Effect of food deprivation on response of the mite, Dermanyssus gallinae, to heat

Freshly blood-fed adult females of the chicken mite Dermanyssus gallinae DeGeer (Acari: Dermanysidae) were food-deprived during 1, 2-3, 8-10, 14-16 and 22-23 days. These mites were tested in groups of 10 to determine their sensitivity to a heat cue delivered for a 60 s period under controlled laboratory conditions (24 degrees C, simulated dark conditions of 2 lx). Immobile mites were videotaped and start of activation (for individual mites) and percentage of mites activated in the 60 s period were related to temperature changes. Mites were activated with temperature gradients as low as 0.003-0.005 degrees C/s. Mites that had fed the previous day had a significantly lower activation (20%) than other groups. Activation was highest at 2-3 days (60%) and 8-10 days (75%) post-feeding. Activation declined significantly to 45% at 14-16 days and to 30% at 22-23 days post-feeding. Activation patterns probably reflect mite physiological condition and declining responsiveness to heat cues concomitant with starvation and higher risks associated with activation in the prolonged absence of a host.     

Ambulatory dispersal of the susceptible and propargite-resistant strains of Tetranychus urticae and its influence on pesticide resistance dynamics

The distribution of resistant individuals is determined by the amount of movement between populations. The differential rate of dispersal of a susceptible and a pesticide-resistant strain could influence the resistance dynamics under field conditions. The dispersal rate and dispersal efficiency of the susceptible and propargite-resistant strains of Tetranychus urticae were measured in separate-release and mixed-release experiments. The diffusion coefficient (D) of both strains did not differ significantly (P > 0.344) and an estimate of the asymptotic rate of advance (2 √ rD) (for one generation) was estimated at 0.1047 and 0.0930 cm per degree day for the susceptible and propargite-resistant strains, respectively. The dispersal efficiency of the two strains differed significantly (P < 0.005) as more susceptible mites than propargite-resistant mites crossed into specified zones more quickly after 290 and 366 degree days. Significantly (P < 0.05) higher number of susceptible adults, immatures and eggs were found in the outer most zone of an arena as compared to that of the propargite-resistant mites. The bioassay of the two strains showed a similar pattern of the spread of the adult females across the specified zones in the mixed-release experiment. The relatively lower dispersive tendency of the propargite-resistant T. urticae and the smaller proportion of adult females exhibiting that behaviour increase the chances of developing resistant ‘hotspots’ in field specially after an acaricide application.     

A DIPPING APPARATUS FOR ESTIMATING THE TOXICITY OF INSECTICIDES IN LIQUID MEDIA

An apparatus and a technique are described for the study of the effect of liquid insecticidal preparations by dipping insects in the toxic material. The method is applicable to quick-settling suspensions and quick-creaming emulsions as well as to solutions. Dipping is performed at constant temperature with end-over-end shaking; and the technique has the advantage over the other dipping methods that have been described in that handling of individual insects whilst wet is eliminated.     

The N-terminal 17% of apoB binds tightly and irreversibly to emulsions modeling nascent very low density lipoproteins

The N-terminal 17% of apolipoprotein B (apoB-17) readily associates with dimyristoylphosphatidylcholine (DMPC) multilamellar vesicles (MLV) to form large (240-A diameter) discoidal particles. Because apoB is normally secreted with triacylglycerol (TAG)-rich lipoproteins, we studied the binding of apoB-17 to triolein-rich emulsions modeling nascent TAG-rich very low density-like lipoproteins. Emulsions with the following composition (by weight) were prepared: 85--89% triolein, 1.1--1.4% cholesterol, and 10--14% phosphatidylcholines (PC) including either egg yolk (EY)-, dimyristoyl (DM)-, or dipalmitoyl (DP)-PC representing (at 25 degrees C), respectively, a fluid surface, a surface at transition, and a mainly solid surface. The respective sizes were 1,260 +/- 500, 1,070 +/- 450, and 830 +/- 300 A mean diameter. The emulsions were incubated with conditioned medium containing apoB-17, and then reisolated by ultracentrifugation. Analysis of the emulsion-bound proteins by gel electrophoresis showed that all three emulsions bound primarily apoB-17. The DPPC emulsions bound more apoB-17 than EYPC or DMPC emulsions. Immunoaffinity-purified apoB-17 exhibited saturable, high affinity binding to EYPC and DPPC emulsions. The respective K(d) values were 32 +/- 23 and 85 +/- 27 nM and capacities (N) were 10 and 58 molecules of apoB-17 per particle. When apoB-17 bound to emulsions was incubated with DMPC MLV at 26 degrees C for 18 h, it remained bound to the emulsions, indicating that once bound to these emulsions it is unable to exchange off and solubilize DMPC into discs. In contrast, apoE-3 bound to emulsions dissociated from the emulsions when incubated with DMPC MLV and formed discs.Thus, apoB-17 binds strongly and irreversibly to emulsions modeling nascent lipoproteins. It therefore may play an important role in the stabilization of nascent VLDL and chylomicrons.- Herscovitz, H., A. Derksen, M. T. Walsh, C. J. McKnight, D. L. Gantz, M. Hadzopoulou-Cladaras, V. Zannis, C. Curry, and D. M. Small. The N-terminal 17% of apoB binds tightly and irreversibly to emulsions modeling nascent very low density lipoproteins. J. Lipid Res. 2001. 42: 51;-59.     

Does time spent on adult bees affect reproductive success of Varroa mites?

Reproduction ofVarroa jacobsoni Oudemans (Acari: Varroidae) and the number ofVarroa mites that were found dead on the bottom board of the hive, were studied in relation to the period the mites spent on adult honey bees,Apis mellifera L. (Hymenoptera: Apidae), prior to invasion into brood cells. The maximum period on adult bees was 23 days. To introduce mites, combs with emerging worker brood, heavily infested with mites, were placed into a colony and removed the next day. At the beginning of the first day following emergence from brood cells, 18% of the mites introduced into the colony was found on the bottom of the hive. Part of these mites may already have died inside the capped brood cells, and then fallen down after cleaning of cells by the bees. At the second and third day following emergence, respectively 4% and 2% of the mites on adult bees at the previous day was recovered on the bottom, whereas from the fourth day on only 0.6% of the mites on adult bees was recovered on the bottom per day. After invasion into brood cells, 8–12% of the mites did not produce any offspring. Of the mites that did reproduce, the total number of offspring was 4.0–4.4 per mite during one reproductive cycle, part of which may reach maturity resulting in 1.2–1.3 viable daughters, and 8–10% of the mites produced only male offspring. Reproduction was independent of the period the mites had spent on adult bees prior to invasion into brood cells.     

Photosynthetic oxygen evolution and CO2 photoassimilation by cyanobacteria that form water-bloom spots in a sulfur spring with a high sulfide content

Cyanobacteria belonging mainly to the genera Anabaena and Oscillatoria were isolated from water-bloom spots of a sulfur spring in Staraya Matsesta. Their suspensions evolved O2 at a rate of 6--8 nM/min per 1 mg of dry cell weight at an intensity of solar radiation being 60--75 mV/cm2 per 1 sec. The cells were also capable of CO2 photoassimilation in the presence of solfide at a rate of 10(-4) mg C per mg per hour. DCMU at a concentration of 10(-5) M completely inhibited O2 evolution and inhibited CO2 fixation by 80%. Oxygen assimilation in dark by the suspensions did not depend on the addition of cyanide and was caused apparently by nonenzymatic reduction of O2 with sulfide dissolved in the spring water. Oxygen assimilation by the suspensions in light in the presence of DCMU was by 20--30% greater than in dark. Therefore, the cells of cyanobacteria are characterized by photorespiration at the level of photosystem I. Presumably, sulfide at a concentration of 9 mM cannot significantly inhibit the photosynthetic processes in cyanobacteria producing water-bloom spots in the sulfur spring.     

Factors influencing the stability of acid-precipitated polyvalent Bordetella pertussis bulk suspensions.

According to the statistical analysis of the potency values of acid precipitated polyvalent bulk suspensions of Bordetella pertussis, the potency of suspensions decreased below 8 IU/30 IOU during storage for 5 to 9.8 years. The average annual decrease over a 13-year period was 2.03 IU/30 IOU. The periodicity in the decrease of potency values was assumed to be connected with changes in the quality of the casein hydrolysate ingredient of the medium. Periodic functions employed to approach potency values with limits of 1 SD falling within the range of 64--156% indicated that the potency decreased below 8 IU/30 IOU after 9 years.     

Diseases of Mites

An overview is given of studies on diseases of mites. Knowledge of diseases of mites is still fragmentary but in recent years more attention has been paid to acaropathogens, often because of the economic importance of many mite species. Most research on mite pathogens concerns studies on fungal pathogens of eriophyoids and spider mites especially. These fungi often play an important role in the regulation of natural mite populations and are sometimes able to decimate populations of phytophagous mites. Studies are being conducted to develop some of these fungi as commercial acaricides.Virus diseases are known in only a few mites, namely, the citrus red mite and the European red mite. In both cases, non-occluded viruses play an important role in the regulation of mite populations in citrus and peach orchards, respectively, but application of these viruses as biological control agents does not seem feasible. A putative iridovirus has been observed in association with Varroa mites in moribund honeybee colonies. The virus is probably also pathogenic for honeybees and may be transmitted to them through this parasitic mite.Few bacteria have been reported as pathogens of the Acari but in recent years research has been concentrated on intracellular organisms such as Wolbachia that may cause distorted sex ratios in offspring and incompatibility between populations. The role of these organisms in natural populations of spider mites is in particular discussed. The effect of Bacillus thuringiensis on mites is also treated in this review, although its mode of action in arthropods is mainly due to the presence of toxins and it is, therefore, not considered to be a pathogen in the true sense of the word.Microsporidia have been observed in several mite species especially in oribatid mites, although other groups of mites may also be affected. In recent years, Microsporidia infections in Phytoseiidae have received considerable attention, as they are often found in mass rearings of beneficial arthropods. They affect the efficacy of these predators as biological control agent of insect and mite pests. Microsporidia do not seem to have potential for biological control of mites.     

Linkage mapping of autosomal dominant retinitis pigmentosa (RP1) to the pericentric region of human chromosome 8.

Linkage mapping in a large, seven-generation family with type 2 autosomal dominant retinitis pigmentosa (ADRP) demonstrates linkage between the disease locus (RP1) and DNA markers on the short arm of human chromosome 8. Five markers were most informative for mapping ADRP in this family using two-point linkage analysis. The markers, their maximum lod scores, and recombination distances were ANK1 (ankyrin)--2.0 at 16%; D8S5 (TL11)--5.3 at 17%; D8S87 [a(CA)n repeat]--7.2 at 14%; LPL (lipoprotein lipase)--1.5 at 26%; and PLAT (plasminigen activator, tissue)--10.6 at 7%. Multipoint linkage analysis, using a simplified pedigree structure for the family (which contains 192 individuals and two inbreeding loops), gave a maximum lod score of 12.2 for RP1 at a distance 8.1 cM proximal to PLAT in the pericentric region of the chromosome. Based on linkage data from the CEPH (Paris) reference families and physical mapping information from a somatic cell hybrid panel of chromosome 8 fragments, the most likely order for four of these five loci and the diseases locus is 8pter-LPL-D8S5-D8S87-PLAT-RP1. (The precise location of ANK1 relative to PLAT in this map is not established). The most likely location for RP1 is in the pericentric region of the chromosome. Recently, several families with ADRP with tight linkage to the rhodopsin locus at 3q21-q24 were reported and a number of specific rhodopsin mutations in families with ADRP have since been reported. In other ADRP families, including the one in this study, linkage to rhodopsin has been excluded. Thus mutations at two different loci, at least, have been shown to cause ADRP. There is no remarkable clinical disparity in the expression of disease caused by these different loci.     

Water mites as potential long-term bioindicators in formerly drained and rewetted raised bogs

Many environmental studies of restored peatlands focus on biogeochemical cycles, productivity and decomposition. However, changes in the composition and structure of invertebrate assemblages in restored bogs have received little attention. In the present study we describe effects of rewetting on the water mite faunas (Acari: Hydrachnidia) of four raised bogs located in northwestern Germany. All examined peatlands had been drained in the past, and two of them had been subjected to peat extraction. The examined sites had been rewetted 2, 12, 14 and 25 years prior to our surveys, and currently represent different stages of plant succession. With increasing age after rewetting, the vegetation developed more complex structure as defined by Sphagnum status, and water mite fauna became somewhat similar to the fauna in an undisturbed raised reference bog. Water mites were found almost exclusively in bogs 25 years after wetting, and in these bogs they occurred in sites with more complex vegetation structure. Because water mites have high demands on abiotic and biotic factors due to their complex life cycle (i.e., the larvae are parasites, and the nymphs and adults are predators), we can infer that their mere presence irrespective of species abundance and richness reflects positive effects of the rewetting measures conducted in peat bogs.     

Population dynamics of Aceria guerreronis Keifer (Acari: Eriophyidae) and associated predators on coconut fruits in Northeastern Brazil

Aceria guerreronis Keifer can cause severe damage to coconuts in several countries around the world. Rare studies have been conducted to determine the predatory mites associated with A. guerreronis in Brazil. The study evaluated the prevalence of A. guerreronis and associated predators on the bracts and on the surface of the fruits underneath the bracts, for 12 months, on coconut palms grown along the coast of the States of Alagoas, Paraíba and Pernambuco, Northeastern Brazil. Mites of 10 families were found, but by far the most abundant species was A. guerreronis, corresponding to 99.5% of the mites collected. The prevailing species amongst the predators were the Phytoseiidae mites Neoseiulus baraki (Athias-Henriot) and Neoseiulus paspalivorus (De Leon). These are flat mites that have short limbs, characteristics that allow them to invade the main habitat occupied by A. guerreronis. Other predators were found, but in low numbers, due mainly to their difficulty in reaching the fruit areas most inhabited by A. guerreronis. However, these mites could prey on that pest when it leaves its preferred habitat to disperse. No significant correlations were observed between the levels of abiotic factors and the population levels of A. guerreronis or of the phytoseiids associated with it. This probably occurred due to the simultaneous and conflicting effects of those factors on the mites in the field, or to significant differences between the climatic factors measured in the environment and those prevailing in the habitat occupied by A. guerreronis.     

Storage mites

The interest in allergy to storage mites has increased over the past few years. Storage mites feed on a variety of substances and they can be found in many different products such as grain, flour, hay and straw, but also in house dust samples. The more common genera areLepidoglyphus, Tyrophagus, Glycyphagus, Acarus andBlomia. Several species of storage mites have been shown to cause IgE-mediated sensitization among rural workers, who to a varying extent develop asthma, rhinitis or conjunctivitis when exposed to barn dust. However, a number of studies, have reported on sensitization to storage mites also among urban people, indicating that sensitization is not restricted to individuals with occupational exposure. Regarding the allergenic relationship between storage mites and house dust mites, there appears to be a limited allergenic cross-reactivity between the two species. However, both species also possess their own unique allergens. Further research on identification and characterization of storage mite allergens and their cross-reactivity is required to understand the complexity of epitopes and allergens.     

Molecular cloning and the allergenic characterization of tropomyosin from Tyrophagus putrescentiae

Storage mites have been recognized as a cause of asthma and rhinitis. Studies from several countries have shown that the IgE-mediated allergy to storage mites is of considerable importance, especially in rural populations. This study aimed to identify and characterize new allergens from Tyrophagus putrescentiae. A partial cDNA sequence encoding tropomyosin was isolated from the cDNA library by immunoscreening using anti-mouse IgG1 sera raised against T. putrescentiae whole body extract. The deduced amino acid sequence shares 64-94% identity with previously known allergenic tropomyosins. Its recombinant protein was produced by using a pET 28b expression system and purified by affinity chromatography using Ni-NTA agarose. The IgE reactivities of tropomyosins from T. putrescentiae and Dermatophagoides farinae were compared by enzyme linked immunosorbent assay (ELISA). Recombinant Tyr p 10 showed 12.5% (5/40) IgE-binding reactivity, whereas recombinant Der f 10 showed 25% (10/40) IgE-binding reactivity against the same sera from storage mite-sensitized and house dust mite-sensitized subjects. Both recombinant Tyr p 10 and Der f 10 showed little inhibition of IgE binding to T. putrescentiae crude extract by ELISA. Tropomyosin seems to contribute only a small portion of the cross-reactivity with house dust mites.     

THE FLOCCULATION OF BACTERIA BY PROTEINS

1. The effect of adding pure proteins to bacterial suspensions at different H ion concentrations has been studied. 2. The zone of flocculation of protein-treated bacteria bears a significant relationship to the isoelectric point of the protein used. With the higher concentration of protein, agglutination occurs at or near the isoelectric point of that protein; at reactions acid to this, the bacteria carry a positive charge and are not agglutinated. With diminishing concentration of protein, the zone of flocculation shifts toward and goes beyond that characteristic of the untreated bacteria. This occurs both in the presence and absence of salts. 3. A diversity of other suspensions, such as sols of gold, mastic, cellulose nitrate, cellulose acetate, Fe(OH)₃, oil emulsions, and erythrocytes, have been found by ourselves and others to exhibit a similar altered stability when treated with proteins in the same way.     

Clinical significance of dust mite allergens

Dust mites are an important cause of allergic diseases worldwide. The traces of Dermatophagoides farinae and Dermatophagoides pteronyssinus can be found all over the world, while Blomia tropicalis are more common allergenic mites in tropical areas. A variety of allergenic components in dust mites have been found, apart from the different positive rates of IgE reactions in dust mite allergic patients, their biological characteristics, effects on the innate immune system, and especially their distribution characteristics in patients are different. Studying the relationship between dust mite allergens and clinical significance will help for diagnosis of patients and formulation of corresponding Allergen Specific Immunotherapy.

     

Diminution of phagocytosed perfluorocarbon emulsions using perfluoroalkylated polyethylene glycol surfactant

Perfluorocarbon emulsions have been considered as potential blood substitutes for years due to their high capacity of dissolving respiratory oxygen and carbon dioxide. However, they have been reported to associate with side effects (e.g., flu-like syndrome) after being injected into animal's bloodstream. The cause of these side effects is related to the phagocytosis of perfluorocarbon emulsions by cells (e.g., macrophages). Inspired by the approach of using polyethylene glycol (PEG) to camouflage liposomes, we synthesized a perfluoroalkylated PEG (R(F)-PEG) surfactant to provide steric hindrance for decreasing phagocytosis of perfluorocarbon emulsions. The R(F)-PEG surfactant along with Pluronic F-68 and egg yolk phospholipid mediated perfluorocarbon emulsions were incubated individually with J774A.1 macrophages to examine the degree of phagocytosis. 19F NMR studies were used to quantitatively determine the amount of perfluorocarbon emulsions phagocytosed by macrophages. Results showed that the degree of phagocytosis was diminished to a large extent for perfluorocarbon microparticles emulsified by the R(F)-PEG surfactant.     

Experimental method for isolating and identifying dust mites from sputum in pulmonary acariasis

The aim of this study was to pilot a simpler and more effective method for identifying dust mites in sputum. Dust mites and their allergens have been implicated in respiratory diseases, including pulmonary acariasis, and several studies have identified mites in sputum. Further research is dependent on the development of a faster and simpler diagnostic test. We have demonstrated that dust mites artificially introduced into sputa, could be identified after the sputa were liquefied with bleach, when the liquid sample was observed under the microscope. Liquefaction times for serous, mucous, purulent and hemoptoic sputa varied from 10 to 30 min (mean 17.5). The test had a sensitivity of 80% (95% CI 68.2–88.2%) as 46/60 mites were identified. This procedure can be performed quickly at room temperature, is simple, inexpensive, repeatable, and less labourious than previous methods.     

Parasitic mites as part-time bodyguards of a host wasp

Some bees and wasps that host mites have peculiar pocket-like structures called acarinaria. These have long been considered as morphological adaptations to securely transfer beneficial mites into nests, and thus are thought to be the product of a mutualistic relationship. However, there has been little compelling evidence to support this hypothesis. We demonstrated that the parasitic mite Ensliniella parasitica, which uses acarinaria, increases the reproductive success of its host wasp Allodynerus delphinalis by protecting it from parasitoid wasps. Every time the parasitoid Melittobia acasta accessed a prepupal or pupal wasp host cell, adult mites attacked it, continuously clinging to it and possibly piercing the intersegmental membrane of the parasitoid with their chelicerae. Subsequent mortality of the parasitoid depended on the number of attacking mites: an average of six mites led to a 70% chance of mortality, and 10 mites led to a 100% chance of mortality. In this way, parent mites protect the food source (juvenile wasps) for themselves and ultimately for their offspring. We propose that wasps evolved acarinaria to maintain this protective guarding behaviour.     

Potential negative effects on biological control by Sancassania polyphyllae (Acari: Acaridae) on an entomopathogenic nematode species

Sancassania polyphyllae (Acari: Acaridae) is associated with larvae of the white grub, Polyphylla fullo (Coleoptera: Scarabaeidae), and will feed on the infective juveniles of entomopathogenic nematodes in the families Steinernematidae and Heterorhabditidae which are important biological control agents of soil insect pests. We conducted laboratory studies to determine the potential negative effects this mite species might have on biological control of soil insect pests. Our objectives in this study were to (1) determine the response of S. polyphyllae adult mites to a nematode-killed insects on agar, (2) evaluate the predation by mites on Steinernema feltiae infective juveniles from nematode-killed insects on agar and in soil, and (3) assess predation efficiency of the mite on the infective juveniles in the soil. On agar, we found (1) significantly more adult female mites near or on a nematode-killed Ceratitis capitata (Diptera: Tephritidae) larva than near or on the freeze-killed larva or a bamboo mimic suggesting that a chemical or an odor from the nematode-killed larva attracted the mites, and (2) 10 mites consumed 96% of infective juveniles that emerged from an insect cadaver. In soil with a nematode-killed insect, the average number of infective juveniles recovered was <30 when mites were present, whereas the average number of infective juveniles recovered was >375 when the mites were absent. When the infective juveniles alone were placed in different depths in relation to the mites in the soil column for 4 and 10 days, S. polyphyllae was not as efficient at finding the infective juveniles when they were separated from each other in the soil lending support to the idea that the mites were cueing in on the cadaver as a food resource. Our data suggest that emerging infective juveniles from an insect cadaver in the soil in the presence of S. polyphyllae can adversely affect biological control because of nematode consumption by the mites.     

Physicochemical characterization of a thermostable glycoprotein bioemulsifier from Solibacillus silvestris AM1

A novel estuarine bacterial strain, Solibacillus silvestris AM1, was found to produce an extracellular, multimeric glycoprotein bioemulsifier, termed AM1, with a MW of 200 kDa and containing 30 kDa monomeric subunits. The bioemulsifier contained 3.6% of the minor carbohydrate components galactose and ribose/xylose. LC/MS-MS of the 30 kDa subunit revealed its homology with a flagellin-like protein arranged in the form of fibers, as shown by transmission electron micrographs. This is the first report of a flagellin-like protein that exhibits bioemulsifier activity being produced from a member of the Solibacillus genus. Bioemulsifier AM1 has a high emulsification index of 62.5% with 10^?2 critical micellar dilution. It was found to be thermostable and active in the pH 5–9 and 0–5 M NaCl ranges. Moreover, AM1 formed stable emulsions with a broad range of solvents, including aliphatics, aromatic hydrocarbons and oils, performing better than the well-known bioemulsifier emulsan. Emulsions formed with trichlorobenzene and paraffin oil have a pseudoplastic non-Newtonian rheological property, as observed by particle size and shear stress analysis. AM1, an eco-friendly bioemulsifier, formed stable emulsions in varied physical conditions, and these attributes may prove to be advantageous in cosmetic, pharmaceutical and environmental applications.