Laboratory tests for controlling poultry red mites (Dermanyssus gallinae) with predatory mites in small ‘laying hen’ cages

To assess their potential to control poultry red mites (Dermanyssus gallinae), we tested selected predaceous mites (Androlaelaps casalis and Stratiolaelaps scimitus) that occur naturally in wild bird nests or sometimes spontaneously invade poultry houses. This was done under laboratory conditions in cages, each with 2–3 laying hens, initially 300 poultry red mites and later the release of 1,000 predators. These small-scale tests were designed to prevent mite escape from the cages and they were carried out in three replicates at each of three temperature regimes: 26, 30 (constant day and night) and 33–25?°C (day-night cycle). After 6?weeks total population sizes of poultry red mites and predatory mites were assessed. For the temperature regimes of 26 and 33/25?°C S. scimitus reduced the poultry red mite population relative to the control experiments by a factor 3 and 30, respectively, and A. casalis by a factor of 18 and 55, respectively. At 30?°C the predators had less effect on red mites, with a reduction of 1.3-fold for S. scimitus and 5.6-fold for A. casalis. This possibly reflected hen manure condition or an effect of other invertebrates in the hen feed. Poultry red mite control was not negatively affected by temperatures as high as 33?°C and was always better in trials with A. casalis than in those with S. scimitus. In none of the experiments predators managed to eradicate the population of poultry red mites. This may be due to a prey refuge effect since most predatory mites were found in and around the manure tray at the bottom of the cage, whereas most poultry red mites were found higher up in the cage (i.e. on the walls, the cover, the perch, the nest box and the food box). The efficacy of applying predatory mites in the poultry industry may be promoted by reducing this refuge effect, boosting predatory mite populations using alternative prey and prolonged predator release devices. Biocontrol success, however, will strongly depend on how the poultry is housed in practice (free range, cage or aviary systems) and on which chemicals are applied to disinfect poultry houses and to control other pests.     

Infestation by the mite Harpirhynchus nidulans in the Bearded Tit Panurus biarmicus

Capsule Mites sometimes induced voluminous subcutaneous cysts in featherless parts.

Aims To describe the first reported infestation by the skin-dweller mite Harpirhynchus nidulans in Bearded Tits Panurus biarmicus and for the Timaliidae family, to detect possible fitness costs for the host and to determine the distribution of the parasite within the distribution range of the host.

Methods Parasites were identified using a microscope. Wing-length and body mass were recorded on both uninfected and infected birds captured at different times during the year. We also considered historical data, and contact was made with 32 European ringing stations to identify the distribution range of the parasite.

Results Subcutaneous reproduction of the mite Harpirhynchus nidulans induced the development of voluminous dermal nodules in Panurus biarmicus. There were no differences in body mass or wing-length with respect to infestation. In the south of France, prevalence changed from 10.6% in spring to 4.7% in autumn. Both sexes are equally parasitized. Occurrence of dermal cysts is reported from several southern European populations of Bearded Tits, whereas it seems to be absent from northern latitudes.

Conclusion The occurrence of a Harpirhynchus mite in wild bird populations is reported for the first time. We consider aspects of its biology, host–parasite system, host-specificity, co-adaptation of the mite reproductive cycle to the social dynamics of its host and metapopulational host–parasite dynamics.     

Interspecific transmission of endosymbiotic Spiroplasma by mites

The occurrence of closely related strains of maternally transmitted endosymbionts in distantly related insect species indicates that these infections can colonize new host species by lateral transfer, although the mechanisms by which this occurs are unknown. We investigated whether ectoparasitic mites, which feed on insect haemolymph, can serve as interspecific vectors of Spiroplasma poulsonii, a male-killing endosymbiont of Drosophila. Using Spiroplasma-specific primers for PCR, we found that mites can pick up Spiroplasma from infected Drosophila nebulosa females and subsequently transfer the infection to Drosophila willistoni. Some of the progeny of the recipient D. willistoni were infected, indicating successful maternal transmission of the Spiroplasma within the new host species. However, the transmission rate of the infection from recipient flies to their offspring was low, perhaps due to low Spiroplasma density in the recipient flies.     

First report of Demodex bovis infestation in bovine besnoitiosis co-infected dairy cattle in Italy

A form of generalized demodectic mange in two dairy cows infected with Besnoitia besnoiti is described. The herd was endemically infected with bovine besnoitiosis; an overall seroprevalence of B. besnoiti antibodies of 23.5%, that increased up to 43.5% considering only cows, was reported. Two out of the cows seropositive to B. besnoiti, at clinical examination presented skin nodules, widespread all over the body, and in particular in anterior regions. Skin biopsies from the region of the neck were collected and the nodules were microscopically examined through compression method. B. besnoiti tissue cysts were not revealed but a semi-solid yellowish content was evidenced with the presence of several mites, morphologically identified as Demodex bovis. Histological examination of skin biopsies evidenced slight acanthosis and hyperkeratosis of the epidermis and superficial dermatitis with oedema and macrophagic and eosinophilic infiltration. Cystic formations located in the deep dermis were lined by metaplastic squamous epithelium and severe cellular infiltration. A treatment with eprinomectin was attempted and clinical improvement of both cows was observed, particularly at the fifteenth day after treatment, with nodules reduced in size and mites in there degenerated. This is the first report of the co-infection of D. bovis infestation and bovine besnoitiosis in cattle. Furthermore, it was demonstrated that D. bovis circulates in the Italian cattle population, but subclinical forms could be underdiagnosed.     

Pasteurellosis as a cause of genital lesions in rams. A descriptive study

Pasteurellosis is one of the most prevalent diseases of sheep, but the involvement of Pasteurellae in genital pathology of rams has been described rarely. One hundred and eighty-four rams showing palpable lesions in testes, epididymides or scrotum were submitted to bacteriological studies, and seven mature rams found infected with bacterial species belonging to the Pasteurella cluster (i.e., Mannheimia, Pasteurella and Bibersteinia (M/P/B)). The M/P/B cultures obtained were pure and/or heavy, and were confirmed after necropsy in the five M/P/B infected rams that could be slaughtered for further pathological examinations. Pasteurella multocida infected rams exhibited fibrinous exudate and generalized adhesions between the vaginal and the external scrotal layers. Testicular atrophy and epididymal sperm granulomas were also evident in these rams. Microscopically, epithelial hyperplasia with intraepithelial cysts, fibrosis and spermatic granulomas were present in the epididymis, while testis showed sperm stasis foci, microcalcifications and fibrosis. Mannheimia haemolytica infected rams showed severe unilateral epididymitis and testicular atrophy, being microscopically similar to the lesions found in P. multocida infected rams. The ram found infected with B. threalosi had severe unilateral lesions in testis, epididymis and scrotum. Microscopically, abscesses in epididymis and testis, and severe fibrosis and interstitial round cells infiltrates in testis were observed. Further studies should be conducted to determine properly the role played by the Pasteurella cluster in the pathogenesis of genital lesions in rams.     

Ear Mite Removal in the Santa Catalina Island Fox (Urocyon littoralis catalinae): Controlling Risk Factors for Cancer Development

Ear mites (Otodectes cynotis) and ear canal tumors are highly prevalent among federally endangered Island foxes (Urocyon littoralis catalinae) living on Santa Catalina Island off the coast of Southern California. Since studies began in the 1990s, nearly all foxes examined were found to be infected with ear mites, and ceruminous gland tumors (carcinomas and adenomas) were detected in approximately half of all foxes ≥ 4 years of age. We hypothesized that reduction of ear mite infection would reduce otitis externa and ceruminous gland hyperplasia, a risk factor for tumor development. In this study, we conducted a randomized field trial to assess the impact of acaricide treatment on ear mite prevalence and intensity of infection, otitis externa, ceruminous gland hyperplasia, and mite-specific IgG and IgE antibody levels. Treatment was highly effective at eliminating mites and reducing otitis externa and ceruminous gland hyperplasia, and mite-specific IgG antibody levels were significantly lower among uninfected foxes. Ceruminous gland hyperplasia increased in the chronically infected, untreated foxes during the six month study. Our results provide compelling evidence that acaricide treatment is an effective means of reducing ear mites, and that mite removal in turn reduces ear lesions and mite-specific IgG antibody levels in Santa Catalina Island foxes. This study has advanced our understanding of the underlying pathogenesis which results in ceruminous gland tumors, and has helped inform management decisions that impact species conservation.     

Candidate predators for biological control of the poultry red mite Dermanyssus gallinae

The poultry red mite, Dermanyssus gallinae, is currently a significant pest in the poultry industry in Europe. Biological control by the introduction of predatory mites is one of the various options for controlling poultry red mites. Here, we present the first results of an attempt to identify potential predators by surveying the mite fauna of European starling (Sturnus vulgaris) nests, by assessing their ability to feed on poultry red mites and by testing for their inability to extract blood from bird hosts, i.e., newly hatched, young starlings and chickens. Two genuine predators of poultry red mites are identified: Hypoaspis aculeifer and Androlaelaps casalis. A review of the literature shows that some authors suspected the latter species to parasitize on the blood of birds and mammals, but they did not provide experimental evidence for these feeding habits and/or overlooked published evidence showing the reverse. We advocate careful analysis of the trophic structure of arthropods inhabiting bird nests as a basis for identifying candidate predators for control of poultry red mites.     

Detection of Spiroplasma from the mite Macrocheles sp. (Acari; Macrochelidae) ectoparasitic to the fly Drosophila hydei (Diptera; Drosophilidae): a possible route of horizontal transmission?

Some members of the genus Spiroplasma are vertically transmitted endosymbionts of insects. Among them, Spiroplasma sp. Dhd, a member of the Spiroplasma poulsonii clade, is highly prevalent among worldwide populations of Drosophila hydei. Here we found that 53 out of 3,763 wild-caught D. hydei (1.4 %) were ectoparasitized by the mite that belong to the genus Macrocheles. Many of the ectoparasitized flies (79 %) had a single mite, but some flies had up to five mites. Among 59 mites subjected to Spiroplasma-specific PCR, 15 individuals were found to be positive. Infection status of Spiroplasma in flies and the associated mites were incongruent. Partial nucleotide sequences of the Spiroplasma P58 gene suggest that some of the mites are infected with a Spiroplasma, which is identical or closely related to Spiroplasma sp. Dhd. This finding provides a potential route of horizontal Spiroplasma transmission between D. hydei individuals in natural populations. In addition, a Spiroplasma strain that does not form a monophyletic group with S. poulsonii was also found from a mite individual.     

Habitat Fragmentation and Ecological Traits Influence the Prevalence of Avian Blood Parasites in a Tropical Rainforest Landscape

In the tropical rainforests of northern Australia, we investigated the effects of habitat fragmentation and ecological parameters on the prevalence of blood-borne parasites (Plasmodium and Haemoproteus) in bird communities. Using mist-nets on forest edges and interiors, we sampled bird communities across six study sites: 3 large fragments (20–85 ha) and 3 continuous-forest sites. From 335 mist-net captures, we recorded 28 bird species and screened 299 bird samples with PCR to amplify and detect target DNA. Of the 28 bird species sampled, 19 were infected with Plasmodium and/or Haemoproteus and 9 species were without infection. Over one third of screened birds (99 individuals) were positive for Haemoproteus and/or Plasmodium. In forest fragments, bird capture rates were significantly higher than in continuous forests, but bird species richness did not differ. Unexpectedly, we found that the prevalence of the dominant haemosporidian infection, Haemoproteus, was significantly higher in continuous forest than in habitat fragments. Further, we found that ecological traits such as diet, foraging height, habitat specialisation and distributional ranges were significantly associated with blood-borne infections.     

Eimeria acervulina: The influence of inoculation dose on transmission between broiler chickens

The course and clinical appearance of an Eimeria species infection in chicken flocks depend on the response of an individual bird to infection and on population-dynamics of the infection in the flock. Differences in ingested numbers of oocysts may affect oocyst load in the flock and the subsequent infectious dose for not yet infected birds. To study the link between numbers of oocysts excreted by infected birds and transmission of Eimeria acervulina, experiments were carried out with 42 pairs of broiler chickens using inoculation doses with 5, 50, 500 or 50,000 sporulated oocysts. In each pair one bird was inoculated and the other bird was contact-exposed. All contact birds became infected, which occurred on average within 34 h after exposure to an inoculated bird. Although a higher inoculation dose resulted in higher oocyst excretion in inoculated and contact-infected birds, only small non-significant differences in transmission rates between groups were found.     

Molecular Prevalence of Acarapis Mite Infestations in Honey Bees in Korea

Acarapis mites, including Acarapis woodi, Acarapis externus, and Acarapis dorsalis, are parasites of bees which can cause severe damage to the bee industry by destroying colonies and decreasing honey production. All 3 species are prevalent throughout many countries including UK, USA, Iran, Turkey, China, and Japan. Based on previous reports of Acarapis mites occurring in northeast Asia, including China and Japan, we investigated a survey of Acarapis mite infestations in honey bees in Korean apiaries. A total of 99 colonies of Apis mellifera were sampled from 5 provinces. The head and thorax of 20 bees from each colony were removed for DNA extraction. PCR assays were performed with 3 primer sets, including T, A, and K primers. Results indicated that 42.4% (42/99) of samples were Acarapis-positive by PCR assay which were sequenced to identify species. Each sequence showed 92.6-99.3% homology with reference sequences. Based on the homology, the number of colonies infected with A. dorsalis was 32 which showed the highest infection rate among the 3 species, while the number of colonies infected with A. externus and A. woodi was 9 and 1, respectively. However, none of the Acarapis mites were morphologically detected. This result could be explained that all apiaries in the survey used acaricides against bee mites such as Varroa destructor and Tropilaelaps clareae which also affect against Acarapis mites. Based on this study, it is highly probable that Acarapis mites as well as Varroa and Tropilaelaps could be prevalent in Korean apiaries.     

Metabolism of 5′-methylthioadenosine in Aspergillus nidulans an alternative pathway for methionine synthesis via utilization of the nucleoside methylthio group

Experiments in which 5′-methylthioadenosine was used as a culture supplement for methionine-requiring mutants of Aspergillus nidulans with various enzymatic lesions indicated that the methylthio group derived from the nucleoside can be recycled to methionine. The results strongly suggest that methionine may be synthesized in the reaction catalyzed by homocysteine synthase (EC 4.2.99.10) in which O-acetylhomoserine is an acceptor of the methylthio group. The first step on the salvage pathway of the methylthio group is, in Aspergillus nidulans, phosphorolytic cleavage of 5′-methylthioadenosine to adenine and 5-methylthioribose 1-phosphate catalyzed by a specific phosphorylase.     

The influence of mistletoes on birds in an agricultural landscape of central Mexico

Mistletoes are hemiparasitic flowering plants that function as keystone resources in forests and woodlands of temperate regions, where a positive relationship between mistletoe density and avian species richness has been observed. Mistletoes have been less studied in tropical regions and the relationship between birds and mistletoes has seldom been explored in tropical agricultural systems. Therefore, we studied the presence of infected trees and infection prevalence (i.e., number of parasitized trees/total number of trees) by Psittacanthus (Loranthaceae) mistletoes in 23 hedgerows located in an agricultural landscape of central Mexico during the dry and rainy seasons, and investigated the relationship between bird species richness and abundance and the abundance of mistletoes. We found a mean of 74 mistletoe plants per 100-m transect of only one species, Psittacanthus calyculatus. Thirty-one percent of the trees surveyed were infected and tree species differed in infection prevalence, mesquite (Prosopis laevigata) being the most infected species with 86% of the surveyed trees infected. For both seasons, we found a positive and significant association between bird species richness and number of mistletoe plants. The same pattern was observed for total bird abundance. Many resident and Neotropical migratory birds were observed foraging on mistletoes. Our results show that mistletoes are important in promoting a higher bird species richness and abundance in tropical agricultural landscapes.     

The testing of antibodies raised against poultry red mite antigens in an in vitro feeding assay; preliminary screen for vaccine candidates

Dermanyssus gallinae (De Geer), the poultry red mite, is a blood-feeding ectoparasite that infests many bird species. We have used an in vitro feeding assay to allow the identification of protective D. gallinae antigens that may have potential as vaccine candidates. Homogenised mites were extracted sequentially with PBS, Tween 20, Triton X100 and urea giving four protein fractions. Five experimental groups of Lohmann Brown hens were used to generate antibodies; four groups were injected with one of each of the protein fractions in QuilA adjuvant and a control group was injected with adjuvant only. Booster injections were administered 2 and 4 weeks after initial immunisation. Eggs were collected throughout the experiment and soluble IgY antibodies were extracted from a pool of egg yolks collected at week six post-injection. Western blots, performed using post vaccination antibodies from test and control groups, revealed a strong antibody response against a range of injected proteins. Fresh chicken blood, supplemented with antibodies raised against these protein fractions, was fed to mites in an in vitro feeding assay in order to determine whether the antibodies had an anti-mite effect. Although there was variability in the numbers of feeding mites, it was found that the strongest anti-mite effect was seen with the PBS protein fraction, which had a cumulative average mortality of 34.8% 14 days after feeding compared with 27.3% for the control group (P = 0.043).     

Interference of Griseofulvin with the Segregation of Chromosomes at Mitosis in Diploid Aspergillus nidulans

Low concentrations of the antibiotic griseofulvin were found to cause increased frequencies of somatic segregation due to chromosome nondisjunction in a diploid strain of Aspergillus nidulans.     

New hosts for the mite Ornithonyssus bursa in Argentina

The mite Ornithonyssus bursa (Berlese) (Mesostigmata: Macronyssidae) is considered a poultry pest causing important infestations in chickens and it is considered a potential vector of arbovirus. Despite being considered a common parasite in wild birds, there is scarce published information about its potential hosts and effects on them. Here we present new bird hosts for O. bursa, assess the presence of Alphavirus, Flavivirus and Bunyavirus in mites from three host species, and discuss its potential impact on wild bird populations. We found O. bursa infecting five raptor and six passerine wild bird species. For nine of these species, this is the first record of infection by O. bursa. Although all analysed mites were negative for the examined arboviruses, the small sample size of mites does not allow further conclusions at the present moment. Because of the general nature of this ectoparasite, its presence in migratory long dispersal and endangered bird species, and the seropositivity for arboviruses in some of the species studied here, we consider it critical to assess the role of O. bursa and other ectoparasites as vectors and reservoirs of pathogens and as potential deleterious agents in wild bird populations.     

Fine‐tuned distribution of feather mites (Astigmata) on the wing of birds: the case of blackcaps Sylvia atricapilla

The distribution of feather mites (Astigmata) along the wing of passerine birds could change dramatically within minutes because of the rapid movement of mites between feathers. However, no rigorous study has answered how fine‐tuned is the pattern of distribution of feather mites at a given time. Here we present a multiscale study of the distribution of feather mites on the wing of non‐moulting blackcaps Sylvia atricapilla in a short time period and at a single locality. We found that the number and distribution of mites differed among birds, but it was extremely similar between the wings of each bird. Moreover, mites consistently avoided the first secondary feather, despite that it is placed at the centre of the feathers most used by them. Thus, our results suggest that feather mites do precise, feather‐level decisions on where to live, contradicting the current view that mites perform “mass”, or “blind” movements across wing feathers. Moreover, our findings indicate that “rare” distributions are not spurious data or sampling errors, but each distribution of mites on the wing of each bird is the outcome of the particular conditions operating on each ambient‐bird‐feather mite system at a given time. This study indicates that we need to focus on the distribution of feather mites at the level of the individual bird and at the feather level to improve our understanding of the spatial ecology of mites on the wings of birds.     

Mycobacterium avium Bacilli Grow Saprozoically in Coculture with Acanthamoeba polyphaga and Survive within Cyst Walls

Protozoans are gaining recognition as environmental hosts for a variety of waterborne pathogens. We compared the growth of Mycobacterium avium, a human pathogen associated with domestic water supplies, in coculture with the free-living amoeba Acanthamoeba polyphaga with the growth of M. avium when it was separated from amoebae by a 0.1-μm-pore-size polycarbonate membrane (in a parachamber). Although viable mycobacteria were observed within amoebal vacuoles, there was no significant difference between bacterial growth in coculture and bacterial growth in the parachamber. This suggests that M. avium is able to grow saprozoically on products secreted by the amoebae. In contrast, Legionella pneumophila, a well-studied intracellular parasite of amoebae, multiplied only in coculture. A comparison of amoebae infected with L. pneumophila and amoebae infected with M. avium by electron microscopy demonstrated that there were striking differences in the locations of the bacteria within amoebal cysts. While L. pneumophila resided within the cysts, M. avium was found within the outer walls of the double-walled cysts of A. polyphaga. These locations may provide a reservoir for the bacteria when environmental conditions become unfavorable.     

Sporogenic Effect of Polyunsaturated Fatty Acids on Development of Aspergillus spp.

Aspergillus spp. are frequently occurring seed-colonizing fungi that complete their disease cycles through the development of asexual spores, which function as inocula, and through the formation of cleistothecia and sclerotia. We found that development of all three of these structures in Aspergillus nidulans, Aspergillus flavus, and Aspergillus parasiticus is affected by linoleic acid and light. The specific morphological effects of linoleic acid include induction of precocious and increased asexual spore development in A. flavus and A. parasiticus strains and altered sclerotium production in some A. flavus strains in which sclerotium production decreases in the light but increases in the dark. In A. nidulans, both asexual spore production and sexual spore production were altered by linoleic acid. Spore development was induced in all three species by hydroperoxylinoleic acids, which are linoleic acid derivatives that are produced during fungal colonization of seeds. The sporogenic effects of these linoleic compounds on A. nidulans are similar to the sporogenic effects of A. nidulans psi factor, an endogenous mixture of hydroxylinoleic acid moieties. Light treatments also significantly increased asexual spore production in all three species. The sporogenic effects of light, linoleic acid, and linoleic acid derivatives on A. nidulans required an intact veA gene. The sporogenic effects of light and linoleic acid on Aspergillus spp., as well as members of other fungal genera, suggest that these factors may be significant environmental signals for fungal development.