The effects of juvenile hormone III (JH III) on the premolting period and mortality of nymphal Haemaphysalis longicornis, and 2,6-dichlorophenol (2,6-DCP) synthesis in its female were determined. Nymphs were treated topically with 1, 5 and 10 μg/tick JH III on day 2 (2-PE), day 7 (7-PE), and day 10 (10-PE) post engorgement. The premolting periods of nymphs were prolonged by all doses in nymphs of the 2-PE group, but were normal in those of the 7-PE and 10-PE groups. With the increase of doses, the mortality rose in all groups. Inoculation of JH III on newly molted females enhanced the level of 2,6-DCP synthesis. Our results suggest that JH III is involved in the regulation of nymphal development and synthesis of 2,6-DCP in females of this tick species.

Resistant strains of Tetranychus viennensis Zacher were selected and developed in the laboratory by treating the basic strains collected from several peach trees on the campus of Gansu Agricultural University with omethoate, fenpropathrin and propargite. The rate of resistance development after 15 sprays was the quickest in the fenpropathrin-resistant (FR) strain (192-fold increase), the second in the propargite-resistant (PR) strain (130-fold increase) and the slowest in the omethoate-resistant (OR) strain (31-fold increase). Tests on crossresistance to 14 insecticides among the three resistant strains show that OR strain had no cross-resistance to fenpropathrin (the resistance factor, RF LC₅₀ (R)/LC₅₀ (S) 0.7) and bifenthrin (RF 0.89), but had cross-resistance to monocrotophos (RF 13.2), quinalphos (RF 16.5) and isocarbophos (RF 16.9), FR strain had cross-resistance to bifenthrin (RF8.1), cyhalothrin (RF18.4) and quinalphos (RF 6.7), but no cross-resistance to pyridaben (RF 0.71) and slight cross-resistance to dicofol (RF4.9), PR strain had no cross-resistant to cyhalothrin (RF 0.9) and yamanchun (RF 0.93), but had cross-resistance to quinalphos (RF 6.7).

In order to establish the most sensitive and specific method in the detection of Rickettsia tsutsugamushi in Leptotrombidium deliense, mice and patients, a comparative study on DNA extraction, PCR, hybridization and PCR-hybridization was conducted. The results showed that the sensitivity of PCR-hybridization was 10 times higher than that of PCR and 1000 times higher than that of hybridization. Quick DNA extraction method could take the place of phenol-chloroform method to prepare DNA template when detecting the rickettsiae in mice and patients' blood by PCR. De-inhibitor quick DNA extraction method could improve the detection rate of rickettsiae from chigger mites.

The morphometry of midgut digestive cells of female Ixodes sinensis Teng after infesting rabbits with or without special immunity were analyzed by stereological methods. The DNA content of the cells was also determined by an image analyzer to explore the mechanism of host immunity against tick. The results showed that the midgut of ticks feeding on vaccinated animals enlarged with its wall thickened, the number and volume of digestive cells increased, and the DNA content rose along with the progression of tick feeding. In the group of the second infestating ticks (SI), changes of midgut were not as evident as those in the first infesting group (FI). It is suggested that the host rabbit can produce immune responses against the tick after its infestation causing destruction and exfoliation or inhibited proliferation of digestive cells in ticks. The normal digestive physiology of ticks in those immunized groups, especially in the 105kDa purified whole tick antigen vaccinated animal group (PA), was not as evident as those in the adjuvant control group (AC). The sectional number of digestive cell was reduced to less than 1/2 of that of AC group. The intensity of resistance to tick infestation was in the order PA>MA>SGA>CA. The results from the egg antigen group (EA) were similar to those of the AC group. All these indicated that the infestation of I. sinensis could induce effective resistance of the host against the tick by destroying its midgut digestive cells. Vaccination by antigens, i.e. 105kDa purified whole tick antigen, midgut antigen, salivary gland antigen, and crude whole tick antigen but not egg antigen, produced specific resistance against infestation. The 105kDa purified whole tick antigen was proved to be the most effective one and may serve as the choice of vaccine.

Risk of infection with most tick-borne pathogens depends directly on the duration of tick attachment. To determine the duration of attachment of nymphal and adult female Ixodes scapularis Say, previous studies have used polynomial regression to model tick engorgement with a fixed time of initial tick attachment. We studied the impact of the time of day of initial tick attachment on engorgement rates in the nymphal stage, and found that ticks attaching early in the photophase engorged at significantly slower rates than ticks attaching later. We propose an improved method of predicting duration of tick attachment that incorporates this variability in tick engorgement rates. A graphical method is presented to facilitate prediction.

To understand the influence of hosts, habitats and other factors on the ectoparasites, the clusters of small mammals in different habitat regions in western Yunnan of China and the ectoparasitic gamasid mites on their body surface were studied. The investigated indoor (houses, barns and stables) and outdoor cultivated areas (rice fields, dry tillable lands and bush areas etc.) were divided into two habitats and five regions forming 10 habitat regions (five indoor habitat regions and five outdoor habitat regions) according to the altitude and zoogeographical position. Fuzzy clustering analysis was used to classify the community-groups of the gamasid mites and their small mammal hosts. All the small mammal host communities in 10 habitat regions were clustered into two community groups, indoor group and outdoor group. In each group, the host community in the highest altitude region showed a low similarity to that in other altitude regions. The clustering pattern of gamasid mite communities in different habitat regions did not follow that of the small mammal host communities in the corresponding habitat regions exactly, but all the mite communities in the indoor habitats were still clustered into one group prominently. The results implied that the habitats (indoor and outdoor) may be the most prominent factor influencing the distribution of small mammals and the altitude may come next. Though the distribution of the gamasid mites could be influenced by the habitats and altitude etc., the hosts are considered the most prominent influencing factor.

The species-abundance distribution of the gamasid mite community on 25 species of small mammals in western Yunnan, China was mathematically described. On the basis of the species-abundance distribution, the expected total numbers of species were further estimated according to a mathematical process. In a semilogarithmic rectangular coordinate system with a logarithmic scale in X-axis and a common arithmetic scale in Yaxis, the species-abundance distribution of the gamasid mite community can be fitted by a lognormal distribution theoretically with 0.8263 of the coefficient of determination (R²). In the studied community, the dominant species with abundant individuals and the rare species with only one individual were much less prevalent than the common species with a moderate number of individuals. The expected total number of species of the gamasid mite community were estimated to be 79, which was 21 more than the actual 58 collected species and this suggests that there were about 21 species that were missed in the actual field investigation.

Typhlodromus bambusae Ehara is a dominant predator species associated with the spider mite Schizotetrany-chus nanjingensis Ma & Yuan on the giant bamboo (Phyllostachys pubscens) in Fujian, China. In the field, increaseddensities of T. bambusae were associated with reduced densities of S. nanjingensis on bamboo leaves. Laboratory studies at 22–30°C on a diet of S. nanjingensis showed that females of T. bambusae completed a full egg-egg cycle in 7.5 days and mated females laid an average of 3.2 eggs per female per day. The number of female prey consumed by predator females increased with prey density very fast initially at prey densities of ≤5 but levelled off as prey density was further increased. Prey handling time was over 40% shorter and the rate of successful attack was twice higher at 28–30°C than at 22–24°C. When fed the pollen of Luffa cylindrica or eggs and larvae of Tyrophagus putrescentiae, T. bambusae females could not survive to layeggs.However,predator females readily attacked females of T. kanzawai and were able to reproduce normally on this diet. T. bambusae could complete development on T. kanzawaias fast as on S. nanjingensis. The potential of T. bambusae as a biocontrol agent in integrated control of S. nanjingensis is discussed.

Schizotetranychus nanjingensis Ma & Yuan is a mite pest injurious to the giant bamboo (Phyllostachys pubscens) in Fujian, China. The predatory mite Amblyseius longispinosus was explored as a potential biocontrol agent against S. nanjingensis in a series of experiments. Functional response experiments at six different temperatures showed that handling time (Th) generally decreased with temperature, whereas successful attack rate (a) increased with temperature and levelled off at >20° (Table 2). Judging by a/Th values, A. longispinosus Was most efficient against S. nanjingensis at 30–35°C, about half as efficient at 20 and 25°C and performed poorly at 10–15°C. The rate of oviposition increased linearly with prey density. As expected, the number of eggs laid by predators increased linearly with the number of prey they consumed. With a fixed number of prey available, predation rates per predator decreased with predator density. The potential of A. longispinosus as a biocontrol agent against A. nanjingensisis discussed.

Life table parameters including net reproductive rate (R₀), finite rate of increase (λ), doubling time for population (dt) and mean generation time (T) of Eotetranychus kankitus Ehara were studied at five constant temperatures. The intrinsic rate of natural increase (r_m) of E. kankitus was compared to those of two associated mites on citrus, Panonychus citri (McGregor) and Agistemus exsertus Gonzalez. The highest mean number of eggs (87.96 eggs/female), with daily oviposition rate of 2.06 eggs/female/day, was obtained at 20°C whereas the highest daily oviposition rate (3.73 eggs/female/day ) was observed at 35°C with a total of 55 eggs produced by each female. At 15°C , the lowest R₀ (16.64) and the longest generation time (T=48.62 days) resulted in a lowest rm (0.058) and longest dt (11.95 days). The highest r_m (0.223) and λ (1.2493) were obtained at 35°C and population can double in only 3.11 days. The r_m values of E. kankitus at the five tested temperatures are lower than those of P. citri and A. exsertus.

The spider mite Schizotetranychus nanjingensis Ma & Yuan is a major pest on the giant bamboo ( Phyllostachys pubscens ) in Fujian, China. This species constructs nests with very dense web roofing on the underside of bamboo leaves. Immatures feed and develop inside the nests and could not develop/survive if nests were damaged. Egg hatchability fell between 81–100% at 22–30°C and averaged only 33% at 35°C. After reaching deutonymphal stage (absent in males), some females moved out of their parent's nest to build their own on the same leaf or other leaves nearby. Durations of immature stages decreased with increasing temperature within the range of 15–29°. Development from eggs to adults took on average two weeks at 29°C. The cumulative effective temperature for egg-adult period was on average 196 degree days. After mating, females actively fed for 5–6 days before oviposition and the egg-egg generation time was 24–25 days at 24–26°C. Gravid females continued to feed and strengthen the nest to 5–6 layers of silk, under which they normally lay one egg per day or 2–3 eggs every other day. Fecundity was normally 30–35 eggs per female.

The effects of simulated acid rain sprayed directly on carmine spider mite, Tetranychus cinnabarinus,were investigated in a series of laboratory trials. The indirect effects, by the induced changes of development, physiological and biochemical aspects of host plant were eliminated from this experiment. The results indicated that there was no acute lethality of sprayed simulated acid rain of pH 4.0–3.0 on the tested developmental stages of carmine spider mite. However, the developmental duration of larvae, nymph and pre-oviposition was prolonged; and the longevity of adult mite and the duration of generation were shortened. The results of the life table study showed that the mite, which was sprayed directly by the simulated acid rain of pH 4.0, 3.5 and 3.0, had lower values of the net reproduction rate (R0), innate rate of increase (rm), finite rate of increase (λ) and mean generation duration (T), and greater population doubling time (t) than controls. The results implied that the population development and reproduction of the mite were restrained by direct application of acid rain (pH4.0–3.0)

Field survey during 1995–1996 in Shanxi province, China revealed that the rates of parasitism of Aphis gossypii, Myzus persicae, Schizaaphis graminum and Lipaphis erysimi by larvae of Allothrombium ovatum averaged 42.9%, 13.1%, 5.5% and 0.6%, respectively. Among different stages of A. gossypii , alatae were parasitized by more mites (mite load 2–4) than apterae (mite load 1–2). Laboratory choice tests using Ivelev index showed that the preference of larval mites for aphid hosts decreased in the order: A. gossypii (0.2168)> M. persicae (0.1004)> S. graminum (-0.0569) > L. erysimi (-0.5033).

A key to species in the genus Proprioseius Chant is provided and two new species, Proprioseius gibbus n.sp. and Proprioseius aculeatus n.sp., are described from Brazil.

This paper proposes a new species group, oguroi species group of the genus Amblyseius, including 17 species, a checklist of species, two new species and one new synonym.

This paper describes three new species of oribatid mites from Shergyla Mts., southeast Tibet, at elevations between 4100 and 4700 m.a.s.l. They are Oxybrachioppia glabriseta sp. nov. belonging to the family Oppiidae Grandjean and Umbellozetes squamaceus sp. nov. and U. combinatus sp. nov. belonging to the family Tegoribatidae Grandjean. The new species were collected from alpine meadow, mosses and forest litter, lichens on stones and thin soils, respectively. The holotypes are deposited in the Institute of Zoology, Academia Sinica, Beijing, China. The paratypes are deposited in Beijing Normal University, Beijing, China, Institute of Zoology, Academia Sinica, Beijing, China, and University of Bergen, Bergen, Norway.

Steneotarsonemus stipa sp. nov. is described from specimens collected on Stipa grandis P. Smirn from Ximeng, Inner Mongolia, China. The type specimens are deposited in the Mite Collection of the Plant Protection Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou, China.

Chrysomelobia oneili sp. nov. is described based on specimens collected on Leptinotarsa undecemlineata (Stahl) (Coleoptera: Chrysomelidae) from Honduras.

Aceria cordata sp.nov. and Tetra striata sp.nov. (Acari: Eriophyidae) are described from leaf erineum galls on Matisia cordata (H. & B.) (Bombacaceae) from Colombia.

Three new species from Guangxi, China, namely Epitrimerus ipomoeae sp. nov., Tergilatus camelliae sp. nov. and Calepitrimerus litseae sp. nov., are described and illustrated.

The genera Ledermuelleriopsis Willmann and Pseudostigmaeus Wood are historically reviewed. Two new species: Ledermuelleriopsis verricula and Pseudostigmaeus ueckermanni, collected from China, are described.

Leptus zhangi sp. nov. (Acari: Erythraeidae) is described and illustrated from larvae ectoparasitic on Hyponomeuta malinella (Lepidoptera: Hyponomeutidae) from Uromieh, Iran.

Walchiidae stat. n. differs from both Trombiculidae Ewing and Leeuwenhoekiidae Womersley by larval scutum lacking anteromedian setae and anteromedian projection with expanded sensillae, leg segments 7.6.6 without tibial solenidion and mastisetae on leg III (Φ³ or ti³ =0, fmt=0000), and lacking stigma and tracheae. Walchiidae stat. n. comprises two subfamilies including four tribes, and 17 genera and 17 subgenera, among them three new genera and eight new subgenera are proposed in the present article. Currently, this family has approximately 240 nominated species. If we consider the loss of the anteromedian setae as an apomorphy, then Walchiidae stands at the most advanced stage of evolution of sand-mite parasitism. Prolongation of the scutum in Walchiidae provided the great possibility of diversifying scutal sizes and shapes for this family compared to those of Trombiculidae and Leeuwenhoekiidae. It is rational to unify three sand-mite families, Leeuwenhoekiidae, Trombiculidae and Walchiidae, their larvae parasitic on vertebrates into a single superfamily, Trombiculoidea nec Welbourn, 1991, separable from Trombidioidea s.l. of arthropod parasitic larvae and standing at most advanced level of evolution of Parasitengona. Walchiid sand-mites are essentially an Old World family and best developed in the Oriental Region with the centre of development in Southeast Asia.

An intranasal sand-mite subgenus Traudia sg.n. other than Fainiella of the genus Walchia comprising five species from Austro-Malayan and Oriental Regions is erected. A new species, Walchia (Traudia) traubobi sp. n., is described from Australia. A comparison of the measurements of the five known species of the subgenus Trau-dia is made.

The sand-mite tribe Intermedialiini Wen, 1984 of Walchiidae was revised in accordance with newly erected genus Wuella Wang et al., 1997. Two genera, Intermedialia, comprising subgenera Intermedialia and Jianxia, and Wuella are included in this tribe. Redescription of Wuella quadriseta in comparison with W. sagitta (Goff, 1983) comb. n. was provided. Keys to genera including subgenera, and all nine species of the tribe Intermedialiini are given.

Allothrombium shirazicum is a common natural enemy of Aphis punicae and other arthropods in Iran. It is univoltine in Iran. The eggs hatch in spring, nymphs emerge in summer and adults appear in autumn. Larvae are ectoparasites of A. punicae whereas deutonymphs and adults are free-living predators of small arthropods and their eggs. Both adults and eggs overwinter. Adults hibernate in the soil and different shelters and eggs hibernate in the soil. At the end of winter, overwitered female lay eggs in the soil. These eggs and overwintered eggs hatch in spring.