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At least 307 records · Page 17Linked to original sources
PubMed2005

Neoseiulus californicus (Acari: Phytoseiidae) as a potential control agent of Tetranychus urticae (Acari: Tetranychidae): effect of pest/predator ratio on pest abundance on strawberry.

Neoseiulus californicus (McGregor) is a promising agent for successful Tetranychus urticae Koch control through conservation techniques, in strawberry crops in La Plata (Buenos Aires, Argentina). In prey-predator interaction, initial relative densities have an important effect on system dynamics. The economic threshold level (ETL) used for this pest in the present study was 50 active mites per leaflet. In our laboratory experiments, initial T. urticae to N. californicus ratio had a significant effect on the population abundance of T. urticae at a 7-day period. When pest/predator ratio was 5/1 (at initial pest densities from 5 to 15 females/leaflet) the final number of active T. urticae/leaflet was significantly lower than the ETL, while at 20 females/leaflet this number did not differ from the ETL. At 7.5/1 ratio, the final number of active T. urticae/leaflet, at initial pest densities from 5 to 15 females/leaflet, reached the ETL without surpassing it. At 10/1 and 15/1 ratios, pest densities exceeded the ETL only at 15 initial T. urticae/leaflet. Most greenhouse and field observations were consistent with the predictions of a graphical model based on experimental results. This predator was very effective in limiting pest densities at a 7-day period and within the range of pest-predator ratios and absolute densities used in this study. Conservation of N. californicus promoting favorable pest/predator ratios may result in early control of T. urticae.

Animals↗
PubMed2005

Beauveria bassiana pathogenicity to the citrus rust mite Phyllocoptruta oleivora.

The pathogenicity of Beauveria bassiana to one of the major pests of citrus crops, Phyllocoptruta oleivora, was assessed by inoculating mites with different concentrations of conidia (1 x 10(6), 5 x 10(6), 1 x 10(7), 5 x 10(7) and 1 x 10(8)). Treated mites were kept at controlled conditions (25 +/- 0.5 degrees C, 12 h photoperiod and 98% relative humidity) and mite survivorship was evaluated daily. Mortality was found to increase in time and was dependent on the conidia concentration, with values ranging from 24 to 91% for the lowest and highest conidia concentration, respectively. The calculated LC50 on the fifth day was 4.23 x 10(6) conidia/ml. Mean lethal time was 3.98, 9.79, 3.09 and 2.74 days for 5 x 10(6), 1 x 10(7), 5 x 10(7) and 1 x 10(8) conidia/ml, respectively. Conidia were found to adhere all over the mite body surface, especially at the anal region, where vegetative mycelium was found entering the mite body. We noticed the formation of small crystals inside the mite's body that were produced during colonization of the body cavity by the fungus. This is the first report of B. bassiana pathogenicity for this species.

Animals↗
PubMed2005

Intraguild predation and feeding preferences in three species of phytoseiid mite used for biological control.

The ecological impact of introduced biological control agents on native species of arthropods is a matter of considerable debate. This study investigated the ability of the non-native predatory mite Neoseiulus californicus to feed on the native Typhlodromus pyri and vice versa, as both species now co-occur in UK orchards. Typhlodromips montdorensis is a candidate for introduction into the UK as a glasshouse biological control agent. The ability of T. montdorensis to feed on the widely used N. californicus was investigated to identify possible intraguild predation, which might influence the effectiveness of either or both species as predators of Tetranychus urticae. Both N. californicus and T. pyri consumed larval stages of each other, but in choice experiments both showed a preference for T. urticae. Both N. californicus and T. montdorensis also fed on each other, but whereas N. californicus again showed a preference for T. urticae, T. montdorensis fed equally on T. urticae and N. californicus. Interactions between N. californicus and T. pyri and N. californicus and T. montdorensis are discussed in relation to their effectiveness as biological control agents in the glasshouse and the natural control of spider mite in the field.

Animals↗
PubMed2005

Cannibalism and interspecific predation in a phytoseiid predator guild from cassava fields in Africa: evidence from the laboratory.

Interspecific predation and cannibalism are common types of interaction in phytoseiid predator guilds, but the extent and nature of these interactions have not been determined yet in phytoseiid guilds composed of African native and neotropical exotic phytoseiid predators found in cassava habitat in southern Africa. We determined in laboratory experiments the level of cannibalism and interspecific predation among the three phytoseiid mite species Euseius fustis, Iphiseius degenerans, and Typhlodromalus aripo in the absence of food and in the presence of limited or abundant quantities of two food types--Mononychellus tanajoa and maize pollen--commonly found on cassava in Africa. When confined without food, only two T. aripo females laid each two eggs within 5 days, and this species survived longer than I. degenerans and E. fustis. In the presence of con- or hetero-specific larvae or protonymphs, the three species fed more on the former than on the latter, and more on hetero-specifics than on con-specifics. Oviposition rates of the three species did not exceed 0.7 egg/female/day on con- and hetero-specific immatures. Typhlodromalus aripo and E. fustis survived longer on con-specific and hetero-specific larvae and on hetero-specific protonymphs than in the absence of any food, while T. aripo survived longer than the two other species on the same diets. Provision of limited quantity of food decreased interspecific predation rate by I. degenerans and T. aripo, but not by E. fustis, and increased oviposition rate and longevity of all three species. Provision of abundant food, however, eliminated cannibalism by all three species and further reduced interspecific predation rates, but their oviposition and longevity remained relatively unchanged compared with limited food provision. Potential consequences of cannibalism and interspecific predation among phytoseiid mites on cassava for the biological control of M. tanajoa are discussed.

Animals↗
PubMed2006

Effect of air humidity on the egg viability of predatory mites (Acari: Phytoseiidae, Stigmaeidae) common on rubber trees in Brazil.

Rubber pest mites, Calacarus heveae and Tenuipalpus heveae, reach economic damage levels at the end of the rainy season and the beginning of the dry season in Brazil. Therefore, low humidity adaptation might be an important characteristic for predatory mites to successfully control pest organisms. This study determined the effect of the relative humidity (RH) levels of 30-100% on the hatching of larvae of Amblyseius acalyphus, Euseius citrifolius, Iphiseiodes zuluagai, Metaseiulus camelliae, Agistemus floridanus and Zetzellia malvinae at 25 +/- 0.5 degrees C. These predatory mites are common on rubber trees in the state of São Paulo and might be used for introduction in the major rubber tree production regions in the state of Mato Grosso. At 70% RH or higher, viability was 70% or higher for all species, indicating that their performance might be higher during the rainy season than during the dry season. Eggs of E. citrifolius and M. camelliae presented higher viability at the lower relative humidity levels than those of other species, indicating that these species might have higher chance to persist in the dry season. It is suggested that M. camelliae should be further evaluated for introduction in the state of Mato Grosso, considering that this mite is not yet present in that area.

Animals↗
PubMed2006

Life history of Kampimodromus aberrans as a predator of Phytoptus avellanae (Acari: Phytoseiidae, Phytoptidae).

The biology of Kampimodromus aberrans (Oudemans), a predator of the big bud mite, Phytoptus avellanae Nalepa, was studied under laboratory conditions. All experiments were conducted on hazelnut leaf discs in an incubator at 25 +/- 1 degrees C, with 16:8 h L:D, at an average daily relative air humidity of 76%. Observations were made twice daily for the immature stages and daily for the adults to determine developmental time, survival and fecundity. The mean developmental time for females was 6.90 days and for males was 7.10 days, and mean adult longevity for females was 11.67 days. The mean total and daily egg production were 12.67 and 1.85 eggs, respectively. The net reproduction rate (R0) was 7.09 females/female, intrinsic rate of increase (rm) was 0.153 female/female/day and mean generation time (T0) was 12.80 days. The mortality rate of immature stages was 0.66% and the sex ratio was 0.51 female.

Animals↗
PubMed2006

Susceptibility of Brevipalpus phoenicis to entomopathogenic fungi.

The pathogenicity of 52 isolates from several fungus species was studied for the false spider mite Brevipalpus phoenicis. In addition, the main stages during the course of infection by Hirsutella thompsonii, by far the most virulent pathogen, were studied by means of light and electron microscopy. Adult mites were confined to arenas prepared with citrus leaves in acrylic dishes containing agar-water. Conidial suspensions containing 10(8) conidia/ml were applied, except for H. thompsonii, where a concentration of 10(7) conidia/ml was used. The H. thompsonii isolates caused higher mortality, with indices higher than 90%. Observations under the scanning electron microscope (SEM) were performed at 0, 6, 12, 24, 48, 72, and 120 h after application of a H. thompsonii suspension containing 10(7) conidia/ml. Twenty-four hours after inoculation, H. thompsonii conidia were observed attached to the mite's integument. The conidia germinated and penetrated through the base of the setae on the hysterosoma. Colonization occurred after 48 h, as evidenced by mortality. Conidiogenesis occurred after 120 h, with the development of mycelium and conidiophores emerging from the posterior and anterior parts of the mite.

Animals↗
PubMed2006

Four new species of the feather mite genus Vanginyssus Mironov, 2001 (Astigmata: Pteronyssidae) from the vangas (Passeriformes: Vangidae) in Madagascar.

Four new feather mite species of Vanginyssus Mironov, 2001 are described from vangas (Passeriformes: Vangidae), an endemic passerine family from Madagascar: Vanginyssus euryceros n. sp. from the helmet vanga Euryceros prevostii Lesson, V. madagascarinus n. sp. from the blue vanga Cyanolanius madagascarinus (Linnaeus), V. mystacornis n. sp. from the Crossley's babbler Mystacornis crossleyi (Grandidier) and V. orioliae n. sp. from the Bernier's vanga Oriolia bernieri Geoffroy Saint-Hilaire. A key to the five known species of Vanginyssus is provided.

Animals↗
PubMed1975

Familial hypersensitivity pneumonitis.

Two families are described in which seven members of a total of 19 were found to have hypersensitivity pneumonitis due to exposure to avian antigens. Diagnosis was made on the basis of characteristic roentgenologic changes together with respiratory function and immunologic studies. The latter included screening for precipitins, macrophage migration inhibition (MMI) to specific antigens in avian serum and droppings, quantitation of immunoglobulin and alpha1 antitrypsin (AAT) levels and assessment of the complement system. Specific precipitins to pigeon and/or budgerigar serum were found in the serum of only four of the seven patients. Six of these seven patients, however, had a positive MMI. Thus, the MMI test, at least in this group of patients appeared to be a more sensitive indicator of active disease. The finding of seven members of two families with disease led to a search for predisposing factors, either genetic or environmental. Evidence for a genetic predisposition came from tissue typing studies. In the first family, both paternal haplotypes were associated with disease; the maternal haplotype HLA3,7 was not inherited by any child with disease. In the second family, the disease developed in three of four members with the haplotype HL-A2,W15, who were significantly exposed to avian antigen. In the light of recent studies showing an association between immune response (Ir) genes, histocompatibility antigens and disease susceptibility, these findings were interpreted as possible evidence for a subtle genetically linked immune defect in hypersensitivity pneumonitis. Evidence for an environmental predisposition was less clear cut, but it is interesting that members of both families used a gamma isomer of hexachlorobenzene (Nickoff) to eradicate mite infestations in their birds which might have damaged the bronchial mucosa or acted as an immunologic adjuvant in a person with underlying susceptibility to disease. The presence of subclinical respiratory disease in two family members is reported, and the importance of performing a range of investigations of respiratory function in order to detect disease and monitor its progress is emphasized.

Adolescent↗
PubMedDate not supplied

Effect of ivermectin on the ear mange mite, Psoroptes cuniculi, of rabbits.

Rabbits, naturally infected with ear mange mite, Psoroptes cuniculi, were injected subcutaneously with a single dose of ivermectin at 200 micrograms or 400 micrograms/kg of body weight. The effect of the drug was evaluated clinically and parasitologically over 4 weeks. The animals in both groups became negative for mites 6 days after treatment and remained so until the end of trial. The ear lesions disappeared in both groups. However, the regression of lesions was faster in rabbits administered 400 micrograms/kg of ivermectin.

Animals↗
PubMed1989

Trixacarus caviae infection of guinea pigs with genetically determined differences in susceptibility to Trichostrongylus colubriformis infection.

Guinea pigs with genetically determined resistance or susceptibility to infection with the nematode parasite Trichostrongylus colubriformis were allowed to become infected with the sarcoptid mite Trixacarus caviae. Compared with nematode-susceptible guinea pigs, nematode-resistant animals had larger populations of mites and developed a more severe dermatitis, with greater mast cell hyperplasia and many more infiltrating eosinophils. The results suggest that animals bred for resistance to one parasite may have greater susceptibility to other parasites.

Animals↗
PubMed1981

Studies in atopic asthma with emphasis on correlation among various tests and various antibodies.

The prick-test titration, allergen provocation test, acetylcholine inhalation test, total serum IgE measurement, histamine release test, and serum IgE, IgG, IgA, and IgM antibody determinations were carried out in atopic asthmatic patients who had never received immunotherapy with mite extract. Comparison of these procedures shows good correlation between them. Skin-test titration appears to be a fairly accurate and reliable method to determine causative allergens. The antigen inhalation provocation test tends to be positive among subjects with low thresholds to acetylcholine. This indicates that patients with airway tracts hyperreactive to acetylcholine are prone to asthma attacks even with exposure to small amounts of specific allergen and probably to various stimuli. Atopic subjects produce more IgE antibody and other antibodies than nonatopic subjects do. The quantity of specific antibodies to mite was lowest for IgM in atopic subjects.

Adolescent↗
PubMed1992

Evidence of immunosuppression by Demodex canis.

Three clinically normal beagles, 3 beagles with localized demodectic mange (LDM), and 3 beagles with generalized demodectic mange (GDM) were investigated simultaneously 1-3 and 4-6 weeks from the appearance of the clinical signs. Blood clinical examination and reactivity of peripheral lymphocytes to Con A and PHA were investigated in the first instance, and reactivity to Con A, PHA, and LPS in the second. Eight aliquots were used in each blastogenesis assay for each dog. All dogs were negative for rheumatoid factor. The results of blastogenesis showed that many observations were distributed non-normally, and that not all dogs in each group responded homogeneously. Comparison of blastogenesis results between dogs demands careful statistical analysis. Responses to mitogens were normal in all dogs at 1-3 weeks except for the LDM dogs that showed an increased response to PHA. Only the response to Con A was moderately inhibited in the LDM dogs at 4-6 weeks. All responses were severely depressed in the GDM dogs at 4-6 weeks. This means that immunosuppression follows rather than precedes the clinical manifestations of GDM, and implies that the phenomenon is induced by the parasite or the host's reaction to it.

Animals↗
PubMed1982

The infectivity of surviving Psoroptes ovis (Hering) on cattle treated with ivermectin.

Ivermectin, 22,23-dihydroavermectin B1 (Merck MK-933), injected intramuscularly at the rate of 200 microgram kg-1 body wt., completely eliminated Psoroptes ovis populations from 6 Hereford cattle within 2 weeks after treatment. However, mites surviving 1, 3, and 5 days after treatment were viable and infective when transferred to untreated cattle. Mites surviving 7 days after treatment did not cause scabies or establish a colony of mites when transferred to untreated cattle. These results indicate that cattle treated with ivermectin for control of psoroptic scabies should be isolated from other cattle for at least 5 days after treatment.

Animals↗
PubMed1985

Psoroptic ear mange (Psoroptes cuniculi, Delafond, 1859) in domestic and wild ruminants in Israel.

Otoacariasis, caused by Psoroptes cuniculi (Delafond, 1859) is reported in sheep (Ovis aries), domestic goats (Capra aegagrus hircus), mountain goats (Capra ibex nubiana) and Yaez (a cross between domestic and mountain goats). Captive and captured deer (Gazella gazella and Gazella dorcas) were found negative for ear mites. Sheep and mountain goats were found to be the most affected while goats and Yaez only sporadically so. The clinical manifestations are described and the results are discussed in the light of the pertinent literature.

Animals↗
PubMed1985

Amitraz in the control of non-ixodide ectoparasites of livestock.

Amitraz has been shown to be successful in controlling mange and lice infestations on pigs which had failed to respond to diazinon and gamma-BHC, respectively, and by the use of a prophylactic programme to maintain pig herds mange free. In addition, trials have indicated the elimination of psoroptic mange from sheep by applying the compound to the animal using either conventional or less conventional methods of treatment. Mixed infections of Chorioptes spp., Psoroptes spp. and Sarcoptes spp., in cattle have also been controlled using spray applications of amitraz, where in some cases organochlorine, organophosphorus and organotin compounds had failed. In a pilot study a heavy infestation of chorioptic mange was controlled on a calf using a pour-on formulation of amitraz.

Animals↗