Honeybees Apis Mellifera Ligustica Research Articles

Changes of Western honey bee Apis mellifera ligustica (Spinola, 1806) ventriculus microbial profile related to their in-hive tasks

The effects of in-hive tasks on the honey bee (Apis mellifera L.) ventriculus microbial profile were investigated by analysing honey bees belonging to six in-hive tasks (newly-emerged, nurses, wax builder, guardians, young foragers, old foragers). Total viable aerobic bacterial count, Enterobacteriaceae, staphylococci, Escherichia coli, lactic acid bacteria, Pseudomonas spp., aerobic bacterial endospores, and Enterococcus spp. were determined using a culture-based method. Significant in-hive tasks-dependent microbial profiles were detected for all cultured bacteria (p < 0.001), with the lowest values for newly-emerged and wax builder and the highest for old foragers. Pseudomonas spp. and Staphylococcus spp. were quantitatively lower in young foragers than in old foragers, while they were absent in the other investigated in-hive tasks. E. coli and Enterococcus spp. were detected only in old foragers. 1Lactic acid bacteria were higher in nurses and old foragers compared to the other in-hive tasks, while the newly-emerged showed the lowest amount of lactic acid bacteria. The results from this investigation showed that ventriculus microbiological profile of Apis mellifera ligustica undergoes changes based on the in-hive task, and, as concerns foragers, on their age.

Glucansucrases produced by fructophilic lactic acid bacteria Lactobacillus kunkeei H3 and H25 isolated from honeybees.

Twenty fructophilic isolates from the stomachs of honeybee Apis mellifera ligustica from the region of Plovdiv, Bulgaria were obtained. Fructophilic isolates H3 and H25 showed formation of mucous colonies during cultivation on medium with sucrose, suggesting exopolysaccharide synthesis. The sequencing analysis of 16S rRNA identified isolates H3 and H25 as fructophilic lactic acid bacteria Lactobacillus kunkeei. The in situ analysis and periodic acid-Schiff's staining, showed that Lb. kunkeei H3 and H25 produce extracellular glucansucrases with molecular weight of about 300 kDa. In the cell-associated fractions, additional glucansucrase is detected with molecular weight of about 180 kDa. The content of α-(1 → 6) linkages in the glucans synthesized with extracellular glucansucrases from H3 and H25 after dextranase hydrolysis was significantly lower than this one of the classical dextran - about 35 and 62%, respectively. These results suggest a more branched structure of the studied polymers.

Western Honeybee Drones and Workers (Apis mellifera ligustica) Have Different Olfactory Mechanisms than Eastern Honeybees (Apis cerana cerana)

The honeybees Apis mellifera ligustica (Aml) and Apis cerana cerana (Acc) are two different western and eastern bee species that evolved in distinct ecologies and developed specific antennal olfactory systems for their survival. Knowledge of how their antennal olfactory systems function in regards to the success of each respective bee species is scarce. We compared the antennal morphology and proteome between respective sexually mature drones and foraging workers of both species using a scanning electron microscope, two-dimensional electrophoresis, mass spectrometry, bioinformatics, and quantitative real-time polymerase chain reaction. Despite the general similarities in antennal morphology of the drone and worker bees between the two species, a total of 106 and 100 proteins altered their expression in the drones' and the workers' antennae, respectively. This suggests that the differences in the olfactory function of each respective bee are supported by the change of their proteome. Of the 106 proteins that altered their expression in the drones, 72 (68%) and 34 (32%) were overexpressed in the drones of Aml and Acc, respectively. The antennae of the Aml drones were built up by the highly expressed proteins that were involved in carbohydrate metabolism and energy production, molecular transporters, antioxidation, and fatty acid metabolism in contrast to the Acc drones. This is believed to enhance the antennal olfactory functions of the Aml drones as compared to the Acc drones during their mating flight. Likewise, of the 100 proteins with expression changes between the worker bees of the two species, 67% were expressed in higher levels in the antennae of Aml worker contrasting to 33% in the Acc worker. The overall higher expressions of proteins related to carbohydrate metabolism and energy production, molecular transporters, and antioxidation in the Aml workers compared with the Acc workers indicate the Aml workers require more antennal proteins for their olfactory mechanisms to perform efficient foraging activities than do the Acc worker bees. These data decipher the mechanisms of the western and eastern drone and worker bees acting in response to their different olfactory system in their distinct ecosystem.

Field assessment of Bt cry1Ah corn pollen on the survival, development and behavior of Apis mellifera ligustica

Honeybees may be exposed to insecticidal proteins from transgenic plants via pollen. An assessment of the impact of such exposures on the honeybee is an essential part of the risk assessment process for transgenic Bacillus thuringiensis corn. A field trial was conducted to evaluate the effect of transgenic Bt cry1Ah corn on the honeybee Apis mellifera ligustica. Colonies of honeybees were moved to Bt or non-Bt corn fields during anthesis and then sampled to record their survival, development and behavior. No differences in immature stages, worker survival, bee body weight, hypopharyngeal gland weight, colony performance, foraging activity or olfactory learning abilities were detected between colonies that were placed in non-Bt corn fields and those placed in Bt corn fields. We conclude that cry1Ah corn carries no risk for the survival, development, colony performance or behavior of the honeybee A. mellifera ligustica.

Defence reactions of Apis mellifera ligustica against attacks from the European hornet Vespa crabro

The predatory behaviour of Vespa crabro hornets on the honeybee Apis mellifera ligustica and the counter strategy of the prey were observed and described in two apiaries of 27 and 41 colonies in Central Italy. Observations were carried out in the second half of October and accompanied by experiments aimed at determining the mechanisms of honeybee defence. We confirmed that V. crabro represents a relatively mild predator for A. mellifera ligustica but it can have a considerable impact on already debilitated colonies. Hornet predatory strategy is to spot then swoop on returning foragers. Honeybee defence centres on forming packed aggregations of individuals near the hive opening, which probably deters the wasps from entering. Coordinated behaviour by the bees, which cling together in groups, can knock the approaching hornets down, which are then totally covered by the bees. This balling behaviour has the effect of over-heating the predator whose lethal thermal limit is about 44 °C, although other factors, such as carbon dioxide emission and the release of venom by the honeybees, may also contribute to the death of the hornet. Comparing the differences and similarities of this behaviour with those observed in other species of Apis and Vespa reveals that these two species are an interesting model for the study of the evolutionary arms race.

Assessment of the mitochondrial origin of honey bees from Argentina

SummaryThe molecular diversity of the honey bee Apis mellifera in the province of Buenos Aires (Argentina) has been analysed through the study of the mitochondrial DNA. The mitochondrial haplotype corresponding to the intergenic region tRNAleu-COII has been determined in samples from 300 colonies from 150 apiaries distributed in 71 localities of the province of Buenos Aires. Eight different haplotypes have been found, four of the African, three of the West European and one of the East European evolutionary lineages. The frequency of these haplotypes corroborates that the European yellow honey bee Apis mellifera ligustica is predominant in the Buenos Aires province whereas the black European bee A. m. mellifera is rare. The presence of the African haplotypes A1 and A4 common in Africanized honey bees, confirms a border of the africanization process located around the 30°-35° SL parallels. The other two African haplotypes (A8 and A11) are indicative of an Iberian or North African origin of some colonies. The influence of the transhumance and beekeeping practices is discussed in relation to the genetic variability detected.

Oxygen consumption in the foraging honeybee depends on the reward rate at the food source.

Oxygen consumption of the honeybee Apis mellifera ligustica was measured as a function of the flow rate supply of sucrose solution at an automatic feeder located inside a respirometric chamber. Trained bees freely entered the respirometric chamber and collected the sucrose solution supplied. The mean value of the O2 consumption rate per visit increased with the sucrose flow rate, and for a given flow rate, with increasing locomotor activity. However, when no locomotor activity was displayed, O2 consumption also increased with increasing nectar flow rate. Crop load attained at the end of the visit showed a positive relationship with the nectar flow rate; however, for a given flow rate, O2 consumption showed either no correlation or a negative one with the final crop load attained. It is concluded that the energy expenditure of the foraging bee is controlled by a motivational drive whose intensity depends on the reward rate at the food source.

Odour and colour information in the foraging choice behaviour of the honeybee

1. Honeybees Apis mellifera ligustica were trained to work on a patch with artificial rewarding and non-rewarding flowers, coupled to an air extractor. The perceptual colour distance between the rewarding and the non-rewarding flowers was varied and the flower choice and the repellent scent-marking behaviour of the bees were recorded. 2. The discrimination between rewarding and non-rewarding flowers depended on their colour distance, improving with a greater colour difference. This task was guided thus visually and was not affected by activating the air extractor. 3. The scent-marking activity was only observable when the colour information of both groups of flowers was the same or very similar. This thus represents the first reported case of a modulation of an olfactory activity through the visual input provided by colour distances. When the air extractor was activated, rejections associated with the scent-marking behaviour disappeared, thus confirming the olfactory nature of this behaviour. 4. Honeybees are thus capable of using one or more sensory cues to enhance their foraging efficiency, according to the environmental situation. This great plasticity allows them to attain an enhanced efficiency while foraging. 5. We successfully applied the model of colour choice behaviour of the honeybee. Since the original theory was developed for Apis mellifera carnica, this work also constitutes the first attempt to describe the behaviour of the honeybee race, Apis mellifera ligustica, using the postulated model, and reaffirms thus its generality.

Efficient floret inspection by honeybees in capitula of Carduus acanthoides

Abstract. 1. The floret inspection by honeybees Apis mellifera ligustica on inflorescences of Carduus acanthoides was studied in a natural patch. First‐day stage capitula were protected with a net hood against insect visits. The next day, the net hood was removed at the time of maximal nectar accumulation, allowing a bee to visit the inflorescence. Walking trajectories on the capitula, the number of florets inspected and the duration of the visit were recorded. After the bee's departure, the inflorescence was cut off and analysed in the laboratory to determine the presence or absence of nectar in each of its florets.2. Bees made inspection trajectories without a defined systematic pattern.3. The number of floret inspections performed represented a high percentage of the available florets (57.37 ± 2.81%; mean ± SE; n = 8).4. The number of depleted florets coincided with the number of floret inspections.5. The number of times a floret is visited in a bee's trajectory is non‐random.6. Strategies that might account for this high foraging efficiency are discussed.

Foraging by honeybees on Carduus acanthoides: pattern and efficiency

Abstract. The relationship between the fluctuation in total quantity of sugar available in the nectar of Carduus acanthoides inflorescences and the foraging behaviour of honeybees Apis mellifera ligustica was studied in a patch under natural conditions. Every day, three inflorescence populations coexisted, one for each day of the inflorescence life‐span. The maximum availability of sugar occurred in second‐day capitula from 12.00 to 15.00 hours. Bee arrivals at the patch were positively correlated with the total availability of sugar as determined by sampling. Bees responded to variation in the availability of sugar by visiting the inflorescence stage that was most rewarding at that time of day. Early in the morning, when the frequency of visits was low, the bees worked the third‐day capitula, which were the best available choice at that time. Similarly, beginning at 12.00 hours, bees switched to second‐day capitula. At the end of the day, some bees switched to third‐day capitula where a slightly superior quantity of sugar could be obtained from a small number of florets although other bees continued to work the second‐day capitula. Individual bees switched to another inflorescence stage after a high proportion of their visits to a small number of capitula of one kind had provided a low reward. The number of florets visited per minute per bee varied throughout the day and was positively correlated with the availability of sugar.

Colour generalization and choice behaviour of the honeybee Apis mellifera ligustica

The colour choice of free-flying honeybees Apis mellifera ligustica was tested on a food-source simulator with 12 non-rewarded and coloured feeders (blue, violet or yellow) after training to rewarded feeders marked with aluminium discs. Bees trained to the aluminium signal showed a preference for violet followed by blue and finally by yellow. These results are interpreted using a model which allows a determination of the bee's perceptual distances between the stimuli used. The rank order obtained in colour-choice experiments can be related to generalization processes in which bees trained to the aluminium signal preferred the colour signal which is perceptually closest to the pretrained signal, even if innate colour preferences could not be discarded. Since bees generalize effectively from one visual cue to the other, it is to be expected that any pretraining would have a strong impact on the colour choice even if no obvious colour marks or “neutral” marks (aluminium discs) are used.

Colour signals and choice behaviour of the honeybee ( Apis mellifera ligustica)

The colour choice of honeybees Apis mellifera ligustica was tested on a food source simulator providing sucrose solution in coloured feeders blue or yellow. No asymmetry for colour choice was detected in the present experimental set-up. Test of Runs showed that colour is used to switch from one group of coloured feeders to the other in a strategy that seems related to the probability of finding a reward on the same colour.

The Development ofAscosphaera Apiswithin Larvae ofApis Mellifera Ligustica

SummaryIt was established that in northern Italy chalk-brook disease is due to infection of larvae with Ascosphaera apis. A histological study was carried out to follow fungal development in the tissues of infected larvae of the Italian honeybee Apis mellifera ligustica.

Toxic and repellent effects of cypermethrin on the honeybee: Laboratory, glasshouse and field experiments

AbstractCypermethrin is highly toxic to the honeybee Apis mellifera ligustica. The action of the chemical is rapid (within 2 days) and it has no long‐term effects. The sensitivity of the bees increases with decrease in breeding temperature and with increasing age of the insect. The commercial formulation ‘QCymbush’ is repellent to bees: the effect appears to be due to the formulation ingredients because cypermethrin itself is not repellent. A floral odour lost its natural attractiveness in the presence of ‘Cymbush’. The repellency appears to persist for some 2 days after treatment, during which time the bees learnt to avoid the crop. No residues of cypermethrin were found in the hive products (pollen, wax or honey), nor in the oilseed rape at harvest.