Response of foster Asian honeybee (Apis cerana Fabr.) colonies to the brood of European honeybee (Apis mellifera L.) infested with parasitic mite,Varroa jacobsoni oudemans

The response of Asian honeybee (Apis cerana Fabr.) colonies toward the introduced worker brood of the European honeybee (Apis mellifera L.) infested with the parasitic mite Varroa jacobsoni Oudemans was investigated. When no mites were present, 40% of the healthy open brood and 3% of the healthy capped brood of the European honeybees were rejected by the Asian honeybee colonies. When the brood was infested, brood rejection was significantly higher for open (P < 0.05) and capped broods (P < 0.01). The brood removal activity decreased with time. The quantity of brood removed was also correlated with mite infestation level for open (r² = 0.933) and sealed broods (r² = 0.918). The feasibility of using heterospecific colonies to control Varroa mite is unclear and is discussed from behavioral and ecological points of view.     

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.     

Preparation for disturbance-induced absconding of Cape honeybee colonies (Apis mellifera capensis Esch.)

African honeybees, Apis mellifera, are characterised by frequent disturbance-induced absconding. However, the effectiveness in preparation before such disturbance-induced absconding has not been rigorously quantified yet. We investigated the effectiveness of preparation for disturbance-induced absconding by evaluating colony phenotypes prior to and after absconding in ten colonies of the Cape honeybee, A. m. capensis. Seven non-absconding colonies at the same apiary were used as controls. While seven absconded colonies left neither stores nor brood behind, three colonies abandoned only a small area of honey, pollen, open or capped brood. At the end of the observations, the control colonies still had pollen and honey stores and brood. The mean reduction rate between a major disturbance and the absconding event was 0.052 ± 0.018 cm² stores and open brood per worker per day. Our results demonstrate that disturbance-induced absconding can also occur with preparation, if the disturbance is not highly destructive and enough time for preparation is available. We conclude that Cape honeybee colonies can show a considerable high effectiveness in their preparation before disturbance-induced absconding, which limits the loss of colony resources. In light of the general high mobility of African honeybee colonies such an efficient behaviour is probably adaptive. Received 22 December 2004; revised 3 June 2005; accepted 13 June 2005.     

Reproduction of Varroa destructor in worker brood of Africanized honey bees (Apis mellifera)

Reproduction and population growth of Varroa destructor was studied in ten naturally infested, Africanized honeybee (AHB) (Apis mellifera) colonies in Yucatan, Mexico. Between February 1997 and January 1998 monthly records of the amount of pollen, honey, sealed worker and drone brood were recorded. In addition, mite infestation levels of adult bees and worker brood and the fecundity of the mites reproducing in worker cells were determined. The mean number of sealed worker brood cells (10,070 ± 1,790) remained fairly constant over the experimental period in each colony. However, the presence and amount of sealed drone brood was very variable. One colony had drone brood for 10 months and another for only 1 month. Both the mean infestation level of worker brood (18.1 ± 8.4%) and adult bees (3.5 ± 1.3%) remained fairly constant over the study period and did not increase rapidly as is normally observed in European honey bees. In fact, the estimated mean number of mites fell from 3,500 in February 1997 to 2,380 in January 1998. In May 2000 the mean mite population in the study colonies was still only 1,821 mites. The fertility level of mites in this study was much higher (83–96%) than in AHB in Brazil(25–57%), and similar to that found in EHB (76–94%). Mite fertility remained high throughout the entire study and was not influenced by the amount of pollen, honey or worker brood in the colonies. This revised version was published online in July 2006 with corrections to the Cover Date.     

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.     

Hygropreference and brood care in the honeybee (Apis mellifera)

Terrestrial organisms need to limit evaporation from their bodies in order to maintain a homeostatic water balance. Owing to a large surface to volume ratio, arthropods are particularly susceptible to desiccation and have evolved behavioural and physiological mechanisms to conserve water. In social insects, water balance is also affected by the interactions between nestmates and by the architecture of the nest. For honeybees, humidity is particularly important for the brood because it affects the hatching success of eggs and because, unlike ants, honeybees cannot relocate their brood to parts of the nest with more favourable humidity. To advance the understanding of the water economy in honeybee nests, we investigated whether workers exhibit a hygropreference when exposed to a gradient of 24-90% relative humidity (RH) and whether the expression of this preference and their behaviour is affected by the presence of brood. The results show that young honeybee workers in the absence of brood exhibit a weak hygropreference for approximately 75% RH. When brood is present the expression of this preference is further weakened, suggesting that workers tend to the brood by distributing evenly in the gradient. In addition, fanning behaviour is shown to be triggered by an increase in humidity above the preferred level but not by a decrease. Our results suggest that humidity in honeybee colonies is actively controlled by workers.     

Adaptation of hypopharyngeal gland development to the brood status of honeybee (Apis mellifera L.) colonies

We studied pollen consumption, head weight, hypopharyngeal gland (HPG) acini diameter, and protein synthesis and transfer in honeybee workers reared in colonies with normal and with decreasing amounts of brood. We found that head fresh weight is correlated with size of the glands and that pollen consumption is positively correlated with gland development. An effect of brood on size of the glands could be confirmed, but was not as profound as in previous studies. Similarly, no difference in the amount of protein synthesized or transferred in workers living under the two brood conditions was found. We suspect this is due to the fact that HPGs also supply food to young bees and in our study young bees were always present while in previous studies, colonies often lacked both brood and young bees.     

Honeybee Colony Disorder in Crop Areas: The Role of Pesticides and Viruses

As in many other locations in the world, honeybee colony losses and disorders have increased in Belgium. Some of the symptoms observed rest unspecific and their causes remain unknown. The present study aims to determine the role of both pesticide exposure and virus load on the appraisal of unexplained honeybee colony disorders in field conditions. From July 2011 to May 2012, 330 colonies were monitored. Honeybees, wax, beebread and honey samples were collected. Morbidity and mortality information provided by beekeepers, colony clinical visits and availability of analytical matrix were used to form 2 groups: healthy colonies and colonies with disorders (n = 29, n = 25, respectively). Disorders included: (1) dead colonies or colonies in which part of the colony appeared dead, or had disappeared; (2) weak colonies; (3) queen loss; (4) problems linked to brood and not related to any known disease. Five common viruses and 99 pesticides (41 fungicides, 39 insecticides and synergist, 14 herbicides, 5 acaricides and metabolites) were quantified in the samples.The main symptoms observed in the group with disorders are linked to brood and queens. The viruses most frequently found are Black Queen Cell Virus, Sac Brood Virus, Deformed Wing Virus. No significant difference in virus load was observed between the two groups. Three acaricides, 5 insecticides and 13 fungicides were detected in the analysed samples. A significant correlation was found between the presence of fungicide residues and honeybee colony disorders. A significant positive link could also be established between the observation of disorder and the abundance of crop surface around the beehive. According to our results, the role of fungicides as a potential stressor for honeybee colonies should be further studied, either by their direct and/or indirect impacts on bees and bee colonies.     

Primer effects of a brood pheromone on honeybee behavioural development

Primer pheromones are thought to act in a variety of vertebrates and invertebrates but only a few have been chemically identified. We report that a blend of ten fatty-acid esters found on the cuticles of honeybee larvae, already known as a kairomone, releaser pheromone and primer pheromone, also act as a primer pheromone in the regulation of division of labour among adult workers. Bees in colonies receiving brood pheromone initiated foraging at significantly older ages than did bees in control colonies in five out of five trials. Laboratory and additional field tests also showed that exposure to brood pheromone significantly depressed blood titres of juvenile hormone. Brood pheromone exerted more consistent effects on age at first foraging than on juvenile hormone, suggesting that the primer effects of this pheromone may occur via other, unknown, mechanisms besides juvenile hormone. These results bring the number of social factors known to influence honeybee division of labour to three: worker-worker interactions, queen mandibular pheromone and brood pheromone.     

THE INFLUENCE OF STORED POLLEN AND OF COLONY SIZE ON THE BROOD REARING OF HONEYBEES

Four hundred and thirty records of the numbers of bees in honeybee colonies and of the amounts of brood and pollen present have been kept during various months of the years 1945-53, and the data have been used to calculate total and partial regression coefficients showing the influence of stored pollen and of colony size on brood rearing throughout the year.
It was found that pollen storage and colony size were correlated but that, even allowing for this, colony size and pollen both independently influenced brood rearing.
The annual distribution of the total regression coefficients of brood on pollen was somewhat similar to the brood curve itself, rising from a minimum in October and November to a maximum in midsummer, while the partial regression coefficients showed less clearly marked but similar features.
Both total and partial regression coefficients showing the influence of colony size on the amount of brood reared were also at a minimum in October and November, but reached their peaks in May.
The quantities of brood present in these colonies at Aberdeen, Scotland, followed a pattern similar to that given by Nolan for colonies near Washington, D.C.     

Survival of honeybees in cold climates: the critical timing of colony growth and reproduction

Abstract. 1. The adaptive significance of the timing of growth and reproduction by honeybee, Apis mellifera L., colonies in cold climates was studied by describing the seasonal patterns of food storage, brood rearing, and swarming, and then observing the consequences of experimentally perturbing the seasonal cycles of brood rearing and swarming.
2. Colonies consume large amounts of food over winter (20+ kg of honey), but have only a brief period (about 14 weeks) for food collection each year.
3. The honeybee's striking habits of starting brood rearing in midwinter and swarming in late spring evidently help colonies achieve maximum use of the short summer season. Colonies whose onset of-brood rearing was experimentally postponed until early spring showed greatly retarded colony growth and swarming. Other experiments demonstrated that late swarms starve more often during winter than do early swarms.
4. We conclude that the timings of colony growth and reproduction are essential elements in the honeybee's suite of adaptations for winter survival.     

Net reproductive rate of unmanaged honeybee colonies, (Apis mellifera L.)

Summary The net reproductive rate of unmanaged honeybee colonies has never been fully determined for honey bees in temperate climates. In this study, five overwintered colonies in Kansas, USA, were allowed to swarm naturally (Winston. 1980). These colonies and their swarms were studied over the winter (i.e. one generation). The net reproductive rateR ₀ was estimated to be 2.18. Afterswarms were found to contribute substantially (41.2%) to this net reproductive rate. The autumn and spring food reserves and brood areas of established colonies and colonies established from prime swarms and afterswarms are compared. Winter survival of afterswarms was related to autumn honey stores, and the brood areas of surviving afterswarms were smaller than those of prime swarms or established colonies.     

The prevalence of the honeybee brood pathogens Ascosphaera apis,Paenibacillus larvae and Melissococcus plutonius in Spanish apiaries determined with a new multiplex PCR assay

The microorganisms Ascosphaera apis, Paenibacillus larvae and Melissococcus plutonius are the three most important pathogens that affect honeybee brood. The aim of the present study was to evaluate the prevalence of these pathogens in honeybee colonies and to elucidate their role in the honeybee colony losses in Spain. In order to get it, a multiplex polymerase chain reaction (PCR) assay was developed to simultaneously amplify the16S ribosomal ribonucleic acid (rRNA) gene of P. larvae and M. plutonius, and the 5.8S rRNA gene of A. apis. The multiplex PCR assay provides a quick and specific tool that successfully detected the three infectious pathogens (P. larvae, M. plutonius and A. apis) in brood and adult honeybee samples without the need for microbiological culture. This technique was then used to evaluate the prevalence of these pathogens in Spanish honeybee colonies in 2006 and 2007, revealing our results a low prevalence of these pathogens in most of the geographic areas studied.     

Neonicotinoid-Coated Zea mays Seeds Indirectly Affect Honeybee Performance and Pathogen Susceptibility in Field Trials

Thirty-two honeybee (Apis mellifera) colonies were studied in order to detect and measure potential in vivo effects of neonicotinoid pesticides used in cornfields (Zea mays spp) on honeybee health. Honeybee colonies were randomly split on four different agricultural cornfield areas located near Quebec City, Canada. Two locations contained cornfields treated with a seed-coated systemic neonicotinoid insecticide while the two others were organic cornfields used as control treatments. Hives were extensively monitored for their performance and health traits over a period of two years. Honeybee viruses (brood queen cell virus BQCV, deformed wing virus DWV, and Israeli acute paralysis virus IAPV) and the brain specific expression of a biomarker of host physiological stress, the Acetylcholinesterase gene AChE, were investigated using RT-qPCR. Liquid chromatography-mass spectrometry (LC-MS) was performed to detect pesticide residues in adult bees, honey, pollen, and corn flowers collected from the studied hives in each location. In addition, general hive conditions were assessed by monitoring colony weight and brood development. Neonicotinoids were only identified in corn flowers at low concentrations. However, honeybee colonies located in neonicotinoid treated cornfields expressed significantly higher pathogen infection than those located in untreated cornfields. AChE levels showed elevated levels among honeybees that collected corn pollen from treated fields. Positive correlations were recorded between pathogens and the treated locations. Our data suggests that neonicotinoids indirectly weaken honeybee health by inducing physiological stress and increasing pathogen loads.     

Chemical and biological properties of wheat soil in response to paddy straw incorporation and its biodegradation by fungal inoculants

A field experiment was conducted to evaluate the relative contribution of organic fertilizers (paddy straw, microbial inoculants and vermicompost) and inorganic fertilizers (urea and superphosphate) in improving pH, C, N, humus, microbial biomass, dehydrogenase, phosphatase, cellulase, β-glucosidase and xylanase activities of soil under wheat crop. Vermicompost fertilization resulted in highest microbial biomass, available phosphorus, and nitrogen content of wheat soil. It was also found effective in minimizing the alkalinity of soil compared to other treatments as indicated by pH change. However incorporation of paddy straw in conjunction with N₆₀P₆₀ and T. reesei inoculation resulted in maximum dehydrogenase, alkaline phosphatase and highest humus content of soil. Mixed inoculation of A. awamori and T. reesei did not prove effective in improving the soil biochemical properties in comparison to single inoculation of T. reesei. Results showed that in situ incorporation of paddy straw in combination with N₆₀P₆₀ and T. reesei inoculation can be used as an effective measure for valuable disposal of paddy straw and to improve the soil health by reducing mineral fertilization.     

Comparative study on the dynamics and performances of Apis mellifera jemenitica and imported hybrid honeybee colonies in southwestern Saudi Arabia

The aims of this study were to assess the seasonal population dynamics and evaluate the performance of Apis mellifera jemenitica (local bee) and introduced hybrid honeybee colonies in the lowlands and highlands of southwestern Saudi Arabia. Data regarding the performance and population dynamics parameters such as brood and adult bee population, amounts of stored pollen and nectar were gathered from the two races (25 colonies of each) for one year (April 2013 through March 2014), and statistically tested. The results indicated that at low lands, local bee colonies maintained relatively high brood and adult bee populations (P < 0.05) than introduced honeybee colonies and produced more (P < 0.05) honey. The local bee colonies were able to hoard three times more (P < 0.05) pollen and built more (P < 0.05) queen cells than introduced bees in both the low and highland areas. The annual survival rate of local bee colonies was almost double (P < 0.05) than that of introduced honeybee colonies. Moreover, local bees had greater (P < 0.05) adult bee and brood populations than imported, throughout the year. The relatively good performance of local colonies could be due to their long year’s adaptation to cope with resource scarcity and unpredictable environmental conditions of the regions. The possible reasons for the dwindling of the imported hybrid colonies could be due to continuing to exhibit adaptive characteristics of their original that might not fit well with the new environment.     

Comparison of the activity and productivity of Carniolan (Apis mellifera carnica Pollmann) and Yemeni (Apis mellifera jemenitica Ruttner) subspecies under environmental conditions of the Al-Ahsa oasis of eastern Saudi Arabia

This study was conducted at the apiary of the Agricultural and Veterinary Training and Research Station of King Faisal University in the Al-Ahsa oasis of eastern Saudi Arabia. We performed a comparison between Carniolan (Apis mellifera carnica Pollmann) and Yemeni (Apis mellifera jemenitica Ruttner) honeybee races to determine the monthly fluctuations in foraging activity, pollen collection, colony growth and honey yield production under the environmental conditions of the Al-Ahsa oasis of eastern Saudi Arabia. We found three peaks in the flight activity of the two races, and the largest peaks occurred during September and October. Compared to Carniolan bee colonies, the performance of Yemeni bee colonies was superior in terms of stored pollen, worker and drone brood rearing, and the adult population size. The Carniolan bee colonies produced 27.77% and 27.50% more honey than the Yemeni bee colonies during the flow seasons of alfalfa and sidir, respectively, with an average increase of 27.64%. It could be concluded that the race of bees is an important factor affecting the activity and productivity of honeybee colonies. The Yemeni bee race produced more pollen, a larger brood and more bees, which exhibited a longer survival. The imported Carniolan bees can be reared in eastern Saudi Arabia, but the Yemeni bee race is still better.     

蜜蜂群内生殖分工体系的形成及其维持

本文对蜜蜂群内生殖分工体系的形成及其维持机制进行综述。蜜蜂群体具有完善的劳动分工(包括生殖分工)体系,蜂王垄断生殖权力,而工蜂生殖器官发育不完全,在蜂王信息素和幼虫信息素的作用下产卵受到抑制。蜂王的多雄交配机制降低了群内个体间的亲缘关系,但也促进了工蜂间相互监督机制的形成。工蜂间的相互监督,结合蜂王和幼虫信息素对工蜂卵巢发育的影响,解决了蜂王与工蜂、工蜂与工蜂间的生殖利益冲突,保障了蜂群内的生殖分工体系,提高了群体效率,维护了蜂群的真社会性。     

秸秆全量还田对稻田土壤溶解有机碳含量和水稻产量的影响

以南粳44为供试材料,在粘土和砂土土壤中,设置麦秸秆不还田和全量还田(6000 kg·hm^-2)及3种施氮量(0、225、300 kg·hm^-2)试验,研究了麦秸秆全量还田的腐解率和有机碳释放量动态变化,及其对稻田0～45 cm土壤溶解有机碳(DOC)含量和水稻产量的影响.结果表明： 麦秸秆还田的前期(0～30 d)其腐解率和有机碳释放量最高,腐解率为35.0%(粘土)和31.7%(砂土),有机碳释放率为34.1%(粘土)和33.1%(砂土);30 d后两者均减小.施用氮肥可显著促进秸秆腐解和有机碳释放量,粘土中麦秸秆腐解率和有机碳释放量明显大于砂土.麦秸秆还田后土壤DOC含量逐渐增加,至25 d达最大值,粘土和砂土分别为60.18和56.62 mg·L^-1,此后逐渐减小并趋于稳定.麦秸秆还田处理15 cm处土壤DOC含量显著高于未还田处理,但两者在30和45 cm处土壤DOC含量差异不显著,说明秸秆还田主要增加了稻田0～15 cm土层DOC含量.与不施氮处理相比,施氮处理土壤DOC含量降低,2种施氮处理间差异不显著.秸秆还田减少了水稻前期分蘖发生量,显著降低了有效穗数,增加了穗粒数、结实率和千粒重,显著提高了水稻产量.     

Dwindling pollen resources trigger the transition to broodless populations of long-lived honeybees each autumn

Abstract.  1. Each autumn in northern regions, honeybee colonies shift from populations of short-lived workers that actively rear brood to broodless populations of long-lived winter bees. To determine if dwindling pollen resources trigger this transition, the natural disappearance of external pollen resources was artificially accelerated or delayed and colonies were monitored for effects on the decline in brood-rearing activity and the development of populations of long-lived winter bees.
2. Delaying the disappearance of pollen resources postponed the decline in brood rearing in colonies. Colonies with an extended supply of pollen reared workers longer into October before brood rearing ended than control colonies or colonies for which pollen supply was cut short artificially in autumn.
3. Colonies with extended pollen supply produced more workers throughout autumn than colonies with less pollen, but the development of the population of long-lived winter bees was delayed until relatively later in autumn. Colonies produced similar numbers of winter bees, regardless of the timing of the disappearance of pollen resources.
4. Mean longevity of autumn-reared workers was inversely related to the amount of brood remaining to be reared in colonies when workers eclosed. Consequently, long-lived workers did not appear in colonies until brood rearing declined, which in turn was controlled by the availability of pollen.
5. Dwindling pollen resources provide a powerful cue that initiates the transition to populations of broodless winter bees because it directly affects the brood-rearing capacity of colonies and indirectly indicates deteriorating environmental conditions associated with the approach of winter.