Microarthropod Fauna Research Articles

Effects of dry sludge application on soil microarthropod communities in a reclaimed desert ecosystem

Summary The ecological impact of dried sewage sludge addition to reclaimed soil was assessed by comparing soil microarthropod fauna (oribatid and collembolan populations) of sewage sludge treated plots with those of adjacent control plots. An Egyptian orchard of newly reclaimed soil cultivated with guava trees (sandy soil) at E1 Salheya region was selected for the present investigation. Sludge application was performed at three doses i.e. 1.6 ton/ha, 3.3 ton/ha and 6.5 ton/ha. Four replicates were conducted for each dose application through a one-year period (during the four seasons). Sludge application had a marked influence on some soil microarthropods but no influence could be detected on others. The intensity of the effect was strongly correlated to sludge doses. Also, a marked quantitative and qualitative influence could be observed on soil-bound mites. It was discovered that application of sludge up to 6.5 ton/ha over the period of a year to the reclaimed area produced a marked significant effect on the oribatid community. Scheloribates laevigatus, Epilohmannia c. cylindrica and Isotomina thermophila may serve as bioindicators to evaluate the role of sewage sludge application on the soil habitat.

Stability, ephemerality and dispersal ability: microarthropod assemblages on fungal sporophores

Abstract A comprehensive analysis of the microarthropod fauna from fungal sporophores revealed a series of recurrent patterns demonstrating the non-random structure of these assemblages. Despite the existence of a strong species-area relationship from sporophores of certain fungi, particularly among perennial species, several small sporophores always maintained a more diverse microarthropod fauna than fewer large sporophores of equivalent total area. A consistently high degree of overlap in microarthropod species occurrence between larger and smaller sporophores was indicated by the presence of highly significant nested subset structure. The fauna from Heterobasidion annosum sporophores was the most nested, followed by Hypholoma fasciculare and a collection of pooled agarics, respectively. When the fauna was split into functional groups, microphytophages were always significantly nested in their distributions but, when significant, macrophytophages and panphytophages had stronger nested hierarchies. Non-random organization was least evident among predatory species. Microarthropods had significantly ordered distributions on sporophores of various fungi. Many species occurred on perennial H. annosum sporophores of all sizes while others had more restricted distributions. Most species from very ephemeral agarics, including those which were widely distributed on H. annosum , were restricted to a small number of larger sporophores. The pattern from H. fasciculare was intermediate; most species had narrow distributions and were present only on larger sporophores, except a small number of more widely distributed species.

Stability, ephemerality and dispersal ability: microarthropod assemblages on fungal sporophores

A comprehensive analysis of the microarthropod fauna from fungal sporophores revealed a series of recurrent patterns demonstrating the non-random structure of these assemblages. Despite the existence of a strong species-area relationship from sporophores of certain fungi, particularly among perennial species, several small sporophores always maintained a more diverse microarthropod fauna than fewer large sporophores of equivalent total area. A consistently high degree of overlap in microarthropod species occurrence between larger and smaller sporophores was indicated by the presence of highly significant nested subset structure. The fauna fromHeterobasidion annosumsporophores was the most nested, followed byHypholoma fasciculareand a collection of pooled agarics, respectively. When the fauna was split into functional groups, microphytophages were always significantly nested in their distributions but, when significant, macrophytophages and panphytophages had stronger nested hierarchies. Non-random organization was least evident among predatory species. Microarthropods had significantly ordered distributions on sporophores of various fungi. Many species occurred on perennialH. annosumsporophores of all sizes while others had more restricted distributions. Most species from very ephemeral agarics, including those which were widely distributed onH. annosum, were restricted to a small number of larger sporophores. The pattern fromH. fascicularewas intermediate; most species had narrow distributions and were present only on larger sporophores, except a small number of more widely distributed species.

Ecological Effects Assessment of Industrial Sludge for Microarthropods and Decomposition in a Spruce Plantation

Effects of dried, granulated industrial sludge-containing residues of organic pesticides and precursors were assessed for microarthropod fauna and the decomposition of a spruce forest floor. The investigation was highly realistic, using large plots of about 12 ha, and the application was done with professional equipment. The ecological effects of the sludge were compared with the ecological effects of an inorganic fertilizer. Decreases in abundance of the microarthropods ranged from 20 to 80% of the control level after 1 year.Isotoma notabilisSchäffer was the only species that exhibited stimulation at twice the control level due to the sludge. The least affected collembolan species wasLepidocyrtus cyaneusTullberg, a member of the surface-dwelling life forms. Sensitive species wereIsotoma anglicanaLubbock andIsotomiella minorSchäffer. In subhabitats with almost no application of sludge due to a heterogeneous horizontal distribution, the microarthropods were still affected to the same degree as those in the zones of maximum application. Laboratory tests withFolsomia candidaWillem gave results similar to the effects on field populations concerning the sludge but revealed no adverse effects of the fertilizer. Decomposition was stimulated to the same extent in the field by the two types of fertilizer but in the laboratory the sludge caused the largest stimulation. The effects on the microarthropod fauna are suggested to be the result of a combination of direct toxicity and changes in the microbial community due to fertilizers.

Low summer temperatures: a potential mortality factor for high arctic soil microarthropods?

Throughout the summers of 1992–1994 the low temperature performance of soil microarthropods at Ny Ålesund, Spitsbergen (78 °56′N 10 °53′E), was investigated. Species studied were the Collembola Hypogastrura tullbergi (Schäffer), Onychiurus arcticus (Tullberg) and Onychiurus groenlandicus (Tullberg) and the mites Diapterobates notatus (Thorell), Hermannia reticulata (Thorell), Camisia anomia Colloff and Ceratoppia hoeli (Thor). The results show that: (i) The supercooling ability of these animals decreased rapidly on regaining activity in spring. For example, the supercooling point (scp) of H. tullbergi when heat extracted from frozen ground, decreased from −20 to −8 °C within 4 h. Population scp profiles of all species determined throughout the summer showed distinct bimodal distribution; (ii) starvation for 14 days, desiccation or a combination of both, resulted in little change in the mean scp of the collembolan O. arcticus; (iii) survival of the animals after a brief exposure to a sub-zero temperature was poor, in either humid or dry atmospheres. For example, 77% of H. tullbergi died after cooling to −5 °C at 1 °C min −1. Comparison with scp data indicates that animals died before they froze; (iv) all species examined showed some locomotory ability at temperatures approaching −3 °C; (v) polyols occurred in low concentrations, although elevated levels of glucose were observed in early spring and late autumn in O. arcticus; and (vi) soil temperature declined to −29.6 °C in the winter of 1992/93 and remained below zero for up to 289 days and the animals can be encased in ice for 75% of the year. Average daily soil temperatures for July and August rarely exceed 8 °C and were typically in the range 3–6 °C. Estimation of previous years soil temperatures from screen temperature records indicate that July /August ground surface temperatures < 0 °C occurred on 25 and 28 occasions between 1969–1993 at the polar semi-desert and tundra heath sites respectively; but, that soil temperatures at a depth of 3 cm are buffered against temperature extremes and temperatures below 0 °C are rarely encountered. The consequences for the soil microarthropod fauna of such extended periods of low temperature and the effects of climate change on these species are discussed.

Impact of insecticides on nontarget microarthropod fauna in agricultural soil

Ecologically important soil microarthropods were used to evaluate the direct and residual toxicities of some insecticides under field and laboratory conditions. The density of total microarthropods and major groups, namely Acarina and Collembola, suffered a statistically significant and persistent decline in the aldrin 30 EC (0.25%)- and endosulfan 35 EC (0.33%)-treated soil of wheat fields. But dimethoate 30 EC (0.125%) and phosphamidon 85 EC (0.03%) applied in mustard fields produced only a temporary decline. Laboratory studies showed that all the above insecticides and monocrotophos 36 EC (0.2%), methyl parathion 50 EC (0.05%), chlordane 20 EC (0.125%), and carbaryl 50 WP (0.625%) had a direct knockdown effect on Cyphoderus sp. but another collembolan species, Xenylla sp., appeared to be somewhat resistant. Only endosulfan was toxic to a common soil Acarina species, Lancetoppia sp. Among four soil media, toxicity was maximum in pure sand, followed by sandy loam, clay, and organic soil. The residual toxicity of phosphamidon, dimethoate, methyl parathion, and endosulfan was more prolonged for Cyphoderus sp. than for Xenylla sp. Only the larval stage of Lancetoppia sp. was susceptible to the residual effect of endosulfan. LD 50 and bioassay studies showed that Cyphoderus sp. can be employed as a potential biomonitor of insecticide pollution in soil.

Caractéristiques biodémographiques d'un acarien oribate (Carabodes willmanni) des pelouses xérophiles

An analysis of biodemographic characteristics was undertaken under experimental conditions in Carabodes willmanni, the first study of its kind in the superfamily Carabodoidea. The species dominates the microarthropod fauna of dry Cladonia cover. Immature stages have a very soft integument and live within the decomposing lichen layer. The population is characterized by the following: (i) low fecundity, strongly density dependent; (ii) relatively long postembryonic development for such a small species, lasting 117 days at 20 °C; (iii) extended premoulting stage (pupation), lasting 28% of postembryonic development; (iv) high but very variable longevity, with values varying from 200 to 600 days between egg laying and death of the adult; (v) strong influence of temperature on fecundity, adult survival, and duration of embryonic and postembryonic developments: development is inhibited at 10 °C. Based on previously acquired information on the phenology of the population, a model for the life cycle under natural conditions is proposed. Periods favorable to development being greatly shortened by environmental factors, the duration of the cycle is lengthened and probably takes as much as 1 year under the harshest conditions. The success of C. willmanni in such an environment can be explained by the capacity of the immature stages to take advantage of the lichen substrate both as a source of food and as a means of protection against desiccation.[Journal translation]

The microarthropod fauna associated with a deep rooted legume, Prosopis glandulosa, in the Chihuahuan Desert

The rhizosphere microarthropod fauna of a woody, deep-rooted legume, Prosopis glandulosa, was sampled at four sites in the northern Chihuahuan Desert and compared with the rhizosphere microarthropod fauna of a co-dominant shrub, Larrea tridentata. Prostigmatid mites (Speleorchestes sp.,Neognathus sp., Rhagidia sp., Tydaeolus sp., Steneotarsonemus sp., Tarsonemus sp., Nanorchestes sp., Gordialycus sp.), the cryptostigmatid mites (Bankisonoma ovata and Passalozetes neomexicanus), the mesostigmatid (Protogamasellus mica), and the collembolan (Brachystomella arida) characterized the fauna at depths greater than 1 m. Microarthropods were recovered from soils at a depth of 13 m at the edge of a dry lake and at depths of 7 m in a dry wash which were pre-European man P. glandulosa habitats. In habitats where P. glandulosa is a recent invader, root depth and microarthropods were less than 3 m. In most habitats, population densites of microarthropods at depths 0.5 m were more than 100 times those at depths ≫ 0.5 m. Population densities of microarthropods associated with P. glandulosa growing at the edge of a dry wash were not significantly smaller at 0.5−1.0 m depth than at 0−0.5 m. The deep-rhizosphere microarthropod fauna is a reduced subset of the fauna of surficial soils, suggesting that this fauna plays a role in decomposition and mineralization processes functionally similar to that of microarthropods in surficial soils.

Distribution and diversity patterns of soil mites and other microarthropods in a Chihuahuan desert site

This paper reports the results of a pilot survey of the patterns of distribution and species diversity of soil microarthropods from 12 different sites in a Chihuahuan Desert watershed in southern New Mexico. A total of 18 orders of arthropods was recorded from 49 samples, distributed across this watershed. Mites and Collembola predominated throughout. Mites were more abundant than Collembola in all sites except in Prosopis litter from the edge of a playa. At this site, collembolan density was estimated to be 24,460/m 2 . Four orders of mites occurred in the sites surveyed: Prostigmata, Cryptostigmata, Mesostigmata and Astigmata. The last-named group was so infrequent that it was not considered further. The Mesostigmata were numerous only in Atriplex litter. Prostigmata and Cryptostigmata were equally abundant at only two sites: the litter under Prosopis on the bajada site and the mineral soil under Fallugia. Elsewhere, Cryptostigmata tended to be more numerous than Prostigmata where the organic content of the substratum was high (> 30%) and vice versa. The highest total mite density occurred in the Juniperus litter (29, 486/m 2 ), the lowest in Larrea litter (8274/m 2 ). These estimates are considerably higher than those recorded from a Juniperus site in the more arid Mojave Desert, but they are much lower than densities considered typical of cool, moist temperate deciduous forests. The densities of Prostigmata and Mesostigmata compare favourably with those reported from sites with similar rainfall in Australia. Cryptostigmatid densities are much higher in the Chihuahuan sites, however. An Index of Diversity, calculated for the various groups of microarthropods at the 12 sites, was very variable, but values approximating to those reported for the microarthropod fauna of an English beech woodland were obtained for several sites. The equitability component of this species diversity provided a good indicator of the relative stability of the sites studied.

Microarthropods of a Desert Tabosa Grass (Hilaria mutica) Swale

We examined soil microarthropod populations inhabiting a clay-silt soil of a tabosa grass (Hilaria mutica) swale in southern New Mexico. Maximum population densities of soil microarthropods occurred in September (48,400.m-2) and lowest densities were in July (1,250-m 2). These densities were 50% lower than those reported for well-drained soils on the upper parts of the same watershed. Prostigmatid mites made up 67% and cryptostigmatid mites, 26%, of the total microarthropod population. The ratio between prostigmatid and cryptostigmatid mites, approximately 4:1, was consistent throughout the year. Overall densities of microarthropod groups were correlated with soil moisture but many individual taxa were not. The most numerous and frequently occurring taxa [nanorchestid, tydeid and bdellid mites (Prostigmata); Aphelacarus sp. and Cosmochthonius sp. (Cryptostigmata)] are common in all Chihuahuan desert habitats examined to date and are common in other North American desert areas. INTRODUCTION Microarthropods constitute a numerically important component of the soil fauna. Microarthropods play an active role in breakdown of dead plant parts (Santos and Whitford, 1981), in vertical transport of organic material through the soil profile, in humus formation, and they may also increase microbial activity by disseminating fungal spores (Wallwork, 1970). Santos et al. (1978) and Franco et al. (1979) found that, in two North American desert areas, the microarthropod fauna was dominated by prostigmatid mites rather than the oribatid mites that feed on dead plant material in more mesic environments. Loots and Ryke (1967) working in different South African biotopes found that the soil moisture content was not always the most important factor determining the composition of the soil rnicroarthropod fauna. They found a significant correlation between the ratio of oribatei/trombidiformes (= prostigmata) and the percentage of organic matter in different soils. Montane piedmonts, bajadas, in the desert Southwest of North America, drain onto clay basins or flats which form from the deposition of fine particles. The clay and swales are characterized by poor drainage and poor percolation. Following rains, they may be inundated for varying periods. Clay pans may be unvegetated or have sparse shrub and grass cover. Swales are characterized by a dense cover of tabosa grass, Hilaria mutica. Litter accumulation constitutes an important storage reservoir in desert ecosystems and may affect soil water, which is generally thought to affect the density of soil fauna. Because of the soil characteristics of swales, i.e., poor drainage, low infiltration and percolation, high soil water content and relatively high vegetative cover, we hypothesized that the soil fauna would differ in taxonomic composition and exhibit less seasonal change in population size than microarthropod populations in better-drained desert soils. We further hypothesized that the population densities would be higher and numbers of taxa would be lower than those found in erosional soils. Whitford et al. (1981) used simulated rainfall in comparison to natural rainfall to follow the responses of a number of taxa as the soils dried. They found marked shifts in 1Present address: Department of Biology, Bar-Ilan University, Ramat Gan, Israel. 2Address reprint requests to: W.G. Whitford, Department of Biology, New Mexico State University, Las Cruces 88003.

Composition and vertical distribution patterns of the microarthropod fauna in a Negev desert soil

The faunal composition and changes in the vertical distribution patterns of soil mites and other microarthropods were described and monitored over an 18‐h period at a site in the Negev desert of southern Israel. There was an overwhelming predominance of prostigmatid mites (55%) compared with Cryptostigmata (33%) in the collections. Specific determinations on the Cryptostigmata indicated that taxa, which could be identified as Mediterranean, made a sizeable contribution to this fauna. Microarthropod densities in general, and those of Prostigmata, Cryptostigmata and Mesostigmata in particular, compared favourably with those recorded from other arid desert sites in N. America and Australia. Prior to the sampling period which commenced at 6 p.m., the site was exposed to the drying effects of the Khamsin wind. Microarthropod populations were mainly located at depths below 6 cm during the following 18‐h period, and this may be interpreted as an avoidance of the arid conditions obtaining at the surface, particularly during the hours from 6 p.m. to midnight. Soil temperatures remained low after midnight, but the relative humidity above the soil increased to 90% and there may have been some internal dew formation in the soil surface horizon at this time. There is some evidence of an upward movement of prostigmatid and cryptostigmatid mites as a response to increasing levels of humidity in the surface horizon during this period. We suggest that this study confirms the findings of Whitford et al. (1981) that soil microarthropods are sensitive to changes in soil moisture characteristics which operate on a diurnal scale.

Soil microarthropods from the Chihuahuan Desert of New Mexico

An account is given of the soil‐ and litter‐dwelling microarthropods collected under three species of desert shrub in southern New Mexico. Particular attention is paid to the acarine component which represents 80% of the microarthropod fauna. Comparisons made with samples collected one hour after wetting show that only the Collembola respond rapidly to changes in the moisture content of the soil. The results of the study suggest that the depth and stability of the surface litter determine the degree to which microarthropod activity is affected by the application of water.

Seasonal and Spatial Variation in the Soil Microarthropod Fauna of the White Sands National Monument

The only microarthropod taxon found at all sample stations in a gypsum sand dune field was the mite Speleorchestes sp., family Nanorchestidae. The highest densities and largest number of taxa of microarthropods (Acari and Collembala) were under shrubs at the edge of the dune field. Changes in number of taxa and density were directly correlated with temperature and rainfall. During the warmer months, the microarthropod fauna was dominated by tydeid and tarsonemid mites under shrubs on dunes, and pyemotid mites in interdune spaces. The densities, number of taxa and taxonomic composition of the gypsum dune microarthropod fauna were similar to those found in non-gyphic soils on a nearby desert watershed. The few studies of desert soil faunas have been conducted in areas of stable soils (Wallwork, 1972; Santos et al., 1978; Franco et al., 1979). These studies indicated that prostigmatid mites dominate the soil fauna of North American hot deserts. Further, these authors documented the relationship between plant litter accumulations or organic matter content and the density and diversity of the soil microarthropod fauna. The White Sands National Monument provides a unique ecosystem for examining the relationships of substratum stability and organic matter and the soil arthropod biota. In addition, the dunes and the soil are either pure gypsum or gypsum impregnated, thus providing an opportunity to examine the effect of this limited habitat type on the soil microarthropod fauna. Because of the instability of the dunes and the chemical composition of the White Sands, we hypothesized that the density and taxonomic diversity of

Arthropod Use of Invertebrate Carrion

Arthropods associated with cricket carcasses placed on top and within deciduous forest litter were collected for 12 months. Vespid wasps and ants quickly removed carcasses left on top of forest litter, but carcasses placed within litter persisted throughout the study. Major consumers of carcasses in litter varied seasonally; maggots dominated on fresh carcasses in summer, but fresh carcasses placed in litter in autumn were consumed by other arthropods. A gamasid mite, Hypoaspis (Laelaspis) johnieae, dominated the microarthropod fauna found on exoskeleton fragments. A method for collecting invertebrate carrion feeders and measuring carrion disappearance is presented. 15 references, 2 tables.

Vertical Distribution of Soil-Inhabiting Microarthropods in an Agricultural Habitat in California 1

Vertical distribution patterns of soil-inhabiting microarthropods in an agricultural region of the San Joaquin Valley, CA, are described. Eight samples, each 122 cm deep and with surface areas of 426.5 cm 2 , yielded 7727 specimens with 33% from the upper 15.2 cm of the profile and 24% from the 15.2–30.5 cm depth. About 30% were collected from below 46 cm. An additional 16 samples, 4 extending to depths of ca. 250 cm and 12 to ca. 311 cm, and each encompassing a surface area of 426.5 cm 2 , yielded 5904 specimens. Of these, 51% was collected from the upper 15.2 cm and 21.5% from the 15.2–30.5 cm depth. About 20% of the fauna was collected from below 55 cm, and 1.8% or 109 specimens were obtained from depths below 200 cm. Distribution data are presented for the total microarthropod fauna as well as for major component taxa including Acarina, Collembola, Psocoptera, Pauropoda, Protura, Symphyla, larvae of Coleoptera and Diptera, and Japygidae (Diplura). Results are discussed in relation to sampling requirements.

Soil micro—arthropods of a virgin forest and adjoining tea fields in the Western Ghats in Kerala—a brief ecological study

Abstract A study of the soil micro-arthropods of a virgin forest and an adjoining tea plantation in Kerala has revealed that site characters changed with conversion of the forest into a tea plantation. In the course of deforestation. there was a drastic change in the micro-arthropod fauna. Qualitative and quantitative differences in the populations of Symphyla, Collembola, Protura and mites are shown and results analyzed in relation to deforestation and cultivation.

Microarthropod Ecology of a Porcupine‐Inhabited Cave in Nova Scotia

The most important source of organic detritus in Nova Scotia caves is feces of the porcupine, Erethizon dorsatum. The high organic content of this cave detritus supports a numerically rich microarthropod fauna, composed of epigean species preadapted to a troglic environment. The fauna is of recent, postglacial origin, and no troglobites were identified. Three distinct stages in detritus decomposition presented three stages in ecological succession, each with a characteristic fauna. The majority of the cave Collembola were eyeless and unpigmented. The Isotomidae accounted for 83.5% of the cave fauna. All families of Collembola were represented except the Poduridae. Recognizable trophic levels and food web patterns exist in the cave biotic community. The fauna is active all year, since deep in the cave temperatures remain above freezing during the winter.