The diversity of soil mites (Acari: Mesostigmata) in yellow ant (Lasius flavus) nests along a gradient of land use

Mesostigmatid mites communities in yellow ant (Lasius flavus) hills and phoresis of mites on this ant species were analysed in the Wielkopolska Region, Central Poland. Samples were collected from ant nests located along a gradient of four different types of land use: forest, ecotone, meadow and garden. In total, 132 mites were collected in ant nests among which 26 species were identified. The highest total abundance of mites was observed in the ecotone. Moreover, 14 mite specimens were found on L. flavus workers bodies. These are the first records of phoresis of mesostigmatid mites on this ant species.     

Communities of uropodine mites (Acari: Mesostigmata) in selected oak-hornbeam forests of the Wielkopolska region (Poland)

Pristine oak-hornbeam forests are among the richest flora and fauna environments in Poland. The agricultural development of the Wielkopolska region has led to the replacement of forest area with farmland. Consequently, the oak-hornbeam forests became fragmented, resulting in the isolation of local arthropod populations. The aim of this study was to compare the communities of uropodine mites in selected parts of a forest, differing in stand age and composition, physical soil condition and degree of anthropogenic pressure. Species composition of mite communities in a forest near Duszniki (West Poland), transformed by humans, was compared with the mite species composition observed in three nature reserves in its close vicinity. The analyses showed that Trachytes aegrota and Olodiscus minima constitute more than 50% of all communities in each type of tree stand. Diversity in Uropodina communities was higher in older tree stands, as well as in protected areas. Some species, such as Uroobovella pulchella, Uroobovella pyriformis and Dinychus woelkei, are related to specific microhabitats (e.g., they inhabit only dead wood) but there are also ubiquitous species, occurring in all types of environment, e.g., Oodinychus ovalis. Species like Oodinychus karawaiewi and Dinychura cordieri indicate a high degree of forest disturbance. Presence of such species as Trachytes lamda, Cilliba rafalskii, Cilliba cassideasimilis and Trematurella elegans points at high naturalness of soil in oak-hornbeam forests. These species have been found in old (>100 years old) tree stands, where Uropodina communities were also the richest.     

Dynamic associations between <Emphasis Type="Italic">Ips sexdentatus</Emphasis> (Coleoptera: Scolytinae) and its phoretic mites in a <Emphasis Type="Italic">Pinus pinaster</Emphasis> forest in northwest Spain

The relationship between the pine bark beetle Ips sexdentatus and its phoretic mites in a Pinus pinaster forest in northwest Spain was studied during 2014. Four species of mites were collected, three of them from the body of the beetle—Histiostoma ovalis, Dendrolaelaps quadrisetus and Trichouropoda polytricha—the fourth, Cercoleipus coelonotus, was collected from the sediments. The main aims of this study were to explore (1) mite diversity and related parameters, (2) the location on the body of the (male and female) beetle, as well as mite assemblages, and (3) the seasonal dynamic association between mite species and the beetle. Results indicated that the diversity oscillated around 0.71 through the study period and the most dominant, frequent and abundant mite was H. ovalis. Histiostoma ovalis was found attached to almost all parts of the body (mainly on the elytral declivity and ventral thorax), whereas D. quadrisetus was exclusively found under the elytra, and T. polytricha displayed affinity towards the elytral declivity as well as the ventral thorax. None of the mite species displayed any preference for the sex of the beetle and the most frequent mite assemblage was H. ovalis, T. polytricha and D. quadrisetus all together. Maximum abundance of each phoretic mite species was related with each of the flight peaks of the beetle that would indicate that these mite species use phoresy as a primary method of transport for colonizing new food sources.     

New associations of phoretic mites on <Emphasis Type="Italic">Pityokteines curvidens</Emphasis> (Coleoptera,Curculionidae, Scolytinae)

The species composition and abundance of phoretic mites of the bark beetle Pityokteines curvidens caught in pheromone traps were investigated in Croatia. The P. curvidens trapping programs have been in an experimental phase in Croatia since 2004 as a possible monitoring and control system. The trapping program also permits the opportunity to sample phoretic mites found associated with the beetles. Beetles were caught using Curviwit pheromones in Theysohn traps placed in the Litorić region of Croatia. A total of 12 mite species were recovered, including Schizostethus simulatrix, Dendrolaelaps quadrisetus, Histiostoma piceae, H. cf. varia, Paraleius leontonychus, Pleuronectocelaeno barbara, Tarsonemus minimax, Trichouropoda lamellosa, Uroobovella ipidis, Schwiebea sp., Phauloppia lucorum and Dolicheremaeus dorni. Five species, Pl. barbara, Schwiebea sp., H. cf. varia, Ph. lucorum and Do. dorni, are identified for the first time in association with P. curvidens. These findings increase the number of mite species known to be phoretic on P. curvidens from 11 to 16. The present study also increases the number of known mite associates of Pityokteines spp. from 14 to 18.     

Behaviours of phoretic mites (Acari) associated with Ips pini and Ips grandicollis (Coleoptera: Curculionidae) during host‐tree colonization

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Antagonisms, mutualisms and commensalisms affect outbreak dynamics of the southern pine beetle

Feedback from community interactions involving mutualisms are a rarely explored mechanism for generating complex population dynamics. We examined the effects of two linked mutualisms on the population dynamics of a beetle that exhibits outbreak dynamics. One mutualism involves an obligate association between the bark beetle, Dendroctonus frontalis and two mycangial fungi. The second mutualism involves Tarsonemus mites that are phoretic on D. frontalis (“commensal”), and a blue-staining fungus, Ophiostoma minus. The presence of O. minus reduces beetle larval survival (“antagonistic”) by outcompeting beetle-mutualistic fungi within trees yet supports mite populations by acting as a nutritional mutualist. These linked interactions potentially create an interaction system with the form of an endogenous negative feedback loop. We address four hypotheses: (1) Direct negative feedback: Beetles directly increase the abundance of O. minus, which reduces per capita reproduction of beetles. (2) Indirect negative feedback: Beetles indirectly increase mite abundance, which increases O. minus, which decreases beetle reproduction. (3) The effect of O. minus on beetles depends on mites, but mite abundance is independent of beetle abundance. (4) The effect of O. minus on beetles is independent of beetle and mite abundance. High Tarsonemus and O. minus abundances were strongly correlated with the decline and eventual local extinction of beetle populations. Manipulation experiments revealed strong negative effects of O. minus on beetles, but falsified the hypothesis that horizontal transmission of O. minus generates negative feedback. Surveys of beetle populations revealed that reproductive rates of Tarsonemus, O. minus, and beetles covaried in a manner consistent with strong indirect interactions between organisms. Co-occurrence of mutualisms embedded within a community may have stabilizing effects if both mutualisms limit each other. However, delays and/or non-linearities in the interaction systems may result in large population fluctuations. Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

Community structure and dispersal of mites (Acari, Mesostigmata) in nests of the white stork (Ciconia ciconia)

The fauna of Mesostigmata in nests of the white stork Ciconia ciconia was studied in the vicinity of Poznań (Poland). A total of 37 mite species was recovered from 11 of the 12 nests examined. The mite fauna was dominated by the family Macrochelidae. Macrocheles merdarius was the most abundant species, comprising 56% of all mites recovered. Most of the abundant mite species were associated with dung and coprophilous insects. It is likely that they were introduced into the nests by adult storks with dung as part of the nest material shortly before and after the hatching of the chicks.     

Phoretic mites and nematode associates of Scolytus multistriatus and Scolytus pygmaeus (Coleoptera: Scolytidae) in Austria

Abstract 1 The species assemblages and abundance of phoretic mites and nematodes associated with the elm bark beetles, Scolytus multistriatus and Scolytus pygmaeus, were studied in Austria. 2 A total of 3922 individual mites were recorded from 144 adults of S. multistriatus and 178 adults of S. pygmaeus. The species spectrum was identical and the relative abundance of mites was very similar for both species of scolytids. Nine mite species, Pyemotes scolyti, Pseudotarsonemoides eccoptogasteri, Trichouropoda bipilis, Tarsonemus crassus, Proctolaelaps eccoptogasteris, Proctolaelaps scolyti, Chelacheles michalskii, nr. Eueremaeus sp. and Elattoma sp. were detected. Two of the nine species, nr. Eueremaeus sp. and Elattoma sp., are documented here as new associates of Scolytus spp. 3 Pyemotes scolyti was the most frequent mite species, and Ps. eccoptogasteri and T. bipilis were relatively common, whereas the other mites occurred occasionally or were rare. 4 The trophic roles of most of the mites associated with S. multistriatus and S. pygmaeus are poorly known, but they may include fungivores, parasitoids of bark beetle broods, predators of bark beetle broods and/or mites and/or nematodes. 5 Besides phoretic mites, two nematode associates were seen on the investigated insects. A species of Cryptaphelenchus occurred under the elytra of both scolytid species, whereas the adults of a Neoparasitylenchus sp. were present inside abdomens of S. multistriatus, but absent from S. pygmaeus.     

Mite‐y bees: bumble bees (Bombus spp., Hymenoptera: Apidae) host a relatively homogeneous mite (Acari) community,shaped by bee species identity but not by geographic proximity

1. Parasites can affect the communities of their hosts; and hosts, in turn, shape communities of parasites and other symbionts. This makes host–symbiont relationships a key but often overlooked aspect of community ecology. 2. Mites associated with bees have a range of lifestyles; however, little is known about mites associated with wild bees or about factors influencing the make‐up of bee‐associated mite communities. This study investigated how mite communities associated with bumble bees (Bombus spp.) are shaped by the Bombus community and geographic proximity. 3. Bees were collected from 15 sites in Ontario, Canada, and examined for mites. Mite abundance and species richness increased with local bee abundance. Several bee species also differed in mite abundance, species richness, prevalence, and diversity. Locally uncommon species tended to have more mites than other bees. Queen bees had the most mites, and males had more mites than workers. 4. Spatial proximity was not a predictor of mite community composition, despite a strong effect of proximity on bee community similarity. 5. On the 11 Bombus spp. examined, 33 mite species were found. Whereas nearly half of these mite species are obligate associates of bumble bees, none was restricted to particular Bombus species. 6. The best predictor of mite community composition was bee identity. Although many parasite communities show strong geographic patterns, the communities of primarily commensalistic bee‐mites in this study did not. These findings have implications for bumble bee conservation, given that pollen‐feeding commensals might become harmful at high densities or act as disease vectors.     

新疆玛纳斯河流域土壤螨类群落多样性

为探究玛纳斯河流域不同生境土壤螨类群落多样性及其时空特征,采用野外采样和改进的Tullgren法采集土壤螨类进行分类鉴定及比较分析。结果,共采集土壤螨类33208只,隶属4亚目86科140属。其中Ceratozetes和Oribatula为优势类群。不同垂直带生境土壤螨类个体数量和类群数量之间差异显著(P0.05),个体数依次为ⅥⅪⅧⅨⅠⅩⅦⅣⅤⅡⅢⅫ。垂直分布表明不同土层间的个体数差异极显著(P0.01),土壤螨类主要集中分布于表层土壤。不同生境土壤螨类在不同季节均有显著差异(P0.05),个体数依次为9月4月7月11月。在12种不同生境之间土壤螨类群落多样性指标均有显著差异(P0.05),Shannon-Wiener多样性指数(H)依次为ⅠⅤⅣⅥⅢⅩⅡⅨⅧⅦⅪⅫ,而Margalef(M)丰富度指数依次为ⅠⅥⅢⅩⅪⅧⅤⅣⅦⅡⅨⅫ。不同生境土壤螨类群落间的相似性处于中等不相似。结果表明研究流域不同垂直带生境土壤螨类群落多样性具有明显的生境和季节变化特征。     

Bark and ambrosia beetles (Curculionidae: Scolytinae), their phoretic mites (Acari) and associated Geosmithia species (Ascomycota: Hypocreales) from Virgilia trees in South Africa

Bark and ambrosia beetles are ecologically and economically important phloeophagous insects that often have complex symbiotic relationships with fungi and mites. These systems are greatly understudied in Africa. In the present study we identified bark and ambrosia beetles, their phoretic mites and their main fungal associates from native Virgilia trees in the Cape Floristic Region (CFR) of South Africa. In addition, we tested the ability of mites to feed on the associated fungi. Four species of scolytine beetles were collected from various Virgilia hosts and from across the CFR. All were consistently associated with various Geosmithia species, fungi known from phloeophagous beetles in many parts of the world, but not yet reported as Scolytinae associates in South Africa. Four beetle species, a single mite species and five Geosmithia species were recovered. The beetles, Hapalogenius fuscipennis, Cryphalini sp. 1, and Scolytoplatypus fasciatus were associated with a single species of Elattoma phoretic mite that commonly carried spores of Geosmithia species. Liparthrum sp. 1 did not carry phoretic mites. Similar to European studies, Geosmithia associates of beetles from Virgilia were constant over extended geographic ranges, and species that share the same host plant individual had similar Geosmithia communities. Phoretic mites were unable to feed on their Geosmithia associates, but were observed to feed on bark beetle larvae within tunnels. This study forms the first African-centred base for ongoing global studies on the associations between arthropods and Geosmithia species. It strengthens hypotheses that the association between Scolytinae beetles and dry-spored Geosmithia species may be more ubiquitous than commonly recognised.     

The trophic structure of bark-living oribatid mite communities analysed with stable isotopes (15N, 13C) indicates strong niche differentiation

The aim of the present study was to identify food sources of bark-living oribatid mites to investigate if trophic niche differentiation contributes to the diversity of bark living Oribatida. We measured the natural variation in stable isotope ratios (¹⁵N/¹⁴N, ¹³C/¹²C) in oribatid mites from the bark of oak (Quercus robur), beech (Fagus sylvatica), spruce (Picea abies) and pine (Pinus sylvestris) trees and their potential food sources, i.e., the covering vegetation of the bark (bryophytes, lichens, algae, fungi). As a baseline for calibration the stable isotope signatures of the bark of the four tree species were measured and set to zero. Oribatid mite stable isotope ratios spanned over a range of about 13 δ units for ¹⁵N and about 7 δ units for ¹³C suggesting that they span over about three trophic levels. Different stable isotope signatures indicate that bark living oribatid mites feed on different food sources, i.e., occupy distinct trophic niches. After calibration stable isotope signatures of respective oribatid mite species of the four tree species were similar indicating close association of oribatid mites with the corticolous cover as food source. Overall, the results support the hypothesis that trophic niche differentiation of bark living oribatid mites contributes to the high diversity of the group.     

Mite species inhabiting commercial bumblebee (<Emphasis Type="Italic">Bombus terrestris</Emphasis>) nests in Polish greenhouses

Nests of social insects are usually inhabited by various mite species that feed on pollen, other micro-arthropods or are parasitic. Well-known negative effects of worldwide economic importance are caused by mites parasitizing honeybee colonies. Lately, attention has focused on the endoparasitic mite Locustacarus buchneri that has been found in commercial bumblebees. However, little is known of other mites associated with commercial bumblebee nests. Transportation of commercial bumblebee colonies with unwanted residents may introduce foreign mite species to new localities. In this study, we assessed the prevalence and species composition of mites associated with commercial bumblebee nests and determined if the mites are foreign species for Poland and for Europe. The study was conducted on 37 commercial bumblebee nests from two companies (Dutch and Israeli), originating from two greenhouses in southern Poland, and on 20 commercial bumblebee colonies obtained directly from suppliers. The species composition and abundance of mites inhabiting commercial bumblebee nests were determined. Seven mite species from three families were found in nests after greenhouse exploitation. The predominant mite species was Tyrophagus putrescentiae (Acaridae) that was a 100-fold more numerous than representatives of the family Laelapidae (Hypoaspis marginepilosa, H. hyatti, H. bombicolens). Representatives of Parasitidae (Parasitellus fucorum, P. crinitus, P. ignotus) were least numerous. All identified mite species are common throughout Europe, foreign species were not found. Mites were not detected in nests obtained directly from suppliers. We conclude that probably bumblebee nests are invaded by local mite species during greenhouse exploitation.     

Gene pool state and degree of infestation by bark beetle (<Emphasis Type="Italic">Ips tipographus</Emphasis> L.) of Norway spruce (<Emphasis Type="Italic">Picea abies</Emphasis> L. Karst.) natural populations and planted stands in Moscow region

A comparative analysis of the gene pool state in natural populations and planted stands of Norway spruce and the degree of their infestation by the bark beetle in the Moscow region was conducted taking into account the dynamic state of communities (4 populations, 148 samples, 24 isoenzyme loci). The degree of infestation by the bark beetle of conditionally native communities is 0%; for planted stands, it is 90–100%; and for a short-term community, it is 15–20%. The comparison of “healthy” populations and those infested with bark beetle by average values of observed heterozygosity (H _O) detected no significant differences. However, the test on allelic frequency heterogeneity demonstrated the difference of planted stands from conditionally native populations both by three loci (Fe-2, Idh-1, Mdh-3) and by the totality of 18 polymorphic isoenzyme loci; the short-term population differs from conditionally native population only by two loci. The value of the inbreeding coefficient by the Idh-1 locus is significantly higher in both populations infested with the bark beetle than in “healthy” populations. The results of conducted studies demonstrate the necessity of continuation of the study on the gene pool state in Norway spruce populations owing to the degree of their infestation by the bark beetle along with the study on the dynamic state of the communities; this can provide a key to solving the problem of the forest preservation from pests.     

新疆天山森林公园土壤螨类群落多样性与环境因子的相关性

为探讨西北干旱区森林土壤螨类群落和环境因子的相互关系,于2014年对新疆天山森林公园七种不同生境进行土壤螨类群落调查与环境因子测定,并采用除趋势对应分析法(DCA)和冗余分析法(RDA)对土壤螨类群落结构和多样性特征及其与环境因子之间的关系进行相关分析。结果表明,共捕获土壤螨类成体标本24399只,隶属4目56科108属(包括9个中国新记录属),其中小甲螨属Oribatella为优势类群。方差分析表明,在7种不同生境之间土壤螨类群落多样性指标均存在显著差异(P<0.05),Shannon-Wiener多样性指数(H)依次为针叶林>苗圃林>阔叶林>灌木林>针阔混交林>草甸草原>林中草地。RDA分析结果表明,第一主轴和第二主轴分别解释了土壤螨类主要群落总变量的34.8%和27.3%,所有环境因子共解释了土壤螨类群落物种组成变异的82.1%。蒙特卡罗置换检验显示,十种环境因子与全部排序轴(F=7.355,P=0.002)均存在极显著的相关性。研究表明,海拔、土壤含水量和有机质含量对螨类群落结构和多样性的影响显著。     

<Emphasis Type="Italic">Geosmithia</Emphasis> Fungi are Highly Diverse and Consistent Bark Beetle Associates: Evidence from their Community Structure in Temperate Europe

Geosmithia spp. (Ascomycota: Hypocreales) are little-studied, dry-spored fungi that occur in galleries built by many phloeophagous bark beetles. This study mapped the distribution and environmental preferences of Geosmithia species occurring in galleries of temperate European bark beetles. One hundred seven host tree samples of 16 tree species infested with 23 subcortical insect species were collected from across Europe during the years 1997–2005. Over 600 Geosmithia isolates from the beetles were sorted into 17 operational taxonomic units (OTUs) based on their phenotype similarity and phylogeny of internal transcribed spacer (ITS) region of rDNA (ITS1-5.8S-ITS2). The OTUs represent six known species and eight undescribed taxa. Ninety-two samples infested with subcortical insects were characterized by the presence/absence of OTUs and the similarity among the samples was evaluated. Geographically distant populations of the same beetle species host relatively uniform Geosmithia communities across large geographic areas (ranging from southern Bulgaria to the Czech Republic). This suggests effective dispersal of Geosmithia spp. by bark beetles. Clustering of similar samples in ordination analysis is correlated predominantly with the isolation source (bark beetles and their respective feeding plant), but not with their geographical origin. The composition of the Geosmithia OTU community of each bark beetle species depends on the degree of isolation of the species’ niches. Thus, Geosmithia communities associated with regularly co-occurring bark beetle species are highly similar. The similarity decreases with decreasing frequency of beetle species’ co-occurrence, a pattern resembling that of entomochoric ophiostomatoid fungi. These findings suggest that: 1) communities of Geosmithia spp. are vector-specific; 2) at least in some cases, the association between Geosmithia OTUs and bark beetles may have been very stable and symbioses are likely to be a fundamental factor in the speciation of Geosmithia fungi; and 3) that even nonsticky spores of Geosmithia are suitable for maintaining an insect–fungus association, contrary to previous hypotheses. An erratum to this article can be found at     

Dispersal patterns of oribatid mites across habitats and seasons

Oribatid mites are tiny arthropods that are common in all soils of the world; however, they also occur in microhabitats above the soil such as lichens, mosses, on the bark of trees and in suspended soils. For understanding oribatid mite community structure, it is important to know whether they are dispersal limited. The aim of this study was to investigate the importance of oribatid mite dispersal using Malaise traps to exclude sole passive wind-dispersal. Oribatid mite communities were collected over a 3-year period from five habitat types (coniferous forests, deciduous forests, mixed forests, meadows, bog/heathlands sites) and three seasons (spring, summer, autumn) in Sweden. Mites entered traps either by walking or by phoresy, i.e., by being attached to flying insects. We hypothesized (1) that oribatid mite communities in the traps differ between habitats, indicating habitat-limited dispersal, and (2) that oribatid mite communities differ among seasons suggesting that dispersal varies due to changing environmental conditions such as moisture or resource availability. The majority of the collected species were not typically soil-living species but rather from habitats such as trees, lichens and mosses (e.g., Carabodes labyrinthicus, Cymbaeremaeus cymba, Diapterobates humeralis and Phauloppia lucorum) indicating that walking into the traps or entering them via phoresy are of greater importance for aboveground than for soil-living species. Overall, oribatid mite communities collected in the traps likely originated from the surrounding local habitat suggesting that long distance dispersal of oribatid mites is scarce. Significant differences among seasons indicate higher dispersal during warm and dry periods of the year. Notably, 16 species of oribatid mites collected in our study were sampled for the first time in Sweden. This study also demonstrates that Malaise traps are a meaningful tool to investigate spatial and temporal patterns of oribatid mite communities.

     

Strong indirect interactions of Tarsonemus mites (Acarina: Tarsonemidae) and Dendroctonus frontalis (Coleoptera: Scolytidae)

Phoretic mites of bark beetles are classic examples of commensal ectosymbionts. However, many such mites appear to have mutualisms with fungi that could themselves interact with beetles. We tested for indirect effects of phoretic mites on Dendroctonus frontalis, which attacks and kills pine trees in North America. Tarsonemus mites are known to carry ascospores of Ophiostoma minus, which tends to outcompete the mutualistic fungi carried by D. frontalis. Experimental additions and removals of mites from beetles demonstrated that Tarsonemus propagate O. minus in beetle oviposition galleries. Furthermore, the abundance of Tarsonemus and O. minus tended to covary in nature. These results verified a strong mutualism between Tarsonemus and O. minus. Results also indicated that O. minus is an antagonist of D. frontalis: beetle larvae seldom survived in the presence of O. minus (compared to 83% survival elsewhere). Apparently, this is an indirect result of O. minus outcompeting the two species of mycangial fungi that are critical to beetle nutrition. Thus, Tarsonemus mites close a loop of species interactions that includes a commensalism (mites and beetles), a mutualism (mites and O. minus), asymmetric competition (O. minus and mycangial fungi), and another mutualism (mycangial fungi and beetles). This interaction system produces negative feedback that could contribute to the endogenous population dynamics of D. frontalis. Reproductive rate of Tarsonemus was more temperature‐sensitive than beetle generation time (which constrains the time for mite reproduction within a tree). This differential temperature sensitivity produces a narrow range of temperatures (centred at 27°C) in which mite reproduction per D. frontalis generation can attain its maximum of 100 mites/beetle. Consequently, seasonal oscillations in temperature are predicted to produce oscillations in the D. frontalis community, and climatic differences between regions could influence the community to dampen or exacerbate the cyclical outbreak dynamics of D. frontalis.     

华北平原地区景观格局对麦田害螨种群数量的影响

农业生产的集约化经营导致农田景观格局日趋单一,而农田景观格局的变化势必对害虫种群产生深刻的影响,阐明景观因子对害虫种群的作用是通过生境管理进行害虫控制的基础。以华北平原地区的山东省为研究区域,24个县级单元为样点,通过对卫星遥感影像和土地覆盖分类数据的分析,获取了样点单元的景观格局指数,同时定点调查了样点单元的麦田害螨种群数量。利用相关性分析明确了影响麦田中两种害螨—麦岩螨(Petrobia latens(Müller))和麦圆叶爪螨(Penthaleus major(Duges))种群发生的主要景观因子。研究结果表明景观因子对麦田中两种害螨种群均有显著影响,而两种害螨对景观因子的响应并不一致。麦岩螨的发生量与森林的最大斑块面积指数和平均斑块面积均呈显著正相关,而与森林类的形状和水体的景观形状指数均存在显著负相关;麦圆叶爪螨的发生量同水体的总面积、斑块面积比例、最大斑块面积指数以及县域范围的平均斑块面积均呈显著负相关,而与水体类的形状呈显著正相关。因此在麦田害螨发生较重的地区,在区域性景观规划时,可以通过优化农田周围的森林和水体管理,不利于其种群发生,从而达到对麦田害螨种群生态调控的目的。     

The role of volatiles in aggregation and host-seeking of the haematophagous poultry red mite <Emphasis Type="Italic">Dermanyssus gallinae</Emphasis> (Acari: Dermanyssidae)

Infestations with ectoparasitic poultry red mites (Dermanyssus gallinae) pose an increasing threat to poultry health and welfare. Because of resistance to acaricides and higher scrutiny of poultry products, alternative and environmentally safe management strategies are warranted. Therefore, we investigated how volatile cues shape the behavior of D. gallinae and how this knowledge may be exploited in the development of an attract-and-kill method to control mite populations. A Y-tube olfactometer bio-assay was used to evaluate choices of mites in response to cues related to conspecific mites as well as related to their chicken host. Both recently fed and starved mites showed a strong preference (84 and 85%, respectively) for volatiles from conspecific, fed mites as compared to a control stream of clean air. Mites were also significantly attracted to ‘aged feathers’ (that had remained in the litter for 3–4 days), but not to ‘fresh feathers’. Interestingly, an air stream containing 2.5% CO₂, which mimics the natural concentration in air exhaled by chickens, did attract fed mites, but inhibited the attraction of unfed mites towards volatiles from aged feathers. We conclude that both mite-related cues (aggregation pheromones) and host-related cues (kairomones) mediate the behavior of the poultry mite. We discuss the options to exploit this knowledge as the ‘attract’ component of attract-and-kill strategies for the control of D. gallinae.