Uncapped Brood Research Articles

Evaluation of queen cell acceptance and royal jelly production between hygienic and non-hygienic honey bee (Apis mellifera) colonies.

Honey bees are crucial for pollination services globally and produce important hive products including honey, royal jelly, pollen, and propolis that are being used commercially in food, cosmetics, and alternative medicinal purposes. Among the bee products, royal jelly (RJ) has long attracted scientists' interest because of its importance in honey caste differentiation. The present research was carried out to determine the acceptance rate of queen cells, and RJ production between the hygienic and non-hygienic lines. Further, this study unveils the effect of pollen substitute diets on the queen cell acceptance rate and RJ yields between both bee stocks. Results showed that the uncapped brood cells and dead brood's removal percentage was significantly more in hygienic bee colonies in comparison to non-hygienic bee colonies (p < 0.05). The average percentage of larval acceptance was statistically higher in hygienic lines (64.33 ± 2.91%) compared to non-hygienic lines (29.67 ± 1.20%). Similarly, the RJ mean weight per colony differed statistically between both bee stocks (p<0.001), which were 12.23 ± 0.52 g and 6.72 ± 0.33 g, respectively. Moreover, our results demonstrated that a significant difference was observed in larval acceptance rate, RJ yields (per colony and per cup) between both bee stocks those fed on various diets. However, no significant difference was recorded in RJ yields (per colony and per cup) between both bee stock that feeds on either commercially available pollen or pollen substitute. This study may provide future applications in helping bee breeders to choose the bees that carry a higher level of hygienic behavior with high RJ production traits.

Automated image analysis to assess hygienic behaviour of honeybees.

Focus of this study is to design an automated image processing pipeline for handling uncontrolled acquisition conditions of images acquired in the field. The pipeline has been tested on the automated identification and count of uncapped brood cells in honeybee (Apis Mellifera) comb images to reduce the workload of beekeepers during the study of the hygienic behavior of honeybee colonies. The images used to develop and test the model were acquired by beekeepers on different days and hours in summer 2020 and under uncontrolled conditions. This resulted in images differing for background noise, illumination, color, comb tilts, scaling, and comb sizes. All the available 127 images were manually cropped to approximately include the comb area. To obtain an unbiased evaluation, the cropped images were randomly split into a training image set (50 images), which was used to develop and tune the proposed model, and a test image set (77 images), which was solely used to test the model. To reduce the effects of varied illuminations or exposures, three image enhancement algorithms were tested and compared followed by the Hough Transform, which allowed identifying individual cells to be automatically counted. All the algorithm parameters were automatically chosen on the training set by grid search. When applied to the 77 test images the model obtained a correlation of 0.819 between the automated counts and the experts' counts. To provide an assessment of our model with publicly available images acquired by a different equipment and under different acquisition conditions, we randomly extracted 100 images from a comb image dataset made available by a recent literature work. Though it has been acquired under controlled exposure, the images in this new set have varied illuminations; anyhow, our pipeline obtains a correlation between automatic and manual counts equal to 0.997. In conclusion, our tests on the automatic count of uncapped honey bee comb cells acquired in the field and on images extracted from a publicly available dataset suggest that the hereby generated pipeline successfully handles varied noise artifacts, illumination, and exposure conditions, therefore allowing to generalize our method to different acquisition settings. Results further improve when the acquisition conditions are controlled.

The effect of a lack of uncapped brood on social interactions between honey bee workers and the queen

Vibro-acoustic communication is used by honey bees in many different social contexts. Our previous research showed that workers interact with their queen outside of the swarming period by means of wing-beating behaviour. Therefore, the aim of this study was to verify the hypothesis that the wing-beating behaviour of workers attending the queen stimulates her to lay eggs. The behaviour of workers and the queen was recorded using a high-speed camera, at first in the presence of uncapped brood in the nest and then without one. None of the queens performed wing-beating behaviour. On the other hand, the workers attending the queen demonstrated this behaviour two times per minute, on average, even in the presence of uncapped brood in the nest. After removing the combs with the uncapped brood, the incidence of wing-beating behaviour increased significantly to an average of four times per minute. Wing-beating behaviour did not differ significantly in its characteristics when uncapped brood was present or absent in the nest. During 3 days after removing the combs with the uncapped brood, there was no significant increase in the rate of egg lying by the queen. Therefore, the results presented here do not convincingly confirm that the wing-beating behaviour of workers affects the rate of queen's egg-lying. This negative result can be related to colony disturbance and longer time required by the queen to increase egg production.

Correlação da infestação de Varroa destructor sobre o comportamento higiênico de abelhas Apis mellifera

The hygienic behavior of Apis mellifera L., the honey bee, is one of the most important defense mechanisms against brood diseases. It is the ability of bees to detect and uncap the combs with diseased or dead brood and remove them. The aim of this study was to determine whether there is a correlation between the infestation of Varroa destructor mite and the hygienic behavior of Africanized Apis mellifera bees in different flowering. Twenty colonies of Africanized Apis mellifera were installed in Langstroth hives. One comb was removed from each colony and approximately 100 uncapped brood aged 10 to 14 days were pierced with an entomological pin. After piercing, the frame of brood was returned to the respective colonies for the worker bees to remove the dead brood. To estimate the hygienic behavior (HB) of each colony, after 24 h, empty cells from which the bees removed the dead brood by the pin were counted. Hygienic colonies were considered those with a removal rate greater than or equal to 80%. The average frequency of HB in the three periods was 82.58%, which categorizes them as hygienic colonies and shows their genetic potential for production of selected queens. Although the data shows that there were no statistical differences between the three periods, the percentage removal of brood in the flowering period was higher than in the dry period, possibly due to the higher food availability during these periods, causing bees to drive their attention more to the internal activities of the colonies such as the cleaning and removal of dead and diseased brood.

An Evaluation of the Honey Bee (Hymenoptera: Apidae) Safety Profile of a New Systemic Insecticide, Flupyradifurone, Under Field Conditions in Florida.

Flupyradifurone (Sivanto) is a novel systemic insecticide from the butenolide class developed by Bayer. Based on available data (USEPA 2014), this insecticide appears to have a favorable safety profile for honey bee colonies. As a result, the label permits the product to be applied during prebloom and bloom in various crops, including citrus, except when mixed with azole fungicides during the blooming period. We placed 24 honey bee (Apis mellifera L.) colonies adjacent to eight flowering buckwheat (Fagopyrum esculentum Moench) fields that either had been sprayed with the maximum label rate of flupyradifurone or with water only (control fields), with three colonies placed adjacent to each field. We conducted colony strength assessments during which the number of adult bees, eggs, uncapped brood cells, capped brood cells, food storage cells, and weights of honey supers and brood chambers were determined prior to, during, and after the flowering period. We also analyzed bee-collected pollen and nectar for flupyradifurone residues. Overall, there were no differences in any colony strength parameter for colonies placed at control and flupyradifurone-treated buckwheat fields. Residue analyses showed that pollen (x = 565.8 ppb) and nectar (x = 259.4 ppb) gathered by bees on fields treated with flupyradifurone contained significantly higher flupyradifurone residues than did bee bread and unprocessed nectar collected by bees from control fields (75% of samples <LOD). Within the conditions set forth by our experimental design, our collective data suggest no adverse effects of flupyradifurone on honey bee colonies when following label directions.

Apitoxin harvest affects population development but not the hygienic behavior of African-derived honey bees

The biological properties of apitoxin have prompted its production for use in human and animal health applications. However, the apitoxin harvest triggers a defense reaction in honeybee colonies, which includes the release of alarm pheromones (isopentyl acetate and 2-heptanone), which cause stress and could cause behavioral changes that influence the routine activities of the colony. Considering the lack of data in the literature describing the effects of the prolonged harvesting of apitoxin, the present study conducted over a period of one year, aimed to investigate whether the apitoxin harvest influences population development and hygienic behavior of African-derived Apis mellifera (L.). We observed that apitoxin harvest affected the uncapped brood area of the colonies during the months of April, May, and June, and affected the capped brood area in July. The hygienic behavior of the colonies was not affected. Furthermore, we observed that during the study year, there was loss by abandonment of nine of the colonies subjected to apitoxin harvesting. We conclude that under the conditions of this study, the apitoxin harvest can negatively influence the development of the colony population during certain times of the year, without affecting the hygienic behavior of the colonies.

Mapping sleeping bees within their nest: spatial and temporal analysis of worker honey bee sleep.

Patterns of behavior within societies have long been visualized and interpreted using maps. Mapping the occurrence of sleep across individuals within a society could offer clues as to functional aspects of sleep. In spite of this, a detailed spatial analysis of sleep has never been conducted on an invertebrate society. We introduce the concept of mapping sleep across an insect society, and provide an empirical example, mapping sleep patterns within colonies of European honey bees (Apis mellifera L.). Honey bees face variables such as temperature and position of resources within their colony's nest that may impact their sleep. We mapped sleep behavior and temperature of worker bees and produced maps of their nest's comb contents as the colony grew and contents changed. By following marked bees, we discovered that individuals slept in many locations, but bees of different worker castes slept in different areas of the nest relative to position of the brood and surrounding temperature. Older worker bees generally slept outside cells, closer to the perimeter of the nest, in colder regions, and away from uncapped brood. Younger worker bees generally slept inside cells and closer to the center of the nest, and spent more time asleep than awake when surrounded by uncapped brood. The average surface temperature of sleeping foragers was lower than the surface temperature of their surroundings, offering a possible indicator of sleep for this caste. We propose mechanisms that could generate caste-dependent sleep patterns and discuss functional significance of these patterns.

Boron fertilizers in rape – a risk for honey bees?

AbstractRape (Brassica napus L.) is foraged intensively by honey bees (Apis mellifera). Pesticide applications during bloom are sometimes combined with foliar boron fertilizer applications. Boron has insecticidal properties, and therefore, risk to honey bees cannot be excluded. This study was conducted to test whether foliar boron fertilizers could be hazardous for bees under real field conditions. Six colonies were transferred to a rape field in bloom which was treated with boron (1 kg/ha). Six control colonies were transferred to an untreated rape field approximately 7 km away. Performance parameters of the colonies were measured. Samples of honey and beebread were collected from all colonies before and after boron fertilizer application. The contents of boron and of Al, Cd, Cr, Fe, K, Mn, Ni, P, Pb, S and Zn were measured in honey by inductively coupled plasma mass spectroscopy (ICP MS) and by ICP–atomic emission spectroscopy (ICP‐OES). No significant differences were found in honey yield (P = 0.622), number of capped brood (P = 0.089), number of uncapped brood (P = 0.123) or number of bees (P = 0.87). Application of boron fertilizer did not affect the concentration of boron in honey (P = 0.656) or beebread (P = 0.665). The concentrations of other elements confirmed the suitability of rape nectar for bee nutrition. This study suggests that the application of foliar boron fertilizers in blooming rape is not hazardous for bee colonies.

The microsporidian Nosema ceranae, the antibiotic Fumagilin-B®, and western honey bee (Apis mellifera) colony strength

Western honey bees (Apis mellifera) are under threat from a number of emerging pathogens, including the microsporidian Nosema ceranae historically of Asian honey bees (Apis cerana). Because of its recent detection, very little is known about the biology, pathology, and control of N. ceranae in western honey bees. Here we investigated effects of the antibiotic Fumagilin-B®, which is commonly used to control the historical Nosema parasite of western honey bees Nosema apis, on N. ceranae and effects of N. ceranae on colony strength (i.e., number of bees and amount of capped and uncapped brood, honey, and pollen) and colony mortality. Similar to our previous study, fall Fumagilin-B® treatment lowered, albeit weakly, N. ceranae intensity the following spring. However, N. ceranae was not associated with variation in colony strength measures or with higher colony winter mortality.

Short-Term Fumigation of Honey Bee (Hymenoptera: Apidae) Colonies with Formic and Acetic Acids for the Control of &lt;I&gt;Varroa destructor&lt;/I&gt; (Acari: Varroidae)

Controlling populations of varroa mites is crucial for the survival of the beekeeping industry. Many treatments exist, and all are designed to kill mites on adult bees. Because the majority of mites are found under capped brood, most treatments are designed to deliver active ingredients over an extended period to control mites on adult bees, as developing bees and mites emerge. In this study, a 17-h application of 50% formic acid effectively killed mites in capped worker brood and on adult bees without harming queens or uncapped brood. Neither acetic acid nor a combined treatment of formic and acetic acids applied to the West Virginia formic acid fumigator was as effective as formic acid alone in controlling varroa mites. In addition, none of the treatments tested in late summer had an effect on the late-season prevalence of deformed wing virus. The short-term formic acid treatment killed > 60% of varroa mites in capped worker brood; thus, it is a promising tool for beekeepers, especially when such treatments are necessary during the nectar flow.

Effect of triflumuron on brood development and colony survival of free‐flying honeybee, Apis mellifera L.

Abstract: The effect of the insect growth regulator (IGR) triflumuron (Alsystin® 25 WP) on honeybee, Apis mellifera L. (Hym., Apidae), was studied in a semi‐field test. Free‐living colonies were fed one litre per hive of sucrose syrup containing 0, 0.025, 0.25 or 2.5 g of triflumuron. A significant reduction in flight activity was noted 6–10 weeks post‐treatment at the two higher doses. These colonies reared less brood than before treatment. While the comb area occupied by uncapped brood was as high as [0.025 and 0.25 g active ingredient (a.i.)] or higher (2.5 g a.i.) than before treatment, there was a significant decline in capped brood at the two higher doses, indicating enhanced larval mortality. No capped brood was reared in the hive treated at the highest dose from 3–9 weeks post‐treatment. Yet there was a significant accumulation of pollen and honey in the brood compartment at all doses. All colonies except the one treated at the highest dose survived the following winter. However, at 43 weeks post‐treatment, hives treated at intermediate and low doses showed a significant increase in uncapped brood and a significant decrease in capped brood. This study revealed a strong residual toxicity of triflumuron to brood and substantiated its classification as hazardous to honeybee.

Differences in olfactory sensitivity and behavioral responses among honey bees bred for hygienic behavior

Honey bees, Apis mellifera L., bred for hygienic behavior uncap and remove diseased and mite-infested brood. We hypothesized that within a colony bred for hygienic behavior, there would be differences in olfactory sensitivity among bees of the same age. We predicted that bees that initiate the behavior by perforating and uncapping brood would have greater olfactory sensitivity to the odor of the diseased brood, and would be better able to discriminate between odors of healthy and diseased brood, compared to bees that complete the behavior by removing the uncapped brood from the cells. Electroantennogram recordings of 15- to 21-day-old bees from three colonies demonstrated that bees collected while uncapping dead brood had significantly greater olfactory sensitivity to all concentrations of diseased brood odor compared to bees collected while removing brood. Proboscis-extension reflex discrimination conditioning demonstrated that 15- to 21-day-old bees collected while uncapping discriminated significantly better and generalized significantly less between the odors of diseased and healthy brood compared to bees collected while removing, when the odor of diseased brood was rewarded, but not when the odor of healthy brood was rewarded. Bees collected while uncapping brood that had been pierced with a pin had significantly less olfactory sensitivity than bees collected while uncapping freeze-killed brood, most likely because the pierced brood had greater stimulus intensity. Initiation of hygienic behavior depends on the olfactory sensitivity of the bee and stimulus intensity of the abnormal brood. Differential olfactory sensitivity and responsiveness among hygienic bees could lead to the apparent partitioning of the behavior into uncapping and removing components.

Influence of management and environmental factors on mating success of Africanized queen honey bees

SUMMARYEnvironmental factors and management techniques were evaluated in São Paulo, Brazil, for enhanced production of Africanized queen honey bees. Queens were reared by the Doolittle method; 12 breeder, 6 cell-builder, and 36 3-frame nucleus colonies were used. Nine groups of four virgin Africanized queen honey bees were subjected to the following treatments: queens were either 1–2, 3–4 or 5–6 days old and were released into mating nuclei containing either capped brood, uncapped brood or no brood. This was repeated sixteen times between August 1990 and August 1992. Seven repetitions occurred during nectar flow periods and nine repetitions occurred during nectar-dearth periods. Overall, 59% of 576 queens were successfully introduced and mated. The best results (93% success) were obtained during nectar flows, with 3- to 4-day-old queens released into nuclei containing capped brood. During nectar dearths the best mating success came from queens introduced into broodless nuclei (63%), the age of the queen did not influence mating success. Mating success decreased when wind velocity increased; this was the only significant meteorological effect found.

Fumagillin Affects Nosema apis and Honey Bees (Hymonopterai Apidae)

Two formulations of bicyclohexy lammonium fumagillin, Fumagilin Band Fumidil B, were equally effective treatments for Nosema apis Zander infecting honey bees (Apis mellifera L.). Caged worker bees consumed either formulation in sucrose syrup as readily as syrup without fumagillin. Either formulation suppressed infection when fed with Nosema spores to caged workers for 7 d or when fed to workers for 3 d after they had consumed spores without fumagillin for 4 d. When consumed in sucrose syrup by bee colonies, neither fumagillin formulation significantly affected queen survival. More uncapped brood was reared by the colonies consuming fumagillin than those consuming syrup without fumagillin. Capped brood and total brood rearing was similar for colonies consuming fumagillin or syrup without fumagillin. Fumagilin B is more soluble in sucrose solution than Fumidil B, but both are easily prepared at the U.S. Food and Drug Administration approved level of 26 mg/liter in sucrose solution.

Foraging Rates and Hive Contents During the Establishment of Honeybee Colonies (Apis MelliferaL.)

SummaryFour artificial honeybee swarms, as genetically similar to one another as possible, were established on the same day in the same apiary. Each contained a sister queen inseminated with 2 microlitres of mixed semen from seven drones. For each queen, the seven drones were taken respectively from each of seven drone-mother colonies. Each queen, accompanied by 0·91 kg of her own progeny, was placed in a 42–1 hive body provided with 1 frame containing approximately 40 × 30 cm of drawn comb, 9 undrawn frames of comb foundation, and 2·27 kg of sugar syrup. Foraging rates and hive contents were then periodically measured through the summer.The four colonies demonstrated synchronous fluctuations in foraging rates that were not generally associated with amounts of uncapped nectar, capped honey, pollen, or capped brood in the hives. Two colonies reduced their brood rearing early in the summer, and in these colonies there were no significant correlations between foraging rates and amounts of uncapped brood. The other two colonies reared brood at high levels throughout the summer, and the foraging rates were significantly positively correlated with their amounts of uncapped brood. The latter result is consistent with earlier reports of brood pheromone influences on foraging in larger established colonies.

Short-Term and Long-Term Effects of Methamidophos on Brood Rearing in Honey Bee (Hymenoptera: Apidae) Colonies

Within 7 d, small honey bee ( Apis mellifera L.) colonies that consumed low levels of methamidophos in sugar syrup lost more eggs and larvae than control colonies, without conspicuous loss of adult worker bees. Youngest brood and brood at the transition between developmental stages were most sensitive. Development of surviving brood was not slowed appreciably by colony consumption of methamidophos. Environmental variables affected the sensitivity of brood to the pesticide. Colonies observed over a 13-wk period recovered rapidly and completely from a single 2.0 mg/liter treatment, without residual effect on uncapped brood, capped brood, honey storage, or queen survival. Larvae were more sensitive than queens, and adult workers were least sensitive. Brood and queens were less sensitive in small colonies than in large colonies. Implications for the mechanisms of pesticide damage to brood rearing and for remedial actions by beekeepers are discussed. The techniques described are effective for short-term and long-term studies of pesticide consumption on brood rearing and queen survival.