Surface-dwelling Arthropods Research Articles

Effects of mowing on the arthropod community in grass buffers and adjacent crop fields.

Grass buffers are commonly planted along crop borders to filter nutrient and pesticide runoff. These buffers also provide food and shelter for beneficial and herbivorous arthropods and can serve as corridors for their movement into neighboring crops. Mowing is a common maintenance practice to control woody plants in these buffers. Field experiments were conducted to determine whether mowing influences the movement of arthropods into neighboring soybean plantings (Glycine max L) and impacts their abundance in corn (Zea mays var. indentata) the following spring. Results showed that mowing had varying effects on the abundance of herbivores, saprovores, parasitoids, and predators, particularly in the grass buffers. Aerially active arthropods in the plant canopy were more adversely affected by mowing than surface-dwelling arthropods. Mowing significantly reduced grasshopper (Orthoptera: Acrididae) density in the buffers, but did not trigger their movement into adjoining soybean fields. Parasitoids, predators, and thrips (Thysanoptera: Thripidae) were dissimilarly affected by mowing, and their responses were influenced by grass type. Altogether, these findings indicate that mowing did not cause notable movement of arthropods from grass buffers into adjoining crops and had minimal effects on the community of beneficial arthropods the following spring. Also, there were no differences in the level of insect feeding injury in crop fields next to mowed and unmowed buffers.

Investigating the Assemblages of Two Groups of Collembola (Strong Furca and Weak Furca) under Different Agricultural Management Systems, Northeastern China

Agriculture itself has been considered one of the leading reasons for biodiversity loss because of the huge quantity of land dedicated to just this activity, and agricultural intensification has impacted soil organisms at several taxonomic levels. Soil biota is a vital component of the agricultural system, providing essential ecosystem services while also having synergistic impacts on crop yield. Preservation of their diversity becomes a major element of an agricultural sustainability strategy. Many studies focused on agricultural activities’ effects on soil organisms, but few of them have focused on their effects on the co-occurrence patterns of their communities. Collembola communities are frequently employed as a substitute for soil organisms; thus, as a surface-dwelling arthropods representative, we investigated assemblages of soil Collembola in reaction to the arrangement of 6 treatments varying in crop rotation (MC: monoculture (corn) vs. CS: corn–soybean rotation) and tillage types (MP: mould ploughing; RT: ridge tillage; and NT: no-tillage). We hypothesized that Collembola communities with strong furca would respond well to the agricultural practices than those with weak furca, and there would be strong co-occurrence between species of Collembola communities belonging to the treatments with less intensity of soil disturbance and more variation in crop rotation. Our study found no clear evidence of a beneficial effect of crop rotation on Collembola communities. Although Collembola with strong furca shows higher abundances in plots with mold plowing, weak furca abundances were not showing any difference (differences in abilities to move fast from harsh habitats could be the reason for different responses of these two groups). Network analysis revealed that Collembola assemblages seem to occur more responsive to tillage intensity than crop rotation. Network graphs of treatments with ridge tillage are significantly more clustered than all others. For the first time, we can show that assemblages of springtails in agriculture were distinguished by a pattern of co-occurrence alongside agricultural practices (crop rotation, soil tillage), showing variations in the disturbance of soil and soil nutrients. Our results, contrary to our expectations, demonstrated that the effects of agricultural activities on Collembola abundance and diversity could be weak after long-term application of the same treatment, but still, they will clearly affect the bonds between Collembola species by affecting their co-occurrence pattern in Collembola communities.

Tillage intensity and herbicide application influence surface-active springtail (Collembola) communities in Romanian vineyards

Vineyards are important perennial, often intensively managed agroecosystems. In most vineyards, ground vegetation is controlled by tillage and/or the application of broadband herbicides with scarcely known effects on the soil fauna. We studied a total of 16 commercial vineyards in the Târnave wine region, a typical viticultural region in Transylvania, Central Romania. As a model organism for surface-dwelling arthropods we examined the response of springtail (Collembola) species richness and activity density to vineyard tillage practices, fertilization, and herbicide application. A total of 24 species in 10 families were found in the studied vineyards. Principal coordinates analysis (PCoA) identified three distinct springtail communities linked to tillage and fertilization practice. Springtail species richness was positively associated with high tillage intensity (frequency: once or twice a year). Springtail activity density in inter-rows was positively correlated with inter-row tillage and herbicide application under grapevines. For the first time we could show that springtail species assemblages in vineyards were characterized by high niche overlap regarding soil quality (organic matter, pH, CaCO3, P and K), indicating similar resource utilization. We conclude that the positive influence of vineyard management and disturbance on surface-dwelling springtail communities is possibly due to the exclusion of potential competitors and predators, the stimulation of microorganisms and/or an increased nutrient input.

Melanization in response to wounding is ancestral in arthropods and conserved in albino cave species

Many species adapted to aphotic subterranean habitats have lost all body pigmentation. Yet, melanization is an important component of wound healing in arthropods. We amputated appendages in a variety of cave-adapted and surface-dwelling arthropods. A dark clot formed at the site of injury in most species tested, including even albino cave-adapted species. The dark coloration of the clots was due to melanin deposition. The speed of wound melanization was uncorrelated with a difference in metabolic rate between surface and cave populations of an amphipod. The chelicerate Limulus polyphemus, all isopod crustaceans tested, and the cave shrimp Troglocaris anophthalmus did not melanize wounds. The loss of wound melanization in T. anophthalmus was an apomorphy associated with adaptation to subterranean habitats, but in isopods it appeared to be a symplesiomorphy unrelated to colonization of subterranean habitats. We conclude that wound melanization i) is an important part of innate immunity because it was present in all major arthropod lineages, ii) is retained in most albino cave species, and iii) has been lost several times during arthropod evolution, indicating melanization is not an indispensable component of wound healing in arthropods.

The Ground-Dwelling Arthropod Community of Península Valdés in Patagonia, Argentina

This is the first study based on a planned and intensive sampling effort that describes the community composition and structure of the ground-dwelling arthropod assemblage of Península Valdés (Patagonia). It was carried out using pitfall traps, opened for two weeks during the summers of 2005, 2006 and 2007. A total of 28, 111 individuals were caught. Ants (Hymenoptera: Formicidae) dominated this community, followed by beetles (Coleoptera) and spiders (Araneae). The most abundant species were Pheidole bergi Mayr (Hymenoptera: Formicidae) and Blapstinus punctulatus Solier (Coleoptera: Tenebrionidae). Two new species were very recently described as new based on specimens collected during this study: Valdesiana curiosa Carpintero, Dellapé & Cheli (Hemiptera, Miridae) and Anomaloptera patagonica Dellapé & Cheli (Hemiptera, Oxycarenidae). The order Coleoptera was the most diverse taxa. The distribution of abundance data was best described by the logarithmic series model both at the family and species levels, suggesting that ecological relationships in this community could be controlled by a few factors. The community was dominated by predators from a trophic perspective. This suggests that predation acts as an important factor driving the distribution and abundances of surface-dwelling arthropods in this habitat and as such serves as a key element in understanding desert, above-ground community structure. These findings may also be useful for management and conservation purposes in arid Patagonia.

The influence of weather conditions on the activity of high-arctic arthropods inferred from long-term observations

BackgroundClimate change is particularly pronounced in the High Arctic and a better understanding of the repercussions on ecological processes like herbivory, predation and pollination is needed. Arthropods play an important role in the high-arctic ecosystem and this role is determined by their density and activity. However, density and activity may be sensitive to separate components of climate. Earlier emergence due to advanced timing of snowmelt following climate change may expose adult arthropods to unchanged temperatures but higher levels of radiation. The capture rate of arthropods in passive open traps like pitfall trap integrates density and activity and, therefore, serves as a proxy of the magnitude of such arthropod-related ecological processes. We used arthropod pitfall trapping data and weather data from 10 seasons in high-arctic Greenland to identify climatic effects on the activity pattern of nine arthropod taxa.ResultsWe were able to statistically separate the variation in capture rates into a non-linear component of capture date (density) and a linear component of weather (activity). The non-linear proxy of density always accounted for more of the variation than the linear component of weather. After accounting for the seasonal phenological development, the most important weather variable influencing the capture rate of flying arthropods was temperature, while surface-dwelling species were principally influenced by solar radiation.ConclusionConsistent with previous findings, air temperature best explained variation in the activity level of flying insects. An advancement of the phenology in this group due to earlier snowmelt will make individuals appear earlier in the season, but parallel temperature increases could mean that individuals are exposed to similar temperatures. Hence, the effect of climatic changes on the activity pattern in this group may be unchanged. In contrast, we found that solar radiation is a better proxy of activity levels than air temperature in surface-dwelling arthropods. An advancement of the phenology may expose surface-dwelling arthropods to higher levels of solar radiation, which suggest that their locomotory performance is enhanced and their contribution to ecological processes is increased.

Edge effects on ant community structure and species richness in an agricultural landscape

The effect of sharp edges between three different types of land use on the species richness and structure of ant communities was examined in an agricultural landscape within Central Hesse, Germany. Species richness and nest densities of ants at the centres and the edges of meadows, crop fields, and fallow land were recorded by hand sampling during 1997 and 1998. Edges between different land-use types did not increase ant species richness at the landscape scale, nor were they unique habitats for a specialised ant fauna. Nonetheless, most species shared ‘ecotonal effects’ in the way that their relative abundance either decreased (e.g. Myrmica scabrinodis) or increased (e.g. Lasius niger, Lasius flavus) at the edges, resulting in different community structure between edges and centres of the land-use types. This was influenced by two major factors: (i) the boundary contrast between the neighbouring habitats (i.e. in terms of disturbance caused by agricultural practices), and (ii) the response of different species to changing abiotic conditions. High nest densities of aggressive species with large colonies occurred along edges. We hypothesise that this can significantly reduce edge permeability for surface-dwelling arthropods.

Beneficial Arthropods Associated with Buffalograss

Beneficial arthropods collected from buffalograss, Buchloe dactyloides (Nuttall) En­ gelmann, evaluation plots and vegetatively established buffalograss lawns included predatory ants, spiders, ground beetles, rove beetles, big-eyed. bugs, and several species of hymenopterous parasi­ toids. Ants and spiders were the most abundant beneficial arthropods collected, representing 84% of the total beneficial arthropods captured. Pitfall traps collected >2.5 times as many (16,094) beneficial arthropods as sod plug samples (6,054), demonstrating that pitfall traps are a more effective technique than sod plugs for capturing highly mobile surface-dwelling arthropods. Families of parasitoids captured on sticky traps during the 2-yr sampling period included Scelionidae, Encyrti­ dae, Mymaridae, and Trichogrammatidae. Mymarids and trichogrammatids were the most abundant parasitoid families, representing 76.8% ofthe total parasitoids collected. Total numbers ofbeneficial arthropods collected from sites maintained at higher and lower management levels were not significantly different, suggesting that beneficial arthropod abundance may not be adversely affected by the 2 management regimes applied in this study.

Comparison of Three Methods for Sampling Arthropod Pests and Their Natural Enemies in Peanut Fields

We compared the use of beat sheets, pitfall traps, and sweep nets for sampling common arthropods in peanut fields by taking weekly samples in the 1987 to 1989 growing seasons. We used σ 2/ x ratios and number of samples needed as the criteria for comparing sampling techniques. Pitfall trap samples had the largest means for soil surface-dwelling arthropods such as Labidura riparia (Pallas) (Dermaptera: Labiduridae), Oxyopes salticus Hentz (Arachnida: Araneae: Oxyopidae), ground beetles, rove beetles, and wolf spiders. Beat sheet samples had the smallest σ 2/ x ratios for Solenopsis invicta (Buren) (Hymenoptera: Formicidae) and Peucetia viridans Hentz (Arachnida: Araneae: Oxyopidae). Samples from sweep nets had the smallest σ 2/ x ratios for Geocoris spp. (Hemiptera: Lygaeidae). All three techniques had similar σ 2/ x ratios for Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) and the Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae). Sweep net samples had the smallest σ 2/ x ratios for Spissistilus festinus (Say) (Homoptera: Membracidae). None of the techniques adequately sampled all common pest and beneficial arthropods in peanuts.

The Use of Pit-fall Traps for Estimating the Abundance of Arthropods, with Special Reference to the Tenebrionidae (Coleoptera)

Pitfall trapping of several species of tenebrionid beetles was undertaken at study sites in Rock Valley, Nevada, during weeks 10-37 of 4 consecutive years, 1971-1974. Six species were studied by mark-recapture, five for the full term of the study. Absence of recapture of several species resulted in no estimates of numbers for several species in 1974. We conclude that the Geometric Model for Frequency of Recapture gives the most conservative estimates. Utilizing this model, we estimated numbers per hectare and determined the 95% confidence limits. We concluded that pitfall trapping is not uniformly applicable to all species of surface-dwelling arthropods with the vagility of a species appearing to be a most important factor. However, surface-dwelling Tenebrionidae would seem more amenable to this method than most surface-dwellers.

Comparative Analysis of the Feeding Habits of Two Species of Arizona Blind Snakes, Leptotyphlops h. humilis and Leptotyphlops d. dulcis

Stomach content analyses of 28 Leptotyphlops humilis humilis and 17 L. dulcis dulcis indicate that these snakes feed extensively on ants and termites which compromise 54-64 per cent of the total diet. L. d. dulcis appears to be more fossorial in its feeding activity than L. h. humilis which preys on a greater percentage of surface-dwelling arthropods. Presumably, this serves to reduce competition for the available food supply in geographical areas of sympatry. Both species show a definite preference for soft-bodied prey-types. In addition, several insect species which live as commensals in ant and termite nests are readily consumed along with their hosts. INTRODUCTION Most of the existing literature on the blind snakes of the genus Leptotyphlops deals specifically with the systematics of the group (Klauber, 1940) and their general ecology and geographical distribution (Banks and Farmer, 1963; Banta, 1965; Brattstrom, 1953; Turner and Wauer, 1963). Previous investigations on the feeding behavior of the Western Blind Snake, Leptotyphlops humilis humilis, and the Texas Blind Snake, L. dulcis dulcis, have demonstrated that these fossorial species feed extensively on ants and termites (Brattstrom and Schwenkmeyer, 1951; Reid and Lott, 1963; Stebbins, 1966). It has been further shown that L. d. dulcis frequently utilizes the pheremone trails of some ant species to locate its prey (Watkins, Gehlbach and Baldridge, 1967). Although it has been suggested that additional softbodied arthropods are also consumed (Stebbins, 1954), quantitative and qualitative information concerning the specific food preferences of these snakes is lacking. The purpose of the present study was to accurately analyze the feeding habits of these two species in an area of sympatry as well as to determine what differences, if any, exist in their food preferences. MATERIALS AND METHODS Twenty-eight L. h. humilis and 17 L. d. dulcis were collected 5 km ESE of Chiricahua, Cochise Co., Arizona during May through August 1971. The area was characterized by sand flats and intermittent boulder-strewn hillsides. Several rocky canyons with dry creek beds were present. There were no apparent micro-habitat differences between the two species. The prevalent vegetation included mesquite (Prosopis juliflora), incense bush (Symphoricarpos sp.), creosote (Covillea) and ocotillo (Fouquieria splendens). Most specimens were collected along paved and dirt roads at night. Several individuals were found within rocky crevices during the day. L. h. humilis specimens ranged in length from 21.4-33.8 mm; L. d. dulcis individuals from *Current Address: Dept. of Zoology & Entomology, Iowa State University, Ames, Iowa 50010, USA.