Prelude to a study of the feather mites of Australia (Acariformes: Astigmata)

This paper reviews the state of knowledge of the feather mites of Australia (Arachnida: Acariformes: Astigmata). The known fauna includes 149 species arranged in 95 genera and 24 families, in the Superfamilies Analgoidea and Pterolichoidea. A checklist of the fauna is provided, including bibliographic details for every species and genus. The bird host and collecting localities are listed for every species, and taxonomic and nomenclatural problems are discussed where necessary. The total fauna may include as many as 800 undescribed species. The checklist is preceded by a brief review of some aspects of the biology of feather mites, which have not been studied in the context of the Australian fauna.The correct spelling for a family of respiratory tract parasites is confirmed as Kytoditidae. Dabertia indistincta (Dabert & Atyeo, 1993) comb. n. (Syringobiidae) and Hemialges australis (Trouessart, 1885) comb. n. (Analgidae) are new combinations proposed herein.

Landscapes within landscapes: A parasite utilizes different ecological niches on the host landscapes of two host species

Parasites are distributed across populations of hosts, but also across microhabitats on or inside hosts: together the host population distribution and "host landscape" distribution comprise a part of the ecological niche of a parasite. In this paper we examine how a generalist parasite, the tick Ixodes holocyclus, is distributed at both the host population and host landscape scales in two species of host (Perameles nasuta and Rattus rattus) that co-occur. We anaesthetized wildlife to locate ticks from five generalized host body regions; we then analysed the distribution of ticks among the populations of hosts (aggregation) and the distribution of ticks among the available host body regions as niches. Ixodes holocyclus is more aggregated in the R. rattus population. At the host landscape scale, I. holocyclus's utilized niche includes the entire surface of P. nasuta equally, while the niche on R. rattus is focused on the head. Differences in tick aggregation between host species may reflect tick habitat suitability at the host landscape scale, as well as differences in ecological and evolutionary histories. By exploring the distribution of parasites at multiple scales, including host landscapes, we can better understand the complex ecology of parasites.

Feather mites (Acari: Astigmata) of captive Psittaciformes in Brazil

ABSTRACT Feather samples were obtained from the following Psittaciformes birds: Amazona amazonica, Amazona aestiva, Aratinga jandaya, Brotogeris spp., Ara ararauna and Ara chloropterus (total of 37 individuals). These birds were housed at the Wild Animal Screening Center of Maranhão, São Luís, Brazil. Four feathers were taken from the following regions: head, back, wings, belly/breast, thighs, and tail/covert. Mites were found on 17 birds (45.94%). Astigmatid mites belonging to the genera Fainalges (Xolalgidae), Chiasmalges (Psoroptoididae) and Tanyaralichus (Pterolichidae) were identified. The highest dominance coefficient was for the mite Fainalges sp. (DC= 96.29). Chiasmalges sp. was obtained only from Ara chloropterus, and Tanyaralichus was found in A. aestiva. The genus Fainalges was obtained from all the species of Psittaciformes studied, except for A. ararauna. In evaluating mite density according to body region, statistical differences were found between the back and wing regions (P= 0.041), back and thighs (P= 0.02), wings and tail (P= 0.002), belly and tail (P= 0.031) and thighs and tail (P= 0.001). The morphological variations observed in Fainalges spp. suggested the existence of three species that probably have not been described yet. This was the first record of the genus Tanyaralichus in Brazil.

Evaluation of Proctophyllodes huitzilopochtlii on feathers from Anna's (Calypte anna) and Black-chinned (Archilochus alexandri) Hummingbirds: Prevalence assessment and imaging analysis using light and tabletop scanning electron microscopy

Proctophyllodes huitzilopochtlii Atyeo & Braasch 1966 (Acariformes: Astigmata: Proctophyllodidae), a feather mite, was found on feathers collected from five hummingbird species in California. This mite has not been previously documented on feathers from Anna’s (Calypte anna [Lesson 1829]) or Black-chinned (Archilochus alexandri [Bourcier & Mulsant 1846]) Hummingbirds. A total of 753 hummingbirds were evaluated for the presence of mites by species (Allen’s n = 112; Anna’s n = 500; Black-chinned n = 122; Rufous n = 18; Calliope n = 1), sex (males n = 421; females n = 329; 3 unidentified), and age (juvenile n = 199; after-hatch-year n = 549; 5 unidentified). Of these 753 hummingbirds evaluated, mites were present on the rectrices of 40.9% of the birds. Significantly more Anna’s Hummingbirds were positive for rectricial mites (59.2%) compared with 8.2% of Black-chinned, 0.9% of Allen’s, 5.6% of Rufous Hummingbirds, and 0% for Calliope (p-value < 0.0001). Across all hummingbird species, male hummingbirds (44.9%) had a higher prevalence of rectricial mites compared to female hummingbirds (36.2%; p-value = 0.004), while juvenile hummingbirds (46.2%) had a non-significantly higher prevalence compared to after-hatch-year hummingbirds (39.0%; p-value = 0.089). On average, the percentage of the long axis of the rachis occupied by mites for the outer rectrices (R4 and R5) was 19%, compared to 11% for inner rectrices (R1 and R2), a significant difference (p-value = <0.0001). There was a marginal lack of significance for symmetrical distribution of tail mites with the mean left side percentage of long axis of the rachis occupied by mites being 16% and very close to the mean right side score of 18% (p-value = 0.003). The identification of the feather mite species was based on light microscopic morphometry, and mite distribution on feathers was further evaluated using tabletop scanning electron microscopy (TSEM). The hummingbird–feather mite relationship is not well understood, but the specialized TSEM technique may be especially useful in examining natural positioning and developmental aspects of the mites since it allows in situ feather examination of live mites.

Different scales of spatial segregation of two species of feather mites on the wings of a passerine bird

The "condition-specific competition hypothesis" proposes that coexistence of 2 species is possible when spatial or temporal variations in environmental conditions exist and each species responds differently to those conditions. The distribution of different species of feather mites on their hosts is known to be affected by intrinsic host factors such as structure of feathers and friction among feathers during flight, but there is also evidence that external factors such as humidity and temperature can affect mite distribution. Some feather mites have the capacity to move through the plumage rather rapidly, and within-host variation in intensity of sunlight could be one of the cues involved in these active displacements. We analyzed both the within- and between-feather spatial distribution of 2 mite species, Trouessartia bifurcata and Dolichodectes edwardsi , that coexist in flight feathers of the moustached warbler Acrocephalus melanopogon. A complex spatial segregation between the 2 species was observed at 3 spatial levels, i.e., "feather surfaces," "between feathers," and "within feathers." Despite certain overlapping distribution among feathers, T. bifurcata dominated proximal and medial regions on dorsal faces, while D. edwardsi preferred disto-ventral feather areas. An experiment to check the behavioral response of T. bifurcata to sunlight showed that mites responded to light exposure by approaching the feather bases and even leaving its dorsal face. Spatial heterogeneity across the 3 analyzed levels, together with response to light and other particular species adaptations, may have played a role in the coexistence and segregation of feather mites competing for space and food in passerine birds.

Adaptive host-abandonment of ectoparasites before fledging? Within-brood distribution of nest mites in house sparrow broods

We studied the within-brood distribution of a haematophagous mite Pellonyssus reedi living on nestling house sparrows (Passer domesticus) near the time of fledging. We measured the natural level of infestation of individual nestlings, and determined the feeding efficiency of mites, by scoring their feeding status. Within-brood distribution of mite loads was unrelated to nestling body mass, tarsus length, or immunocompetence. These results did not support parasite preference for large or susceptible hosts. Mite feeding-efficiency was also unrelated to these nestling characteristics, confirming that large nestlings or nestlings with less-developed immunocompetence did not provide superior feeding conditions for mites. Therefore, our results do not support the hypothesis that within-brood distribution of avian ectoparasites is explained by the parasites' preferences for characteristics, such as large body size or low immunocompetence, that make nestlings suitable hosts. On the other hand, we found that mite loads were negatively correlated with nestling age and feather length, suggesting that nestlings closer to fledging harbored fewer mites then their less-developed nestmates. Furthermore, feather length had a stronger relationship with parasite distribution than did nestling age. We presume, therefore, that feather characteristics, i.e., length, may serve as a signal for mites to perceive the ready-to-fledge state of nestlings, inducing abandonment behavior. These results support another, largely neglected hypothesis, i.e., that the avoidance or abandonment of those nestlings that are close to fledging may also explain the parasites' distribution in a brood. This hypothesis is based on the argument that many nest-dwelling ectoparasites breed in the nest material and emerge only periodically to feed on nestlings. In such parasites, the ability to recognize and avoid mature fledglings can be adaptive because this may help the parasites to avoid their removal from the nest so they can continue to reproduce by feeding on unfledged chicks of the current or later broods. Our results suggest that adaptive host-abandonment by nest-dwelling ectoparasites can influence within-brood parasite distributions around the time of fledging.