Penetration of light into carpet, and responses of the European house-dust mite (Dermatophagoides pteronyssinus) to varying light intensity and diurnal cycle

This study examined the question of what effect exposure to light might play in determining the vertical distribution of house-dust mites in carpet, and the degree to which light penetrates worn and unworn carpets of different pile conformation (loop- versus cut-pile), height and colour. The effect on population increase of a diurnal lighting cycle versus continual darkness was also investigated. It was found that the penetration of light into carpets was largely unaffected by pile colour or conformation. Pile height was an important factor, however, and for a given height within the pile, light intensity was higher in carpets subjected to a greater degree of wear. This corresponded to the reduction in effective pile height that occurs with carpet use. Whilst the differences observed were sometimes large (up to two-fold for a given height within the pile), Petri dish studies suggested no mite preference for habitation of areas of low light intensity compared to high intensity. Additionally, culturing mites under a diurnal light cycle was shown to be no more efficient than culturing in complete darkness. These results suggest that exposure to light is not an important determinant of house-dust mite behaviour, or their ability to colonise textile substrates.     

Feeding and Avoiding Predation Hazard: the Behavioral Response of the Prey

A forager may respond to the hazard of predation by (1) ignoring the hazard and eating maximally at all levels of food (risk-reckless); (2) avoiding the hazard and minimizing eating (risk-avoiding); (3) reducing feeding by the same amount at each level of food, making greater reductions as hazard increases (risk-adjusting); (4) reducing feeding at low levels of food, while accepting a greater hazard when food levels are high (risk-balancing). We experimentally distinguished these four nominal responses using 9 three-spined sticklebacks, Gasterosteus aculeatus in a 3 times 4 factorial, repeated measures design. The fish were tested in an aquarium containing a refuge inaccessible to predatory trout, Salmo trutta, in 12 combinations of food (low, medium, high) and predation hazard (predator density = 0, 1, 2, 3). With predators, sticklebacks ate less and used the refuge more. Amount eaten, but not time spent out of the refuge, was positively correlated with food, even in the absence of predators. Since sticklebacks as a group appeared to depress feeding by equal amounts at all levels of food, they employed a risk-adjusting response. However, individuals varied in their response to hazard.     

Do Inactivated Microbial Preparations Improve Life History Traits of the Copepod <Emphasis Type="Italic">Acartia tonsa</Emphasis>?

We have tested a microbial preparation with probiotic effects (PSI; Sorbial A/S DANISCO) on the calanoid copepod Acartia tonsa (Dana) development time and reproduction effectiveness in culture. The hypotheses were that PSI increases the productivity and quality of copepods in culture (increased egg production and hatching success, HS). This was carried out because the use of copepods as live prey in aquaculture could increase the number of fish successfully raised through their entire life cycle. However, the availability of copepods is limited by their difficulty to be effectively raised. Our results show that the addition of PSI to the algal food increased the individual size of the adult females and their egg production. The PSI, together with Rhodomonas salina, also increased the HS of the eggs produced by PSI-treated females. These effects were observed despite that the biochemical analysis of the PSI revealed that it is a nutritionally poor food lacking essential fatty acids, and hence it cannot be used alone to raise copepods but instead as a food additive. This is the first demonstration that the effectiveness of copepod culturing can be improved using microbial preparations as a food additive.     

Effects of five insect growth regulators on laboratory populations of the North American house-dust mite,Dermatophagoides farinae

The potential of insect growth regulators (methoprene, hydroprene, fenoxycarb, diflubenzuron and triflumuron) to control populations of the North American house-dust miteDermatophagoides farinae (Hughes) was assessed in laboratory bioassays. Methoprene was most effective at suppressing population growth, especially at concentrations of 1.0% (10 000 ppm) and 5.0% (5000 ppm) active ingredient. Hydroprene, structurally related to methoprene, also suppressed house-dust mite populations but not as consistently as methoprene. Fenoxycarb may be effective at controlling house-dust mites but at greater concentrations than were tested. Diflubenzuron and triflumuron, two chitin-synthesis inhibitors, failed to suppress mite numbers and may, in fact, stimulate reproduction in some cases. Almost all concentration of the insect growth regulators were shown to be ineffective when assayed 90 days after treatment.     

“Escherichia coli‐milk” biofilm removal from stainless steel surfaces: Synergism between ultrasonic waves and enzymes

Three different methods to standardize biofilm removal for in situ sanitary control of closed surfaces in the food industry have been developed and compared, i.e. sonication, enzymatic treatment and a combined treatment which involved the application of ultrasound to enzyme preparations. The biofilm studied was an Escherichia coli model biofilm, made with milk on stainless steel sheets. Plate counting and epifluorescence microscopy were used to assess the efficiency of each treatment. The results are expressed in percentages, 100% denoting total removal, obtained with a flat ultrasonic transducer (T1) developed and presented in a previous study. The application of ultrasound by a patented curved transducer, T2 (10 s, 40 kHz), specifically devised for closed surfaces, was not sufficient to completely remove the biofilm (30 ± 7%). This biofilm was dislodged by two proteolytic enzyme preparations tested by immersion, viz. a 15‐min application of protease (84±1%) and a 30‐min trypsin application (95±8%). Using a combined treatment, the results showed a synergism between ultrasonic waves and proteolytic or glycolytic enzyme preparations, with removal of a significant amount of biofilm, i.e. 61–96% depending on the conditions tested, i.e. two to three times greater compared to sonication alone (30%). This application was in agreement with an industrial control, i.e. a good reproducible recovery of the biofilm in 10 s compared with 30 or 15 min with the enzyme alone.     

Experimental demonstration of close-range olfaction and contact chemoreception in the Brazilian harvestman, Iporangaia pustulosa

We studied the ability to detect food by close-range olfaction and contact chemoreception in the harvestman Iporangaia pustulosa Mello-Leitão (Opiliones: Laniatores: Gonyleptidae). We first tested the reaction of individuals towards tasteless (pure agar), aversive (agar with salt), and food-intake stimulating substrates (agar with saccharose). Only the substrate containing saccharose was consumed. Contact (mainly with legs II) was necessary for detection of the agar and, before ingestion, the stimulus was always tapped with legs I. In the second experiment, we observed the behavior of individuals in an arena with a screened plastic box containing pieces of Tenebrio molitor L. (Coleoptera: Tenebrionidae) larvae. Individuals spent more time on the box containing food than on the control. In the third experiment, in an arena identical to that used in Experiment 2, we introduced a live but motionless T. molitor larva in the box. There was no difference between experimental and control treatments. We also observed the behavior of I. pustulosa in an arena containing live isopods. In first capture attempts, isopods were only detected upon contact, mainly with legs I. Our results suggest that (i) I. pustulosa is capable of detecting food only by its chemical properties; (ii) food with weak odor may not be detected by close-range olfaction; and (iii) legs I and II are important for food detection but, before ingestion, legs I are used to examine potential food items.     

Spatial heterogeneity of trophic pathways in the invertebrate community of a temperate bog

Summary 1. To examine spatial heterogeneity of trophic pathways on a small scale (<5 m diameter), we conducted dual stable isotope (δ¹³C and δ¹⁵N) analyses of invertebrate communities and their potential food sources in three patchy habitats [sphagnum lawn (SL), vascular‐plant carpet (VC) and sphagnum carpet] within a temperate bog (Mizorogaike Pond, Kyoto, Japan). 2. In total, 19 invertebrate taxa were collected from the three habitats, most of which were stenotopic, i.e. collected from a single habitat. Amongst the habitats, significant variation was observed in the isotopic signatures of dominant plant tissues and their detrital matter [benthic particulate organic matter (BPOM)], both of which were potential organic food sources for invertebrates. Site‐specific isotopic variation amongst detritivores was found in δ¹³C but not in δ¹⁵N, reflecting site‐specificity in the isotopic signatures of basal foods. The eurytopic hydrophilid beetle Helochares striatus was found in all habitats, but showed clear site variation in its isotopic signatures, suggesting that it strongly relies on foods within its own habitat. 3. The most promising potential foods for detritivores were the dead leaf stalks of a dominant plant in the VC and BPOM in the SL and carpet. An isotopic mixing model (IsoSource version 1.3.1) estimated that aquatic predators rely on unknown trophic sources with higher δ¹³C than detritus, whereas terrestrial predators forage on allochthonous as well as autochthonous prey, suggesting that the latter predators might play key roles in coupling between habitats. 4. Our stable isotope approach revealed that immobile detritivores are confined to their small patchy habitats but that heterogeneous trophic pathways can be coupled by mobile predators, stressing the importance of habitat heterogeneity and predator coupling in characterising food webs in bog ecosystems.     

Effects of continuous gastric infusion of food dyes on developing rat pups

The consequences of chronic percutaneous gastric infusion of food dyes on the activity levels and shock avoidance performance of normal developing rats and those treated with 6-hydroxydo p-amine (6-OHDA) were investigated. All pups were artificially reared from four days of age and a liquid diet containing either food dyes (D) or no colorings (N) was infused into both 6-OHDA (T) and sham-treated pups (V). Pups receiving food dyes were significantly more active than comparable pups not receiving food dyes at all ages tested, an effect observed in both 6-OHDA and shamtreated pups. Pups treated with food dyes exhibited an impaired avoidance performance in a shuttle box at 28 days of age. VD and TN pups displayed an over 100% impairment in avoidance performance in comparison with VN pups. These results suggest that food dyes and/or their metabolites may exert deleterious effects on the behavioral repertoire of the developing rat pup.     

Use of Oospore Formulations of Pythium oligandrum for Biological Control of Pythium Damping-off in Cress

Oospore preparations of Pythium oligandrum produced by liquid and solid-substrate fermentations were evaluated for biocontrol activity against Pythium damping-off in cress in artificially infested sand and naturally infested soil. Oospore biomass preparations from liquid fermentation of six isolates of P. oligandrum were equally effective in reducing damping-off in sand when tested as seed-coatings, whereas this type of preparation of a single isolate formulated as a kaolin dust, on Perlite and as alginate pellets incorporated into sand gave little or no control. None of the formulations containing oospores produced by solid-substrate fermentation incorporated into sand had any effect. In soil, a formulation containing oospores produced in a barley-Perlite solid-substrate fermentation and all oospore-biomass formulations which were prepared increased seedling survival, but none of these were as effective as a propamocarb HCl drench.     

Reduced cytotoxicity of polyhexamethylene biguanide hydrochloride (PHMB) by egg phosphatidylcholine while maintaining antimicrobial efficacy

Liposomes or oil-in-water emulsions containing egg yolk phosphatidylcholine (EPC) were combined with aqueous polyhexamethylene biguanide hydrochloride (PHMB). The bactericidal activity of these preparations against Pseudomonas aeruginosa and Staphylococcus aureus as well as their cytotoxicity on cultured murine fibroblasts (L929 cells) was then assayed for either 30 min or 60 min in the presence of cell culture medium containing 10% fetal bovine serum as surrogate for wound fluid. We used two assay designs: in the first bactericidal activity and cytotoxicity were determined in separate experiments; in the second both were determined in one experiment. Combining PHMB and EPC containing o/w emulsions or liposomes protects mammalian cells without neutralizing the antiseptic effect. From all tested combinations the o/w emulsions containing 0.05% PHMB proved to be superior in this respect to the aqueous preparation.     

The Little Miss Muffet Effect: Quantifying the Effect of Predation Risk on Foraging Patch Choice by Houseflies (<Emphasis Type="Italic">Musca domestica</Emphasis>)

The ability of the ideal free distribution (IFD) to predict patch choice of female houseflies (Musca domestica) was determined by examining their distribution between two patches containing unequal amounts of food. The effect of predation risk was then quantified in energetic terms by examining fly distribution between patches of equal food, with one containing spiders. Results were used to predict how much extra food must be added to the risky patch to offset the risk of predation. Flies were found to conform fairly closely to the IFD. Predation risk had a major effect on their distribution, with fewer flies feeding in the presence of predators as risk increased. Addition of extra food to the risky patch was successful in offsetting the risk of predation. These results suggest that the effect of risk on housefly foraging behavior can be quantified in energy terms, providing a common currency for predicting the effects of resources and predation risk on habitat use.     

Tracking dispersal across a patchy landscape reveals a dynamic interaction between genotype and habitat structure

Theoretical and empirical studies often show that within populations, individuals vary in their propensity to disperse. We aspired to understand how this behavioural variation is impacted by the distribution and pattern of food patches across a landscape. In a series of experiments we examined how inter-patch distance and the distribution of food patches influenced dispersal in wild-type strains of Drosophila melanogaster with natural allelic variants of the foraging (for) gene known to influence dispersal in this species. The ‘rover' strain was homozygous for the for^R allele (more dispersive) whereas the ‘sitter' strain was homozygous for for^s (less dispersive). We also assessed an outbred population of flies with an unknown dispersal propensity. Dispersal was assayed in a multi-patch lab arena (25 cells, 5 × 5 array). In the inter-patch distance trials, landscapes of two different sizes (small versus large) were used, both with food in all 25 cells. Dispersal was reduced in the large landscape relative to the small landscape for all three fly strains. Sitter dispersal was lowest relative to both rovers and the outbred flies, whose dispersal tendencies were similar. In the patch distribution trials, flies were assayed in landscapes with varying distribution and number of cells containing food. Dispersal generally increased as the number of patches with food increased, however, rovers and sitters adopted similar dispersal strategies when food was fixed and limited. Conversely, their strategies differed when the total amount of food increased with the number of patches. We find that both the inter-patch distance and distribution can influence dispersal. However, the effect of inter-patch distance and distribution on dispersals depends on genotype × environment interaction. Our findings highlight the importance of considering G × E when assessing how dispersal strategies and landscape dynamics influence the distribution of animal communities.     

Relationship between mycobiota in wall-to-wall carpet dust and age of carpet

The objective of this study was to evaluate thefungal concentrations within carpets of the same typeand manufacture during their first 2 years of life.The carpets tested came from several different branchoffices of a bank.A total of 60 dust samples from 20 carpets (3samples per carpet) was analysed. The age of thecarpets varied from 50 to 666 days. Analysis of therelationship between fungal concentration and time wasmade by the Pearson test.Fungal concentrations were very different withina same carpet. Moreover, species distribution was alsoheterogeneous; thus the fungi in 1 m² carpet didnot reflect mycobiota of the whole carpet. Very localfungal contaminations (>10 CFU/mg/dust) were builtup in a relatively short time (138 days). Thehighest concentrations (maximum: 200 CFU/mg dust) weremainly due to species of coelomycetes (mitosporicfungi forming conidia in closed bodies) and to variousyeasts. Comparisons of the 20 carpets sampled did notshow significant differences; the fungal level did notincrease with time (P > 0.05). A decrease waseven noticed. The age of carpets had no significanteffect either on the number of CFU/mg dust of the mainfungal taxa (P > 0.10).It was concluded that these carpets, which wereregularly cleaned, in this particular environment, donot favour important fungal growth. Moreover, sincethe species responsible for the highest contaminationobserved produce conidia or cells not easilytransported through the air, their role in respiratoryallergy would be relatively limited.     

Food interactions with once-a-day theophylline preparations: a review

At present, theophylline is used predominantly as sustained-release dosage forms. Since the mid-seventies many such products have been introduced and have found huge application for use with a dosage interval of 12 hr ('twice-a-day' preparations). Since 1983 theophylline has also been available as preparations that can be given with an interval of 24 hr ('once-a-day' preparations). The release of theophylline from sustained-release dosage forms can be influenced (either increased or decreased) by concomitant intake of food. Obviously, ultra-slow-releasing products are most vulnerable to food effects. With some preparations the composition of the meal, especially its fat content, determines the degree of the food effect. The effect of meal timing and content on once-a-day theophylline preparations must be known since rather large doses are ingested all at a single time. If food can alter the release of theophylline in an unexpected manner from ultra-slow preparations, drug effectiveness may be impaired if release is inhibited or toxicity might result if sudden release of drug occurs. Herein, information about food interaction with once-a-day theophylline preparations is reviewed as this topic is important both for clinicians as well as those concerned with chronopharmacologic investigations of such medications.     

Effectiveness of vacuum cleaning and wet cleaning in reducing house-dust mites,fungi and mite allergen in a cotton carpet: A case study

In order to evaluate the effect of continuous, thorough vacuuming on house dust organisms and mite allergen, a cotton carpet was vacuumed every other day, six times in total. Seven weeks later, the carpet was cleaned by means of spray extraction. Samples were taken before and after this wet cleaning.In total 1150 g of dust was collected, containing approximately 174 000 arthropods (dead and alive) and 9000×10⁶ fungal spores. In the course of the experiment, the amount of dust collected at each vacuuming decreased. The number of extracted house dust mites did not decrease significantly, but that of the predator miteCheyletus did. The number of extracted fungal spores showed a significant decrease (from 142 to 16×10⁶ spores/m² per minute vacuuming), as did the extracted mite allergen per m². After 7 weeks the number of mite eggs and complete house dust mites had increased enormously. After cleaning by spray extraction another increase in the number of complete mites and mite eggs was found, while the amount of mite allergen was diminished.The population growth of the house dust mite between the 6th and the 7th vacuuming is probably due to the decrease of their most important predator,Cheyletus. After the wet cleaning a number of extra eggs hatched, probably due to the high humidity in the carpet. The procedures used in this study to combat house dust mites may have an adverse effect in the long run.     

Multimethod assessment of commercial nisin preparations

Nisin is a GRAS preservative effective against several Gram-positive organisms including Listeria monocytogenes. Commercial preparations are usually fermentation products containing 2.5% pure nisin along with insoluble material which, in this study, was found to influence the quantification and activity of nisin under different conditions. Commercially available samples of nisin were tested for efficacy using various methods, such as well diffusion, time to turbidity, and GUS (where a reporter compound is induced in response to nisin). SDS-PAGE detected a single peptide band, corresponding with the molecular weight of nisin. Protein quantified using the Bradford method indicated that the carrier of some samples was proteinaceous. Though the activity of commercially available nisin preparations is indicated on the label, end users should determine the effect of changing their source of nisin. Received 13 February 2002/ Accepted in revised form 26 July 2002     

Pre-ingestive and post-ingestive effects of soya bean extracts and rutin on Trichoplusia ni growth

Total ethanolic crude extracts from soya bean (Glycine max L. Merrill) PI 227687 and `Davis', three purified fractions (A, B and C) from PI 227687, and pure rutin were tested for their effect on the growth of Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae) larvae, from egg hatching to pupation. Analysis of covariance (ANCOVA), followed by bicoordinate utilisation plots, was used to remove the effect of feeding time from consumption and weight of pupae and to separate pre- ingestive and post- ingestive effects of different diets on T. ni growth. Survival, pupal weight, and feeding time of T. ni were all negatively affected by PI 227687 total extracts. Pupal weight and consumption remained affected by diet, after removing the effect of feeding time by ANCOVA. Larvae fed on the `Davis' extract diet grew larger and consumed more rapidly a larger amount of food than those fed on PI 227687 and control diets. T. ni pupal weight was strongly influenced by consumption. In general, those insects that consumed more food were heavier but larvae fed on diet containing PI 227687 extract grew less than the others, irrespective of the amount of ingested and digested food. The feeding time was adversely affected by PI 227687 fraction A, composed of two flavonol glycosides (rutin and quercetin 3-O-glucosylgalactoside) and of an isoflavone glycoside (genistin). Survival and pupal weight were not affected, although the consumption and assimilation of ingested food was lower when larvae were fed on fractions A and C. The toxicity of the higher rutin concentration (2%) was similar to that observed when the insects were fed on unfractioned PI 227687, except that effects on food consumption were not observed. Results indicated that the feeding deterrence of PI 227687 must be caused by other compounds from fractions A and C. Moreover, rutin, acting as an antibiotic, appears to account for the adverse effects of PI 227687 on the physiology of T. ni.     

Trophic interactions involving mysid shrimps (Mysidacea) in the near-bottom habitat in the Baltic Sea

In a six month mesocosm tank experiment, hypotheses were tested concerning the role of benthopelagic mysid shrimps (Mysidacea) in the near-bottom food web of the Bothnian Sea, in the northern Baltic Sea. The first hypothesis tested was that the mysids interact, through predation, with benthic deposit-feeding Monoporeia affinis amphipods. A second hypothesis tested was that the sediment type is important for the overwintering success of the mysids. Changes in abundance and mass were recorded for M. affinis and mysids when separate and when coexisting, in two sediment types differing in organic content (food level); soft muddy clay (rich) and fine sand (poor). Despite the fact that newborn M. affinis offspring, a plausible target for predation by mysids, were present in substantial numbers in the tanks, no consistent evidence for any interaction between these taxa was found. The biomass of mysids was slightly higher in the muddy clay than in the sand tanks, and the mechanism behind this substrate effect is discussed. A third hypothesis, that the mysids interact with near-bottom zooplankton, was investigated. The tanks were continually supplied with in situ near-bottom sea-water containing a semi-natural assemblage of near-bottom plankton. As a result of mysid predation, tanks with mysids had lower abundance and biomass of cyclopoid copepods than tanks without mysids. Thus, the major interaction found was predation on near-bottom zooplankton by mysids and it is suggested that this interaction could potentially be an important food link, especially during periods with low food availability in the pelagic system.     

The control of Monomorium pharaonis (Hymenoptera: Formicidae) with Bacillus thuringiensis

In this study, the effect of different preparations made from Bacillus thuringiensis var. thuringiensis (strains: CCEB 555 and CCEB 058) on ants, Monomorium pharaonis, under laboratory conditions is reported. The different preparations tested consisted of (1) a liquid culture of the strain B. thuringiensis CCEB 555 (containing spores and exotoxin), (2) the supernatant of the culture broth of strain CCEB 555 (containing exotoxin), and (3) the biological preparation “Bathurin” prepared from the strain B. thuringiensis CCEB 058 (containing spores and inclusions, without exotoxin). The preparations were used either pure or in alternation with borax, i.e., 1 wk borax, 3 wk the respective preparation for several months. All preparations were found to be toxic to M. pharaonis and their effect was characterized by a slow extinction of the ant colony. Administration of “Bathurin” (1.3%) yielded a 100% mortality after 20 wk. Using a liquid culture of B. thuringiensis var. thuringiensis, 100% mortality was recorded after 21 wk, a period of time which did not differ from that obtained with the supernatant of the culture containing exotoxin. The alternation with borax was found to accelerate ant mortality by 9–10 wk after administration. In all experiments, the worker ants died first, the queen ants surviving them by 1–3 wk.In experiments employing worker ants only, a 100 and 98% mortality, respectively, occurred within 3 wk after administration of a liquid culture of B. thuringiensis and “Bathurin” supplemented with borax.     

Evaluation of two human plasma pools as candidate international standard preparations for syphilitic antibodies

A collaborative study was designed to asses two freeze-dried human plasma preparations containing anti-Treponema pallidum antibodies, 05/132 and 05/122, for their suitability as international reference reagents for syphilis serology. Both preparations are intended as replacements of the first international standard (IS) for syphilitic serum antibodies (HS). Samples were tested by eight laboratories using the T. pallidum passive particle agglutination assay (TPPA), the venereal disease research laboratory test (VDRL) and the rapid plasma reagin test (RPR). In addition a range of immunoassays was also used. The outcome of the collaborative study revealed that candidate standard 05/132 contains T. pallidum-specific IgG and IgM and is reactive in VDRL or RPR, and that 05/122 contains T. pallidum-specific IgG but is not reactive in either the VDRL or RPR test. Both 05/132 and 05/122 are reactive in the TPPA. On the basis of these results the Expert Committee on Biological Standardization of the World Health Organization designated 05/132 as the 1st IS for human syphilitic plasma IgG and IgM with a unitage of 3 IU per ampoule relative to HS and 05/122 as the 1st IS for human syphilitic plasma IgG with a unitage of 300 mIU per ampoule relative to 05/132.