Is the number of antennal plate organs (sensilla placodea) greater in hygienic than in non-hygienic Africanized honey bees?

Hygienic behavior is a desirable trait in honey bees (Apis mellifera L.), as hygienic bees quickly remove diseased brood, interrupting the infectious cycle. Hygienic lines of honey bees appear to be more sensitive to the odors of dead and diseased honey bee brood, and Africanized honey bees are generally more hygienic than are European honey bees. We compared the number of sensilla placodea, antennal sensory structures involved in the perception of odor, in 10 bees from each of six hygienic and four non-hygienic colonies of Africanized honey bees. The sensilla placodea of three of the terminal segments (flagellomeres) of the right antenna of each bee were counted with a scanning electron microscope. There were no significant differences in the mean numbers of sensilla placodea between the hygienic and non-hygienic bees, though the variance was higher in the hygienic group. Flagellomere 4 had significantly more sensilla placodea than flagellomeres 6 and 8. However, there was no significant difference between the other two flagellomeres. As hygienic bees are capable of identifying dead, injured, or infested brood inside a capped brood cell, sensilla placodea probably have an important role in enabling worker bees to sense sick brood. However, we did not find greater numbers of this sensory structure in the antennae of hygienic, compared to non-hygienic Africanized honey bees.     

Six quantitative trait loci influence task thresholds for hygienic behaviour in honeybees (Apis mellifera)

Honeybee hygienic behaviour provides colonies with protection from many pathogens and is an important model system of the genetics of a complex behaviour. It is a textbook example of complex behaviour under simple genetic control: hygienic behaviour consists of two components – uncapping a diseased brood cell, followed by removal of the contents – each of which are thought to be modulated independently by a few loci of medium to large effect. A worker’s genetic propensity to engage in hygienic tasks affects the intensity of the stimulus required before she initiates the behaviour. Genetic diversity within colonies leads to task specialization among workers, with a minority of workers performing the majority of nest‐cleaning tasks. We identify three quantitative trait loci that influence the likelihood that workers will engage in hygienic behaviour and account for up to 30% of the phenotypic variability in hygienic behaviour in our population. Furthermore, we identify two loci that influence the likelihood that a worker will perform uncapping behaviour only, and one locus that influences removal behaviour. We report the first candidate genes associated with engaging in hygienic behaviour, including four genes involved in olfaction, learning and social behaviour, and one gene involved in circadian locomotion. These candidates will allow molecular characterization of this distinctive behavioural mode of disease resistance, as well as providing the opportunity for marker‐assisted selection for this commercially significant trait.     

Varroa destructor infestation in untreated honey bee (Hymenoptera: Apidae) colonies selected for hygienic behavior

Honey bee (Apis mellifera L.) colonies bred for hygienic behavior were tested in a large field trial to determine if they were able to resist the parasitic mite Varroa destructor better than unselected colonies of"Starline" stock. Colonies bred for hygienic behavior are able to detect, uncap, and remove experimentally infested brood from the nest, although the extent to which the behavior actually reduces the overall mite-load in untreated, naturally infested colonies needed further verification. The results indicate that hygienic colonies with queens mated naturally to unselected drones had significantly fewer mites on adult bees and within worker brood cells than Starline colonies for up to 1 yr without treatment in a commercial, migratory beekeeping operation. Hygienic colonies actively defended themselves against the mites when mite levels were relatively low. At high mite infestations (>15% of worker brood and of adult bees), the majority of hygienic colonies required treatment to prevent collapse. Overall, the hygienic colonies had similar adult populations and brood areas, produced as much honey, and had less brood disease than the Starline colonies. Thus, honey bees bred for hygienic behavior performed as well if not better than other commercial lines of bees and maintained lower mite loads for up to one year without treatment.     

Hygienic behavior of the honey bee (Apis mellifera) is independent of sucrose responsiveness and foraging ontogeny

Hygienic behavior in honey bees is a behavioral mechanism of disease resistance. Bees bred for hygienic behavior exhibit an increased olfactory sensitivity to odors of diseased brood, which is most likely differentially enhanced in the hygienic line by the modulatory effects of octopamine (OA), a noradrenaline-like neuromodulator. Here, we addressed whether the hygienic behavioral state is linked to other behavioral activities known to be modulated by OA. We specifically asked if, during learning trials, bees from hygienic colonies discriminate better between odors of diseased and healthy brood because of differences in sucrose (reward) response thresholds. This determination had to be tested because sucrose response thresholds are susceptible to OA modulation and may have influenced the honey bee's association of the conditioned stimulus (odor) with the unconditioned stimulus (i.e., the sucrose reward). Because the onset of first foraging is also modulated by OA, we also examined whether bees from hygienic colonies differentially forage at an earlier age compared to bees from non-hygienic colonies. Our study revealed that 1-day- and 15- to 20-day-old bees from the hygienic line do not have lower sucrose response thresholds compared to bees from the non-hygienic lines. In addition, hygienic bees did not forage at an earlier age or forage preferentially for pollen as compared to non-hygienic bees. These results support the idea that OA does not function in honey bees simply to enhance the detection of all chemical cues non-selectively or control related behaviors regardless of their environmental milieu. Our results indicate that the behavioral profile of the hygienic bee is sculpted by multiple factors including genetic, neural, social and environmental systems.     

Olfactory and behavioral response thresholds to odors of diseased brood differ between hygienic and non-hygienic honey bees (Apis mellifera L.)

Through the use of proboscis-extension reflex conditioning, we demonstrate that honey bees (Apis mellifera L.) bred for hygienic behavior (a behavioral mechanism of disease resistance) are able to discriminate between odors of healthy and diseased brood at a lower stimulus level than bees from a non-hygienic line. Electroantennogram recordings confirmed that hygienic bees exhibit increased olfactory sensitivity to low concentrations of the odor of chalkbrood infected pupae (a fungal disease caused by Ascosphaera apis). Three-week-old hygienic bees were able to discriminate between the brood odors significantly better than three-week old non-hygienic bees. However, the differential performance in brood odor discrimination was primarily genetically based, not a direct result of age, experience, or the temporary behavioral state of the bee. Lower stimulus thresholds for both the olfactory and behavioral responses of hygienic bees may facilitate their ability to detect, uncap and remove diseased brood rapidly from the nest. In contrast, non-hygienic bees, possessing higher response thresholds, may not be able to detect diseased brood as easily. Our results provide an example of how physiological and behavioral differences between the hygienic and non-hygienic honey bee lines, operating at the level of the individual, could produce colony-specific behavioral phenotypes.     

Microbiological Contamination of Carcasses Related to Hygiene Practice and Facilities on Slaughtering Lines

The purpose of the study was to investigate the association between the hygienic practice of slaughterhouse workers and the microbiological contamination level of carcasses. In 5 Finnish slaughterhouses the workers’ hygienic practice was observed and the carcasses were sampled by the swabbing method. The overall means (log10 cfu cm−2) of the aerobic plate count in pork and beef carcasses were 3.23 and 2.65, respectively. Hygienic practice was found to be associated with the carcass contamination level, especially the disinfection frequency. In those slaughterhouses, where the disinfection frequency was low, the contamination level of carcasses was high. Designing slaughtering lines so as to make hygienic working possible is evidently very important. However, the enforcement of hygienic practice, such as the regular disinfection of working tools, is also important in reducing the microbiological contamination of carcasses.     

Desalinated water hygiene and scientific bases for its investigation

In view of the increasing scarcity of fresh water reserves in many countries of the world, a thorough hygienic evaluation of the different methods of desalinating highly mineralized underground and sea waters for economic and drinking purpose becomes indispensable. In addition to generally accepted hygienic criteria (favourable organoleptic properties, innocuous chemical composition and epidemiological safety), introduction of supplementary criteria for the assessment of the characteristic of the quality of freshened drinking water is necessary, i.e., its full value in the physiological sense and stability of drinking properties. The necessity of hygienic tests concerned with the study and regulation of the mineral and microelement composition of desalinated drinking water as well as of its microbial composition, structural peculiarities, the so-called "deuterium number" and the presence of various organic substances in desalinated water was pointed out. A certain degree of priority should be given to the study of the mentioned indices in hygienic assessment of the different methods of water desalination (distillation, freezing out, ion exchange, electrodialysis, inverse osmosis and others).     

Resistance to Chalkbrood disease in Apis mellifera L. (Hymenoptera: Apidae) colonies with different hygienic behaviour

Chalkbrood disease affects the larvae of honeybees Apis mellifera L. and is caused by the fungus Ascosphaera apis. Infected larvae die when they are stretched in the cap cell and suffer a gradual hardening that ends in a very hard structure (mummie). Several studies have demonstrated that colonies that express an efficient hygienic behaviour (uncapping of cell and subsequent removal of dead brood) exhibit a higher resistance to the disease. However, it remains unclear whether the advantage of hygienic colonies over less hygienic ones lies in the ability to remove mummies or in the early detection of infected larvae and its cannibalization before they harden. To elucidate this aspect, the hygienic behaviour of 24 colonies, which were subsequently provided with pollen cakes containig A. apis, was evaluated. The number of mummies and the number of partially cannibalized and whole larvae in uncapped cells were recorded. The most hygienic colonies controlled the disease better. These colonies also had a higher tendency to uncap cells that contained infected larvae and cannibalize them. The presence of A. apis in partially cannibalized and whole larvae in uncapped cells indicate that the advantage of hygienic colonies over less hygienic ones lies in the early detection of infected larvae death and their quick removal from the cell before they become mummies.     

Brood Odor Discrimination Abilities in Hygienic Honey Bees (Apis mellifera L.) Using Proboscis Extension Reflex Conditioning

To understand the effect of abnormal brood odors on the initiation or control of hygienic behavior in honey bees, we employed the associative learning paradigm, proboscis extension reflex conditioning. Bees from two genetic lines(hygienic and non-hygienic) were able to discriminate between high concentrations of two floral odors equally well. Differential discrimination abilities were observed between the two lines when healthy and diseased brood odors were used, with the bees from the hygienic line discriminating between the pair of brood odors better than the non-hygienic bees. These results suggest that hygienic behavior in individual bees is associated with the bees' responses to olfactory stimuli emanating from diseased brood.     

Maternal exposure to paternal antigens can modulate the foetus immune system and is associated with reduced atopy in the childhood

The influence of the maternal immune system on pregnancy and on the foetus immune system have given rise to a variety of observations and interesting hypotheses. For example, the higher prevalence of atopy in first-born children as compared to their brotherhood is known as the “birth order effect”. The “hygienic hypothesis” states that more hygienic live conditions, and consequently reduced exposure to pathogens in young age (included the period of foetal development), increases the risk of atopy. Here we review the ideas concerning maternal exposure to paternal antigens and immunomodulation. In particularly, we discuss the idea that this phenomenon may induce a regulatory environment in women that interfere with the developing foetal immune system. This regulatory environment could be responsible for protecting children to the development of atopy during adulthood. We propose that maternal exposure to paternal antigens through different situations, such as pregnancy, repeated exposure to sperm or Paternal Leukocyte Immunization (PLI) would combine the “birth order effect” and the “hygienic hypothesis” and thus lower the risk to atopy in children through the transference of a regulatory environment to the foetus.     

Physico-chemical and hygienic property modifications of stainless steel surfaces induced by conditioning with food and detergent

The effect of repeated conditioning procedures (25 runs), consisting of soiling (milk and meat products) and cleaning steps, on the hygienic status, physico-chemical properties and surface chemical composition of stainless steel (SS) surfaces, was investigated. Five SSs differing in grade and finish were used. Both soiling and surface cleaning/conditioning procedures resulted in a similar increase in the surface contamination with carbon, while the changes in the basic component of the surface free energy depended on the conditioning procedure. The passive film was also affected, the Fe/Cr ratio in particular. The hygienic status was also changed, especially with milk as shown by monitoring the number of residual adhering Bacillus cereus spores after contaminating the surface with spores followed by cleaning. The results show that in food environments, the presence and the nature of conditioning molecules play a major role in the hygienic status of SS surfaces.     

Physico-chemical and hygienic property modifications of stainless steel surfaces induced by conditioning with food and detergent

The effect of repeated conditioning procedures (25 runs), consisting of soiling (milk and meat products) and cleaning steps, on the hygienic status, physico-chemical properties and surface chemical composition of stainless steel (SS) surfaces, was investigated. Five SSs differing in grade and finish were used. Both soiling and surface cleaning/conditioning procedures resulted in a similar increase in the surface contamination with carbon, while the changes in the basic component of the surface free energy depended on the conditioning procedure. The passive film was also affected, the Fe/Cr ratio in particular. The hygienic status was also changed, especially with milk as shown by monitoring the number of residual adhering Bacillus cereus spores after contaminating the surface with spores followed by cleaning. The results show that in food environments, the presence and the nature of conditioning molecules play a major role in the hygienic status of SS surfaces.     

On hygienic and ecological approaches in radiation protection

In this paper the problem of substantiation of one of the basic radiation protection ensurance principle is considered: sufficiency of a man radiation safety ensuring for guaranteed ensuring of radiation safety of the environment living components. This paradigm formulated in ICRP recommendations and is often referred to as hygienic or anthropocentric approach to environment radiation protection is laid down the basis of all national, including Russian, regulations in the field of radiation safety. During the last 5-10 years a lot of papers have been published, in which the hygienic principle of environmental safety ensuring is considered as a matter of dispute and the certain logical basis and the quantitative comparative estimations of human exposure doses and most irradiated vulnerable parts of nature doses are given. Change of one of the main radiation protection paradigms will demand for resolution of the enormously difficult and labor-consuming scientific problems. In the present paper, on the basis of UNSCEAR models of critical population groups dose formation and consistent application of conservativeness principle it is shown that for the ground ecosystems today there is no strong reasons for refusal of a hygienic radiation protection principle for benefit of ecological one.     

Prevalence of Helicobacter pylori infection in Warao lineage communities of Delta Amacuro State, Venezuela

The purpose of this study was the evaluation of Helicobacter pylori infections in children and adults from two indigenous communities of Delta Amacuro State, Venezuela, that differ in hygienic conditions of the housing. The evaluation was performed in 98 children (mean age 7 +/- 3.37 years) and their mothers (33.96 +/- 13.77 years) from two communities of Warao lineage. Anti-H. pylori serum IgG and secretory anti-H. pylori IgA antibodies were determined, as well as total secretory IgA and H. pylori antigens in feces. Serological prevalence of H. pylori infection was 38% in children and 84% their in mothers. Children from the community that had the most deficient sanitary and hygienic conditions had significantly lower titers of specific IgG antibodies and total secretory IgA (P<0.0001) and a high percentage of them had H. pylori antigens in their feces (P<0.0001). The levels of specific IgA were similar in both groups. The results indicate that in these populations there is a high prevalence of H. pylori infection and that poor hygienic conditions can increase the risk of infection and damage to the gastrointestinal tract.     

Guanine as a hygienic index for allergologically relevant mite infestations in mattress dust

Since guanine is not only an essential constituent of vital nucleic acids, but also the main end product of nitrogenous waste excretion in arachnids, it is a potential candidate for a hygienic index for mite activity in house dust. The public health significance of these mites is based on their production of allergen in the home environment.In 101 mattress-dust samples, total number of mites and guanine content were positively correlated. The hygienic standard of 10 mites per 0.1 g dust (as derived from Danish investigations) was met in all samples with less than 0.06% guanine in the dry dust. Where the guanine content was more than or equal to 0.25% in the dry dust, mite numbers were higher than 10 mites per 0.1 g dust in 43 of the 44 samples. The three different groups (negligible mite content, possibly allergologically relevant mite concentration and allergologically unhygienic mite situation) could be easily discriminated on the color scale.The guanine-AZO-dye reaction in vacuum cleaner dust is a strong and promising candidate for an allergologically relevant hygienic index in the home.     

Welfare, health, and hygiene of laying hens housed in furnished cages and in alternative housing systems

The aim of this review was to compare welfare, health, and hygienic status of laying hens housed in furnished cages and in alternative systems. In alternative systems (floor housing and aviaries), birds have more freedom of movement and a more complex environment than in furnished cages. However, housing birds in much larger flocks in alternative systems leads to an increased risk of feather-pecking. Furthermore, air quality can be poorer in alternative systems than in furnished cages. This can affect health and hygienic status. There are only limited data on a direct comparison between furnished cages and alternative systems. Therefore, there is a need for an on-farm comparison of welfare, health, and hygienic status in these systems.     

Prevention of the genetic consequences of using pesticides: the reality and the necessity

The system of genetic and hygienic evaluation of pesticide preparations requires improvements as there are many mutagens among widespread chemical means of plant protection. A successful solution of the problem of the environment protection from genetic consequences of pesticide application is possible if the hygienic regulation of the pesticide application will be based not only on the results of its experimental check, but also on the ecological and genetic studies. The latter are to include identification of the environmental mutagenic background and the level of mutagenic and genotypic variability in populations.     

Hygienic behavior in the honey bee (Apis mellifera L.) and the modulatory role of octopamine

Honey bees, Apis mellifera, which perform hygienic behavior, quickly detect, uncap and remove diseased brood from the nest. This behavior, performed by bees 15-20 days old and prior to foraging, is likely mediated by olfactory cues. Because the neuromodulator octopamine (OA) plays a pivotal role in olfactory-based behaviors of honey bees, we examined whether bees bred for hygienic and nonhygienic behavior differed with regard to their OA expression and physiology. We compared the staining intensity of octopamine-immunoreactive (OA-ir) neurons in the deutocerebral region of the brain, medial to the antennal lobes, between hygienic and nonhygienic bees (based on genotype and phenotype). We also tested how the olfactory responses of the two lines, based on electroantennograms (EAGs), were affected by oral administration of OA and of epinastine, a highly specific OA antagonist. Our results revealed that bees expressing hygienic behavior (irrespective of genotype) possessed OA-ir neurons that exhibited more intense labeling than same-aged bees not performing the behavior. In bees bred for nonhygienic behavior, OA significantly increased the EAG response to low concentrations of diseased brood odor. Conversely, in bees bred for hygienic behavior, epinastine significantly reduced the magnitude of the EAG response, a reduction not observed in nonhygienic bees. Our results provide two lines of evidence that OA has the potential to facilitate the detection and response of honey bees to diseased brood. We discuss the contributions of OA for behavioral shaping and its ability to bias the nervous system to express one form of behavior over another.     

Physicochemical, toxicological and hygienic aspects of ethylene oxide application for the sterilization of medical products. III. Setting hygienic norms in sterilized medical products

Some of the drawbacks are discussed associated with hygienic norms for gaseous sterilizing agents in polymeric products for medical applications. A new approach is proposed for regulating ethylene oxide (EO) in such products. To this end, limiting types of biological effect and its pathways have been determined and substantiated as well as the reliability factor for establishing hygienic norms for EO in medical products. Daily threshold EO limit values were calculated for momentary and repeated exposure of humans. The duration of long-term and short-term exposure of the patient to sterilized products was evaluated on the basis of EO extraction kinetics from a variety of materials. Using daily threshold limit values, threshold residual values (TRV) of EO were calculated for different groups of polymeric products for medical applications.