Artificial feeding of northern fowl mites, Ornithonyssus sylviarum (Canestrini and Fanzago) (Acari: Macronyssidae), through membranes

A new device and technique are described for the in vitro feeding of northern fowl mites, Ornithonyssus sylviarum (Canestrini and Fanzago). The device consisted of a glass cylinder 25 mm in length and in outside diameter, capped with a chick skin membrane at one end and a snap-cap with a wire cloth window at the other end. Maximum feeding by northern fowl mites on warmed heparinized chicken blood occurred after 60 min and at a blood temperature range of 36-42 C. Skin membranes prepared from 1-wk-old chicks gave significantly higher feeding rates than those from 4-wk-old chicks, but unfrozen skins and skins frozen up to 4 wk were equally effective. Also, mites fed equally well through white leghorn and broiler chick skin membranes. About 80% of northern fowl mites fed. The in vitro technique described simplifies the approach to studies of northern fowl mite biology and physiology.     

Patterns of Haemoproteus beckeri parasitism in the gray catbird (Dumatella carolinensis) during the breeding season

We determined the prevalence and intensity of blood parasites in breeding gray catbirds (Dumatella carolinensis) at Killbuck Wildlife Area in Wayne and Holmes Counties, Ohio (USA) from June through August 2000. Of 98 catbirds sampled, 40 (40.8%) had detectable infections of Haemoproteus beckeri. Overall prevalence of H. beckeri in this population is high relative to that reported in earlier blood parasite surveys of both breeding and migrant catbirds. Mean intensity of H. beckeri infection did not vary significantly between young and old birds or among sampling periods. We found no effect of age on prevalence or intensity of H. beckeri infection. Older birds were not more likely to be infected than younger birds, despite longer exposure to arthropod vectors. Prevalence varied significantly with season and was highest in June and lowest in August. This pattern also was observed in older birds sampled repeatedly. This seasonal variation may reflect both newly acquired infections and chronic infections relapsing in response to hormonal changes associated with breeding. Evidence of transmission was observed in the single hatching year bird that lacked detectable infection in early summer, but demonstrated a very high intensity infection in late summer. These observations provide supportive evidence that hematozoa infections are acquired on the breeding grounds during the first year of life and relapse during the breeding season in subsequent years.     

Northern fowl mite (Ornithonyssus sylviarum) in Sweden

Haematophagous mites were collected from the vent region and plumage of chickens in six hobby flocks of ornamental breeds in Sweden, one of which included turkeys. Soiled vent skin and feathers, dermatitis, hyperkeratosis, skin necroses and ulcers were observed in 12 necropsied birds from two of the flocks. The mites were identified as the northern fowl mite Ornithonyssus sylviarum (Mesostigmata: Macronyssidae). This was supported by sequence analysis of a 642‐bp region in the mitochondrial cytochrome oxidase subunit 1 (COI) gene (COI) in mites collected from five flocks, which showed 97–99% sequence similarity to O. sylviarum by blast analysis. Pairwise sequence comparisons revealed nucleotide variations in the range of 0–2.8%, whereas amino acid sequences were highly conserved. This paper represents one of very few records of O. sylviarum in European poultry, and is the first to report COI sequence data for O. sylviarum from poultry in Europe.     

Susceptibilities of northern fowl mite,Ornithonyssus sylviarum (Acarina: Macronyssidae), and chicken mite,Dermanyssus gallinae (Acarina: Dermanyssidae), to selected acaricides

The relative toxicities of ten acaricides to northern fowl mite,Ornithonyssus sylviarum (Canestrini and Fanzago), and the chicken mite,Dermanyssus gallinae (De Geer), were determined simultaneously by holding the mites inside disposable glass Pasteur pipettes previously immersed in acetone solutions of various concentrations (w/v) of technical grade acaricides. The LC₉₀s (parts per million) of the acaricides after 24 h exposure for the northern fowl mite and the chicken mite, respectively, were: bendiocarb (13.1, 0.18), tetrachlorvinphos (14.5, 4.07), carbaryl (15.0, 0.83), pirimiphos methyl (18.3, 2.03), permethrin (23.1, 8.46), lambda cyhalothrin (80.7, 11.4), dichlorvos (252.8, 3.75), malathion (238.4, 6.59), amitraz (6741, 9430) and fenvalerate (>10000, 60.2). After 48 h exposure there were only slight increases in mortalities of both species except for increased mortalities for the northern fowl mite with lambda cyhalothrin, amitraz and fenvalerate, and for the chicken mite with amitraz.     

Structural features associated with respiration in some intertidal Uropodina (Acarina: Mesostigmata)

The present study suggests that the peritremes of both Phaulodinychus repleta (Berlese) (Uropo-didae) and Thinozercon michaeli Halbert (Thinozerconidae) are incapable of forming peritreme plastrons in the same manner as the Gamasina or Phaulodinychus mitis (Leonardi) (Uropodidae) described in previous studies. However, it is proposed that extra-peritrematic plastrons may be formed by other structures, for example the pedofossae and legs in P. repleta and the coarse sculpturing on the dorsal surface of the peritrematic shield in T. michaeli , which may trap an airfilm during inundation.     

The structure and probable function of the peritreme in intertidal Gamasina (Acarina: Mesostigmata)

The peritremes of the British intertidal Gamasina are structurally similar to those described for species occurring in soil and leaf litter, the highly elaborate peritreme plastrons present in species occurring in low oxygen tension environments are not typical of the fauna. It is shown that elaborate peritremes can form effective gas gills if an airfilm is supported by the peritrematic slit; however, if the airfilm is supported by the micropapillae on the floor of the peritreme, then the respiratory efficiency of the gas gilhbecomes comparable with that of elaborate peritreme plastrons. Evidence is presented reinforcing the theory that the plastron is supported by the micropapillae. The absence of elaborate respiratory peritreme plastrons among the intertidal Gamasina suggests that these mites are preadapted to respiration during tidal inundation. Other preadaptations include the distal parabolic shape of the micropapillae, however in the plastron forming species the micropapillae are shorter and basally thicker to prevent bending under pressure Developmental trends within the peritremes, with respect to plastron formation are discussed.     

Karyotypes of eight species of phytoseiid mites (Acarina: Mesostigmata) from Madagascar

Haplo-diploidy was found to be regular with eight species of phytoseiid mites occurring in Madagascar. The chromosome number in all species was n=4. A variation was found with respect to centromere position.     

Further studies on karyotypes and sex determination of phytoseiid mites (Acarina: Mesostigmata)

Chromosome studies were made on embryonic tissues of eggs of 15 species of predaceous mites of the family Phytoseiidae belonging to six genera: Amblyseius Berlese, Seiulus Berlese, Typhlodromus Scheuten, Phytoseiulus Evans, Phytoseius Ribaga and Paragigagnathus Amitai et Grinberg. In 14 species, the chromosome numbers n=4, 2n=8 were found. In cytological studies of post-embryonic stages based on these results, the haplo-diploid (arrhenotokous) mechanism was established. In the species Amblyseius deleoni Muma et Denmark, which was found to be thelytokous, only metaphases with 8 chromosomes were found.     

Bewsiella Domrow (Acarina: Mesostigmata): a revision and the description of new species

The genus Bewsiella is considered to comprise a considerable number of species, despite having been regarded as monotypic. The structure of the male spermadactyl is proposed as a key character for separating congeneric species. This character seems likely to bear phylogenetic information on both the mites themselves and their hosts. Since the male of Bewsiella fledermaus Domrow, the type-species, has not been found, it is impossible to define the morphology of this species based on both sexes. Consequently, all mites that share many characters with the female of B. fledermaus are placed in a B. fledermaus species group. B. aelleni (Till) is considered as a valid species and both sexes and the protonymph are redescribed and illustrated. B. nycteris n. sp., B. emballonuris n. sp., B. cloeotis n. sp., B. haradai n. sp. and B. coelopos n. sp. are described and illustrated. The genus Bewsiella was originally allocated to the family Laelapidae and later transferred to the family Macronyssidae. Recently, the genus was returned to the Laelapidae, and some evidence supporting this action was obtained during the present study, but further studies are required for confirmation.     

Laboratory studies of predation by the Antarctic mite Gamasellus racovitzai (Acarina: Mesostigmata)

Summary Laboratory investigations of predation by Gamasellus racovitzai (Acarina: Mesostigmata) on Cryptopygus antarcticus (Insecta: Collembola) are described. The predator appeared to search at random, but, when contact with prey had been made, a rapid attack involved looping the forelegs over the prey to hold it whilst the chelicerae moved forward horizontally to puncture the side of the prey. The mean predation rate by deutonymphs, approximately one prey per predator per 12 days, was independent of prey density, but with adults this rate increased to about one prey per predator per 3 days. A study of leg geometry predicted a maximum prey size that could be captured: some experimental evidence suggested that mites selected prey near to this predicted size. The contribution of the laboratory results towards understanding the dynamics of field populations is discussed.     

Biogeographic distribution of the Phytoseiidae (Acari: Mesostigmata)

More than 1982 species in 90 genera were included in an analysis of the biogeography of the Phytoseiidae, a family of predatory mites. Seven biogeographic regions were taken into account: Nearctic, Neotropical, Ethiopian, West Palaearctic, East Palaearctic, Oriental, and Australasian. The number of species was particularly high in the Neotropical, Oriental, and West Palaearctic regions. These regions also present the highest levels of species endemism. The number of genera was quite similar in all regions except for the Neotropics, which also had a high level of endemism. The possible Gondwanian (Neotropical, Ethiopian, Australasian, and Oriental regions) origin of the Phytoseiidae, most probably in the Neotropics, and their possible radiation to Laurasia (Nearctic, West Palaearctic, and East Palaearctic regions) are discussed. The comparison between genera and species in the different biogeographic regions indicate the importance of both dispersal and vicariance events in the evolution of the group. Dispersal is assumed to have been most important between Neotropical and Nearctic regions and between East Palaearctic and Oriental regions, whereas vicariance could have been the dominating process between Australasian, Ethiopian, and Oriental regions, as well as between West and East Palaearctic regions. A parsimony analysis of endemicity showed the Neotropical and the Nearctic regions to be isolated from the other regions. This is certainly due to a diversification after the continents drifted apart and then a high dispersal between Nearctic and Neotropical regions. Different phylogenetic hypotheses and scenarios are proposed for each subfamily based on the results obtained and further investigations are proposed.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 845–856.     

Housing and dustbathing effects on northern fowl mites (Ornithonyssus sylviarum) and chicken body lice (Menacanthus stramineus) on hens

Hen housing (cage or cage-free) did not impact overall abundances of northern fowl mites, Ornithonyssus sylviarum (Canestrini & Fanzago) (Acari: Macronyssidae), or chicken body lice, Menacanthus stramineus (Nitzsch) (Phthiraptera: Menoponidae). Cage-free hens received a dustbox with sand plus diatomaceous earth (DE), kaolin clay or sulphur. Weekly use varied from none to 100% of hens; 73% of hens used the dustbox at least once. Ectoparasite populations on dustbathing hens (users) were compared with those on non-user cage-free and caged hens. All materials reduced ectoparasites on user hens by 80-100% after 1 week of dustbox use. Diatomaceous earth and kaolin failed to reduce ectoparasites on non-user hens, and ectoparasites on user hens recovered after dustbox removal. A sulphur dustbox eliminated mites from all hens (including non-users) within 2-4 weeks. Residual sulphur controlled mites until the end of the experiment (up to 9 weeks), even after the dustbox was removed. Louse populations on hens using the sulphur dustbox were reduced in 1-2 weeks. Residual sulphur effects were less evident in lice, but the use of a sulphur dustbox by a higher proportion of hens extended louse control to all hens. This is the first experimental study to show that bird dustbathing in naturally and widely available dust materials (particularly kaolin) can suppress ectoparasites and thus the behaviour is probably adaptive.