Barry M. OConnor

Biology, ecology, and management of the bulb mites of the genus Rhizoglyphus (Acari : Acaridae)

Bulb mites of the genus Rhizoglyphus (Claparède) (Acari: Acaridae) have been identified as pests of many crops and ornamentals in storage, in the greenhouse, and in the field. The most importanthosts are species in the family Liliaceae (e.g. Allium spp.), but bulb mites will often attack otherimportant crops such as potatoes (Solanum sp.) and carrots (Daucus carota). Despite their economicimportance and broad distribution, the systematics of the genus remains in a state of confusion and is inneed of a comprehensive revision. In addition, the field biology and ecology of these mites is not wellunderstood, and methods for sampling, monitoring, and loss assessment are limited. Management of bulbmites is complicated by their short generation time, high reproductive potential, broad food niche,interactions with other pests and pathogens, and unique adaptations for dispersal. Historically, control ofthese acarine pests has relied on the use of synthetic miticides and insecticides, but this option is nowlimited due to documented resistance and withdrawal of registration of some products. Alternativecontrol strategies, including cultural and biological control, have shown limited success, but need to befurther developed and implemented.

MITES ASSOCIATED WITH THE SMALL GROUND FINCH, GEOSPIZA FULIGINOSA (PASSERIFORMES: EMBERIZIDAE), FROM THE GALÁPAGOS ISLANDS

In collections of ectoparasites from 368 small ground finches, Geospiza fuliginosa, in populations from the islands of Isabela, Santa Cruz, San Cristóbal, and Santa Fé, in the Galápagos Archipelago, Ecuador, we found 8 species of mites. Four mite species were common on all islands sampled, i.e., Mesalgoides geospizae Mironov and Pérez (Psoroptoididae), Xolalges palmai Mironov and Pérez (Xolalgidae), and 2 new species, Trouessartia geospiza n. sp. (Trouessartiidae) and Proctophyllodes darwini n. sp. (Proctophyllodidae). Four other species were represented by single collections from G. fuliginosa, i.e., Pterodectes atyeoi n. sp. (Proctophyllodidae), Strelkoviacarus sp. (Analgidae), Dermoglyphus sp. (Dermoglyphidae), and Dermanyssus sp. (Dermanyssidae). Authorship of new species names is attributed to the 3 authors who prepared the descriptions (B.M.O.C., J.F., D.L.). Trouessartia geospiza and P. atyeoi were also found on previously collected specimens of other Geospiza species in museum collections. For the 4 common species, we found no differences in prevalence among the 4 island populations, but infection prevalence differed among the 4 species. The mean infection prevalence was high for T. geospizae (89%), moderate for M. geospizae (58%) and X. palmai (44%), and low for P. darwini (26%) in all populations. The feather mite fauna of G. fuliginosa was similar to that of other Geospiza species, and generally related to communities found on other emberizid finches.

Origin and higher-level relationships of psoroptidian mites (Acari: Astigmata: Psoroptidia): Evidence from three nuclear genes

Phylogenic relationships of the Psoroptidia, a group of primarily parasitic mites of vertebrates, were investigated based on sequences from three nuclear genes (4.2 kb aligned) sampled from 126 taxa. Several morphological classification schemes and a recent molecular analysis, suggesting that the group may not be monophyletic were statistically rejected by newly generated molecular data, and the results are robust under a range of analytical and partition strategies. Six families Psoroptidae, Lobalgidae (mammalian parasites), Pyroglyphidae (house dust mites and parasites inside feather calamus), Turbinoptidae (upper respiratory track parasites of birds), Psoroptoididae (downy feather mites), and Epidermoptidae (skin parasites of birds) form a well-supported monophyletic group (the epidermoptid-psoroptid complex). These relationships, recovered by combined and separate analyses of all gene partitions, were previously suspected based on some morphological evidence, but evidence has been dismissed as resulting from convergence based on similar parasitic ecologies. The existence of the epidermoptid-psoroptid complex and the statistical rejection of Sarcoptoidea (the morphology-based group joining all mammal-associated mites) indicate that current classification criteria, influenced as they are by host preferences, need to be reassessed for non-pterolichoid superfamilies. However, two of our findings remain sensitive to analytical methods and assumptions: (i) the families Heterocoptidae and Hypoderatidae as the first and second closest outgroups of Psoroptidia, respectively, and (ii) the superfamily Pterolichoidea (including Freyanoidea) forming a sister clade to the remaining psoroptidian superfamilies. Our findings suggest that (i) house dust mites (Pyroglyphidae: Dermatophagoidinae) originated from a parasitic ancestor within the core of Psoroptidia, violating a basic principle of evolution that it is virtually impossible for a permanent parasite to become free-living, and (ii) there were at least two shifts from presumably avian to mammalian hosts.

Multivariate Analysis of Morphological Variation in Two Cryptic Species of Sancassania (Acari: Acaridae) from Costa Rica

Abstract Populations of Sancassania mites were collected in Costa Rica from scarabaeid and passalid beetles and cultured. The populations proved to be reproductively incompatible due to postzygotic isolation and show 1.4% difference in domains 2 and 3 of the 28S nuclear rDNA gene, indicating the populations represent distinct species. Because the mites were virtually indistinguishable morphologically, 61 morphological characters of 50 females and 101 characters of 60 deutonymphs of the two species were analyzed. Traditional univariate morphometrics could not separate them. Multivariate analyses of variance (principal component and discriminant function) were used to interpret morphological differences between the two species in relation to factors that influence their morphology in a laboratory and field setting. Principal component analyses were done on size and shape as well as shape variables alone. The discriminant function analysis was done on a reduced subset of shape variables. In both cases, the shape analyses resulted in complete separation of the two species and the characters contributing strongly to the discrimination were used in formal description of the two species, Sancassania salasi sp. nov. and S. ochoai sp. nov. Although deutonymphs of S. salasi taken from field-collected beetles show a significantly smaller magnitude of size variation, they show significant deviation in shape compared with cultured deutonymphs of the same species, a potential problem for correlation of specimens of other Sancassania species from culture and nature. Characters that provide the strongest contribution to these intraspecific shape changes are, therefore, taxonomically unreliable.

Improved tRNA prediction in the American house dust mite reveals widespread occurrence of extremely short minimal tRNAs in acariform mites.

BackgroundAtypical tRNAs are functional minimal tRNAs, lacking either the D- or T-arm. They are significantly shorter than typical cloverleaf tRNAs. Widespread occurrence of atypical tRNAs was first demonstrated for secernentean nematodes and later in various arachnids. Evidence started to accumulate that tRNAs of certain acariform mites are even shorter than the minimal tRNAs of nematodes, raising the possibility that tRNAs lacking both D- and T-arms might exist in these organisms. The presence of cloverleaf tRNAs in acariform mites, particularly in the house dust mite genus Dermatophagoides, is still disputed.ResultsMitochondrial tRNAs of Dermatophagoides farinae are minimal, atypical tRNAs lacking either the T- or D-arm. The size (49-62, 54.4 ± 2.86 nt) is significantly (p = 0.019) smaller than in Caenorhabditis elegans (53-63, 56.3 ± 2.30 nt), a model minimal tRNA taxon. The shortest tRNA (49 nt) in Dermatophagoides is approaching the length of the shortest known tRNAs (45-49 nt) described in other acariform mites. The D-arm is absent in these tRNAs, and the inferred T-stem is small (2-3 bp) and thermodynamically unstable, suggesting that it may not exist in reality. The discriminator nucleotide is probably not encoded and is added postranscriptionally in many Dermatophagoides tRNAs.ConclusionsMitochondrial tRNAs of acariform mites are largely atypical, non-cloverleaf tRNAs. Among them, the shortest known tRNAs with no D-arm and a short and unstable T-arm can be inferred. While our study confirmed seven tRNAs in Dermatophagoides by limited EST data, further experimental evidence is needed to demonstrate extremely small and unusual tRNAs in acariform mites.

The mite community associated with Xylocopa latipes (Hymenoptera: Anthophoridae: Xylocopinae) with description of a new type of acarinarium

Abstract Seven species of phoretic mites were collected from museum specimens of Xylocopa latipes from Indonesia: Dinogamasus perkinsi, Hypoaspis greeni, Cheletophyes apicola, Tarsonemus platynopodae, Sennertia hipposiderus, S. koptothorsomae and Horstia helenae. In addition to the abdominal acarinarium housing D. perkinsi and other species, this and certain other palaeotropical Xylocopa species possess a pair of acarinaria formed by invaginations of the lateral mesoscutum and mesoscutellum. In X. latipes, these acarinaria housed only C. apicola. The evolutionary ecology of this community is discussed.

New records of Acari from the sub-Antarctic Prince Edward Islands

Abstract Sixty species of Acari are recorded from the sub-Antarctic Marion and Prince Edward Islands (the Prince Edward archipelago). Twenty of the 45 species collected on recent expeditions are new and currently undescribed. Other new taxa include a family of Mesostigmata, four new genera, and the first sub-Antarctic records of Cillibidae (Mesostigmata) and Eryngiopus (Prostigmata). Fifteen of the 31 species previously reported from the islands are confirmed, although eight of the previous accounts remain doubtful. The fauna, which shows a distinction between the shoreline and terrestrial components, comprises endemic, South Indian Ocean Province and sub-Antarctic mite species.

MUSEUM SPECIMENS AND PHYLOGENIES ELUCIDATE ECOLOGY'S ROLE IN COEVOLUTIONARY ASSOCIATIONS BETWEEN MITES AND THEIR BEE HOSTS

Abstract Coevolutionary associations between hosts and symbionts (or parasites) are often reflected in correlated patterns of divergence as a consequence of limitations on dispersal and establishment on new hosts. Here we show that a phylogenetic correlation is observed between chaetodactylid mites and their hosts, the long-tongued bees; however, this association manifests itself in an atypical fashion. Recently derived mites tend to be associated with basal bee lineages, and vice versa, ruling out a process of cospeciation, and the existence of mites on multiple hosts also suggests ample opportunity for host shifts. An extensive survey of museum collections reveals a pattern of infrequent host shifts at a higher taxonomic level, and yet, frequent shifts at a lower level, which suggests that ecological constraints structure the coevolutionary history of the mites and bees. Certain bee traits, particularly aspects of their nesting behavior, provide a highly predictive framework for the observed pattern of host use, with 82.1% of taxa correctly classified. Thus, the museum survey and phylogenetic analyses provide a unique window into the central role ecology plays in this coevolutionary association. This role is apparent from two different perspectives—as (a) a constraining force evident in the historical processes underlying the significant correlation between the mite and bee phylogenies, as well as (b) by the highly nonrandom composition of bee taxa that serve as hosts to chaetodactylid mites.

Astigmatid mites (Acari: Sarcoptiformes) of forensic interest

This paper reviews the occurrence of mites of the infraorder Astigmata in situations involving the legal system, particularly in the area of medicocriminal entomology. Species in the families Acaridae, Lardoglyphidae and Histiostomatidae are encountered in stored food products and in vertebrate carrion, including human remains. Some of these species are incidentals, whereas others are obligate necrophages. Phoretic associations between these mites and insects allows for rapid dispersal and colonization of such patchy resources.

MITES AND NEMATODES ASSOCIATED WITH THREE SUBTERRANEAN TERMITE SPECIES (ISOPTERA: RHINOTERMITIDAE)

Abstract Mites and nematodes associated with three subterranean termite species, Reticulitermes flavipes (Kollar), Reticulitermes virginicus (Banks), and Coptotermes formosanus Shiraki were studied. Mites belonging to 8 families were found associated with the three termite species. Australhypopus sp. (Acari: Acaridae) was the most common mite on R. flavipes and R. virginicus. Histiostoma formosana Phillipsen and Coppel (Acari: Acaridae) was the dominant mite species living on C. formosanus. Nematode, Rhabditis sp. (Rhabditida: Rhabditidae) was found in the three termite species examined. Nematodes did not cause termite mortality or abnormal behavior. Percentages of R. flavipes, R. virginicus, and C. formosanus parasitized by nematodes were 67.9, 38.8, and 3.3%, respectively. The nematodes were found mainly in the termite heads (85.8% in R. flavipes and R. virginicus). The abundance of mites varied with colonies and termite species. Australhypopus sp. occurred in large numbers when injured or dead termites are present, or when moisture of the rearing medium is low in R. flavipes and R. virginicus colonies. Histiostoma formosana and Cosmoglyphus absoloniSam i ák occurred in large numbers in C. formosanus colonies. Australhypopus sp. was tested against R. flavipes in the laboratory. It did not cause significant termite mortality at a rate of 10 mites/termite. From a biological point of view, mites investigated were not good candidates for controlling termites.