Ground-dwelling Arthropods Research Articles

Influence ofBeauveria bassianaStrain Gha on Nontarget Rangeland Arthropod Populations

Arthropod abundance on mixed-grass rangeland was determined before and after spray treatments for grasshopper suppression. These evaluations were made in field plots (16.2 ha) treated with either Beauveria bassiana (Balsamo) Vuillemin strain GHA at 1 × 1013 conidia in 1.89 liter oil per 0.405 ha, carbaryl at 559.88 g (AI) in 0.59 liter total volume per hectare, or no insecticide (untreated controls). Infectivity of B. bassiana was determined by capturing grasshoppers from treatment plots 7 d after application and monitoring them for external growth of the fungus. Major predators, parasitoids, and pollinators were captured with pitfall and malaise traps weekly throughout the summer season. About one-half of the grasshoppers collected from B. bassiana treatment plots exhibited external growth of the fungus. Formicidae, Araneae, and Carabidae decreased in all plots during periods of heavy precipitation after the treatment date, but these declines were not caused by mortality as a result of B. bassiana or carbaryl spray treatments. Ground-dwelling arthropod abundance rebounded to pretreatment levels a2 wk after treatments. No statistical differences in the abundance of aerial insects were detected with respect to treatment effects; however, natural increases in abundance in all plots were observed as the season progressed.

An assessment of the impact of biological and chemical grasshopper control agents on ground-dwelling arthropods in Niger, based on presence/absence sampling

Medium-scale experimental field applications of two grasshopper and locust control agents, the mycoinsecticide Metarhizium anisopliae ( flavoviride) var. acridum (Deuteromycotina: Hyphomycetes) and the organophosphate fenitrothion, were carried out in August 1996 in Maı̈ne Soroa, Niger. The objective was to evaluate effects and side-effects on target grasshoppers and epigeal non-target arthropods, using simple binary (presence/absence) sampling techniques. Plots (≈50 ha, 3 replicates) were treated at standard recommended dose rates of 5 × 10 12 spores/ha ( Metarhizium) and 250 g a.i./ha (fenitrothion). The frequency of occurrence – or total presence – was used as a measure of relative population density. The fauna was monitored at 5 day intervals for 36 days (5 d before and 31 d after treatment) and again in August 1997, using 40 miniature pitfall traps per plot and sampling date. Presence/absence sampling proved appropriate to detect and quantify pesticide effects, and the use of similar techniques in rapid risk assessment programs (RAPs) for locust and grasshopper control is recommended. Both control agents were effective against grasshoppers, reflecting their inherent mode of action and speed of kill. The efficacy of fenitrothion ranged from 75 to 86% over the 31 d post-treatment period. Metarhizium had an efficacy of 76% during the last sampling period (days 21–31). Differences between treatments were not significant during this phase. The non-target arthropods monitored on species or species group level represented four insect families which together made up about 75% of the total catch: Carabidae, Tenebrionidae, Formicidae and Ephydridae. 75% of these taxa were significantly reduced by fenitrothion. The median effect was 69% (first week), 33% (second week) and 51% (third to fourth week), respectively, and fenitrothion was classified as `medium risk'. Most of the non-target fauna had fully recovered after 31 days, but one ant species was still significantly reduced in 1997. None of the taxa monitored proved susceptible to the mycopesticide. The median effect was <25% and the product was classified as `low risk'. The field trials provided further evidence that M. anisopliae var. acridum can be as effective as organophosphates without threatening non-target arthropods other than orthopterans.

Effect of Argentine ant invasions on ground-dwelling arthropods in northern California riparian woodlands.

Although the Argentine ant (Linepithema humile) is a widespread invasive species that displaces native ants throughout its introduced range, the effects of these invasions on arthropods other than ants remain poorly known. This study documents the consequences of Argentine ant invasions on ants and other ground-dwelling arthropods in northern California riparian woodlands. Baits and unbaited pitfall traps were used to sample different components of the arthropod communities at five pairs of uninvaded and invaded sites. Sites occupied by Argentine ants supported almost no native epigeic ants except for the winter-active Prenolepis imparis. Sites with Argentine ants averaged four to ten times more ant workers than did sites with native ants, but ant worker biomass did not differ between uninvaded and invaded sites. Argentine ants recruited to baits in invaded areas, on average, in less than half the time of native ants in uninvaded areas. Despite the loss of epigeic native ants, higher Argentine ant worker abundance, and faster recruitment by Argentine ants at invaded sites, pitfall trap samples from uninvaded and invaded areas contained similar abundances and diversities of non-ant arthropods. These findings suggest that Argentine ants and the native ants they displace interact with the ground-dwelling arthropods of these habitats in a similar manner.

Target and non-target impacts from diazinon applied against &lt;i&gt;Dasineura mali&lt;/i&gt; in a Canterbury apple orchard

The control of apple leafcurling midge (Dasineura mali) with diazinon was investigated as part of an Integrated Fruit Production programme. A soil drench was applied against the emerging adults of the first generation (pre-flowering), and compared with a foliar application against the second generation (early December). Nontarget effects on the biodiversity of ground dwelling arthropods were examined using pitfall traps before and after diazinon applications, and on arboreal diversity using brushed leaf samples. Drench, foliar spray, and a combination of these treatments, all reduced percentage of damaged shoots compared to untreated plots. Drench and foliar applications gave similar results. Little impact on ground-dwelling arthropod biodiversity was detected following the drench or foliar applications. The biodiversity of foliage-dwelling (mainly beneficial) arthropods showed a significant reduction after foliar treatment.

A comparison of relative abundance and biomass of ground-dwelling arthropods under different forest management practices

Habitat structural characteristics and relative abundance and biomass of ground-dwelling arthropods were compared among four replicated stand treatments: intense burning and salvage logging; clearcutting follwed by roller-chopping (100% soil surface disturbance); clearcutting followed by bracke seeding (30% soil surface disturbance); and naturally regenerated mature, forested sand pine scrub. Arthropods were classified by taxa and by mean maximum width. Monthly trends in abundance and biomass of arthropods captured are described. Mature forest differed from the three disturbance treatments in most habitat structural features, but disturbance treatments were similar. Total numbers and dry weight did not differ among treatments but more individuals and biomass of arthropods less than 5 mm mean maximum width occurred in burned sites. These were significantly more arthropods 10 mm or less in mean maximum width than over 10 mm, but arthropods 5–10 mm had the highest biomass. The relative abundance of some taxa differed among treatments, and taxa differed in monthly capture rates. Total numbers and biomass of captured arthropods were greatest from late May through November.

Corridor function of a road verge for dispersal of stenotopic heathland ground beetles carabidae

To reduce the effects of habitat isolation dispersal corridors between habitat fragments are often proposed. In this study the corridor function of a poor sandy roadside verge, adjacent to an open area of drift sand, was investigated for ground-dwelling arthropods. Three species of carabid beetles characteristic of this habitat, Pterostichus lepidus, Harpalus servus and Cymindis macularis, were marked and released at four different sites. Exchange of individuals of these species was recorded between the road verge and the open sandy area, and dispersal along the road verge was established. The rate of movement along the road verge was low compared to that in the open area. Sites with trees and narrow sites at the road verge had a barrier effect. Reproduction was recorded for two species at broad areas in the road verge. Under certain conditions (re) colonization of habitat areas by dispersal along a long, ribbon-like habitat might occur. For each species the specific features of such a corridor is discussed.

The composition of the carabid fauna on poor sandy road-side verges in relation to comparable open areas

In The Netherlands, the majority of heathlands and dry, unproductive grasslands have been brought into cultivation or afforested since the end of the 19th century. As a result, the original landscape has become highly fragmented. Nowadays, the heath habitat occurs in more or less isolated patches only. Many of these fragments show a small spatial variation in conditions. Ground-dwelling arthropods, with a low dispersal power and a specific preference for poor, sandy, open habitats, could disappear from such small fragments under the influence of temporarally unfavourable conditions. As recolonization from other fragments is often very difficult because of hostile surrounding areas, isolated small fragments that have lost their populations will remain unoccupied. The absence of some carabid species in such small, isolated fragments is thought to be the result of this situation. By introducing heathy corridors between such fragments, animals might be enabled to pass a hostile environment. This study shows that heathy road-side verges can possibly function as such a corridor. On the studied road-side verges, carabid species of poor sandy, open habitats were present, including the more rare species. Some species even found a better habitat at road-side verges than in adjacent poor sandy open areas. For other species the road-side verge seemed to be a more marginal habitat in which they occur only because of the presence of a suitable adjacent area. The distance to such an area, as well as the width of the poor sandy, open strip on the road-side verge seem to be important conditions for the occurrence of the latter species. In order to increase the survival chance in such a corridor, it is suggested that some wider strips or patches be created at the road-side verges, suitable for reproduction. In this way, road-side verges might contribute to a metapopulation structure by which species are better protected against regional extinction.

Biogeography and Diversity of Ground-Dwelling Arthropods in Farm Woodlands

Biogeography and Diversity of Ground-Dwelling Arthropods in Farm Woodlands

Abundance of carabid beetles and other ground-dwelling arthropods in conventional versus low-input bean cropping systems

The abundance and seasonal dynamics of carabid beetles and other ground-dwelling arthropods in conventional and low-input dry bean ( Phaseolus vulgaris L.) cropping systems were investigated over two field seasons in Maine, USA. In 1988, carabids and staphylinids were significantly greater in number in the low-input plots. Staphylinids and arachnids were significantly more abundant in the low-input plots in 1989. Elaterid adults were abundant in 1988, and the number in the conventional plots was 23 times higher than in the low-input plots. Multivariate analysis showed that compositions of major ground-dweling arthropods differed significantly between the two cropping systems from the early to middle season of plant growth. Individual carabid species differed between the two cropping systems. Harpalus rufipes, Pterostichus melanarius, Agonum muelleri, Clivina fossor, Carabus memoralis, Carabus auratus, and Loricera pilicornis were dominant carabid species in this study. In 1988, Pterostichus melanarius, Carabus auratus, and L. pilicornis were significantly more abundant in the low-input plots, while A. muelleri and Clivina fossor were significantly more abundant in the conventional plots. In 1989, however, only A. muelleri was significantly different between cropping systems and a significantly higher number was trapped in the low-input plots.

Feeding time strategies of the fringe-toed lizard, Uma inornata, during breeding and non-breeding seasons.

I examined the foraging behavior during the breeding and non-breeding seasons, May and July 1986, of the fringe-toed lizard Uma inornata (Iguanidae). During the breeding season males differ from females in their diet and in their foraging time strategy, males exhibiting time minimization and females energy maximization. In May, plant associated foods were selectively eaten. Males concentrated on flowers, a readily available quick energy food, which reduced foraging time and increased time for reproductive activities. Time budgets indicate that males spend over twice as much time in the open and in movement in May than do females. Females at this time restrict their activities to the cover of perennial bushes, and feed primarily on plant foods (flowers and arthropods). Energy maximization appears to be maintained by both sexes in the non-breeding season when food resources diminished to one-half of those in the breeding season. The lizards were less selective in their July feeding habits, broadening their diets to include ground-dwelling arthropods and foliage. Predation by these lizards follows a wait-ambush mode of foraging.

Predaceous and :Parasitic, Ground-dwelling Arthropods in Different Ecosystems in Western Saudi Arabia

Predaceous and :Parasitic, Ground-dwelling Arthropods in Different Ecosystems in Western Saudi Arabia

The Influence of Weeds and Farmyard Manure on the Activity of Carabidae and other Ground-Dwelling Arthropods in a Sugar Beet Crop

(1) Pitfall traps were used to investigate the effect of weeds and farmyard manure application on arthropod activity in sugar beet, giving particular attention to the activity of predators during the seedling stage of the crop. (2) The most marked increases in both species richness and abundance accompanied weed establishment, well after sowing, on plots not treated with herbicides. These increases were greatest amongst detritivore and weed specific herbivore species, although predatory Staphylinidae and parasitic Hymenoptera had similar responses. (3) Carabidae were the most abundant predators caught but their numbers were not affected obviously by weeds. Farmyard manure application increased the activity of species common early in the season such as Pterostichus strenuus (Panzer) and Bembidion lampros (Herbst) and resulted in an immediate but temporary increase in general species diversity. (4) Weed growth in the crop would not help reduce seedling pest losses because predator responses to weed establishment were too slow. Manure application immediately encouraged beneficial arthropods and seems, potentially, a useful and practical means of promoting natural control of injurious species during crop establishment.

Factors determining the abundance and distribution of rodents in a shrub-steppe ecosystem: the role of shrubs.

This study addressed the relative importances of shrub "resources" on a rodent community in a sagebrush dominated shrub-steppe ecosystem in southwestern Wyoming. Direct effects of shrubs (i.e., providing rodents with "food and cover") were assessed by removing shrubs from a 1.25 ha study plot and monitoring both rodent populations and their food resources. Shrub architecture and shrub-related food resources were found to be unimportant to deermice (Peromyscus maniculatus), Great Basin pocket mice (Perognathus parvus) northern grasshopper mice (Onychomys leucogaster) and Uinta ground squirrels (Spermophilus armatus), as shrub removal caused no significant changes in population sizes, sex ratios or age structure. Least chipmunks (Eutamias minimus) responded to shrub removal by leaving the plot and moving into adjacent shrubland. The montane vole (Microtus montanus) population showed a slight increase following shrub removal. Shrub removal did not alter the abundance of major rodent food resources on the plot (percent cover of herbaceous vegetation, soil seed reserves and ground-dwelling arthropods). Micrometeorological data suggested that shrubs did not significantly ameliorate a nocturnal rodent's micro-climate, but may have affected diurnal rodents' thermal loading rates by removing shade. While shrub architecture and food resources do not directly affect most of the rodents in this shrub-steppe ecosystem, shrubs may be important to rodents in a long-term time frame. Shrubs provide "safe sites" for germination and growth of herbaceous vegetation, thereby enhancing the diversity of the potential rodent food resources.

The Function of Burrow Turrets in a Gregariously Nesting Bee

Diadasia bituberculata, a gregariously nesting bee, builds earthen entrance tubes (turrets) onto its subterranean nest burrows. Turrets are here shown to function in preventing infiling of burrows by dirt or debris. Both turret design and orientation are important in this context. Selection pressures promoting the construction of turrets by bees probably are related to gregarious behavior, which concentrates excavation and nesting activities in a limited area. The behavior of modifying burrow entrances into projecting tubes has evolved in several groups of ground-dwelling arthropods, including ants, spiders, and bees. Entrance tubes (often called turrets) are especially notable in bees that are gregarious but solitary (in the sense that each female makes her own nest and there is no worker caste). These structures typically are formed as thin-walled earthen extensions of a burrow by the cementing together of small earthen pellets (Fig. 1). Although turrets are constructed by numerous species of bees which have received intensive study, little is known about the manner of turret construction and almost nothing is known about turret function. Among suggestions given a priori to explain the usefulness of bee turrets are protection of the burrow entrance from rainwater, parasites, and debris, and possibly social functions (e.g., Malyshev 1935, Linsley et al. 1952, Linsley and McSwain 1957, Linsley 1958, Eickwort et al. 1977). This study assesses the significance of turrets in the biology of the anthophorid bee, Diadasia bituberculata (Cresson). Diadasia is a genus of bees which is common in arid regions of the Western Hemisphere and which usually nest in aggregations. The range of D. bituberculata is listed by Michener (1951) as California. ANIMALS AND METHODS. Populations of D. bituberculata were studied in the Laguna Mountains of southern California (San Diego Co., elev. 1500 m), where females nested in aggregations of up to several hundred individuals on hard-packed surfaces of dirt roads in recently burned chaparral (2-4 years postfire). The behavior and tunneling activities of several such populations were observed intensively for varying periods during June and July of 1972-74. Casts of burrows and adjoining nest cells were made by pouring liquid latex (Rub-R-Mold) into burrow entrances and allowing it to harden overnight. The di-

The Effects of Slope Exposure on Arthropod Distribution Patterns

Pitfall traps were used to collect over 39,000 specimens of 132 species and higher taxa of arthropods from eight different aspects (slope exposures) of a grassy bald in eastern Temqnessee-western North Carolina. Slopes were characterized as to available moisture and temperature; climatic descriptions were based on measurements of rainfall, temperature, prevailing winds, solar radiation and vegetation cover. Southern and western exposures were categorized as warm and dry; northern and eastern exposures were cool and wet. Of the 34 most abundant species of insects and arachnids, 32 were significantly (p < 0.05) more abundant on one or more of the eight aspects. The S-facing slope was the most preferred aspect for arthropod activity. The SE and NW slopes, both windswept, had least activity. INTRODUCTION Little detailed information has been published as to how slope exposure affects the distribution of arthropods. This stands in sharp contrast to the wealth of information available on the effects of slope exposure on plant population distributions. Ayyad and Dix (1964) cite 22 studies dealing with slope exposure and associated vegetation, and plant ecology texts invariably cover the vegetational zonation on different aspects of a mountain (Odum, 1959; Billings, 1970; Whittaker, 1970). While slope-exposure effects on arthropods have not gone completely unnoticed (Bristowe, 19,39 on spiders; Cole, 1940 on ants; Cannon, 1965 on spiders, Geiger, 1965 on grasshoppers, moths and beetles; Lowry, 1972 on desert arthropods), these studies, with the exception of Lowry (1972), are mainly descriptive. This article provides detailed information on slope exposure as it pertains to arthropod distribution. Arthropod distribution was determined with pitfall traps. Pitfall trapping is an appropriate means of measuring slope-exposure effects since it measures ground surface activity and approximates, in many instances, relative abundance (Duffey, 1962). Duffey showed excellent correlation between the activity of ground-dwelling spiders (measured by pitfall traps) and relative density (measured by Tullgren funnel extraction). Surface activity and relative population density are related to the number of ground-dwelling arthropods that cross the pitfall area (Mitchell, 1963), as reported by Aheam (1971). SITE DESCRIPTION The study area was located on the Tennessee-North Carolina boundary in Carter and Mitchell counties. It was situated geographically at 360 06' N latitude and 820 0V W longitude in the Unaka Mountains, a section of the Southern Appalachians. The study site was located at approximately 1750 m (altitude) on