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Peripheral biochemical monitoring involves the use of wearable devices for minimally invasive or noninvasive measurement of analytes in biofluids such as interstitial fluid, saliva, tears and sweat. The goal in most cases is to obtain measurements that serve as surrogates for circulating analyte concentrations in blood. Key technological developments to date include continuous glucose monitors, which use an indwelling sensor needle to measure glucose in interstitial fluid, and device-integrated sweat stimulation for continuous access to analytes in sweat. Further development of continuous sensing technologies through new electrochemical sensing modalities will be a major focus of future research. While there has been much investment in wearable technologies to sense analytes, less effort has been directed to understanding the physiology of biofluid secretion. Elucidating the underlying biology is crucial for accelerating technological progress, as the biofluid itself often presents the greatest challenge in terms of sample volumes, secretion rates, filtration, active analyte channels, variable pH and salinity, analyte breakdown and other confounding factors.

International audience; AbstractWe report factors that are limiting for Ascosphaera apis growth: water activity (aw) and temperature. Features of A. apis were a high water activity, 0.85–0.90 aw at 25/30 °C and 0.90–0.95 aw at 35 °C. A minimum water activity of 0.95 aw was required to produce spores. None of these characteristics changed from cycling or descending/ascending between low and high water activity media. Growth rates varied between isolates. This new study provides the biological data for monitoring and early prediction of disease outbreaks. Beekeepers should note that A. apis has a high water activity for spore production. Healthy bees that keep the internal brood area hot and dry can critically limit incidence of infection and transmission via spores.

Crayfish and their ectosymbiotic worms may be a valuable model system for studying strategies to maintain symbiotic relationships strained by host-induced environmental shifts. Ectosymbiotic branchiobdellidan worms are thought to be dependent on crayfish hosts for reproduction. However, many crayfish species leave surface waters to excavate and reside in subterranean burrows. During this semi-terrestrial phase, crayfish are frequently out of water, subjecting their associated worms to desiccation. Water balance characteristics of Cambarincola mesochoreus, an ectosymbiont of Procambarus clarkii, were examined to elucidate strategies for surviving emersion while maintaining host associations. Emersed worms were characterized by a high water loss rate and low tolerance for dehydration. A lack of direct water contact eventually prompted a coiled, immobile dormant state where water loss was temporarily suppressed. This dormant state was broken by addition of water and re-entered by subsequent emersion. Neither group effects by clustering of many worms, nor water vapor absorption were utilized as mechanisms to increase desiccation hardiness. When crayfish leave surface or subterranean water, worm survival while maintaining host contact is likely facilitated by facultative quiescence. However, this strategy only allows for survival during relatively short-term, cyclic bouts of emersion. Survival of longer-term emersion periods would require worms to leave hosts and remain behind in surface or subterranean water. These strategies likely incur counterbalancing trade-offs: increased mortality but maintenance of host association versus increased survival but temporary or permanent loss of host association and sites for reproduction.

To explore how the one-host tick Dermacentor albipictus survives off-host, we determined water balance characteristics of eggs and larvae. In contrast to eggs, larvae lost water fast, absorbed water vapour and died from a low amount of water loss. Placing mated females under near water-saturated conditions yielded larvae that absorbed and survived only at high relative humidities. We observed larvae forming clusters. Water loss rate of larvae decreased as group size increased. In response to day length, larvae lost water slower under long day than short day conditions. Larvae could switch quickly between fast water loss rate (short day) and slow water loss rate (long day) within a day, independent of the photoperiodic experience of the egg or mother. Long day exposure had no effect on water relations, incubation and survival of eggs. We conclude that eggs are modified for water conservation. Larvae survive by having a water balance maternal effect; i.e. capacity for water vapour absorption in the ...

Sweat sensing may provide a noninvasive means of estimating blood biomarker levels if a number of technological hurdles can be overcome. This report describes progress on a physiologically based transport model relating sweat glucose and key electrolyte concentrations to those in blood. Iontophoretically stimulated sweat glucose and fasted blood glucose were simultaneously measured in 2 healthy human subjects. Sweat glucose was measured with a novel, prototype skin sweat collection/analysis system and blood glucose with a commercial fingerstick glucometer. These data, in combination with data from 3 published studies, were used to calibrate a dynamic mathematical model for glucose transport and uptake in human skin, followed by extraction into sweat. Model simulations revealed that experimental and literature sweat glucose values were well represented under varying physiologic conditions. The glucose model, calibrated under a variety of experimental conditions including electrical enhancement, revealed a 10 min blood-to-sweat lag time and a sweat/blood glucose level ranging from 0.001 to 0.02, depending on the sweat rate. These values are consistent with those reported in the literature. The developed model satisfactorily described the sweat-to-blood relationship for glucose concentrations measured under different conditions in 4 human studies including the present pilot study. The algorithm may be used to facilitate sweat biosensor development.

Fungicides are found in agricultural areas to protect crops from fungal diseases. When sprayed in areas where honey bee colonies are placed for pollination, bees can collect or otherwise be exposed to these compounds. While labeled safe for bees by the manufacturers, our research found that pollen containing fungicides had a negative effect on the beneficial fungi found in bee colonies that help converting the pollen into bee bread and can end up in the bees themselves. As a result, pathogenic fungi (that cause chalkbrood and stonebrood diseases) were not kept in check by the beneficial fungi, including Aspergillus, Penicillium, Cladosporium, and Rhizopus, which were compromised by the presence of fungicides in the hive. Colonies were found to be weakened by the persistent presence of fungicides. Steps to help protect colonies are outlined.

To examine how aggregation by hairworms may enhance survival in freshwater, we determined water balance characteristics of Paragordius varius in groups of different sizes. P. varius is hyperosmotic resulting in high body water content and functions down to one-half of water stores. Absence of a critical transition temperature implies a watertight, low-porosity cuticle. Aggregated worms lose water slowly, as a physiological consequence of reduced motor activity. The water balance strategy shifts from a reliance on high dehydration tolerance for isolated individuals, affording high water loss rates, to suppressed activation energy when aggregated, wherein blocking water gain is important when water loss is slower. Low water loss rate derives from stillness and aggregating that facilitate mating or anti-predator defense, rather than as a behavior to regulate water loss. Presence of hairworms in streams is an indicator of high-quality water that is necessary to maintain water balance.

To correlate proper development and survival with moulting in hot summers for adults of the American dog tick Dermacentor variabilis and the lone star tick Amblyomma americanum, the maximum heat shock response was determined for engorged nymphs. An impressive ability to moult successfully with near complete adult survival occurred with 1-hour heat shock as high as 46°C for both species. Heat shock exposures at and above 48°C were detrimental, disrupting regular life history pattern by extending the crawling phase and severely reducing the number of adults that emerged. Amblyomma americanum was characterized by completion of adult development from engorged nymphs, greater adult yield, and enhanced adult survival in response to short-term heat exposure up to 50°C for engorged nymphs and 54°C for adult females. Both species featured the improved ability to recover from heat-induced injury as adults following prior exposure to heat at an ecologically relevant temperature (32oC) as an engorged nymph. Capacity ...

This study tested the lone star tick, Amblyomma americanum, vector of ehrlichiosis, tularemia, Southern tick-associated rash illness borreliosis, for arrestment to excreta from different tick species. The purpose was to explore off-host clustering along with spread and establishment into habitats occupied previously by other ticks. This response was analysed in relation to relative humidity since this is environmental. Females had the greatest responses towards natural excreta, and excreta components guanine and uric, and nymphs behaved like adults but with lower response levels. Response was poor by larvae, by showing inconsistent, or no response to excreta exposure. Clustering occurred on excreta from Amblyomma maculatum, Dermacentor variabilis, Ixodes scapularis, and Rhipicephalus sanguineus. This indicates there is unlikely a species-specific assembly component in excreta of A. americanum. In fact, highest level of assembly by A. americanum was to I. scapularis excreta. Greater speed and intensity for...

We have observed in the field copperhead snakes with Ixodes scapularis larvae feeding near the head and cloaca opening. Results show that copperhead excreta acts as a host cue that causes a significant proportion of unfed I. scapularis larvae to stop crawling, curl their legs, and remain motionless in short range bioassays. Clustering of larvae on snake excreta-treated surfaces occurred within one hour and aggregations remained for up to 12 hours. Shed skins of copperheads also prompted arrestment of larval activity (i.e., mobility has stopped). Similar levels of arrestment were noted when testing shed skins and excreta from captive ball pythons (Python regius), Burmese pythons (Python moralus), Mexican cantils (Agkistrodon bilineatus), and variable kingsnakes (Lampropeltis mexicana), suggesting that chemical cues utilized by larvae are similar among snake species. Larvae reacted positively by arresting to uric acid (main purine component in reptile excreta) and squalene (main lipid on shed snake skin). U...

To examine whether colonies of seed beetles, Callosobruchus maculatus, may be a health concern as a source of mold allergens to students and teachers, we compared the amount and type of molds present on adult beetles reared with mung beans and cowpeas, Vigna radiata and Vigna unguiculata, respectively (Family Fabaceae). Specimens were analyzed from two elementary schools, a commercial supplier and a university insectary. A total of nine fungal genera were isolated from live and dead adult beetles, consisting primarily of Aspergillus (a large proportion of which was Aspergillus niger) and Penicillium, with lower, variable numbers of Alternaria, Cladosporium, Fusarium, Mucor, Rhizopus, Scopulariopsis, and Trichoderma. Absidia, Geotrichum, and Paecilomyces were additional genera isolated from dead beetles. These molds are medically significant as potential allergens, and others (Aspergillus, Rhizopus, Mucor) can cause secondary infections in people. The mold profile of different beetle colonies are similar i...

The impact of maggot mass size on body water content, net transpiration rate, and dehydration tolerance of fly pupae was examined in six species of necrophagous flies. Species that spent more time on food as larvae, produced pupae with high body water contents. Dehydration tolerance limits of pupae were modest, matching the moisture-rich conditions of decaying carrion for larvae. Protophormia terraenovae pupariates on food as it dries, and this was reflected by pupae having the highest body water content and lowest net transpiration rate. Megaselia scalaris featured the lowest body water content and highest dehydration tolerance, implying that this species is arid-suited, which matches its ability to feed and colonize on post-decay carrion. Lucilia illustris was the most sensitive to larval overcrowding, resulting in a dramatic decrease in pupal size, early dispersal from food, fed less and had fast net transpiration rates. By contrast, Lucilia sericata was the most resistant, by showing no pupal size decrease and no change in net transpiration rate. Other species were between these extremes, requiring larger maggot mass sizes to produce the effect of decreasing pupal size and increasing net transpiration rate. We conclude: (1) the pupa’s response to overcrowding and water balance profile are species-specific, varying according to pupal size and net transpiration rate as independent characteristics; (2) water balance profile of the pupae reflects the behavior and microhabitat of the larva; and (3) danger of lethal desiccation to smaller-sized pupae is circumvented by a faster developmental rate rather than enhanced water conservation.

To determine whether pollen is a significant food source for Balaustium cf. murorum (tentative identification), behavioural responses to pollen feeding were examined in short-range Petri plate bioassays. Evans blue dye was used as a tracer to stain pollen after being incorporated into the gut. The results show that all active stages (larva, deutonymph and adult) ingested whole pollen from viburnum shrub (Viburnum) and daffodil (Narcissus) cultivars. All active stages fed on all types of pollen tested: tulip (Tulipa), daffodil (Narcissus), pear (Pyrus), maple (Acer), viburnum (Viburnum) and crabapple (Malus) cultivars except for tulip in the adult and tulip, pear and crabapple in the deutonymph. A higher percentage of larvae fed on pollen-covered surfaces and cleared pollen at a faster rate than other life stages in the bioassays. Clearance of viburnum and daffodil pollen by larvae and deutonymphs was particularly rapid, but this shifted to maple and crabapple pollen in the adult. In pheromone bioassays, p...

In this study, we provide the first evidence that the mite Gromphadorholaelaps schaeferi is beneficial to the Madagascar hissing cockroach Gromphadorhina portentosa by participating in a cleaning symbiosis and thus prolonging the life of its host. Gromphadorholaelaps schaeferi is a permanent resident of the cockroach and reduces mould levels by removing the food debris from the cockroach that acts as a substrate for fungal growth. To investigate the mould clearance attributes of these mites, we determined the effectiveness of mite infestation for decreasing cockroach mortality from a topically applied entomopathogenic fungus Metarhizium anisopliae. We further determined the effects of regulating cockroach food levels on altering the mycoflora profile of the cockroaches, with and without mites. Results showed that the lifespan of the cockroaches is extended by approximately 9 months when infested with mites. When treated with M. anisopliae (107 conidia/ml), which is pathogenic to the cockroach but not to t...

We examined whether water functions as a developmental cue for hatching in the lone star tick, Amblyomma americanum. The experiments examined various exposure routes to water: submersion, relative humidity and an ecologically relevant setup of moist soil along with soil fungi to mimic fungus–egg interactions at oviposition sites. We demonstrate that eggs survive for up to a week underwater; increasing water entry into the egg suppresses hatching; and exposure to liquid water, H2O or D2O, neither shortens nor prolongs the incubation period of those eggs that remain viable. In response to relative humidity, hatching takes place most readily when the air is nearly or fully saturated (with water); relative humidity neither shortens nor extends incubation period; and the length of incubation time is unrelated to the percentage of larvae that hatch. When incubated with fungi (common soil isolates), Aspergillus niger, Metarhizium anisopliae, Penicillium glabrum, Rhizopus stolonifer, Scopulariopsis brevicaulis, e...

International audience; To examine the link between chalkbrood and treatments applied to honey bee (Apis mellifera) colonies, growth of Ascosphaera apis was determined under chalkbrood-inducing conditions on agar containing crushed bee larvae as a mock infection. Treatments were tested at concentrations in the field, representative of beekeeping practice (at least in the USA). A chilling or warming stress known to heighten chalkbrood caused no growth enhancement of A. apis. Miticides had a negative effect; formic acid killed A. apis and oxalic acid reduced growth by 70 %. High-fructose corn syrups and sucrose syrup undiluted, a 50:50 mixture, alone, and with antibiotics did not alter growth of A. apis. We conclude that chalkbrood does not develop from a temperature- or treatment-induced activation of A. apis. Sugar syrups, miticides, and antibiotics point out other health problems that make bees prone to infection by A. apis. Thus, chalkbrood opportunistically infects bees under other forms of stress.

Fermentation by fungi converts stored pollen into bee bread that is fed to honey bee larvae, Apis mellifera, so the diversity of fungi in bee bread may be related to its food value. To explore the relationship between fungicide exposure and bee bread fungi, samples of bee bread collected from bee colonies pollinating orchards from 7 locations over 2 years were analyzed for fungicide residues and fungus composition. There were detectable levels of fungicides from regions that were sprayed before bloom. An organic orchard had the highest quantity and variety of fungicides, likely due to the presence of treated orchards within bees' flight range. Aspergillus, Penicillium, Rhizopus, and Cladosporium (beneficial fungi) were the primary fungal isolates found, regardless of habitat differences. There was some variation in fungal components amongst colonies, even within the same apiary. The variable components were Absidia, Alternaria, Aureobasidium, Bipolaris, Fusarium, Geotrichum, Mucor, Nigrospora, Paecilomyces, Scopulariopsis, and Trichoderma. The number of fungal isolates was reduced as an effect of fungicide contamination. Aspergillus abundance was particularly affected by increased fungicide levels, as indicated by Simpson's diversity index. Bee bread showing fungicide contamination originated from colonies, many of which showed chalkbrood symptoms.

We report that Rhipicephalus sanguineus (Ixodida: Ixodidae) faeces and its main component, guanine, act as assembly pheromones in short-range Petri plate bioassays. Arrestment activity in response to guanine was lower than that in response to natural excreta, indicating the presence of other active ingredients in natural excreta. The selective removal of appendages was used to establish the important roles played by the palps and the front pair of legs in the detection of the pheromone. Reaction to chemically pure guanine at varying concentrations occurred without a dose response; thus only the presence of guanine, not a critical amount, is required to induce assembly. Higher speed and intensity of clustering occurred at 33% relative humidity (RH). We conclude that female adults of R. sanguineus are more prone to assemble under dry conditions that match the arid microhabitats preferred by this species and that this tendency allows this tick to reside in human dwellings and dog kennels that maintain standards of comfort at 30-50% RH. Cleaning or removing tick excreta-covered surfaces on which ticks aggregate from within and around human dwellings may prove useful as a means of interfering with the establishment of off-host clusters of R. sanguineus.

To examine how traumatic insemination, a wounding process to females inflicted by males during copulation, reduces the longevity of females of the bedbug, Cimex lectularius, we assessed if multiple bouts of mating impact water relations of females by measuring net transpiration water loss rates. Our studies show that net transpiration rate of females correlates with frequency of mating (small increase after exposure to low numbers of males; large increase after exposure to large numbers of males), and this is reflected by reduced female survivorship for as much as 22 days at 75% RH, 25°C. Water loss occurs up to 28% more rapidly in females after being held with large groups of males. Females that were exposed to males having their paramere removed, females exposed only to other females, and females kept in isolation (unmated) exhibited no reduction in ability to retain water, indicating that traumatic insemination was responsible for the net transpiration rate increase. Mechanical piercing of the female's abdominal wall leads to increased net transpiration rates for longer periods than puncturing the ectospermalege (regular mating site), implying that inaccurate copulation by males is extremely detrimental to the water balance of females and that the ectospermalege is uniquely modified to seal off more quickly to prevent excess water loss. Mating frequency and the associated increased water loss is considerably reduced by the addition of bed bug alarm pheromone components. Thus, females experience elevated water stress due to traumatic insemination, especially at high levels and when males fail to pierce the ectospermalege, and water loss prevention, likely by more rapid sealing of the wound, is a novel function of the ectopsermalege.