Abundances and host relationships of chigger mites in Yunnan Province,China

This paper reports on ectoparasitic chigger mites found on small mammals in Yunnan Province, southwest China. Data were accumulated from 19 investigation sites (counties) between 2001 and 2009. A total of 10 222 small mammal hosts were captured and identified; these represented 62 species, 34 genera and 11 families in five orders. From the body surfaces of these 10 222 hosts, a total of 92 990 chigger mites were collected and identified microscopically. These represented 224 species, 22 genera and three subfamilies in the family Trombiculidae (Trombidiformes). Small mammals were commonly found to be infested by chigger mites and most host species harboured several species of mite. The species diversity of chigger mites in Yunnan was much higher than diversities reported previously in other provinces of China and in other countries. A single species of rodent, Eothenomys miletus (Rodentia: Cricetidae), carried 111 species of chigger mite, thus demonstrating the highest species diversity and heaviest mite infestation of all recorded hosts. This diversity is exceptional compared with that of other ectoparasites. Of the total 224 mite species, 21 species accounted for 82.2% of all mites counted. Two species acting as major vectors for scrub typhus (tsutsugamushi disease), Leptotrombidium scutellare and Leptotrombidium deliense, were identified as the dominant mite species in this sample. In addition to these two major vectors, 12 potential or suspected vector species were found. Most species of chigger mite had a wide range of hosts and low host specificity. For example, L. scutellare parasitized 30 species of host. The low host specificity of chigger mites may increase their probability of encountering humans, as well as their transmission of scrub typhus among different hosts. Hierarchical clustering analysis showed that similarities between different chigger mite communities on the 18 main species of small mammal host did not accord with the taxonomic affinity of the hosts. This suggests that the distribution of chigger mites may be strongly influenced by the environment in which hosts live.     

Toxicities of 26 pesticides against 10 biological control species

To determine selective effectiveness for specific pesticides on biological control species we evaluated the contact toxicity of 16 insecticides, 2 acaricides, 3 fungicides, and 5 biopesticides. Targeted species included 3 predatory mites (Phytoseiulus persimilis Athias-Henriot, Amblyseius swirskii Athias-Henriot, and Neoseiulus californicus McGregor), 5 hymenopteran parasitoids (Diglyphus isaea Walker, Aphidius colemani Viereck, Encarsia formosa Gahan, Eretmocerus eremicus Rose and Zolnerowich and E. mundus Mercet), and 2 hemipteran predators (Orius laevigatus Fieber and Nesidiocoris tenuis Reuter) in laboratory condition. In addition, residual toxicity was evaluated on P. persimilis, E. formosa, and O. laevigatus. For contact toxicity, five insecticides (spinetoram, spinosad, lepimectin, chlorfenapyr, and dinotefuran + spinetoram) showed high toxicity to predatory mites. Most pesticides tested were highly toxic to all hymenopteran species except for D. isaea which showed low susceptibility to 11 pesticides. Bistrifluron + flubendiamide and B. valismortis were less toxic to A. colemani, and only B. valismortis was safe to both E. mundus and E. eremicus. Insect growth regulators (methoxyfenozide and bistrifluron), chlorantraniliprole, and bistrifuron + flubendiamide were not toxic to hemipteran predators. Fungicides and biopesticides were safe to hemipteran predators except for two biopesticides (B. subtilis and P. fluorescens). Most pesticides had low residual toxicity to P. persimilis, with the exception of chlorfenapyr whose toxicity persisted over 7 days. One insecticide (cyantraniliprole), 2 acaricides (spiromesifen and fenpyroximate), 1 fungicide (metrafenone), and 4 biopesticides (B. subtilis, P. polymyxa, P. fluorescens, and B. valismortis) showed a much lower residual toxicity to E. formosa. Eight insecticides, 2 acaricides, 3 fungicides, and 5 biopesticides showed low residual toxicity to O. laevigatus.     

腺水螨属二新种记述(蜱螨亚纲:腺水螨总科:腺水螨科)(英文)

本文记述我国腺水螨科Lebertiidae、腺水螨属Lebertia二新种。该属腺毛分布以E1位移于1基节板前端背方为显著特点,基于对两新种的详细观察,描述了腺毛分布体位。三叉腺水螨Lebertia（Piloleberia）trifurcillaJin,sp．nov．本新种近似于印度种Lebertia（P．）carmamayaCook1967,但其E1具发达的毛状表皮突、殖吸盘板后缘刚毛少而短等特征明显别于后者。刷电腺水螨Lebertia（Pilolebertia）ciliaaJin,sp．nov．本新种近似于非洲种L．algeriensisLundblad1942,其以颚底背突长而尖、腹突尖锐等特征显著别于后者。     

SEX RATIO AND AGE STRUCTURE OF GAMASID MITES FROM SMALL MAMMALS IN WESTERN YUNNAN,CHINA*

Abstract A total of 70 species of gamasid mites (7485 individuals) were collected from the body surface of 38 species of small mammals (3023 individuals) during an investigation of 13 counties of western Yunnan, China, from 1990 to 1996. Most species of gamasid mites have more females (80% 100%) than males (P <0.01). Exceptions are Haemogamasus gongshanensis where males outnumber females (P < 0.01) and Haemolaelaps glasgowi where there are similar numbers of males and females (P > 0.05). No larva was found in most of the mite species. The proportion of individuals at the immature stages (mainly protonymphs and deutonymphs) in most mite species is small (0–12.84%) compared to the adults (P < 0.01). Exceptions are Ornithonyssus bacoti and Haemolaelaps glasgowi where 62.84% and 49.48% respectively are nymphs. The biased sex ratios may reflect the probable different bloodsucking preferences and parthenogenesis of the gamasid mites. The absence of larvae and a low proportion of nymph stages in most mite species probably reflect that the larvae or nymphs of most mite species are non‐feeding or non‐blood sucking and are in their hosts' nests. Another possibility is that some species directly produce protonymphs or even deutonymphs without eggs and larvae which makes it difficult to find the larval stage.     

Biological studies of the Australian predatory mite Typhlodromips montdorensis (Schicha) (Acari: Phytoseiidae), a potential biocontrol agent for western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae)

Abstract The biology of the Australian phytoseiid mite Typhlodromips montdorensis is described from material collected in Queensland and South Australia in 1994−1996. At 25°C, when fed on cumbungi ( Typha sp.) pollen, the life cycle was completed in approximately 7 days, with an intrinsic rate of natural increase ( r _m ) of 0.32. Female−male pairs produced a mean total of 52.7 eggs within 28 days of oviposition. Females that were deprived of males after first mating stopped laying eggs after 7−19 days; however, if another male was added, they resumed egg laying and produced, on average, a total of 49.4 eggs. The sex ratio was 2.24 females to one male. At 25°C, fecundity on a diet of thrips larvae (first-instar Frankliniella schultzei Trybom) was high, ranging from 2.72 to 3.58 eggs per day on the third day, depending on previous diet. Consumption rate of thrips was also high, with an average of 7.23−14.44 first-instar larvae eaten per day on the third day, depending again on previous diet and also on number of thrips larvae made available. The species was also observed to feed on: (i) broad mite, Polyphago­tarsonemus latus (Banks); (ii) tomato russet mite, Aculops lycopersici (Massee); and (iii) two-spotted mite, Tetranychus urticae Koch. No diapause was observed under conditions of 25°C, 8 h light and 10°C, 16 h dark. Eggs were sensitive to low humidity, with 50% failing to hatch below 70.8% relative humidity. This species is of interest as a candidate biological control agent for thrips, broad mite and tomato russet mite in protected crops.     

Macrochelid mite fauna in the eastern part of the Lesser Sunda Islands, with description of two new species

Thirteen species in four genera of mites of the family Macrochelidae phoretic on dung beetles were collected in the eastern part of the Lesser Sunda Islands, Indonesia, providing the first record of the family for that area. Of these, two species, Macrocheles entetiensis Hartini and Takaku, sp. nov. and Macrocheles sumbaensis Hartini and Takaku, sp. nov., are new to science. The remaining 11 species are Glyptholaspis fimicola, Holostaspella bifoliata, Macrocheles baliensis, Macrocheles sp. aff. glaber, M. hallidayi, M. kraepelini, M. krantzi, M. limue, M. merdarius, M. oigru and Neopodocinum sinicum.     

The use of image analysis to study the effects of residues of esfenvalerate on the locomotory behaviour of Panonychus ulmi and Typhlodromus pyri (Acari: Tetranychidae, Phytoseiidae)

The influences of esfenvalerate on mite behaviour were investigated by image analysis. Video recordings of the locomotory behaviour of two mite species were converted into a series of x,y coordinates that, when joined, closely resembled their paths. These coordinates were used to calculate walking speed, direction of travel, turning frequency, turn bias and tortuosity. Two experimental arenas were used: (1) a leaf disc arena for the European red mite, Panonychus ulmi and (2) a glass coverslip arena for Typhlodromus pyri. The behavioural responses of P. ulmi and T. pyri to esfenvalerate (field rate) indicated that these mites did not show a preference for the unsprayed halves of the arenas during the first 48 min. However, significant differences between most of the behavioural parameters to esfenvalerate residues were found with P. ulmi when whole arenas were compared. © Rapid Science Ltd. 1998     

New Record of Feather Mite,Neopteronyssus bilineatus Mironov, 2003 (Arachnida: Pteronyssidae), from a Grey-Capped Pygmy Woodpecker,Yungipicus canicapillus in Republic of Korea

This study intended to record a species of feather mite, Neopteronyssus bilineatus Mironov, 2003, (Arachnida: Pteronyssidae), from a grey-capped pygmy woodpecker, Yungipicus canicapillus (Blyth, 1845), in the Republic of Korea. Mite samples were collected from the flight feathers of a woodpecker, preserved directly in 95% ethyl alcohol, and then observed by a light microscope after specimen preparation. Morphology of Neopteronyssus bilineatus is distinguished from other pici group species by opisthosoma part with 2 longitudinal bends, tarsal seta rIII 3 times longer than tarsus III in males, and 2 elongated hysteronotal plates extending beyond the level of setae e2 in females. In the present study, a species of feather mite, N. bilineatus, was newly recorded from Y. canicapillus in Korean fauna.