed nests of different sizes to determine how they scale with respect to the allocation of brood cells among combs. Three patterns were evident: compared to smaller nests, larger nests have (1) more combs and (2) larger combs; and (3) among nests containing the same number of combs, the last two combs diverge in relative size as nest size increases. Taken together, these results suggest that members of a swarm somehow "know" the size of the swarm they are in. This information feeds back to individual builders, which quantitatively modulate their responses to stigmergic cues in ways that result in the nest-size-scaled allocation of brood cells among combs. The patterns also suggest that swarms fine-tune the final size of their nests by making corrections as they build.     

Home Range Analysis in the Study of Spatial Organization on the Comb in the Paper Wasp Polistes Dominulus

In order to understand how the apparent freedom of individual movements can concur with social order in a colony, we investigated spatial relationships between foundresses, workers and immature brood in a paper wasp. This is the first time an ecological analytical approach (home range analysis) has been employed to describe small scale spatial use in a social context. In this study, home range was not used in its strictly ecological sense, but rather applied to the comb. Our results show that the positions individual wasps assumed on Polistes dominulus combs are spatially structured. Workers and foundresses do not occupy the comb in random distribution, but rather follow predictable spatial patterns. Each active wasp has its own spatial fidelity area, at least over a 1 d observation period, spending the majority of its time within a very small area averaging approx. 12% of the comb but occasionally it may cover an area of up to 50% of the comb surface. Dominant females occupied a significantly smaller area that either subordinate foundresses or workers. Areas patrolled by workers varied in shape and size, with no relation to time spent on the comb, wasp density or position of immature brood. All the wasps clumped around the dominant female, who proved to be the only individual affected by cell content. Nevertheless, although the wasps tended to clump together, average superimposition rates among nest‐mates was very low (higher in workers than foundresses), suggesting that the wasps limit each other’s individual spaces.     

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 relationship between comb age and performance of honey bee (Apis mellifera) colonies

A study on the relationship between the age of comb and the activity of the hybrid Carniolan honey bee colonies in collecting pollen activity, worker brood production, colony strength, and honey yield was conducted. In comparison to colonies with combs aged 4-years, colonies with combs aged 1, 2 and 3-years significantly exceeded in the number returning workers, number returning workers with pollen loads, rate of storing pollen, rate of worker brood production, and size of colony population. Colonies with combs aged 1, 2 and 3-years produced significantly more honey than colonies with combs aged 4-years (5.25, 4.90 and 4.65 kg/colony vs. 4.45 kg/colony, respectively). It can be concluded that the foraging rate, gathering and storing pollen, brood production, colony population size, and honey yield significantly depended on the age of combs. Beekeepers can replace old combs with new ones to increase brood and honey production.     

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.     

Stability of oxytetracycline in diets fed to honeybee colonies for disease control

Antibiotic extender patties, pollen patties, and sugar solutions containing oxytetracycline hydrochloride (OTC) were incubated at freezer (−9°C), refrigerator (4°C), room (25°C), and brood nest temperature (34°C) for 1, 2, 3, 7, and 11 weeks to determine the stability of the antibiotic. The OTC in antibiotic extender patties and pollen patties was stable at brood nest temperature for at least 11 weeks. The OTC in sugar solutions degraded within 1 week at brood nest temperature.     

The importance of worker behaviour in the colony organization of the social wasps,Vespula Vulgaris (L.) andV. Germinaca (F.) (Vespidae; Hymenoptera)

Summary With two combs and one or a small number of workers it was found that the comb itself without brood was less attractive than a comb with cocoon caps or larvae, but single workers were equally attracted to combs with a large or small number of larvae, or queen or non-queen larvae. A worker walked at random when off a comb and tended, when on a comb, to stay with the first group of larvae that it found.Observations in the field showed that adults formed a group at night at the bottom of the nest.Records from six observation nests of whole or almost whole colonies have been collected over a period of three years. In all cases a dominant comb, which carried a larger percentage of the workers than any other comb and usually the queen if present, was soon established. The dominant comb always contained brood, was nearest or one of the combs nearest the entrance, received most foragers, and workers grouped on it more frequently than other combs.The grouping behaviour of workers on a comb can be related to background temperature and caused comb temperature to increase to 29° C–32.5° C.The worker attention a larva received increased as the number of workers on its comb increased.Reasons for and the consequences of grouping behaviour, the appearance of a dominant comb and the position of the latter in the nest, are discussed.

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Résumé Au cas où il y a deux rayons et soit un seul, soit un petit nombre d'ouvrières, on constate que le rayon sans couvain attire moins les ouvrières que celui operculé (cocons ou larves). Pour ce qui est d'un petit nombre ou d'un grand nombre de larves, ou encore des larves de reines ou de non-reines, l'attraction est égale pour chaque ouvrière. L'ouvrière ne se trouvant pas sur le rayon se déplace au hasard. De plus, quand elle est sur un rayon elle a tendance à rester avec le premier groupe de larves qu'elle trouve.L'examen des observations effectuées sur le terrain montre que les adultes se groupent la nuit, au fond du nid.Six nids, contenant des colonies entières ou presque entières, ont fait l'objet de plusieurs observations pendant une période de trois ans. Durant la même période, les résultats ont été enregistrés. Dans tous les cas, un rayon dominant s'est établi dans un bref délai. Ce rayon avait un plus grand pourcentage d'ouvrières que tout autre, et comportait généralement la reine. Le rayon dominant contenait toujours du couvain; il se trouvait le plus près de l'entrée du nid (ou bien était parmi les plus près); il recevait le plus grand nombre de butineuses, et des ouvrières s'y groupaient plus fréquemment que sur d'autres rayons.Il est possible d'établir un rapport entre le comportement des ouvrières lorsqu'elles se groupent sur un rayon, et la température ambiante. En effet, ce comportement a entrainé une hausse allant jusqu'à 29° C–32,5° C sur le rayon.L'attention que prêtait une ouvrière à la larve augmentait à mesure que le nombre d'ouvrières sur son rayon augmentait.On traite dans cet article du comportement observé lors d'un groupement, les raisons et les conséquences; ainsi que de l'apparition d'un, rayon dominant et de la position de celui-ci dans le nid.

     

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.     

Information analysis by the paper wasp,Polistes fuscatus,during nest construction (Hymenoptera,Vespidae)

Summary The building decision process of the paper wasp,Polistes fuscatus, was studied by 1) analyzing the search pattern of the wasps prior to the addition of pulp to different areas of the nest, 2) comparing the pulp addition needs of the cell chosen for lengthening to those of other cells in the nest, and 3) presenting the wasps with eight types of dichotomous building choices, which provided information about the relative influence of different building cues. Wasps conduct a hierarchical search prior to pulp addition, which means that they search the comb face and petiole disproportionately more often and more thoroughly than the comb back and sides. Once a particular nest area triggers closer scrutiny, comparisons are made with adjoining areas. The most needy location is then chosen based on nest cues. When lengthening a cell, the development of the brood and relative cell length have a strong influence on which cell is chosen at all times, while distance of the brood from the cell mouth becomes important during the later stages of brood development. The results indicate that there is no simple hierarchical weighting of cues. The decision process involves comparisons among multiple cues, which for the most part have an additive influence when variation in relative cue strength is considered.     

Hoarding by honeybees (Apis mellifera L.)

The food hoarding by groups of fifty bees kept in small cages and provided with sugar syrup was studied. Less food was stored in a new comb than in an old one, whether the old comb had been used for storing food or rearing brood, and there was less in drone than in worker combs. The presence of light, larvae and the odour of honey discouraged storage of syrup, but the presence of a queen encouraged it. The amount stored also varied with the environmental temperature, the age of the bees concerned and with their previous physiological and behavioural experience including food deprivation and length of confinement. Increased food in honeystomachs sometimes compensated for less stored in combs.     

Exposure to an additional alternating magnetic field affects comb building by worker hornets

Oriental hornet workers, kept in an Artificial Breeding Box (ABB) without a queen, construct within a few days brood combs of hexagonal cells with apertures facing down. These combs possess stems that fasten the former to the roof of the ABB. In an ABB with adult workers (more than 24 h after eclosion), exposed to an AC (50 Hz) magnetic field of a magnitude of B = 50-70 mGauss, the combs and cells are built differently from those of a control ABB, subjected only to the natural terrestrial magnetic field. The effects of the additional magnetic field consist of (a) 35-55% smaller number of cells and fewer eggs in each comb, (b) disrupted symmetry of building, with many deformed and imperfectly hexagonal cells, and (c) more delicate and slender comb stems.