Influence of environmental and colony factors on the initial commodity choice of foragers of the stingless bee Plebeia tobagoensis (Hymenoptera, Meliponini)

Novice foragers of social bees have to decide what food commodity to collect when they start foraging for the first time. In this decision making process two types of factors are involved: internal factors (the response threshold) and external factors (environmental and colony conditions). In this study we will focus on the importance of two external factors, pollen storage level and information from experienced foragers about food availability in the field, on the initial commodity choice of foragers of the stingless bee species Plebeia tobagoensis. We also studied the effect of the initial choice of individuals on their subsequent foraging career. This study was performed in a closed greenhouse compartment, where food availability and colony condition could be controlled. Information on food availability in the field from experienced foragers and pollen storage level both greatly influenced the initial commodity choice of individuals, with more choices for the commodity communicated by experienced foragers or lacking in storage. The initial choice of foragers is of importance for their future foraging career, although a substantial proportion of foragers did switch between food commodities. Because of the ability of novice foragers to become flexibly distributed over foraging tasks, social bees are able to react to changes in their environment without directly having to decrease foraging effort devoted to other foraging tasks. This, in combination with individual flexibility during foraging careers makes it possible for colonies of P. tobagoensis to forage efficiently in an ever-changing environment. Received 7 November 2005; revised 12 January 2006; accepted 16 February 2006.     

Effectiveness of recruitment behavior in stingless bees (Apidae,Meliponini)

Summary We examined the ability of stingless bees to recruit nest mates to a food source (i) in group foraging species laying pheromone trails from the food to the nest (Trigona recursa Smith, T. hypogea Silvestri, Scaptotrigona depilis Moure), (ii) in solitary foraging species with possible but still doubtful communication of food location inside the nest (Melipona seminigra Friese, M. favosa orbignyi Guérin), and (iii) in species with a less precise (Nannotrigona testaceicornis Lep., Tetragona clavipes Fab.) or no communication (Frieseomelitta varia Lep.). The bees were allowed to collect food (sugar solution or liver in the necrophageous species) ad libitum and the forager number to accumulate, as it would do under normal unrestrained conditions. The median number of bees collecting differed considerably among the species (1.0–1436.5). It was highest in the species employing scent trails. The time course of recruitment was characteristic for most of the species and largely independent of the number of foragers involved. The two Melipona species recruited other bees significantly faster than T. recursa, S. depilis, and N. testaceicornis during the first 10 to 30 minutes of an experiment. In species laying a scent trail to guide nestmates to a food source the first recruits appeared with a delay of several minutes followed by a quick increase in forager number. The median time required to recruit all foragers available differed among the species between 95.0 and 240.0 min. These differences can at least partly be explained by differences in the recruitment mechanisms and do not simply follow from differences in colony biomass.     

Melissopalynological analysis of stingless bee (Tetragonula pagdeni) honey in Eastern Thailand

Melissopalynological analysis of 72 Tetragonula pagdeni honey samples, collected from various locations in Chanthaburi (A) and Trat (B) provinces, Eastern Thailand during March 2015, was performed. Overall, 45 pollen types species belonging to 22 plant families were identified. The predominant pollen type was from Nephelium lappaceum and comprised 48.5% of the pollen in honey from location A2 (Pathavee district) and 45.3% in location B1 (AoYai district). The secondary pollen types, Wodyetia bifurcata and Mimosa pudica, accounted for 20.1% and 17.0%, respectively, in location B3 (Nhongsamed district), while Cocos nucifera accounted for 17.2% in location A2. In addition, pollen types of C. nucifera, M. pudica, N. lappaceum, Asystasia gangetica, Amaranthus lividus, Areca catechu, Chromolaena odorata and Durio zibethinus were found in T. pagdeni honey from all sampled locations. Furthermore, in the dearth period, T. pagdeni foraged food (as in pollen was present) from Musa sp., Acacia mangium and various weed species, such as A. gangetica, A. lividus, Ageratum conyzoides, Bidens pilosa, C. odorata, Melampodium divaricatum, Mikania cordata, Merremia umbellata, M. pudica, Pennisetum pedicellarum and Thysanoleana maxima, from within a 500?m radius around the hive to maintain their colonies.     

Detection of Deformed wing virus, a honey bee viral pathogen, in bumble bees (Bombus terrestris and Bombus pascuorum) with wing deformities

Honey bees (Apis mellifera) productively infected with Deformed wing virus (DWV) through Varroa destructor (V. destructor) during pupal stages develop into adults showing wing and other morphological deformities. Here, we report for the first time the occurrence of bumble bees (Bombus terrestris, Bombus pascuorum) exhibiting wing deformities resembling those seen in clinically DWV-infected honey bees. Using specific RT-PCR protocols for the detection of DWV followed by sequencing of the PCR products we could demonstrate that the bumble bees were indeed infected with DWV. Since such deformed bumble bees are not viable DWV infection may pose a serious threat to bumble bee populations.     

Signals and cues in the recruitment behavior of stingless bees (Meliponini)

Since the seminal work of Lindauer and Kerr (1958), many stingless bees have been known to effectively recruit nestmates to food sources. Recent research clarified properties of several signals and cues used by stingless bees when exploiting food sources. Thus, the main source of the trail pheromone in Trigona are the labial, not however the mandibular glands. In T. recursa and T. spinipes, the first stingless bee trail pheromones were identified as hexyl decanoate and octyl decanoate, respectively. The attractant footprints left by foragers at the food source are secreted by glandular epithelia of the claw retractor tendon, not however by the tarsal gland. Regarding intranidal communication, the correlation between a forager’s jostling rate and recruitment success stresses the importance of agitated running and jostling. There is no evidence for a “dance” indicating food source location, however, whereas the jostling rate depends on food quality. Thoracic vibrations, another intranidal signal well known in Melipona, were analyzed using modern technology and distinguishing substrate vibrations from airborne sound. Quantitative data now permit estimates of signal and potential communication ranges. Airflow jets as described for the honeybee were not found, and thoracic vibrations do not “symbolically” encode visually measured distance in M. seminigra. We dedicate this review to Martin Lindauer and Warwick Kerr who pioneered research on the communication and recruitment in stingless bees by studies reported in a seminal paper published in this Journal half a century ago in 1958.     

The value of a tree species (Caryocar brasiliense) for a stingless bee Melipona quadrifasciata quadrifasciata

The expansion of crop lands and increased logging for charcoal production in the Brazilian savannahs (cerrados) has reduced richness and abundance of Meliponini bees. This may be a consequence of limitation in the availability of potential nesting substrate. The role of a cerrado-tree (Caryocar brasiliense) in providing nesting substrate for Melipona quadrifasciata quadrifasciata was evaluated. Tree (p= 0.006) and branch (p= 0.001) diameters, number of suitable branches (n= 513), height of the trees and availability of trees suitable for bee nesting were all important to the conservation of M. quadrifasciata. However, the high availability of nesting substrate did not seem to limit nest density nor cause the clumped pattern of nest distributions found for the study site. Nests (n= 48) were found mainly in individuals of C. brasiliense (n= 46) suggesting an active tree selection. In addition, nests located on the highest branches (mean = 4.6 m, sd = 1 m, n= 46) had lower probability of being extirpated by human honey collectors.     

Odor discrimination in classical conditioning of proboscis extension in two stingless bee species in comparison to Africanized honeybees

Learning in insects has been extensively studied using different experimental approaches. One of them, the proboscis extension response (PER) paradigm, is particularly well suited for quantitative studies of cognitive abilities of honeybees under controlled conditions. The goal of this study was to analyze the capability of three eusocial bee species to be olfactory conditioned in the PER paradigm. We worked with two Brazilian stingless bees species, Melipona quadrifasciata and Scaptotrigona aff. depilis, and with the invasive Africanized honeybee, Apis mellifera. These three species present very different recruitment strategies, which could be related with different odor-learning abilities. We evaluated their gustatory responsiveness and learning capability to discriminate floral odors. Gustatory responsiveness was similar for the three species, although S. aff. depilis workers showed fluctuations along the experimental period. Results for the learning assays revealed that M. quadrifasciata workers can be conditioned to discriminate floral odors in a classical differential conditioning protocol and that this discrimination is maintained 15 min after training. During conditioning, Africanized honeybees presented the highest discrimination, for M. quadrifasciata it was intermediate, and S. aff. depilis bees presented no discrimination. The differences found are discussed considering the putative different learning abilities and procedure effect for each species.     

Population dynamics of a stingless bee community in the seasonal dry lowlands of Costa Rica

This study examines the dynamics of a population of stingless bee colonies in the seasonal tropics of Guanacaste, Costa Rica. The community in a forest remnant was compared with that in surrounding deforested areas. During this 4-year study, a total of 192 wild stingless bee colonies were recorded, belonging to 14 species. Population dynamics were highly seasonal. Colony mortality peaked at the end of the wet season (October–November) while colony reproduction was most frequent during the dry season (December to April). Colony survival was not lower in founder colonies compared to established colonies. The most common species, T. angustula, had a much lower probability of annual survivorship in the forest (P = 0.74) than in deforested areas (P = 0.92). This results in an estimated colony life span for T. angustula of 3.8 years in the forest and 12.5 years in deforested areas. T. angustula should swarm once every two years to maintain its forest population, but only once every 12.5 years to maintain its population in the deforested areas. Survivorship of all other stingless bees was similar in the forest and deforested areas and did not significantly differ among the species. The average annual survivorship probability of these species was as high as 0.96, resulting in an estimated colony life span of 23.3 years. On average only one swarm per 20 years is needed to maintain their populations. Life history of the sympatric Africanised honey bee clearly differed from that of the stingless bees, with much lower annual survivorship probabilities for both founder (none survived) and established colonies (P = 0.33). These figures support the general idea that stingless bees invest more in colony survival rather than reproduction, but also show that life history is affected by both species and location. Received 27 October 2004; revised 8 March and 15 June 2005; accepted 5 July 2005.     

Smelling like resin: terpenoids account for species-specific cuticular profiles in Southeast-Asian stingless bees

Insects may be unique in having a cuticle with a species-specific chemical profile. In social insects, colony survival depends not only on species-specific but also on colony-specific cuticular compounds with hydrocarbons playing an important role in the communication systems of ants, termites, wasps and bees. We investigated inter- and intraspecific differences in the composition of compounds found on the body surface of seven paleotropical stingless bee species (Apidae: Meliponini) at two different sites in Borneo (Sabah, Malaysia). Besides hydrocarbons, the body surface of all seven stingless bee species comprised terpenoid compounds, a substance class that has not been reported for chemical profiles of any social insect so far. Moreover, the chemical profile of some species differed fundamentally in the composition of terpenoids with one group (e.g. sesquiterpenes) being present in one species, but missing in another. Chemical profiles of different colonies from the same species showed the same hydrocarbon- and terpenoid compounds over different regions, as tested for Tetragonilla collina and Tetragonula melanocephala. However, chemical profiles differed quantitatively between the different colonies especially in T. melanocephala. It is likely that the terpenoids are derived from plant resins because stingless bees are known to collect and use large amounts of resins for nest construction and defence, suggesting an environmental origin of the terpenoids in the chemical profile of paleotropical stingless bees.     

The dynamics of sleep-like behaviour in honey bees

At night, honey bees pass through a physiological state that is similar to mammalian sleep. Like sleep in mammals, sleep-like behaviour in honey bees is an active process. This is expressed most clearly in these insects by spontaneous antennal movements which appear at irregular intervals throughout the night and interrupt episodes of antennal immobility. Here we present a newly developed video technique for the continuous recording of the position and movements of the bee's antennae. The same technique was used to record head inclination and ventilatory movements. Despite the constancy of the ambient temperature, the magnitudes of antennae-related parameters, as well as head inclination and ventilatory cycle duration, displayed dynamic unimodal time-courses which exhibited a high degree of temporal covariance. The similarity between these time-courses and the nightly time-course of the reaction threshold for a sensory stimulus, investigated previously, indicates that, in honey bees, deepest "sleep" and least ventilatory activity occur at the same time (in the 7th hour of the rest phase).Abbreviations DD continuous darkness - EMG electromyogram - LD periodic alternation between light (L) and darkness (D) - MEST Middle European Summer Time (UTC+2 h); - UV ultraviolet This paper is dedicated to Professor Martin Lindauer, who—to our knowledge—was the first to meticulously record the nightly behaviour of honey bees (Lindauer 1952) and who also inspired one of us (W.K.) to investigate antennal motility during nightly rest in these animals.     

Population demography of Australian feral bees (Apis mellifera)

Honey-bees are widespread as feral animals in Australia. Their impact on Australian ecosystems is difficult to assess, but may include competition with native fauna for floral resources or nesting sites, or inadequate or inappropriate pollination of native flora. In this 3-year study we examined the demography of the feral bee population in the riparian woodland of Wyperfeld National Park in north-west Victoria. The population is very large but varied considerably in size (50–150 colonies/km²) during the study period (1992–1995). The expected colony lifespan for an established colony is 6.6 years, that for a founder colony (new swarm), 2.7 years. The population is expected to be stable if each colony produces 0.75 swarms per year, which is less than the number predicted on the basis of other studies (2–3 swarms/colony per year). Therefore, the population has considerable capacity for increase. Most colony deaths occurred in the summer, possibly due to high temperatures and lack of water. Colonies showed considerable spatial aggregation, agreeing with earlier findings. When all colonies were eradicated from two 5-ha sites, the average rate of re-occupation was 15 colonies/km² per year. Ten swarms of commercial origin were released and were found to have similar survival rates to founder colonies. However, the feral population is self-sustaining, and does not require immigration from the domestic population. Received: 2 September 1996 / Accepted: 26 March 1997     

Conservation of nutrients in larval tissue by cannibalizing honey bees

ABSTRACT. ¹⁴C-phenylalanine appeared in royal jelly secreted by worker honey bees ( Apis mellifera , L.) directly after eating ¹⁴-phenyl-alanine labelled larvae. The amount of labelled phenylalanine in royal jelly was associated directly with the volume of jelly produced. Loss of radio-label from the workers, in the form of O₂¹⁴C, increased when royal jelly secretion ended. These patterns show that conservation of nutrients in cannibalized tissue is enhanced when the cannibal bees are producing royal jelly. Specific activity of radiolabel in worker bee hypopharyngeal glands was higher than in thoracic muscle, showing selective movement within the bees of a nutrient acquired by cannibalism.     

A stingless bee (Melipona seminigra) uses optic flow to estimate flight distances

Foragers of a stingless bee, Melipona seminigra, are able to use the optic flow experienced en route to estimate flight distance. After training the bees to collect food inside a flight tunnel with black-and-white stripes covering the side walls and the floor, their search behavior was observed in tunnels lacking a reward. Like honeybees, the bees accurately estimated the distance to the previously offered food source as seen from the sections of the tunnel where they turned around in search of the food. Changing the visual flow by decreasing the width of the flight tunnel resulted in the underestimation of the distance flown. The removal of image motion cues either in the ventral or lateral field of view reduced the bees' ability to gauge distances. When the feeder inside the tunnel was displaced together with the bees feeding on it while preventing the bee from seeing any image motion during the displacement the bees experienced different distances on their way to the food source and during their return to the nest. In the subsequent test the bees searched for the food predominantly at the distance associated with their return flight.     

Behavioral suites mediate group-level foraging dynamics in communities of tropical stingless bees

Competition for floral resources is a key force shaping pollinator communities, particularly among social bees. The ability of social bees to recruit nestmates for group foraging is hypothesized to be a major factor in their ability to dominate rich resources such as mass-flowering trees. We tested the role of group foraging in attaining dominance by stingless bees, eusocial tropical pollinators that exhibit high diversity in foraging strategies. We provide the first experimental evidence that meliponine group foraging strategies, large colony sizes and aggressive behavior form a suite of traits that enable colonies to improve dominance of rich resources. Using a diverse assemblage of Brazilian stingless bee species and an array of artificial “flowers” that provided a sucrose reward, we compared species’ dominance and visitation under unrestricted foraging conditions and with experimental removal of group-foraging species. Dominance does not vary with individual body size, but rather with foraging group size. Species that recruit larger numbers of nestmates (Scaptotrigona aff. depilis, Trigona hyalinata, Trigona spinipes) dominated both numerically (high local abundance) and behaviorally (controlling feeders). Removal of group-foraging species increased feeding opportunities for solitary foragers (Frieseomelitta varia, Melipona quadrifasciata and Nannotrigona testaceicornis). Trigona hyalinata always dominated under unrestricted conditions. When this species was removed, T. spinipes or S. aff. depilis controlled feeders and limited visitation by solitary-foraging species. Because bee foraging patterns determine plant pollination success, understanding the forces that shape these patterns is crucial to ensuring pollination of both crops and natural areas in the face of current pollinator declines.     

The propolis of stingless bees: terpenes from the tibia of three Frieseomelitta species

The posterior tibia of foraging workers of three species of Frieseomelitta (Hymenoptera: Meliponinae) stingless bees have been shown to carry complex mixtures of plant-derived mono-, sesqui-, di- and tri-terpenes. These subtances were not found on the fore- or mid-legs, nor on other parts of the hind legs. F. silvestrii and F. silvestrii languida, when collecting, appear to exploit different plants for their resin even when housed in the same area. F. varia were found to be not collecting resin at the time of the initial sampling and were therefore sampled later. Mature foragers carry the resin. In the samples studied here, particularly prominent were the monoterpene α-pinene, the sesquiterpenes β-caryophyllene, α-cubebene, α- and γ-muurolene, γ-cadinene, germacrene-D, and elemol and the diterpenes manool and totarol The collected material is used for the resin placed around the entrance to their nests and is also mixed with wax, to produce the cerum used for the structures in the nest.