Molecular methods are becoming increasingly important in systematic acarology. In this review I describe the properties of the ideal molecular marker and compare these with genes that have been used for phylogenetic studies of mites and ticks. The second internal transcribed spacer of the nuclear ribosomal gene cluster (ITS2) and the mitochondrial protein-coding gene cytochrome oxidase I (COI) together provide a powerful tool for phylogenetics at low taxonomic levels. The nuclear ribosomal genes 18S and 28S rDNA are equally powerful tool for phylogenetics at the deepest levels within the Acari. What appear to be lacking are markers that are useful at intermediate levels. The mitochondrial ribosomal genes 12S and 16S rDNA have not lived up to their initial promise. I suggest some nuclear protein-coding genes that may be suitable alternatives. Methods for collection and storage of mites for molecular work, DNA extraction and phylogenetic analysis are also briefly discussed.

To determine the principal vectors of Lyme disease in North China, the capability of I. persulcatus, H. concinna and D. silvarum to transmit Lyme spirochetes transstadially was estimated under laboratory conditions. Results suggest that all three tick species can acquire active Lyme spirochetes by feeding on infected KM mice. However, the three species vary in their ability to maintain spirochetes. Only I. persulcatus can maintain active spirochetes during molting, with subsequent tick stages infectious to innocent KM mice. Haemaphysalis concinna and D. silvarum maintain spirochetes no longer than the digestion period of blood; after molting, no spirochetes were detected in these two tick species. Therefore, I. persulcatus should be considered the principal vector of Lyme disease in North China. The presence of spirochetes in H. concinna and D. silvarum may be tied to co-feeding with I. persulcatus.

The present paper reports the first survey of house dust mites of Panama. Samples of house dust from bedroom floors of 20 houses located in urban and rural areas of La Chorrera, Panama, were examined for the presence of mites. Mites were present in all samples. A total of 9150 mites were isolated and identified as belonging to 21 families, 24 genera and 29 species. We found an average mite density of 1.23 mites/mg dust. Blomia tropicalis (Echimyopodidae) occurred in all the samples examined. All the astigmatid mites we found in urban house dust have been recognized previously as sources of allergens that cause respiratory diseases, but only 71.4 percent of those found in rural areas are known to be allergenic. We present the first record of Glycycometus malaysiensis (Fain & Nadchatram) (Aeroglyphidae) new combination (transferred from Austroglycyphagus) in Panama and the Neotropical region.

During a search for latent vectors of scrub typhus in a focus of the autumn-winter type of this disease, the authors isolated O. tsutsugamushi from larval and nymphal L. linhuaikongense. Isolated O. tsutsugamushi serotyped by indirect immunofluorescence assay (IFA). Larval L. linhuaikongense were initially found in May on the bodies of rodents captured in the field. The infestation reached a peak in August and disappeared in November; chiggers were thus abundant during summer. Nymphal L. linhuaikongense were reared from larvae collected from rodents. Two strains of O. tsutsugamushi were isolated from 4 pools of larvae and 3 pools of nymphs, respectively. This implies that L. linhuaikongense is a potential vector of O. tsutsugamushi, chiefly to rodents but occasionally to humans, during non-endemic seasons.

Separate and combined releases of P. persimilis and N. californicus were tested for the control of T. urticae on greenhouse cut roses under integrated pest management conditions. Release strategies were carried out in separate greenhouses and were not replicated. Mite densities were controlled at regular intervals on 50 single, randomly collected leaves per greenhouse. Natural infestations of 23.9 T. urticae per leaf at the start of the trial were controlled throughout the growing season by the simultaneous, combined release of 26 P. persimilis/m² and 24 N. californicus/ m². Separate releases of each phytoseiid species - 32 P. persimilis/m² at an initial infestation of 0.16 T. urticae per leaf, or 51 N. californicus/m² in total at an initial infestation of 10.2 T. urticae per leaf - failed to adequately suppress spider mite populations. Additional treatments with selective acaricides were required. Reasons for the different control success of the three release strategies and their implications for practical use are discussed.

Arrestment responses to stimuli from Schizotetranychus nanjingensis on bamboo leaves by the predatory mites Typhlodromus bambusae and Amblyseius cucumeris were examined in the laboratory using two-choice tests. Both predator species responded to spider mite females and web-nests, but not to their feces. Furthermore, T. bambusae responded more strongly to intact web-nests than to empty web-nests, whereas A. cucumeris responded more strongly to empty web-nests.

Eotetranychus cendanai Rimando was found on six different citrus species of which one is new host record: Citrus hystrix DC., Citrus aurantifolia Swingle, Citrus reticulata Blanco, Citrus maxima (Burm. f.) Merr., Citrus madurensis Lour. (new record) and Murraya paniculata (Linn.) Jack in 34 provinces of Thailand. Studies on life history of E. cendanai on 5 different host plants were conducted at 28±1 °C and 58±5 % RH. The egg, larva, protonymph and deutonymph stages on 5 different host plants ranged 4.9–5.8, 1.9–3.0, 1.9–2.6 and 1.8–2.7 days, respectively. Completion of the life cycle required 11.2–14.0 days. A fertilized female lived 6.55–10.52 days and produced 6.30–26.38 eggs (0.96–2.43 eggs/day). Fertilized females produced offspring with a sex ratio of male: female 1:1.02–1:2, whereas unfertilized females produced only male offspring. Longevity of an unfertilized female lasted 7.52–11.62 days and 14.35–17.73 eggs (1.40–1.97 eggs/day) were laid per female. A life table study of E. cendanai indicated that net reproductive rate of increase (R_o) = 14.1 times, cohort generation time (T_c) = 17.37 days, intrinsic rate of increase (r_m) = 0.156 individual/day and finite rate of increase (λ) = 1.165. Major mortality occurred during the larval stage followed by the nymphal and egg stages.

Observations on the development, survivorship and reproduction of Tetranychus piercei McGregor reared on fresh banana leaves were conducted at 16, 20, 24, 28, 32 and 36°C. The developmental time from egg to adult varied from 7.2 d at 32°C to 33.1 d at 16°C. The developmental threshold temperatures of egg, larva, protonymph, deutonymph, preoviposition and a whole generation were 11.2, 9.8, 11.9, 12.5, 13.3 and 10.7°C, respectively. The effective accumulated temperatures were 72.3, 33.6, 22.2, 27.8, 17.7 and 163.6 day-degrees, respectively. Within the range of 16 to 36°C, the relationships between developmental and survival rates of all immature stages, average number of eggs/female, longevity of adults and temperatures showed parabolic trends. Survival rate was the highest (96.1%) at 32°C; whereas at 36 and 16°C it decreased to 79.1 and 66.4%, respectively. The highest number of eggs (35.8 eggs/female) was recorded at 28°C; and the lowest at 16°C (17.9 eggs/female). Female longevity was the longest (34.5 d) at 20°C and the shortest (8.2 d) at 36°C. The net reproductive rate (R0) was the highest (23.6525) at 28°C and the lowest (5.1044) at 36°C. The intrinsic rate of increase (rm) and finite rate of increase (l) reached maximal values (0.3488 and 1.4174 respectively) at 32°C, whereas minimal values (0.0724 and 1.0752 respectively) were at 16°C. The mean generation time and time for population doubling were the shortest at 36 and 32°C, respectively, which were 7.2192 d and 1.9871 d. The highest population trend index (25.28) was obtained at 28°C and the lowest (4.88) at 36°C. These population parameters and population trend indices increased with temperatures in a parabolic function. The results suggest that T. piercei could develop and reproduce within a wide range of temperatures, and that temperatures from 25.8–32°C are the most suitable conditions for the development, survival and reproduction of the mite.

Experiments were conducted at Ibadan, Nigeria to assess the effect of leaf trichome characteristics (pubescence intensity index, length, and orientation) on field resistance of cassava to the green spider mite, Mononychellus tanajoa (Bondar). There were significant (P < 0.01) differences in M. tanajoa density, damage score and leaf trichome characteristics among the cultivars. During the dry season (February, 1993 and 1994) and the early part of the rainy season (May, 1993), there were significant (P < 0.01) negative correlations between pubescence intensity index on the top leaves (leaf 3) and mite damage. Significant negative correlations were also obtained between trichome length and damage in the dry season (February, 1993) (P < 0.05), and between trichome orientation and mite damage in the rainy season (May, 1993) (P < 0.01). Correlation between pubescence intensity index and mite density on the top leaves was significant and positive only in the “middle” of the rainy season (August, 1993). A significant (P < 0.01) negative correlation was obtained between trichome orientation and mite density in the dry season (February, 1993). The results suggest that, during the dry season, a high pubescence intensity significantly reduces leaf damage by M. tanajoa through mechanical disturbance of movement and feeding. Trichome length is more important than trichome orientation in cassava resistance to M. tanajoa.

Morphological methods of distinguishing the adult and larval stages of the ticks Ixodes cornuatus and I. holocyclus were examined, using specimens whose identity had been determined using multilocus enzyme electrophoresis. Individual morphological characters identified most, but not all specimens. The only character which unequivocally distinguished males of the two species was the shape of the epimeral plate. Statistical analyses of metric characters revealed significant differences between the two species and among populations of I. holocyclus. However, no single metric character permitted unequivocal identification of all specimens. Discriminant function analyses were employed, resulting in the differentiation of all specimens of both males and females of the two species. In the larval stages, the numbers of marginal dorsal setae and supplementary setae, as well as the lengths of posterior marginal dorsal setae, allowed identification of the two species. The results highlight the advantages of utilising morphological methods in conjunction with genetic techniques to provide markers for accurate identification and characterisation in instances in which taxonomic confusion exists.

Amblyomma auricularium and Amblyomma pseudoconcolor are recorded for the first time in Uruguay parasitizing Dasypus hybridus. These are the first records of ixodids from dasypodids in this country.

Parasitus mycophilus Karg, previously known only from the adult male, is newly recorded from the British Isles and Iceland. The male of the species is redescribed, and the male and female deutonymph described for the first time. A morphological account of a specimen suspected to be a female of P. mycophilus is also given. Rhabdocarpais parvus Athias-Henriot is newly synonymized with P. mycophilus.

The generic characters of Asperoseius are revised and three species from China, including one new species (Asperoseius paraheveae sp.nov.) and two new combinations, are reported. A key to Chinese species is also given.

The family Crotalomorphidae, fam. nov., with type genus Crotalomorpha, gen. nov., are described to validate these names, the previous usage of which was based on nomenclatorially unavailable names. This monobasic family and genus is based on three physogastric, gravid females representing the type species, Crotalomorpha camini sp. nov., collected from beneath the elytra of harpaline carabid beetles of the subgenus Agonoderus, genus Stenolophus, in Kansas and Nebraska, USA. The unique mixture of primitive and derivative characteristics of this taxon and its relationships among others of the cohort Heterostigmata are discussed, and a rationale for considering Crotalomorphidae as the sister group of Dolichocybidae is presented.

One new species of the genus Parabonzia Smiley and one new species of Neoscirula Den Heyer are described and illustrated. Parabonzia zhangi sp. nov. was found in soil in a hole in the tree Platanus hispanica Muenchh in Yichang city, Hubei province, while Neoscirula saitoi sp. nov. was collected on the bark of P. hispanica in Shunchang county, Fujian province. Types were deposited in the collection of Plant Protection Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou 350013, China.

The systematic status of the genus Summersiella Gonzalez is reviewed and a revised definition is proposed. A new species, Summersiella camphorae, from the leaves of camphor tree (Cinnamomum camphora) in Fujian Province of China, is described and illustrated. This new species is distinguished from the only known species, Summersiella coprosmae (Wood), by having an apparently sclerotized hexagonal central hysterosomal shield with five pairs of setae; by having much shorter dorsal setae (ve not exceeding base of sci); by the following ratios: vi/vi-vi = 0.7, ve/ve-sci = 1.0; and by the length of solenidion w on tarsus I (19–21 µm).

Neophyllobius pistaciae Bolland & Mehrnejad is reported for the first time from the west of Iran and three new species, N. astragalusi, N. persiaensis and N. camelli, are illustrated and described. A key to the Iranian Neophyllobius species is given.

A new species, Austroteneriffia kamalii, is described. This is the first record of the family Teneriffiidae from Iran. A revised key to the Austroteneriffia species of the world is given.

Pollux kovalamicus sp. nov. (Acari: Prostigmata: Erythraeidae) is described and illustrated based on larvae from South India.

Leptus hospeticus sp. nov. from India and L. laviniacus sp. nov. (Acari: Prostigmata: Erythraeidae) from Sri Lanka and India are described and illustrated. L. astrubali Haitlinger is reported for the first time from India. Two keys to some species of Leptus are provided.

Southcottella nematii gen. et sp. nov. (Acari: Neothrombiidae) is described and illustrated from larvae ectoparasitic on adults of Gryllus domesticus L. (Orthoptera: Gryllidae) from Ahwaz, Iran. A key to genera of Neothrombiidae of the world (larva) is presented.

The family Walchiidae, one of three families of the superfamily Trombiculoidea sensu Wen, contains two subfamilies: Walchiinae sensu Wen and Gahrliepiinae sensu Wen. The subfamily Walchiinae may be further separated into two tribes: Walchiini and Schoengastielliini. Members of the tribe Walchiini are small to medium sized sand-mites with IP=344–800 and the following features: the scutum ranging from very small to medium size, pentagonal or short tongue-shaped, with uniform punctae but without scrobiculae and with only two pairs of scutal setae consistently (fSc=2AL 2PL), without accessory setae; sensillae expanded; SIF=4B/5B-N/B-3/ 2-2(1)1(0)1(0)0.0000; leg segments fSP=7.6.6 wihtout variation; pedogenualae fg(s)=2.1.1 in most species; fcx=1.1.1 or 1.1.2 in most species, but a few species with 3–6 coxalae III; some species characterized by one of hair-like claws reduced on each leg. Currently, the Walchiini contains 92 nominated species in 2 genera and 15 subgenera (including Wenia sg. n. and Zhangzia sg. n.). The genus Walchia is characterized by fT=4B and acuminated posterior angle, rarely rounded, whereas the genus Ripiaspichia is distinguished by fT=5B and rounded posterior margin. Hosts of the Walchiini are chiefly small ground rodents, insectivores and lagomorphs, rarely bats, deers and horses, and occasionally reptiles. They are pale coloured host-burrow dwellers. Two subgenera, Fainiella and Traudia, are intranasal parasites. Walchiiine sand-mites are essentially confined to the Old World, the largest number of species having been recorded from Southeast Asia. As yet, this tribe has not been reported from the Neotropical Region. A key to the genera and subgenera of the Walchiini is given.

A new species of the subgenus Digenualea of the genus Neotrombicula Hirst was described from Myospalax baileyi Pallas in Huzhu County, Qinghai Province, China.