A change of sensitivity threshold of Apis mellifera to action of pathogen at different periods of starvation

The work studies thresholds of sensitivity in the honeybee Apis mellifera in connection with action of different periods of starvation on biochemical and cellular parameters of protective reactions. Intraspecies differences are shown during additional action of a bacterial preparation at the physiological level. An importance of the hidden (latent) phase for the insects is evaluated in manifestation of the general adaptive syndrome, which precedes the phase of anxiety development. The intraspecies peculiarities of response of protective systems in the honeybee consist not only in the activity level of physiological processes, but also in the rate of overcoming the sensitivity threshold to pathogen.     

Physiological effects of hypoxia in developing and adult honeybees <Emphasis Type="Italic">Apis mellifera</Emphasis> L.

The effect of hypoxia on activity of metabolism was studied in developing and adult honeybees. The feedback was established between the O₂ deficit in the gas medium and its consumption by honeybees. An elevation of temperature within the limits of vital diapason for development of honeybees activated the O₂ consumption regardless of the hypoxia level. A prolonged action of hypoxia on the honeybee physiological state was revealed. There was shown the existence of convergent similarity between the effect of O₂ deficit on honeybees and on homoiothermal animals.     

Synergistic activation of insect cAMP-dependent protein kinase A (type II) by cyclicAMP and cyclicGMP

The high cGMP sensitivity of cAMP-dependent protein kinase A (type II) (PKAII) from invertebrates led to the hypothesis that cGMP directly activates PKAII under physiological conditions. We tested this idea using PKAII holoenzyme purified from the honeybee brain in an assay with short stimulation times. In the presence of very low cAMP concentrations, we found a synergistic increase in PKAII activation by physiological cGMP concentrations. Cloning honeybee regulatory subunit RII and phylogenetic comparison of the two cyclic nucleotide-binding sites of RII reveal a high relation of domain A of insect RII with cGMP-binding domains of cGMP-dependent protein kinases.     

Reaction of Individual Physiological Barriers in Bacterial Infection in Different Races of the Honeybee <Emphasis Type="Italic">Apis mellifera</Emphasis>

This work deals with study of differences between races of the honeybee Apis mellifera with respect to involvement in the protective reaction to bacterial infection of the barrier physiological mechanisms—of responses of intestine and hemolymph cells. The states of the intestine parts is evaluated; the rates of accumulation and elimination of bacteria from the midgut are determined in the honeybees treated once and repeatedly by a preparation based on the food Bacillus thuringiensis (BTB). The hemolymph cells were also studied cytologically. It was shown that under conditions of this experiment the honeybees of the middle-Russian race were characterized by an optimal combination and participation of all considered barrier mechanisms in response to penetration into the organism and development of the bacterial pathogen. A suggestion is put forward about the genetically fixed differences in functions of the physiological mechanisms between the diverged races as well as about the incomplete realization of adaptive potential in the honeybees of Caucasian race introduced in the Republic and in hybrid individuals due to the stress produced by the environmental factors.__________Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 41, No. 3, 2005, pp. 254–258.Original Russian Text Copyright © 2005 by Saltykova, Ben’kovskaya, Gaifullina, Novitskaya, Poskryakov, Nikolenko.     

The <Emphasis Type="Italic">foraging</Emphasis> gene,behavioral plasticity,and honeybee division of labor

In recent years, the honeybee has emerged as an excellent model for molecular and genetic studies of complex social behaviors. By using the global gene expression methods as well as the candidate gene approach, it is now possible to link the function of genes to social behaviors. In this paper, I discuss the findings about one such gene, foraging, a cGMP-dependent protein kinase. The involvement of this gene in regulating division of labor is discussed on two independent, but not mutually exclusive levels; the possible mechanisms for PKG action in regulating behavioral transitions associated with honeybee division of labor, and its possible involvement in the evolution of division of labor in bees.     

New approach to the mitotype classification in black honeybee <Emphasis Type="Italic">Apis mellifera mellifera</Emphasis> and Iberian honeybee <Emphasis Type="Italic">Apis mellifera iberiensis</Emphasis>

The black honeybee Apis mellifera mellifera L. is today the only subspecies of honeybee which is suitable for commercial breeding in the climatic conditions of Northern Europe with long cold winters. The main problem of the black honeybee in Russia and European countries is the preservation of the indigenous gene pool purity, which is lost as a result of hybridization with subspecies, A. m. caucasica, A. m. carnica, A. m. carpatica, and A. m. armeniaca, introduced from southern regions. Genetic identification of the subspecies will reduce the extent of hybridization and provide the gene pool conservation of the black honeybee. Modern classification of the honeybee mitotypes is mainly based on the combined use of the DraI restriction endonuclease recognition site polymorphism and sequence polymorphism of the mtDNA COI–COII region. We performed a comparative analysis of the mtDNA COI–COII region sequence polymorphism in the honeybees of the evolutionary lineage M from Ural and West European populations of black honeybee A. m. mellifera and Spanish bee A. m. iberiensis. A new approach to the classification of the honeybee M mitotypes was suggested. Using this approach and on the basis of the seven most informative SNPs of the mtDNA COI–COII region, eight honeybee mitotype groups were identified. In addition, it is suggested that this approach will simplify the previously proposed complicated mitotype classification and will make it possible to assess the level of the mitotype diversity and to identify the mitotypes that are the most valuable for the honeybee breeding and rearing.     

Antimicrobial factor from <Emphasis Type="Italic">Bacillus amyloliquefaciens</Emphasis> inhibits <Emphasis Type="Italic">Paenibacillus larvae</Emphasis>, the causative agent of American foulbrood

Bacillus amyloliquefaciens LBM 5006 produces an antimicrobial factor active against Paenibacillus larvae, a major honeybee pathogen. The antagonistic effect and the mode of action of the antimicrobial factor were investigated. The antibacterial activity was produced starting at mid-logarithmic growth phase, reaching its maximum during the stationary phase. Exposure of cell suspensions of P. larvae to this antimicrobial resulted in loss of cell viability and reduction in optical density associated with cell lysis. Scanning electron microscopy showed damaged cell envelope and loss of protoplasmic material. The antimicrobial factor was stable for up to 80°C, but it was sensitive to proteinase K and trypsin. Mass spectrometry analysis indicates that the antimicrobial activity is associated with iturin-like peptides. The antimicrobial factor from B. amyloliquefaciens LBM 5006 showed a bactericidal effect against P. larvae cells and spores. This is the first report on iturin activity against P. larvae. This antimicrobial presents potential for use in the control of American foulbrood disease.     

Dynamics and Infradian Rhythmics of Thermal/Pain Sensitivity of the <Emphasis Type="Italic">Helix</Emphasis> Mollusc under the Action of Electromagnetic Fields

We measured characteristics of thermal/pain (th/p) sensitivity of Helix albescens (threshold and latency of the avoidance behavioral reaction) under conditions of the hot-plate test. As was found, weakening (shielding) of the background electromagnetic field, as well as the action of low-intensity radiations of extremalfrequency ranges, induced two-phase changes of these characteristics within a 21-day-long observation period with different manifestations and durations of the phases. Initial increase in the nociceptive sensitivity (hyperalgesia) was followed by an analgesic effect with subsequent return of the examined indices to the initial level. Low-intensity electromagnetic influences also induced modifications of the infradian rhythmics of th/p sensitivity of the molluscs; this was manifested in changes of the spectra and phase shifts of the identified rhythms and trends toward modulation of the amplitudes of these rhythmic components.     

Knock‐on community impacts of a novel vector: spillover of emerging DWV‐B from Varroa‐infested honeybees to wild bumblebees

Novel transmission routes can directly impact the evolutionary ecology of infectious diseases, with potentially dramatic effect on host populations and knock‐on effects on the wider host community. The invasion of Varroa destructor, an ectoparasitic viral vector in Western honeybees, provides a unique opportunity to examine how a novel vector affects disease epidemiology in a host community. This specialist honeybee mite vectors deformed wing virus (DWV), an important re‐emerging honeybee pathogen that also infects wild bumblebees. Comparing island honeybee and wild bumblebee populations with and without V. destructor, we show that V. destructor drives DWV prevalence and titre in honeybees and sympatric bumblebees. Viral genotypes are shared across hosts, with the potentially more virulent DWV‐B overtaking DWV‐A in prevalence in a current epidemic. This demonstrates disease emergence across a host community driven by the acquisition of a specialist novel transmission route in one host, with dramatic community level knock‐on effects.     

The impact of apiculture on the genetic structure of wild honeybee populations (<Emphasis Type="Italic">Apis mellifera</Emphasis>) in Sudan

Apiculture often relies on the importation of non-native honeybees (Apis mellifera) and large distance migratory beekeeping. These activities can cause biodiversity conflicts with the conservation of wild endemic honeybee subspecies. We studied the impact of large scale honeybee imports on managed and wild honeybee populations in Sudan, a centre of biodiversity of A. mellifera, using as set of linked microsatellite DNA loci and mitochondrial DNA markers. The mitochondrial DNA analyses showed that all wild honey bees exclusively belonged to African haplotypes. However, we revealed non-native haplotypes in managed colonies on apiaries reflecting unambiguous evidence of imports from European stock. Moreover, we found significantly higher linkage disequilibria for microsatellite markers in wild populations in regions with apiculture compared to wild populations which had no contact to beekeeping. Introgression of imported honeybees was only measurable at the population level in close vicinity to apicultural activities but not in wild populations which represent the vast majority of honeybees in Sudan.     

Intraspecies differences in mechanisms of formation of protective processes in the honeybee <Emphasis Type="Italic">Apis mellifera</Emphasis>

Presented in the work are data on interrace differences in mechanisms of formation of antioxidant and phenoloxidase complexes in honeybees of the Middle Russian (Apis mellifera L.) and Caucasian (Apis mellifera caucasica Gorb.) geographic races. Different degree has been revealed of activation of these complexes depending on their localization in the insect organism and providing different strategy of adaptation to temperature stress. A diverse role of ascorbic acid in regulation of the honeybee protective system has been shown.     

MtDNA COI‐COII marker and drone congregation area: An efficient method to establish and monitor honeybee (Apis mellifera L.) conservation centres

Honeybee subspecies have been affected by human activities in Europe over the past few decades. One such example is the importation of nonlocal subspecies of bees which has had an adverse impact on the geographical repartition and subsequently on the genetic diversity of the black honeybee Apis mellifera mellifera. To restore the original diversity of this local honeybee subspecies, different conservation centres were set up in Europe. In this study, we established a black honeybee conservation centre Conservatoire de l'Abeille Noire d'Ile de France (CANIF) in the region of Ile‐de‐France, France. CANIF's honeybee colonies were intensively studied over a 3‐year period. This study included a drone congregation area (DCA) located in the conservation centre. MtDNA COI‐COII marker was used to evaluate the genetic diversity of CANIF's honeybee populations and the drones found and collected from the DCA. The same marker (mtDNA) was used to estimate the interactions and the haplotype frequency between CANIF's honeybee populations and 10 surrounding honeybee apiaries located outside of the CANIF. Our results indicate that the colonies of the conservation centre and the drones of the DCA show similar stable profiles compared to the surrounding populations with lower level of introgression. The mtDNA marker used on both DCA and colonies of the conservation centre seems to be an efficient approach to monitor and maintain the genetic diversity of the protected honeybee populations.     

Cold-induced lipid phase transitions

The structural organization of biological membranes is largely determined by the weak interactions existing between their components and between these components and their aqueous environment. These interactions are particularly sensitive to changes in temperature and hydration. The factors influencing membrane lipid phase behaviour are briefly reviewed and used to develop a phase-separation model describing the response of biological membranes to stress. The factors affecting the interaction of cryoprotectants with membrane lipids are explored and their role in the stabilization of membrane organization at low temperatures discussed. It is suggested that the basis of their protective action lies in an ability to preserve the balance of interactions between membrane components at low temperatures at a level similar to that existing under physiological conditions.     

L-Glutamate in formation of long-term memory in the honeybee <Emphasis Type="Italic">Apis mellifera</Emphasis>

Participation of metabotropic glutamate receptors (mGluR) in associative learning of the honeybee Apis mellifera was studied in behavioral and electrophysiological experiments with use of pharmacological analysis. By the method of conditioned reflexes, effects of systemic injections of mGluR agonists and antagonists were studied on retention of elaborated conditioned reflexes in short-term and long-term memory. Injection of aminocyclopentandicarbonic acid (ACPD), ibotenate, and phosphoserine stimulated the memory in 3 h after the single learning procedure. The long- term memory was inhibited by mGluR antagonists — methylcarboxyphenylglycine and amino- phosphonopropionate as well as by non-competitive antagonists of mGluR₁(CPCCOEt) and of mGluR₅ (SIB 1757). Electrophysiological experiments demonstrated changes of characteristics of the action potential recorded from mushroom bodxies in response to stimulation of antennal lobes and during injections of mGluR III phosphoserine and the mGluR₁ antagonist CPCCOEt. The obtained data allow suggesting participation of different groups of metabotropic glutamate receptors in the process of the honeybee associative learning.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 40, No. 6, 2004, pp. 539–545.     

Sensitivity of various <Emphasis Type="Italic">Escherichia coli</Emphasis> strains to 2,4,6-trinitrotoluene

The sensitivity of Escherichia coli strains K-12 and 055 to 2,4,6-trinitrotoluene (TNT) was found to correlate with the structural and functional properties of the outer lipoprotein membrane. The protective ability of the membrane of strain 055 is much lower than that of K-12. This is the cause of the greater sensitivity of 055 to the toxic action of TNT. High TNT concentrations (100–200 mg/l) suppressed the growth of 055, whereas K-12 grew at all TNT concentrations studied. Both strains adapted to high TNT concentrations by converting it by either nitroreduction or denitritation depending on concentration. The denitritation system of strain 055 started TNT degradation earlier than that of K-12.Translated from Prikladnaya Biokhimiya i Mikrobiologiya, Vol. 41, No. 1, 2005, pp. 53–57.Original Russian Text Copyright © 2005 by Kurinenko, Denivarova, Yakovleva.     

Out of the blue: the spectral sensitivity of hummingbird hawkmoths

The European hummingbird hawkmoth Macroglossum stellatarum is a diurnal nectar forager like the honeybee, and we expect similarities in their sensory ecology. Using behavioural tests and electroretinograms (ERGs), we studied the spectral sensitivity of M. stellatarum. By measuring ERGs in the dark-adapted eye and after adaptation to green light, we determined that M. stellatarum has ultraviolet (UV), blue and green receptors maximally sensitive at 349, 440 and 521 nm, and confirmed that green receptors are most frequent in the retina. To determine the behavioural spectral sensitivity (action spectrum) of foraging moths, we trained animals to associate a disk illuminated with spectral light, with a food reward, and a dark disk with no reward. While the spectral positions of sensitivity maxima found in behavioural tests agree with model predictions based on the ERG data, the sensitivity to blue light was 30 times higher than expected. This is different from the honeybee but similar to earlier findings in the crepuscular hawkmoth Manduca sexta. It may indicate that the action spectrum of foraging hawkmoths does not represent their general sensory capacity. We suggest that the elevated sensitivity to blue light is related to the innate preference of hawkmoths for blue flowers.     

On the Front Line: Quantitative Virus Dynamics in Honeybee (Apis mellifera L.) Colonies along a New Expansion Front of the Parasite Varroa destructor

Over the past fifty years, annual honeybee (Apis mellifera) colony losses have been steadily increasing worldwide. These losses have occurred in parallel with the global spread of the honeybee parasite Varroa destructor. Indeed, Varroa mite infestations are considered to be a key explanatory factor for the widespread increase in annual honeybee colony mortality. The host-parasite relationship between honeybees and Varroa is complicated by the mite''s close association with a range of honeybee viral pathogens. The 10-year history of the expanding front of Varroa infestation in New Zealand offered a rare opportunity to assess the dynamic quantitative and qualitative changes in honeybee viral landscapes in response to the arrival, spread and level of Varroa infestation. We studied the impact of de novo infestation of bee colonies by Varroa on the prevalence and titres of seven well-characterised honeybee viruses in both bees and mites, using a large-scale molecular ecology approach. We also examined the effect of the number of years since Varroa arrival on honeybee and mite viral titres. The dynamic shifts in the viral titres of black queen cell virus and Kashmir bee virus mirrored the patterns of change in Varroa infestation rates along the Varroa expansion front. The deformed wing virus (DWV) titres in bees continued to increase with Varroa infestation history, despite dropping infestation rates, which could be linked to increasing DWV titres in the mites. This suggests that the DWV titres in mites, perhaps boosted by virus replication, may be a major factor in maintaining the DWV epidemic after initial establishment. Both positive and negative associations were identified for several pairs of viruses, in response to the arrival of Varroa. These findings provide important new insights into the role of the parasitic mite Varroa destructor in influencing the viral landscape that affects honeybee colonies.     

Development and evolution of caste dimorphism in honeybees – a modeling approach

The difference in phenotypes of queens and workers is a hallmark of the highly eusocial insects. The caste dimorphism is often described as a switch‐controlled polyphenism, in which environmental conditions decide an individual's caste. Using theoretical modeling and empirical data from honeybees, we show that there is no discrete larval developmental switch. Instead, a combination of larval developmental plasticity and nurse worker feeding behavior make up a colony‐level social and physiological system that regulates development and produces the caste dimorphism. Discrete queen and worker phenotypes are the result of discrete feeding regimes imposed by nurses, whereas a range of experimental feeding regimes produces a continuous range of phenotypes. Worker ovariole numbers are reduced through feeding‐regime‐mediated reduction in juvenile hormone titers, involving reduced sugar in the larval food. Based on the mechanisms identified in our analysis, we propose a scenario of the evolutionary history of honeybee development and feeding regimes.     

Effect of physiological heterogeneity of <Emphasis Type="Italic">E. coli</Emphasis> population on antibiotic susceptivity test

According to the instantaneous growth rate (dN/dt) of E. coli CVCC249 growing in batch culture, the entire growth progress was distinguished into four phases: accelerating growth phase, constant growth phase, decelerating growth phase and declining phase, in each of which obvious variation in physiological and biochemical properties was detected, including total DNA, total protein, and MTT-dehydrogenase activity, etc., that led to difference in their antibiotic susceptivity. Antibiotic susceptivity of the population sampled from each phase was tested by Concentration-killing Curve (CKC) approach following the formula N=N ₀/{1+exp[r·(x-BC ₅₀)]}, showing as normal distribution at the individual cell level for an internal population, in which the median bactericidal concentration BC ₅₀ represents the mean level of susceptivity, while the bactericidal span BC ₁₋₉₉=(2lnN ₀)/r indicates the variation degree of the antibiotic susceptivity. Furthermore, tested by CKC approach, the antibiotic susceptivity of E. coli CVCC249 population in each physiological phase to gentamicin or enoxacin was various: susceptivity of the population in the constant growth phase and declining phase all increased compared with that in the accelerating growth phase for gentamicin but declined for enoxacin. The primary investigations revealed that the physiological phase should be taken into account in the context of antibiotic susceptivity and research into antimicrobial mechanism. However there are few reports concerned with this study. Further research using different kinds of antibiotics with synchronized continuous culture of different bacterial strains is required.