Statistical Analysis of the Influence of a Disturbance Factor on Formation of the Spatial Structure of the Great Bustard (<Emphasis Type="Italic">Otis tarda</Emphasis> L.) (Otididae,Aves) Population in the Trans-Volga Region

This paper examines the influence of the location of settlements, railroads, and highways on the spatial structure of the Otis tarda population in the Trans-Volga region that was studied in the years 1998–2016 in a model area of 12000 km² that is located in the southern part of the Saratov Trans-Volga region. The zone of the impact made by our estimated disturbance factor due to the movement of people and a variety of ground vehicles along various-purpose roads on the territorial distribution of bustards in autumn can be denoted as a 300–500 m width band on both sides of the transport communications. Shelterbelts that were created along transport communications render a beneficial effect on the distribution of O. tarda and reduce the influence of the disturbance factor. Furthermore, crop rotation fields with side sizes of more than 1 km can be considered a factor that compensates for the anxiety of birds. We have found that in the Saratov Trans-Volga region, because of the large size of crop rotation fields and significant development of roadside and shelter belts, no special measures are required to protect O. tarda such as restrictions on the movement of people and vehicles over the territory where this species lives.     

Dynamics of the Abundance and Community Structure of Small Mammals in the Saratov Trans-Volga Region

A typical feature of the populations of small mammals in different areas of the Saratov Trans-Volga region is the long-term and constantly increasing abundance of Sylvaemus uralensis and its wide distribution in a variety of habitats. The maximal abundance of S. uralensis is 72.0 individuals per 100 trap-days, and its share in catches is 73.0%. The abundance of Microtus arvalis tends to increase. It was shown that Lagurus lagurus has been found again in the steppe zone, on fallow lands and fields, after a prolonged depression in 2012–2013, the average density of species being 4.0 individuals per 100 trap-days. A high abundance of other typical steppe inhabitants (Allocricetulus eversmanni and Ellobius talpinus) was noted as well. The highest indices of species diversity (H = 1.18) are typical of fallow lands.     

Flowering banker plants for the delivery of multiple agroecosystem services

Ecosystem services provided by agricultural ecosystems include natural pest control and pollination, and these are important to ensure crop productivity. This study investigates the use of the banker plant Calendula officinalis L. to provide multiple ecosystem services by increasing the abundance of natural enemies for biological control of tomato pests, providing forage resources to wild bees, and improving crop yield. C. officinalis was selected for this experiment as it is used as a banker plant for Dicyphini (Hemiptera: Miridae) predators. Strips of flowering C. officinalis were established in the field edges of tomato fields and arthropod visitation to C. officinalis strips and tomato was measured. Crop damage from multiple pests of tomato was assessed in fields with C. officinalis strips and control sites. The contribution of pollination to crop yield was assessed through a pollinator exclusion experiment. The inclusion of C. officinalis in tomato fields was associated with increased abundance of Dicyphini, parasitoids, bees and other arthropod groups within these strips. A reduction in the total leaf crop damage from Lepidoptera pests was recorded in fields with C. officinalis strips. Increased fruit set and biomass were recorded in open-pollinated tomato but this was not significantly different between control and C. officinalis fields. Results presented here demonstrate that the inclusion of a companion plant can improve the conservation of beneficial arthropods and the delivery of agroecosystem services but efficacy is likely to be improved with the addition of plants, with different functional traits, and with improved attractiveness to crop pollinators.     

Gamasid mites of small mammals in the semi-desert territories of Saratov Trans-Volga region

New data on the species composition and comparative analysis of gamasid mites occurring on small mammals in the semi-desert territories of Saratov Trans-Volga region are reported. In all, 18 species of gamasid mites (9 genera, 5 families) were found, including 9 species which had not been previously recorded in the region: Hypoaspis (Stratiolaelaps) miles Berlese, 1882, H. (Geolaelaps) heselhausi Oudemans, 1912, H. (G.) lubrica Oudemans et Voigts, 1904, Laelaps multispinosus Banks, 1909, L. jettmari Vitzthum, 1930, Cyrtolaelaps mucronatus G. et. R. Canestrini, 1881, Haemogamasus citelli Bregetova et Nelzina, 1952, Hirstionyssus eusoricis Bregetova, 1956, and Hi. ellobii Bregetova, 1956; 5 of these species are new to Saratov Province.     

Molecular diversity and distribution of indigenous arbuscular mycorrhizal communities colonizing roots of two different winter cover crops in response to their root proliferation

A clear understanding of how crop root proliferation affects the distribution of the spore abundance of arbuscular mycorrhizal fungi (AMF) and the composition of AMF communities in agricultural fields is imperative to identify the potential roles of AMF in winter cover crop rotational systems. Toward this goal, we conducted a field trial using wheat (Triticum aestivum L.) or red clover (Trifolium pratense L.) grown during the winter season. We conducted a molecular analysis to compare the diversity and distribution of AMF communities in roots and spore abundance in soil cropped with wheat and red clover. The AMF spore abundance, AMF root colonization, and abundance of root length were investigated at three different distances from winter crops (0 cm, 7.5 cm, and 15 cm), and differences in these variables were found between the two crops. The distribution of specific AMF communities and variables responded to the two winter cover crops. The majority of Glomerales phylotypes were common to the roots of both winter cover crops, but Gigaspora phylotypes in Gigasporales were found only in red clover roots. These results also demonstrated that the diversity of the AMF colonizing the roots did not significantly change with the three distances from the crop within each rotation but was strongly influenced by the host crop identity. The distribution of specific AMF phylotypes responded to the presence of wheat and red clover roots, indicating that the host crop identity was much more important than the proliferation of crop roots in determining the diversity of the AMF communities.     

Maximizing survivorship in cold: thermogenic profiles of non-hibernating mammals

Winter-active small mammals residing in seasonal environments employ many different behavioral, anatomical and physiological mechanisms to cope with cold. Herein we review research on survival mechanisms in cold employed by small mammals with emphasis on the families Soricidae, Muridae and Sciuridae. The focus of this review is on research delineating the role of seasonal changes in resting metabolic rate (RMR), nonshivering thermogenesis (NST), body mass, and communal nesting in enhancing winter survivorship of six species of small mammals (masked shrewSorex cinereus, short-tailed shrewBlarina brevicauda, southern red-backed voleClethrionomys gapperi, white-footed mousePeromyscus leucopus, deer mouseP. maniculatus, and southern flying squirrelGlaucomys volans) residing in the Appalachian Mountains of Pennsylvania, USA. Each species shows good over-winter survivorship but exhibits a different suite of mechanisms to maximize survival in cold.B. brevicauda, S. cinereus, andG. volans show slight increases in RMR during winter, whereasPeromyscus andC. gapperi exhibit decreased RMR overwinter. All six species experience elevated NST in winter. The comparatively low RMR and NST ofG. volans during winter was attributable to a decreased energy expenditure due to a larger body mass, coupled with communal nesting in cavities of trees that provided insulation from low ambient temperatures. Squirrels nesting singly experienced a longer period of elevated NST in winter and higher mean NST year-round than did squirrels nesting communally. Energy conservation in the form of growth retardation in winter was exhibited byC. gapperi andS. cinereus but not the other species.     

Characteristics of body mass growth in semialtricial and altricial bird species during the nestling period

The dynamics of body mass growth were studied in nestlings of 22 semialtricial and altricial bird species based on materials collected in seven regions of Russia in the years 1976–2013. The bird species belong to four orders and 13 families. The results of the study indicate the nonuniform growth of nestlings in different bird species. Of the species investigated, only seven were found to reach or exceed the mass of adult birds. Over the nestling period, the nestlings of open-nesting species, such as the hooded crow (Corvus cornix), rook (Corvus frugilegus), magpie (Pica pica), fieldfare (Turdus pilaris), song thrush (Turdus philomelos), and goldfinch (Carduelis carduelis), do not reach the weight of adult birds and their growth continues after they leave the nest. In closed-nesting species, only the nestlings of the barn swallow (Hirundo rustica) reach or exceed the definitive mass, whereas the nestlings of the jackdaw (Corvus monedula), starling (Sturnus vulgaris), wryneck (Jynx torquilla), tree sparrow (Passer montanus), and great tit (Parus major) continue to grow after leaving the nest. The body mass of birds on the day of their hatching and before their departure from the nests and the mass of adult birds depend on the nesting type, duration of the nestling period, size groups of species, and their definitive size. The average specific growth rate of body mass and its maximum values for different species are also associated with these factors. The maximum specific growth rate in small-sized and medium-sized bird species was observed on the 0–1st days of life; in large bird species, on the 2nd–4th days. The specific growth rate did not depend on the type of nesting, but it was inversely related to the duration of the nestling period and the definitive sizes of birds.     

Shrub cover expressed as an ‘arthropod island’ in xeric environments

Based on the vague importance of shrub cover, an attempt was made to create a theoretical concept framework known as an ‘arthropod-island’ analytical model. These models were based on the multi-bond correlation between shrubs, soil properties, and above- and below-ground biotic communities. By utilizing published datasets on (i.e., above- and below-ground) arthropod communities related to shrub species and age, the proposed models for an ‘arthropod island’ were applied in order to determine their fitness for xeric ecosystems. It was found that the ‘arthropod-island’ concept could be the result of statistical differences in ecologically adaptive (i.e., preferable) redistribution of arthropods among the microhabitats beneath the shrub canopy and in the open spaces. Taxon density, relative to the richness and Shannon indices, was found to be more sensitive to the selected models. The relative interaction intensity index [RII = (A ? B)/(A + B), A = shrub canopy value, B = intershrub value] was found to be more suitable for the ‘arthropod island’ at the community level. The relative neighbor effect [RNE = (B ? A)/max(A, B)] and RII were found to be suitable at the population level, while the fitted model heavily depended on the variety of arthropod taxon. It was suggested that there were consistent ‘arthropod island’–shrub relationships between shrub species and between shrub ages in terms of arthropod density at the community level. The arthropod taxon was found to indicate an inconsistent ‘arthropod island’–shrub relationship between shrub species that differed from shrub ages at the population level.     

Precise feeding of probiotics in the treatment of edwardsiellosis by accurate estimation of <Emphasis Type="Italic">Edwardsiella tarda</Emphasis>

Edwardsiella tarda is one of the leading fish pathogens for the aquaculture industry. To realize efficient disease control of edwardsiellosis, a predictive model for E. tarda in seawater was developed. The modified logistic model was used to regress the growth curves of E. tarda JN at five different temperatures (range from 10 to 30 °C) and four organic nutrient concentrations (range from 5 to 40 mg l^?1 measured by chemical oxygen demand (COD)). The modeling effects of temperature and COD on the specific growth rate (μ) were developed by square-root model and saturation-growth rate model, respectively. The growth model was validated in turbot aquaculture tanks by estimating the dynamics of inoculated E. tarda. The accurate feeding of probiotic Bacillus pumilus strain H2 was calculated based on the estimation of E. tarda. Results showed that the logistic model produced a good fit to the growth curves of E. tarda JN (average R²?=?0.962). The overall predictions based on above models agreed well with the growth curve of E. tarda JN observed by plate counting in the validation tests (average Af?=?1.16; average Bf?=?1.32). The use of predicted amount of B. pumilus (5.66 log CFU ml^?1) successfully prevent the deterioration of disease for turbot with 13.3% mortality rate in a recirculating aquaculture system (RAS), while the feeding of 0 and 3.0 log CFU ml^?1 of B. pumilus resulted in 53.7 and 75.3% of turbot mortality rate, respectively. In conclusion, accurate estimation of E. tarda realized the precise feeding of probiotics, which successfully prevent the rapid progression of the edwardsiellosis.     

Patterns of floral resource use by two dominant ant species in a biodiversity hotspot

Ecological dominance in ants is often fuelled by carbohydrate intake. Most studies have focused on the importance of invasive ant mutualistic associations with trophobionts whereas few studies have investigated the importance of floral nectar on invasion success. In this study, utilisation of temporarily available floral nectar by the invasive Argentine ant, Linepithema humile, was compared to that of the dominant native ant, Anoplolepis custodiens, within the Cape Floristic Region (CFR), a biodiversity hotspot. The effect of these two focal ant species on species composition and abundance of ground foraging ants as well as floral arthropod visitors in inflorescences of Proteacea species was assessed. Foraging activity, and trophic ecology inferred from the abundance of natural stable isotopes of Carbon (δ¹³C) and Nitrogen (δ¹⁵N), and the ratio of Carbon to Nitrogen (C:N) were compared between the two ant species during three flowering periods. Linepithema humile significantly reduced the abundance and species diversity of both above-ground and floral arthropod species abundance and composition. Linepithema humile increased its foraging activity with increasing nectar availability, switching its diet to a more herbivorous one. Anoplolepis custodiens did not respond as effectively to increasing floral nectar or negatively impact floral arthropod visitors. This study showed that the availability of floral nectar and ability of L. humile to more effectively utilise this temporarily available resource than native ants, can contribute significantly to the further spread and persistence of L. humile in natural environments in the CFR.     

Passive recovery of an island bird community after rodent eradication

The number and scale of island invasive species eradications is growing, but quantitative evidence of the conservation efficacy of passive recovery is limited. We compare relative abundances of breeding birds on Hawadax Island (formerly named Rat island), Aleutian Archipelago, Alaska, pre- and post- rat eradication to examine short-term (<1 year post-eradication) changes due to rodenticide application, and medium-term (5 years post-eradication) changes due to the absence of invasive rats. In the short term, Bald Eagle (Haliaeetus leucocephalus) numbers decreased from 24 individuals pre-eradication to two individuals <1 year post-eradication, but recovered to 10 individuals (42 % of pre-eradication) 5 years post-eradication, with all individuals nesting (63 % of the pre-eradication nesting). Five years post-eradication relative abundances of most terrestrial birds surveyed using point counts either significantly increased [Gray-crowned Rosy Finch (Leucosticte tephrocotis), Lapland Longspur (Calcarius lapponicus), Snow Bunting (Plectrophenax nivalis), Song Sparrow (Melospiza melodia)] or did not differ [Pacific Wren (Troglodytes troglodytes)]. Shorebirds also increased 5 years post-eradication with Black Oystercatchers (Haematopus palliates) increasing fivefold, and Rock Sandpiper (Calidris ptilocnemis) nesting increasing from one to five nests. We confirmed two species of ground nesting seabirds [Tufted Puffin (Fratercula cirrhata) and Leach’s Storm-petrel (Oceanodroma leucohoa)] as nesting (puffin) or engaged in courtship behavior (Storm-petrel) 5 years post-eradication. Our results indicate that despite the short-term impact on Bald Eagles, and without further human intervention, most terrestrial and marine birds have newly-colonized, re-colonized, or increased in abundance following the eradication of invasive rats.     

Diptera in Nests of the Fieldfare <Emphasis Type="Italic">Turdus pilaris</Emphasis> in Moscow City

The composition of dipterans inhabiting fieldfare nests in a big city was studied for the first time, based on material collected soon after chick fledging. Larvae of 21 species belonging to 14 families were found, including saprophages, necrophages, and predators (Scatopsidae, Ceratopogonidae, Phoridae, Chloropidae, Anthomyiidae, etc.), and also Protocalliphora azurea (Fallén, 1816) (Calliphoridae) and Neottiophilum praeustum (Meigen, 1826) (Neottiophilidae) known as bloodsucking ectoparasites of nestlings. Larvae of P. azurea (up to 121 per nest) were found in both early (April–May) and late (May–June) nests. Larvae of N. praeustum (up to 299 per nest) were recorded only in late nests. The two species occurred both separately and jointly in one nest, with N. praeustum dominating numerically. The seasonal differences in the development of these two parasitic species may account for their high abundance in such ephemeral habitats. Larvae of Trypocalliphora braueri (Hendel, 1901), a subcutaneous parasite of nestlings of many bird species, were not found in the fieldfare nests. A key to the larvae of the three fly species parasitizing nestlings in European Russia is given.     

Use of human-made nesting structures by wild bees in an urban environment

Most bees display an array of strategies for building their nests, and the availability of nesting resources plays a significant role in organizing bee communities. Although urbanization can cause local species extinction, many bee species persist in urbanized areas. We studied the response of a bee community to winter-installed human-made nesting structures (bee hotels and soil squares, i.e. 0.5 m deep holes filled with soil) in urbanized sites. We investigated the colonization pattern of these structures over two consecutive years to evaluate the effect of age and the type of substrates (e.g. logs, stems) provided on colonization. Overall, we collected 54 species. In the hotels, two gregarious species, Osmia bicornis L. and O. cornuta Latr. dominated the community (over 87 % of the data). Over 2 years, the age of the soil squares did not affect their level of colonization and the same was true for the hotels with respect to O. bicornis and ‘other species’. However, O. cornuta occurred less often and raised fewer descendants in 1-year old hotels than in new ones. Bee nesting was not affected by the soil texture and, among above-ground nesting bees, only O. bicornis showed a preference for some substrates, namely Acer sp. and Catalpa sp. In a context of increasing urbanization and declining bee populations, much attention has focused upon improving the floral resources available for bees, while little effort has been paid to nesting resources. Our results indicate that, in addition to floral availability, nesting resources should be taken into account in the development of urban green areas to promote a diverse bee community.     

Nesting Behaviour of the Giant Honeybees <Emphasis Type="Italic">Apis</Emphasis><Emphasis Type="Italic">dorsata</Emphasis> Occurring in Jhargram,West Bengal,India

The giant honeybees Apis dorsata are habituated to construct combs in trees, houses, caves as well as in overhead water reservoir occurring in their nesting localities. To verify their preference for nesting sites if any, surveys were conducted in recent years (2013–16), during nesting seasons of these bees in Jhargram area of West Bengal, India. It is revealed that A. dorsata construct their combs in big, tall, aged simul (Bombax ceiba), bot (Ficus benghalensis) trees mostly, irrespective of localities. Also they were seen to construct nest at the underside of the overhead water reservoir ignoring nesting potential trees occurring nearby. Of course, nesting in the houses, and on the walls of culvert is not uncommon. As the bees constructed more than 100–200 nests at the same nesting site e.g., a tree or/and an overhead water reservoir, depending upon the availability of space for construction of nest it is concluded that these insects prefer colonial nesting.     

Influences of the invasive tamarisk leaf beetle (<Emphasis Type="Italic">Diorhabda carinulata</Emphasis>) on avian diets along the Dolores River in Southwestern Colorado USA

The tamarisk leaf beetle (Diorhabda carinulata), introduced from Eurasia in 2001 as a biological control agent for the invasive plant Tamarix ramosissima, has spread widely throughout the western USA. With D. carinulata now very abundant, scientists and restoration managers have questioned what influence this introduced arthropod might have upon the avian component of riparian ecosystems. From 2009 through 2012 we studied the consequences of biological invasions of the introduced tamarisk shrub and tamarisk leaf beetles on the diets of native birds along the Dolores River in southwestern Colorado, USA. We examined avian foraging behavior, sampled the arthropod community, documented bird diets and the use of invasive tamarisk shrubs and tamarisk leaf beetles by birds. We documented D. carinulata abundance, on what plants the beetles occurred, and to what degree they were consumed by birds as compared to other arthropods. We hypothesized that if D. carinulata is an important new avian food source, birds should consume beetles at least in proportion to their abundance. We also hypothesized that birds should forage more in tamarisk in the late summer when tamarisk leaf beetle larvae are more abundant than in early summer, and that birds should select beetle-damaged tamarisk shrubs. We found that D. carinulata composed 24.0 percent (±?19.9–27.4%) and 35.4% biomass of all collected arthropods. From the gut contents of 188 birds (25 passerine species), only four species (n?=?11 birds) contained tamarisk leaf beetle parts. Although D. carinulata comprised one-quarter of total insect abundance, frequency of occurrence in bird gut contents was only 2.1% by abundance and 3.4% biomass. Birds used tamarisk shrubs for foraging in proportion to their availability, but foraging frequency did not increase during the late summer when more tamarisk leaf beetles were present and birds avoided beetle-damaged tamarisk shrubs. Despite D. carinulata being the most abundant arthropod in the environment, these invasive beetles were not frequently consumed by birds and seem not to provide a significant contribution to avian diets.     

Innate Olfactory Responses of <Emphasis Type="Italic">Asobara japonica</Emphasis> Toward Fruits Infested by the Invasive Spotted Wing Drosophila

Insect parasitoids are often manipulated to improve biological control programs for various arthropod pests. Volatile compounds can be a relevant cue used by most parasitoid hymenoptera for host or host microhabitat location. Here, we studied olfactory responses of the braconid Asobara japonica Belokobylskij, an Asiatic endoparasitoid of the invasive pest Drosophila suzukii (Matsumura), toward its host and host substrates. Adult A. japonica displayed an innate attraction to undescribed volatile cues from infested host fruits irrespectively of the juvenile rearing experience, i.e. they respond to a novel cue subsequently used for microhabitat selection. These data suggest that A. japonica parasitoids mass-reared on artificial diet and factitious host (D. melanogaster) can successfully locate their hosts. Naïve female parasitoids did not show a preference towards any of the tested host media. However, the enforced adult experience with the rearing host medium modified the olfactory preference patterns toward non-natal host fruits. These findings provide evidence of associative learning during the adult stage of A. japonica, and demonstrate its plasticity in exploiting the volatiles from various fruits infested by D. suzukii.     

The invasive herb <Emphasis Type="Italic">Lupinus polyphyllus</Emphasis> attracts bumblebees but reduces total arthropod abundance

Invasive plant species generally reduce the abundance and diversity of local plant species, which may translate into alterations at higher tropic levels, such as arthropods. Due to the diverse functional roles of arthropods in the ecosystems, it is critical to understand how arthropod communities are affected by plant invasions. Here, we investigated the impact of the invasive ornamental herb Lupinus polyphyllus (Lindl.) on arthropod communities during its main flowering period in southwestern Finland over two years. The total number of arthropods was about 46% smaller at the invaded sites than at the uninvaded sites in both study years, and this difference was mainly due to a lower abundance of beetles, Diptera, Lepidoptera, and ants. However, the number of bumblebees (particularly Bombus lucorum) was about twice as high at invaded sites compared with uninvaded sites, even though bumblebee richness did not differ between sites. There was no statistically significant difference between invaded and uninvaded sites in the abundances of the other arthropod groups considered (Hymenoptera (excluding bumblebees and ants), Hemiptera, and Arachnida). In addition, L. polyphyllus affected the relative abundance of four arthropod groups, with the order Lepidoptera being less common at invaded sites than at uninvaded sites, while the opposite was true for bumblebees, Hemiptera, and Arachnida. Overall, these results demonstrate that the negative impact of L. polyphyllus on biodiversity goes beyond its own trophic level, suggesting that this species has the potential to alter the abundance of different arthropod groups and, consequently, the structure of arthropod communities at a large scale.     

Core gut microbiota in Jinhua pigs and its correlation with strain,farm and weaning age

Gut microbial diversity and the core microbiota of the Jinhua pig, which is a traditional, slow-growing Chinese breed with a high body-fat content, were examined from a total of 105 fecal samples collected from 6 groups of pigs at 3 weaning ages that originated from 2 strains and were raised on 3 different pig farms. The bacterial community was analyzed following high-throughput pyrosequencing of 16S rRNA genes, and the fecal concentrations of short-chain fatty acids (SCFAs) were measured by gas chromatograph. Our results showed that Firmicutes and Bacteroidetes were the dominant phyla, and Lactobacillus, Streptococcus, Clostridium, SMB53, and Bifidobacterium were the most abundant genera. Fifteen predominant genera present in every Jinhua pig sample constituted a phylogenetic core microbiota and included the probiotics Lactobacillus and Bifidobacterium, and the SCFA-producing bacteria Clostridium, Prevotella, Bacteroides, Coprococcus, Roseburia, Ruminococcus, Blautia, and Butyricicoccus. Comparisons of the microbiota compositions and SCFA concentrations across the 6 groups of pigs demonstrated that genetic background and weaning age affected the structure of the gut microbiota more significantly than the farm. The relative abundance of the core genera in the pigs, including Lactobacillus, Clostridium, Prevotella, Bacteroides, Roseburia, Ruminococcus, Blautia, and Butyricicoccus varied dramatically in pigs among the 2 origins and 3 weaning ages, while Oscillospira, Megasphaera, Parabacteroides, and Corynebacterium differed among pigs from different farms. Interestingly, there was a more significant influence of strain and weaning age than of rearing farm on the SCFA concentrations. Therefore, strain and weaning age appear to be the more important factors shaping the intestinal microbiome of pigs.     

Population responses by <Emphasis Type="Italic">Orius insidiosus</Emphasis> to vegetational diversity

The abundance of different life stages of Orius insidiosus (Say) (Heteroptera: Anthocoridae) and its prey were recorded in vegetationally diverse (soybean and agronomic weeds) and monoculture (soybean only) fields. Orius insidiosus adults and nymphs were more abundant in diversified plots than in monocultures. A similar number of O. insidiosus eggs were found in the two treatments, but twice as many eggs were laid on non-crop plants than on soybeans within the vegetationally diverse plots. Prey densities were equivalent in the two treatments. In olfactometer assays, naïve O. insidiosus females were unresponsive to odors from three weed species (morning glory, redroot pigweed and velvetleaf). The current results, coupled with previous experimental observations, lead us to believe that higher abundance of O. insidiosus in vegetationally diverse habitats could be related to improved fitness of the predator, which in turn is related to certain plant qualities (e.g., nutrition, plant architecture, etc.). Proximal cues are likely more influential to oviposition decisions by O. insidiosus females than volatile signals.     

Above-ground arthropod community structure and influence of structural-retention management in southern Patagonian scrublands,Argentina

Southern Patagonia’s landscape hosts several semi-natural habitats, traditionally used for sheep production, such as Mulguraea tridens and Lepidophyllum cupressiforme scrublands. Mulguraea scrublands are managed via mechanical shredding to remove shrubs and increase grass availability, alternating with structural-retention strips. We analyzed the influence of structural-retention management (with cut and retention strips) in Mulguraea scrublands with regards to above-ground arthropod community structure, as well as differences between the two natural scrubland types. We worked in Santa Cruz Province (Argentina) with pitfall traps during two summers in the first 2 years after mechanical shredding. Richness, abundance, occurrence frequency, Shannon–Wiener diversity and Pielou evenness indices, and similarity among assemblages were evaluated using univariate and multivariate statistical tests. Complementarily, we described vegetation ground cover and microclimate. We collected 3279 individuals from 38 species belonging to Insecta and Arachnida Classes. Shannon–Wiener diversity and Pielou evenness indices, as well as the overall assemblages, differed significantly between managed cut strips and natural Mulguraea scrublands, mainly due to the loss and introduction of species from surrounding environments; abundance also differed in the first sampling year compared to the second year. Likewise, managed retention strips allowed the partial maintenance of arthropod community structure and had a microclimate that was similar to natural Mulguraea scrublands, although assemblages in managed cut and retention strips became more similar among themselves in the second sampling year. On the other hand, richness, abundance and assemblage of both natural scrubland types differed significantly, with 87?% more indicator species in Mulguraea than in Lepidophyllum scrublands. Greater dissimilarity occurred between both natural scrubland types in dryer years, which could be related with an El Niño Southern Oscillation event. If arthropod community structure changes prove stable over time, mechanical shredding with structural-retention management would allow for an increase in the sheep carrying capacity, while reducing impacts to the arthropod community, thus providing a viable compromise between productivity and conservation in a fragile arid environment. More studies are necessary to evaluate long term changes in above-ground arthropod community structure of scrublands in arid zones of southern Patagonia.