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.

Youki K Yamasaki,Janet E Foley,Patricia E Kysar,Lisa A Tell,Mary H Straub,Barry M Oconnor,Robin S Houston,Emily E Graves,Gregorio Moreno-Rueda

doi:10.1371/journal.pone.0191323

Abstract

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.

Highlights

Evaluating host-mite relationships is important when studying wild bird populations
The same authors reported specimens from an unidentified hummingbird from California [11]. This mite species was later reported from Chlorostilbon lucidus (Shaw 1812) [12] and Amazilia fimbriata (Gmelin 1788) [13] in Brazil, Amazilia rutila in El Salvador [11,14] and Sephanoides sephanoides (Lesson 1827) in Chile [15], greatly increasing the known geographical range of the mite on hummingbird hosts
Males tended to have a higher prevalence of rectricial mites (44.9% of n = 421) than females (36.2% of n = 329) (X-squared = 8.2368, df = 1, p-value = 0.004) and juveniles tended to have higher prevalence (46.2% of n = 199) than after-hatch-years (39.0% of n = 549), the difference was not significant (Xsquared = 2.884, df = 1, p-value = 0.089)

Summary

Introduction

Evaluating host-mite relationships is important when studying wild bird populations. Most of the literature reports for mites found on hummingbirds have predominantly been systematics studies, while hummingbird-mite ecological relationships remain relatively understudied [1]. Sarcoptiform mites in the group Psoroptidia (Astigmata) have been reported from numerous birds and include mite species whose effects on the host range from pathological (e.g. scaly-leg and depluming mites, intranasal and air sac mites), moderately damaging (skin surface feeders) to generally commensal (most feather mites on vanes) or even potentially mutualistic (feather mites that may consume potential microbial or fungal pathogens) [2]. Given this wide range of host-mite relationships, studies evaluating hummingbird-mite interactions will further our knowledge base for these avian pollinators. This mite species was later reported from Chlorostilbon lucidus (Shaw 1812) [12] and Amazilia fimbriata (Gmelin 1788) [13] in Brazil, Amazilia rutila in El Salvador [11,14] and Sephanoides sephanoides (Lesson 1827) in Chile [15], greatly increasing the known geographical range of the mite on hummingbird hosts

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