Optimal efficacy of a fungicide preparation,natamycin, in the control of the house-dust mite,Dermatophagoides pteronyssinus

The efficacy of a fungicidal preparation, natamycin, for the effective control ofDermatophagoides pteronyssinus (Trouessart), was determined at different concentrations on mattress-dust microsites, including ticking. One treatment with the commercially available natamycin concentration (Tymasil) resulted in a 65% reduction of house-dust mite populations within 4 weeks of treatment. The acaricidal control could be proven despite the protective role of mattress fibres such as ticking. However, mite fecundity was much more affected after treatment with twice the commercial concentration, which then assured a long-term control. Concentrations below the commercially available one were not effective. In a maritime climate, six sequential treatments three times a year would be effective for an adequate long-term control because of the high growth of house-dust fungi and the close interaction between the mite and the mouldAspergillus penicilloides.     

Fluorometric enzyme-linked immunosorbent assay for the measurement of IgE antibody to mite Dermatophagoides farinae

We have developed a fluorometric enzyme-linked immunosorbent assay for measuring IgE antibody to Dermatophagoides farinae. Polystyrene microplates were coated with proteins extracted from the mites. The IgE antibody which attached to the solid-phase antigen was detected by anti-IgE antibody conjugated with beta-galactosidase. Four-methylumbelliferyl-beta-D-galactoside was used as the enzyme substrate and the fluorescence intensity of the reaction product was measured. The antibody levels determined by this method well correlated with those determined by the radioallergosorbent test (RAST). This method is simpler and less expensive to carry out than the RAST when dealing with a large number of serum specimens for seroepidemiological studies of asthma and nasal allergy.     

Kinetics of active and passive components of water exchange between the air and a mite, Dermatophagoides farinae

Female North American house dust mites were found to exchange water with the ambient air from two compartments. At humidities above the critical equilibrium activity (CEA), transpiration out of a single large compartment was observed using HTO as a tracer for water. Total sorption into this compartment was also observed by following changes in the specific radioactivity. The sorption data required that an active process or pump be present. The water in this pump is the second compartment above the CEA. Below the CEA the large compartment could be identified as a compartment characterized by a small transpiration rate constant. The pump below the CEA becomes a rapidly transpiring fast compartment. By separating the water pool into two compartments, it was possible to relate a_v to k and $\text{m}\text{?}{}_{\mathrm{<mtext>S</mtext>}}$. The major effect of a_v on k was related to its effect on the permeability of the cuticle. The influence of a_v on $\text{m}\text{?}{}_{\mathrm{<mtext>S</mtext>}}$ was different for active and passive sorption. Above the CEA the pump operated at full capacity and active $\text{m}\text{?}{}_{\mathrm{<mtext>S</mtext>}}$ was directly proportional to a_v. Passive sorption was influenced by a_v in two ways. The driving force for $\text{m}\text{?}{}_{\mathrm{<mtext>S</mtext>}}$ was further reduced below saturation by the effect of a_v on the permeability of the exchange surface.     

The antigenic and allergenic properties of an extract from the house dust mite Dermatophagoides farinae]

To evaluate the antigenic composition and allergenic activity of D. farinae extracts, the methods of rocket and cross immunoelectrophoresis, gel chromatography and the inhibition of the radioallergosorbent test have been used. The presence of 9-20 antigenic components has been established. The fractions of the extract with a molecular weight of 10-200 kD possessed the highest capacity of inhibiting the binding of specific IgE antibodies from the pool of sera from patients sensitized to D. farinae.     

Oxygen consumption in active and quiescent protonymphs of the American house-dust mite

Oxygen consumption in protonymphs of the American house-dust mite was measured by the Cartesian diver technique. Active protonymphs consumed 1.14 × 10^?2 μl/hr/mite under close to optimum temperature and humidity conditions for the species. This consumption is higher than that reported for fasting non-reproducing females. The protonymphs were active when confined in the diver and exhausted their energy reserves in less than 20 hr. Quiescent protonymphs consumed 4 × 10^?4 μl/hr/mite of oxygen, which is 28 times less than the consumption of active mites. The quiescence was not a static state, disturbed quiescent protonymphs had a six times higher oxygen consumption. This additional energy is thought to be spent in repair of injuries caused by collecting, e.g. secretion of wax on places where the layer has been removed.     

Cloning and expression of Der f 6, a serine protease allergen from the house dust mite, Dermatophagoides farinae.

House dust mite allergen is thought to be a major cause of asthma. Characterization of these allergen molecules is therefore an important step for the development of effective diagnostic and therapeutic agents against mite-associated allergic disorders. Here we report molecular cloning and expression of the group 6 (chymotrypsin-like) allergen from the house dust mite, Dermatophagoides farinae. Sequencing analysis indicates that cloned cDNA, designated Der f 6, encodes a 279 amino acid polypeptide which conserves a primary structure characteristic for chymotrypsin-like serine proteases found in mammals. Recombinant Der f 6 expressed in Escherichia coli bound IgE in a pool made of 20 sera, and induced histamine release from patients' peripheral blood cells.     

Effects of insect growth regulators on the tobacco cutworm, Spodoptera litura: Rectal prolapse

Prolapse of the rectum was observed when ZR-515 (isopropyl 11-methoxy-3,7,11-trimethyl-2,4-dodecadienoate) was applied to the 6th instar larva of the tobacco cutworm, Spodoptera litura. It was induced by an administration of ZR-515 in the middle of the 6th instar larval stage, and either by a dose higher than required for the induction of larval-pupal intermediates or by a dose lower than the dose that produces extra larvae. Larvae with a rectal prolapse appeared only on the 3rd day after treatment. These larvae did not survive for more than 1 to 2 days because the prolapsed rectum ruptured, leading to haemorrhage.Rectal prolapse was also induced by other two IGRs, ZR-512 (ethyl 3,7,11-trimethyl-2,4-dodecadienoate) and ZR-619 (ethyl 11-methoxy-3,7,11-trimethyl-2,4-dodecadienethiolate).     

Effects of insect growth regulators on the hairy rose beetle, Tropinota squalida (Col., Scarabeidae)

Abstract:  Saponin extract from alfalfa roots, azadirachtin from the neem seed oil, synthetic ecdysteroid agonist RH-2485, and the juvenoid hydroprene disturb the development and reproduction of Tropinota squalida . Feeding beetles on diets containing 750 p.p.m. saponins, 7.5 p.p.m. RH-2485, and 1.13 p.p.m. azadirachtin reduces their progeny from 51 second instar larvae per female to 24, 15, and 15 larvae, respectively. When the larvae of untreated adults are fed for 1 week on dung with 75 p.p.m. saponins, 50 p.p.m. RH-2485, and 0.45 p.p.m. azadirachtin, the rate of adult emergence drops from 80% (controls) to 20, 0 and 13%, respectively. No adults emerge when the treatment is continued through the second and third larval instars. Two topical treatments of larvae with 0.2  μ g hydroprene decrease the rate of adult emergence from 90 to 11%, and treatments with 2  μ g prevent adult development in all insects. The observed effects warrant testing of azadirachtin, RH-2485, and hydroprene in the field. Several types of their application for the control of T. squalida are suggested.     

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.     

Sublethal toxicity of two insect growth regulators on Habrobracon hebetor (Hymenoptera: Braconidae) under laboratory conditions

The sublethal effects of lufenuron and lufenuron?+?fenoxycarb were tested on the adult stage of the parasitoid wasp Habrobracon hebetor under laboratory conditions. Bioassay tests were carried out in the incubator at a temperature of 26?±?1?°C, relative humidity of 65?±?10% and photoperiod of 16:8 (L:D). Exposure cages were used for the experiments. Tests were conducted in three replications. Young female wasps were exposed to the residues of the pesticides’ sublethal concentrations (LC₂₅) after 1, 24, 48 and 72 h, and then their mortalities were recorded. Results showed that both insecticide treatments had significant differences compared to the control, but not between themselves (df?=?1, F?=?29.21, α?<?.0001). It was also revealed that the time between insecticides application and H. hebetor release would significantly affect the survival of searching parasitoids (df?=?3, F?=?237.01, α?<?.0001). In this regard, the releasing programme should be postponed for at least 24 h after using these insect growth regulators.     

Control of mushroom sciarid fly Lycoriella ingenua populations with insect growth regulators applied by soil drench

Mushroom sciarid fly Lycoriella ingenua (Dufour, 1839) comb. nov., is one of the most common fly pests affecting the cultivation of Agaricus bisporus (Lange) Imbach in Turkey. In this study, eight insect growth regulators (IGRs)--diflubenzuron, flufenoxuron, lufenuron, methoprene, novaluron, pyriproxyfen, teflubenzuron, and triflumuron-were tested for their potential to control L. ingenua populations in two successive growing periods. Treatments were targeted at larvae as soil drenches; treatment efficacy was evaluated by assessing adult emergence and larval damage. These products were compared with a control treated with water (negative control) and a conventional chemical insecticide (chlorpyrifos ethyl) (positive control). Treatments with the IGRs caused significant reductions in emerging adult numbers and sporophore damage rates compared with the water-treated control over the two growing periods. Of the IGRs tested, novaluron, diflubenzuron, and teflubenzuron had significantly lower numbers of emerging adults than the rest of the IGRs and chlorpyrifos ethyl-treated control in both periods. Treatments with teflubenzuron, pyriproxyfen, novaluron, and diflubenzuron resulted in significantly lower sporophore damage rates than all other treatments. Compared with negative control, there were no significant yield reductions due to applications of selected IGRs. The results suggest that all the IGRs tested can be used as alternatives to conventional pesticides in controlling L. ingenua populations on mushroom.     

六种昆虫生长调节剂对葱蝇生长发育和繁殖力的影响

用灭蝇胺、氟铃脲等6种昆虫生长调节剂和对比药剂辛硫磷LC_40-50浓度处理葱蝇1龄和3龄幼虫,观察对其生长发育和繁殖的影响;并且研究了葱蝇成虫取食药剂对其繁殖力的控制效应。结果表明：6种药剂中除虫酰肼外,其余都对葱蝇幼虫发育历期、化蛹率、成虫产卵前期、成虫寿命、产卵量有很大影响,对其生长发育和繁殖表现出显著不利性。其中灭蝇胺和氟铃脲处理1龄幼虫后,存活幼虫的历期和成虫产卵前期各延长3天,化蛹率降低26.7%～30.0％,成虫寿命缩短22.3～24.3天,产卵量降低35.5％～49.9％;处理3龄幼虫主要导致产生畸形蛹,且正常羽化的成虫寿命降低18.0～20.67天,产卵量降低45.7%～57.8％。成虫连续取食用牛奶稀释的２ 000倍的药液,能导致产卵前期延长、产卵量减少、卵孵化率降低,幼虫死亡率极高,达95%以上。结果提示,利用成虫补充营养的特性,将灭蝇胺和氟铃脲等混入牛奶或糖水中诱集成虫取食,可有效降低成虫的繁殖力,有助于实现对葱蝇的无公害治理。     

Effects of insect growth regulators on citrus mealybug parasitoid Leptomastix dactylopii (Hymenoptera: Encyrtidae)

In this study, we measured the effects of three commonly used insecticides classified as insect growth regulators, on the encyrtid parasitoid Leptomastix dactylopii (Howard) when parasitizing citrus mealybug, Planococcus citri (Risso). Kinoprene, pyriproxyfen, and azadirachtin were evaluated in both petri dish and a cage experiment at label-recommended rates to measure their effects on the mortality, parasitization rate, and sex ratio of L. dactylopii. Insecticides were applied to petri dishes and plants either immediately before, 24 h before, or 48 h before release of the parasitoid. Kinoprene applied 24 h before parasitoid release caused 100% mortality of L. dactylopii in petri dishes within 48 h. Mortality rates for L. dactylopii exposed to azadirachtin and pyriproxyfen did not exceed 5% regardless of release time. There were no release time x insecticide interactions on L. dactylopii parasitization rate. The insecticide alone, however, did significantly affect parasitization rates of L. dactylopii on P. citri; the kinoprene treatment significantly reduced L. dactylopii parasitization rates compared with azadirachtin and pyriproxyfen. In a cage experiment with coleus, Solenostemon scutellaroides (L.) Codd, applications of both pyriproxyfen and kinoprene resulted in fewer P. citri parasitized by L. dactylopii than azadirachtin or the control. The sex ratio was equivalent in the petri dish experiment, whereas in the cage experiment the sex ratio was biased toward males, particularly for the kinoprene treatment. Based on the results from this study, we suggest that kinoprene is not compatible with releases of L. dactylopii to control citrus mealybugs.     

Antigen Der f I from the dust mite Dermatophagoides farinae: structural comparison with Der p I from Dermatophagoides pteronyssinus and epitope specificity of murine IgG and human IgE antibodies

The physicochemical and antigenic properties of an allergen purified from Dermatophagoides farinae, Der f I, were compared with Der p I from Dermatophagoides pteronyssinus. On SDS-PAGE, Der f I migrated as a single polypeptide chain with the same m.w. as Der p I (24,000). Two isoallergenic peaks of Der f I were identified on preparative isoelectric focusing (pI 5.7 to 6.3 and pI 6.6 to 6.95). Fractions from each peak were shown to have an identical amino acid composition (which was similar but not identical to Der p I) and the same N-terminal amino acid sequence. There was a good correlation between quantitative intradermal skin tests to both purified allergens and to D. farinae extract in mite-allergic patients, with positive results when using as little as 10(-5) micrograms/ml of Der f I. The majority of sera with detectable IgE antibody to D. farinae also had IgE antibody to Der f I both among children (29/42 = 69%) and adults (55/63 = 87%). By RAST, there was an excellent correlation between IgE antibody to Der f I and Der p I in sera from 42 mite-allergic children (n = 0.94, p less than 0.001). Polyclonal IgG antibodies from six mice immunized with Der f I showed preferential binding to that allergen, and most monoclonal antibodies (16 of 18) raised against Der f I did not bind Der p I. However, two monoclonal antibodies from this fusion showed cross-reactive binding to both allergens. Immunoabsorption experiments, using D. pteronyssinus and D. farinae extracts coupled to Sepharose, showed that a large proportion of murine antibodies (74% to Der p I and 60 to 93% to Der f I) could not be absorbed by the heterologous extract on the immunosorbent. In contrast, in sera from seven mite-allergic patients, most of the specific IgE and IgG antibody (i.e., greater than or equal to 82%) was removed by either immunosorbent. Thus, Der f I and Der p I represent a homologous pair of major allergens which possess both cross-reacting and species-specific epitopes. The antibody response in mice immunized with either allergen in complete Freund's adjuvant was largely directed against species-specific epitopes, whereas in allergic humans, IgE- and IgG-specific antibodies bound predominately to cross-reacting epitopes.     

Cloning and expression of cDNA encoding the complete prepro-form of an isoform of Der f 1, the major group 1 allergen from house dust mite Dermatophagoides farinae

cDNA clones encoding a major house dust mite allergen, Der f 1, were isolated from a Dermatophagoides farinae cDNA library by plaque immunoscreening using rabbit anti-Der f 1 serum. The sequences cover the complete open reading frame encoding the prepro-form. The sequence is different from previously reported cDNA of Der f 1 in six bases and the encoded amino acid sequence is different in two residues. Pro-forms of Der f 1 and its mutant, in which the N-glycosylation motif was disrupted, expressed in Pichia pastoris were converted to the mature forms by an in vitro activation process and they showed significant IgE-binding. The biologically active rDer f 1 molecules would be useful for diagnostic testing and allergen-specific immunotherapy. In contrast, Der f 1 directly expressed in Escherichia coli without the prosequence had very low IgE binding. The hypoallergenic Der f 1 polypeptide could be useful for safer and more effective immunotherapy.