Stanley S. Schneider

The role of the vibration signal during queen competition in colonies of the honeybee, Apis mellifera

Temporary polygyny (the presence of multiple queens) occurs in honeybee colonies when virgin queens (VQs) are reared for reproductive swarming or queen replacement. During these events, workers perform vibration signals on queen cells and emerged queens, and these signals may influence which VQ becomes the new laying queen of a colony. We examined the role of vibration signals during queen competition in two African and six European honeybee colonies. There was pronounced variability in vibration activity between colonies and among queens reared within the same colony. Despite this variation, all colonies showed similar trends in the relationships between the vibration signal and queen replacement. Vibration signals performed on queen cells were not associated with emergence success. Likewise, the signal was not associated with queen emergence order. Early emerging and late-emerging queens were vibrated at similar rates, and there was no clear relationship between emergence order and VQ survival. However, the signals performed on VQs after they emerged were associated with their behaviour and success during the queen elimination period. Emerged VQs that were vibrated at higher rates survived longer, performed more bouts of piping (a characteristic sound produced by queens), eliminated more rivals and were more likely to become the new queens of the colonies. The vibration signal may therefore allow workers a degree of control over the behaviour of emerged VQs, and may influence the outcome of queen competition in honeybees. Differences in vibration activity within and among colonies may reflect differences in the extent to which workers and queens conflict over the timing and outcome of polygyny reduction.

THE INFLUENCE OF HYBRIDIZATION BETWEEN AFRICAN AND EUROPEAN HONEYBEES, APIS MELLIFERA, ON ASYMMETRIES IN WING SIZE AND SHAPE

Abstract We examined the possible role of hybridization in the invasion process of the African honeybee by testing two hypotheses regarding fluctuating asymmetry (FA), a measure of developmental stability, in wing characteristics: (1) FA should be higher in hybrid versus parental genotypes of African and European races; (2) FA should be lower in African bees compared to hybrid and European workers. Parental and reciprocal hybrid worker genotypes were cross fostered in common‐hive rearing environments. We did not find greater FA for wing size and shape in the hybrids compared to both parental types. However, we did find significantly lower FA of shape in the African workers compared to the European and hybrid workers, suggesting that European bees and their hybrids may have compromised fitness relative to African bees. We also found that the two hybrid genotypes significantly differed in overall wing size and shape. If these differences affect wing aerodynamics, then the paternity of hybrids may influence worker performance and could potentially contribute to the loss of European matrilines. Hybridization had few consistent effects on directional asymmetry for wing size and shape. Genotypic factors played a far greater role in determining the effect of hybridization on wing morphology than did differences in rearing environment. Thus, African bees may have lower FA for wing shape (and by inference greater developmental stability) relative to European and hybrid workers, which may contribute to the ability of African bees to displace European honeybee races in invaded regions.

Diet selection and foraging distances of African and European-African hybrid honey bee colonies in Costa Rica

Summary: Diet selection and foraging distances were compared among 3 pairs of matched colonies of African an European-African hybrid honey bees in Northwestern Costa Rica. Mitochondrial DNA (mtDNA) analysis was used to classify each colony as neotropical African (possessing African mtDNA) or hybrid (possessing European mtDNA, and therefore containing workers arising from a European queen mated to African drones). African and hybrid colonies did not differ significantly in population size, the areas of comb devoted to brood rearing and food storage, flight activity, pollen foraging activity, or the distances traveled to pollen and nectar sources. These nonsignificant differences suggest that the foraging behavior of the two colony types may have been more influenced by environmental factors than by genetically determined dietary or movement preferences. Conversely, such genetically determined preferences may have been expressed, but African-like preferences may have been dominant within both colony types. However, while no significant differences were observed, colonies with African mtDNA maintained slightly greater levels of brood rearing, had 1.5 times the level of pollen foraging activity, and traveled on the average 600 m less per round trip of foraging. The potential influence of these slight but consistent differences on the long-term, relative success of African versus hybrid colonies is discussed.

Seasonal cycles of growth, development and movement of the African honey bee,Apis mellifera scutettata, in Africa

SummaryThe relationship between the annual colony cycle and seasonal patterns of forage availability was investigated for the African honey bee,Apis mellifera scutellata, in the Okavango River Delta, Botswana. The annual cycle occurred in three distinct periods. The swarming season occurred from October-November, following two to three months of intense brood production, and coincided with the end of peak forage abundance. The migration season occurred from November-May and coincided with reduced and variable floral resources. During the migration season, brood production and food storage were generally low but quite variable from month to month, and swarms passing over the study area at this time traveled in an easterly direction. The migration season was followed by the establishment period (June-September), in which large numbers of new colonies traveling from the west moved into the study area. The establishment period coincided with, and slightly preceded, the period of peak forage abundance, and colonies devoted resources collected at this time almost entirely to brood rearing, which culminated in swarm production. The data suggest that honey bee colonies in the Okavango are mobile and gear their reproduction and movement to seasonally shifting resource pattern.

The habitat and nesting biology of the African honey beeApis mellifera scutellata in the Okavango River Delta, Botswana, Africa

SummaryThe habitat and nesting biology were studied for naturally occurring colonies of the African honey bee,Apis mellifera scutellata, in the Okavango River Delta, Botswana. Vegetational surveys revealed that the forage available to Delta colonies was abundant and potentially available year round. Colonies had a density of 7.8 nests/km2. Nest cavities occurred with equal frequency in trees and termite mounds, had a volume of approximately 17 L, were unpropolized, and had south-facing, top-located entrances. Delta colonies were small (ca. 6,500 workers), constructed small amounts of comb (ca. 3,000 cm2), stored little food, devoted 78% of comb space to brood production, exhibited little nest defense, and experienced a 48% predation rate during the 5 month study period. The characteristics observed forscutellata in this study are discussed as adaptations to the hot climate, long foraging season, and high predation rate experienced in the Delta. Data for the Delta colonies are compared to those forscutellata in other tropical areas, and to honey bees in temperate climate regions.ZusammenfassungDer Lebensraum und die Nestbiologie der Afrikanischen Honigbiene,Apis mellifera scutellata, wurden an Völkern im natürlichen Verbreitungsgebiet im Delta des Okavango Flusses, Botswana, untersucht. Beobachtungen der Vegetation zeigten, daß den Völkern im Delta das ganze Jahr über reichlich Nahrung zur Verfügung steht. Die Koloniedichte betrug 7.8 Nester/km2. Nesthöhlen fanden sich gleich häufig in Bäumen wie in Termitenhügeln, sie hatten ein Volumen von ca. 17 L, waren nicht propolisiert und hatten nach Süden gerichtete, oben liegende Eingänge. Die Völker im Delta waren klein (ca. 6,500 Arbeiterinnen), sie bauten wenig Waben (ca. 3,000 cm2), speicherten wenig Nahrung, verwendeten 78% der Waben für die Brut und sie verfteidigten ihr Nest nur schwach; die Verlustrate durch Räuber betrug 48%. Die charakteristischen Eigenschaften, die fürscutellata in dieser Untersuchung beobachtet wurden, werden als Anpassungen an das heisse Klima, an die lange Trachtperiode und an die im Delta auftretende hohe Verlustrate diskutiert. Die Ergebnisse, die an Völkern im Delta gewonnen wurden, werden verglichen mit Ergebnissen anscutellata in anderen tropischen Gebieten und mit Ergebnissen anscutellata in anderen tropischen Gebieten und mit Ergebnissen an Honigbienen in gemäßigten Klimazonen.

Spatial Foraging Patterns and Colony Energy Status in the African Honey Bee, Apis mellifera scutellata

The relationship between changes in foraging patterns (inferred from waggle dance activity) and colony energy status (inferred from brood rearing activity, food storage, and colony weight) was examined for the African honey bee during a period of relative resource abundance and resource dearth. When resources were more abundant mean foraging distances (about 400 m) and foraging areas (4–5 km2) were small, and colonies recruited to 12–19 different sites per day. Colony foraging ranges and sites visited increased slightly during the dearth period, yet foraging continued to be concentrated within less than 10 km2. The degree to which fluctuations in foraging patterns were correlated with colony energy status varied with the availability of floral resources. During periods of relative forage abundance, increases in foraging range and number of sites visited were significantly correlated with increases in brood rearing and colony weight. In contrast, colonies examined during periods of resource dearth exhibited no correlations between foraging areas, foraging distances, and fluctuations in brood rearing, food storage, or colony weight. Thus, during dearth periods colonies may not be able to coordinate foraging patterns with changes in colony energy status.

The role of the vibration signal in the house-hunting process of honey bee (Apis mellifera) swarms

The function of the vibration signal of the honey bee (Apis mellifera) during house hunting was investigated by removing vibrating bees from swarms and examining the effects on waggle dancing for nest sites, liftoff preparations and swarm movement. We compared house hunting among three swarm types: (1) test swarms (from which vibrating bees were removed), (2) manipulated control (MC) swarms (from which randomly selected workers and some waggle dancers were removed), and (3) unmanipulated control (UC) swarms (from which no bees were removed). The removal of vibrating bees had pronounced effects on liftoff preparations and swarm movement. Compared to the MC and UC swarms, the test swarms had significantly greater liftoff-preparation periods, were more likely to abort liftoff attempts, and in some cases were unable to move to the chosen site after the swarm became airborne. However, the three swarm types did not differ in overall levels of waggle dance activity, the time required to achieve consensus for a nest site, the rate at which new waggle dancers were recruited for the chosen site, or the ability to maintain levels of worker piping necessary to prepare for flight. The removal of vibrating bees may therefore have altered liftoff behavior because of a direct effect on vibration signal activity. A primary function of the signal during house hunting may be to generate a level of activity in workers that enhances and coordinates responses to other signals that stimulate departure and movement to a new location.

The influence of paternity on virgin queen success in hybrid colonies of European and African honeybees

Abstract When African honeybees, Apis mellifera scutellata, migrate into an area, substantial hybridization occurs with existing European bee populations. However, over time European traits disappear until the populations become predominantly or entirely African. European patrilineal traits could be lost when hybrid colonies raise virgin queens if African-patriline queens have a survival advantage during reproductive competition. We examined queen competition in observation colonies that contained an African (A) or European (E) matriline, and both patrilines. In colonies of either matriline, the virgin queens that survived the elimination process were those that emerged sooner, piped more, eliminated more rivals and received more vibration signals from workers. Hybrid queens had increased piping and vibration rates and greater fighting success than did purebred queens. However, the effects of hybridization were expressed differently in the two matrilines, resulting in significant matriline-by-patriline interactions. In the E-matriline colonies, African-patriline queens emerged sooner, piped more, killed more rivals, were vibrated at higher rates and were more likely to survive the replacement period than were their European-patriline sister queens. In contrast, in the A-matriline colonies, the behaviour of African- and European-patriline queens was highly variable, and the two queen types did not differ for any of the characters examined or the ability to survive the rival elimination period. Thus, African paternity potentially conveys a competitive advantage to queens of European maternity, which would contribute to the spread of African alleles and the loss of European traits in hybrid zones. Furthermore, we observed that vibration signals were produced predominantly by African-paternity workers. The vibration signal may influence the spread of African traits, and this effect may be mediated largely by the behaviour of African-paternity workers. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.

Spatial Foraging Patterns of the African Honey Bee, Apis mellifera scutellata

Recruitment patterns were investigated for the African honey bee in the Okavango River Delta, Botswana. The waggle dances of two observation colonies maintained in the field were monitored and used to construct maps of daily recruitment activity. These maps revealed that the African colonies frequently adjusted the allocation of recruits among food patches, recruited for 16–17 different food sites/day over areas of 55–80 km2,and concentrated the majority of recruitment within 1 km of the hives (median foraging distances for the two colonies were 295 and 563 m). In both colonies pollen foragers were more abundant than nectar foragers, and pollen sources indicated by waggle dancers were significantly closer to the hives than nectar sources. Compared to the recruitment patterns of temperate climate colonies, the African colonies had smaller recruitment areas, smaller mean recruitment distances, and a greater emphasis on pollen foraging. These differences may be related to the contrasting survival strategies followed by tropical-versus temperate-climate honey bees.

The influence of the vibration signal on worker interactions with the nest and nest mates in established and newly founded colonies of the honey bee, Apis mellifera

Abstract.Honey bees adjust cooperative activities to colony needs, based in part on information acquired through interactions with the nest and nest mates. We examined the role of the vibration signal in these interactions by investigating the influence of the signal on the movement rates, cell inspection activity, and trophallaxis behavior of workers in established and newly founded colonies of the honey bee, Apis mellifera. Compared to non-vibrated control bees, vibrated recipients in both colony types exhibited increased movement through the nest and greater cell inspection activity, which potentially increased contact with stimuli that enhanced task performance. Also, compared to controls, recipients in both colony types showed increased rates of trophallactic interactions and spent more time engaged in trophallaxis, which potentially further increased the acquisition of information about colony needs. The vibration signal may therefore help to organize labor in honey bees in part by increasing the rate at which workers obtain information about their colony. Vibrated recipients in the established and newly founded colonies did not differ in any aspect of behavior examined, suggesting that colony developmental state did not influence the degree to which individual workers responded to the signal. However, previous work has demonstrated that newly founded colonies have increased levels of vibration signal behavior. Thus, the vibration signal may help to adjust worker activity to colony conditions partly by stimulating greater numbers of bees to acquire information about colony needs, rather than by altering the level at which individual recipients react to the signal.