Impact of Soil Applications ofBeauveria bassianaandMariannaeasp. on Nontarget Forest Arthropods

Replicated plots were established in pear thrips-infested sugar maple stands. They were treated withBeauveria bassianaas an emulsifiable concentrate and a nutrient-based granular formulation and withMariannaeasp. as a wettable powder. Postapplication invertebrates moving across plots were collected daily for 10 days in pitfall traps. Collected individuals were identified, held for 10 days, and then evaluated for the presence of fungal infection and other potential pathogenic microorganisms. A total of 3615 invertebrates were collected and identified. Of the invertebrate population in treated plots that fell into pitfall traps, 2.8% became infected with eitherB. bassianaorMariannaeasp. The fungi applied also occur naturally in sugar maple forest soils; therefore, it was impossible to confirm whether the infection we observed in treated plots was a result of contact with the spores we applied. Because we obtained infection among invertebrates collected from control plots, it is likely that these fungi do attack invertebrates under natural forest conditions. Of the 2584 invertebrates examined further for obligate internal pathogens, 2.5% were infected with entomophthoralean fungi, protozoans, and/or nematodes. Results suggest thatB. bassianaandMariannaeasp. could be applied to forest soil without a significant negative impact on the forest-dwelling invertebrate population.     

Is there intraguild predation between winter-active spiders (Araneae) on apple tree bark?

We studied whether there si intraguild predation among overwintering invertebrates in bark traps installed on apple trees. We found that 86% of the overwintering invertebrates in traps were predators, which were dominated by spiders (72%) of different guilds and different body sizes. Spiders had spatially segregated in the traps so that smaller specimens hid in an interstitial space that was inaccessible to larger specimens. Spiders of the bark-dwelling guild, Anyphaena and Philodromus, are winter-active and can prey on other smaller spiders. Analysis of their abundance in traps indicated a negative relationship between Anyphaena and Philodromus or other spiders. Inspection of traps during winter revealed an influx of spider specimens confirming their winter-activity. In a semi-field experiment, where overwintering in cardboard bands was studied under controlled conditions, we observed mortality of both winter-active Philodromus and Anyphaena spiders due to their interspecific predation. The mortality was affected by their size ratio – larger specimens consumed smaller ones. Presence of alternative prey, theridiid spiders, did not affect their mortalities, but the presence of shelters (interstitial spaces) did. In boards with interstitial spaces smaller spiders suffered lower mortality than in boards without the interstitial spaces. Obtained results suggest that intraguild predation between overwintering spiders can decrease their population density during winter.     

Alien Grazing: Indirect Effects of Muskrats on Invertebrates

Effects of alien herbivores on plants are quite well known, especially on oceanic islands. Much less is known about the indirect effects of alien herbivores. Via indirect effects indigenous organisms can become more vulnerable to other ecological factors. We studied the effect of dense muskrat population on aquatic invertebrates in patches, which were in different succession phases after grazing. The succession was divided into three phases:(i) open-water area, (ii) mixed floating and submerged vegetation, and (iii) undisturbed Equisetum stands. Intensive muskrat grazing affected especially the size distribution of invertebrates. The proportion of small invertebrates was greatest in clear-cut areas, whereas that of large invertebrates was greatest in the Equisetum-stands. According to activity traps, the clear-cut areas harboured good populations of small perch, which are known as invertebrate predators. The study showed that the indirect effects of alien herbivore can be considerable. In this case, they seemed to be mediated to invertebrates through the change in vegetative habitat structure. This change rendered invertebrates more vulnerable to fish predation.     

Trunk invertebrate faunas of Western Australian forests and woodlands: Influence of tree species and season

Abstract Trunk–associated invertebrates were sampled on two rough‐barked tree species (jarrah, Eucalyptus marginata and marri, E. calophylla) at Karragullen, in the hills near Perth, Western Australia, and on these two species plus two smooth‐barked species (wandoo, E. wandoo, and powderbark wandoo, E. accedens) at Dryandra, a drier site situated 150 km to the south‐east. Invertebrates were sampled by intercept traps, which collect animals that attempt to land on the trunks, and photo‐eclector bark traps, which collect invertebrates that move, or live, on the trunk. The range and abundance of invertebrates sampled was generally greater in the intercept than the bark traps. Invertebrate abundance and activity (but not biomass) on bark was strongly seasonal, with greater numbers being found during the moister periods. The two smooth‐barked species supported, and were visited by, more invertebrates than the two rough‐barked species. There was some evidence that jarrah supported more invertebrates than marri at both Karragullen and Dryandra, although the results were equivocal. Within the two smooth‐barked species, wandoo tended to support more invertebrates than powderbark wandoo. These trends are discussed in terms of the characteristics of the bark of these trees and the environments in which they occur.     

Ground invertebrate fauna associated with native shrubs and exotic pasture in a modified rural landscape, Otago, New Zealand

This study examined whether the diversity and relative abundance of ground-dwelling invertebrates changed in relation to type of vegetation cover. Invertebrate taxon diversity and relative abundance were assessed with pitfall traps placed under the native shrubs Olearia bullata and Coprosma propinqua, and in surrounding patches of exotic pasture. A total of 1935 invertebrates and at least 152 invertebrate taxa were recorded from 49 pitfall traps. The number of native taxa was c.63% of all taxa recorded, whereas exotic invertebrates represented only c.9%. The other c.28% were of undetermined origin. Taxon richness and relative abundance under the two shrub species were statistically similar, although all mean values (except for Coleoptera) were higher for traps set beneath C. propinqua. In contrast, taxon richness and relative abundance were significantly higher in the exotic pasture than under either of the shrub species. The same pattern was evident for exotic invertebrates and the relative abundance of native invertebrates, and for some of the most speciose orders. The data indicate that nearly half of native taxa occurred only under native shrubs. In contrast, 7 out of 12 exotic species were found in all three vegetation types, and all but one of them were recorded at least in exotic pasture. We conclude that the value of locally-modified and patchy vegetation cannot be underestimated for its potential in providing native biodiversity reservoirs for New Zealand’s native invertebrate fauna.     

Prey attraction by larvae of the New Zealand glowworm, Arachnocampa luminosa (Diptera: Mycetophilidae)

Abstract. The hypothesis that bioluminescence produced by larvae of the New Zealand glow-worm, Arachnocampa luminosa , attracts prey was tested experimentally in Reserve Cave, Waitomo, New Zealand, and in its bush-clad entrance over a total of 200 days during winter, spring, and summer. We compared catches on transparent adhesive traps placed either over glowworms or over areas from which glowworms had been removed. Adhesive traps over glowworms caught significantly more invertebrates per trap per day than did control traps. Glowworms in bush attracted greater numbers and types of invertebrates than did glowworms in the cave. Diptera predominated in both bush (86% of the total catch) and cave (89%). Also caught were small numbers of Araneae, Coleoptera, Hymenoptera, Orthoptera, Trichoptera, Gastropoda, Acarina, and Neuroptera—listed in order of abundance—but no adults of A. luminosa were caught. Glowworms under adhesive traps survived with little or no food for up to 78 days.     

Trunk invertebrate faunas of Western Australian forests and woodlands: Seeking causes of patterns along a west‐east gradient

Abstract Trunk‐associated invertebrates were sampled on marri trees (Eucalyptus (Corymbia) calophylla) along a transect from Karragullen, near Perth, through to Dryandra, 150 km to the south‐east. This represents a drop in annual rainfall from 1078 to 504 mm, which is accompanied by a change from jarrah (Eucalyptus marginata) forest to wandoo (Eucalyptus wandoo) woodland. Invertebrates were sampled by intercept traps, which collect invertebrates that attempt to land on the trunks, and bark traps, which collect invertebrates that move, or live, on the trunk. Trends are reported here at the ordinal level. The variety and abundance of invertebrates sampled was generally greater in the intercept than the bark traps. Invertebrate abundance, activity and biomass on bark were strongly seasonal, with greater numbers being found during the moister periods. Invertebrate abundances tended to be greater at the drier, eastern end of the transect, particularly on the three sites within wandoo woodland. These trends were analysed in terms of rainfall, soil nutrients and plant community composition. The analysis failed to detect an underlying influence of any of these factors, suggesting that the observed trends on marri trunks may be the result of invertebrate responses to the dominant tree species at the western and eastern ends of the transect, namely jarrah and wandoo respectively.     

A comparison of pitfall-trap and quadrat methods for sampling ground-dwelling invertebrates in dry riverbeds

The distribution and ecological roles of ground-dwelling invertebrates colonizing dry beds of temporary rivers are poorly known, due in part to the lack of tested sampling methods. Sampling efficiency and completeness and detection biases associated with pitfall-trap and quadrat samples were compared at six sites in the dry beds of two New Zealand rivers. On average, pitfall-trap samples contained 3.5 times more taxa than quadrat samples, and pitfall traps required less time to collect as many taxa as quadrats. Among all taxa collected, 80% were exclusive to pitfall traps and 4% to quadrat samples. Among-sites differences in invertebrate composition were greater in pitfall-trap samples than in quadrat samples. Rarefaction curves indicated that eight to eleven pitfall traps/100 m² were necessary to collect most of the common taxa in the study sites. Differences in the performance of pitfall traps and quadrats in dry riverbeds may be due to the absence of vegetation, to the large range of taxa considered, and to diel movements of some taxa. The large number of samples required at our study sites to reach a high level of sampling completeness suggests that the diversity of ground-dwelling invertebrates in dry riverbeds has probably been underestimated in previous studies.     

The effects of soil tillage on beneficial invertebrates within the vineyard

1 Tillage, commonly used in agroecosystems, can influence the abundance of invertebrates through factors such as habitat change and food availability.
2 The effects of tillage on the composition and abundance of invertebrates were examined in a vineyard near Mildura in Victoria, Australia, focusing particularly on groups that might act as natural enemies in vineyards. We used pitfall traps at ground level and sticky traps in the canopy.
3 The collections were first sorted to order. Beetles (Coleoptera) were sorted to family and ants (Hymenoptera: Formicidae) to genus.
4 Ants were the only group to be affected by tillage when all months were considered. The same genera occurred in both treatments but the abundance of several genera was reduced by tillage. Families of several beetles, including predators, increased in tilled areas. Spider, millipede, centipede and earwig numbers were decreased by tillage. In the canopy, Trichogrammatidae and other parasitoids decreased in abundance after tillage.
5 These results indicate that tillage influences the composition of invertebrates and has the potential to negatively affect the abundance of beneficial groups.     

A novel method for monitoring invertebrates in the burrows of small mammals

A novel method for surveying motile invertebrates in the burrows of small mammals is proposed. The data obtained are expressed as the number of individuals per trap-day and are therefore comparable with the results obtained using Barber traps.     

Do intruding predators and trap position affect the reliability of catches in activity traps?

Forty lakes in Sweden and Finland were sampled in 1990 with activity traps to evaluate the effects of trapped predators on invertebrate catch. Vertebrate (fish, newts) and invertebrate (leeches, dragonflies, water beetles, backswimmers and water scorpions) predators were considered separately. Invertebrate predators affected neither the abundance nor the taxonomic diversity of the catches. Vertebrate predators had no effect on the abundance but reduced the taxonomic diversity of the catches significantly. Thus, vertebrate predators are a possible source of bias in activity trap catches, but only concerning taxonomic diversity. Within the depth gradient studied (0.25–0.75 m), trap position (suspended in mid-water versus on the bottom) did not affect the percentages of nektonic and benthic invertebrates in the catches. The relative abundance of all taxa was similar in the catches from different trap positions, but the relative abundance of the most numerous taxa as well as the diversity of the catches differed between trap positions. We conclude that both mid-water and bottom traps are suitable for monitoring aquatic invertebrates, and that bottom traps may be preferred for practical reasons.     

Detecting invertebrate responses to fire depends on sampling method and taxonomic resolution

New knowledge about the responses of species to fire is needed to plan for biodiversity conservation in the face of changing fire regimes. However, the knowledge that is acquired may be influenced by the sampling method and the taxonomic resolution of a study. To investigate these potential sampling biases, we examined invertebrate responses to time since fire in mallee woodlands of southern Australia. Using a large‐scale replicated study system, we sampled over 60 000 invertebrates with large pitfall traps, wet pitfall traps and sweep nets, and undertook analyses at morphospecies and order level. Large pitfalls and sweep nets detected several strong fire effects, whereas wet pitfall traps detected few effects. Invertebrate abundance in sweep nets was highest shortly after fire because of grasshopper outbreaks. Several additional morphospecies showed strong preferences for different stages in the post‐fire succession. In contrast with morphospecies effects, analyses at order level either failed to detect fire effects or were driven by the most abundant species. For fire research to produce credible results with the potential to guide management, it must use a range of sampling techniques and undertake analyses at (morpho)species level. Homogeneous fire management, such as fire suppression in fragmented landscapes or widespread frequent burning for asset protection, is likely to cause declines in fire‐affected invertebrates.     

Efficiency of modifications in the design and use of submerged funnel traps for sampling Chironomidae (Diptera)

The effects of three modifications in design and use of submerged funnel traps on capture efficiencies for emerging Chironomidae were examined in a recently-created reservoir in northern Manitoba, Canada. The experiments showed that: (1) Sample counts were higher in traps suspended just below the surface of the water than in traps suspended 1.5 m deeper, just above the lake bottom, probably owing to difficulties in handling the deep traps. (2) Sample counts were lower in traps with small cones inserted into the neck of the collecting bottle than in traps without these cones, although the differences were not significant. Bottles fitted with mini-cones usually retained higher numbers of other invertebrates which destroyed much of the chironomid catch. (3) Sample counts were proportionally higher in traps with a basal area of 0.283 m² compared to traps of 0.1 m² area.     

Short-term uptake of heavy metals by periphyton algae

Benthic invertebrates in a tropical river (Menik Ganga) recolonised denuded substrates within 2–3 weeks, though full diversity was not achieved until 4 weeks. No well defined succession was observed. All taxa apparently colonised at random from drift, upstream and vertical sources. Traps colonised from only one of these sources developed as abundant and diverse a fauna as control traps in 5 weeks. Strong spatial heterogeneity in the number and composition of colonisers was observed between replicate traps. It is suggested that colonisation resulted from random foraging activities and most colonists were derived from veryshort distances.     

Heterogeneous relationships between abundance of soil surface invertebrates and radiation from Chernobyl

Although pollution due to nuclear accidents constitutes some of the largest environmental disasters, there is surprisingly little information available on the relationship between abundance of animals and background radiation. We sampled invertebrates with pit-fall traps at Chernobyl in areas differing in background radiation level by more than four orders of magnitude. We obtained samples from 58 traps for 19 taxa of which five showed positive associations (Acari, Araneae, Formica sp., Homoptera), while four showed negative associations (Coleoptera, Collembola, Vespa, Insecta). These relationships were independent of other environmental factors such as habitat, humidity and ecotype. Estimates of the relationship between abundance and background radiation from the pitfall trap study were similar to those from an independent study based on invertebrates found under slices of wood placed on the ground. The differences in relationship between abundance and radiation among taxa may arise from direct effects of radiation. The findings reported here have implications for choice of animal taxa for efficient monitoring of the biological impact of radiation on animals.     

The effect of the bioremediation of soil contaminated with petroleum derivatives on the occurrence of epigeic and edaphic fauna

This field study investigated the colonization process of soil contaminated with different petroleum products (petrol, diesel fuel, spent engine oil; dose: 6000 mg of fuel·kg^?1 dry mass [d.m.] of soil) by epigeic and edaphic invertebrates during the progress of natural bioremediation and bioremediation enhanced using selected microorganisms (ZB-01 biopreparation). Epigeic fauna was captured using pitfall traps. Occurrence of edaphic fauna in soil samples as well as total petroleum hydrocarbon contents (TPH) were also investigated. Results showed that inoculation with ZB-01 biocenosis allowed the degradation of petroleum derivatives in the soil contaminated with diesel fuel and engine oil, with 82.3% and 75.4% efficiency, respectively. Applying bioremediation to all contaminated soils accelerated the process of recolonization by edaphic invertebrates. However, the 28-month period was too short to observe full population recovery in soils contaminated with diesel fuel and engine oil. Microbe-enhanced bioremediation accelerated recolonization by epigeic invertebrates on soil contaminated with diesel fuel, whereas it exerted inhibitory effect on recolonization of soil contaminated with engine oil (especially by Collembola). The observed discrepancies in the rates of recolonization for soils contaminated with petrol and diesel fuel that were still noted at the stage of no longer different TPH levels justify the idea to include the survey of edaphic faunal density as one of the parameters in the ecological risk assessment of various bioremediation techniques.     

The soil macrofauna and organochlorine insecticide residues at twelve agricultural sites near Huntingdon

Ten arable fields and two apple orchards were chosen from a total of thirty-five sites visited to represent typical soils, crop rotations and insecticide applications in the Huntingdon area of East Anglia. Pitfall traps were used to collect insects and other invertebrates during fortnightly periods from early April until harvesting and in one orchard until the following February. Estimates of active biomass were obtained for several groups of invertebrates and differences between the sites are discussed. Samples of beetles, earthworms and slugs were collected during June and were sent with soil samples to the Government Chemist for analysis of organochlorine residues. The soil residues are compared with those in respective invertebrate samples and with stated application rates. It is concluded that soil invertebrates could form a regular source of pesticide residues for ground-feeding birds but that the levels are generally too low to cause acute poisoning.     

Effects of ground cover (straw and compost) on the abundance of natural enemies and soil macro invertebrates in vineyards

1 Herbicides are commonly applied under grapevines in Australia to remove weeds and thereby to avoid water loss through transpiration. 2 Interest in sustainability promotes a reduction in chemical inputs, including herbicides, leading to trials with surface mulches to suppress weeds. 3 Surface mulches may also influence the abundance of a range of invertebrates. Potentially, an increase in natural enemies will contribute to pest control and encourage a reduction in pesticide application. 4 We used three trapping methods and direct soil sampling to assess invertebrates at ground level, in the canopy and in the soil to determine the influence of mulch on natural enemies, potential pests and soil macroinvertebrates, including earthworms. 5 Collections sorted to family demonstrated that the addition of straw or compost mulches increased natural enemies collected with pitfall traps and soil organisms. However, there was no clear indication of the overall superiority of either mulch. 6 Abundance of ground beetles, parasitoid Hymenoptera and spiders collected with pitfall traps were increased by the addition of mulches. In the canopy, predatory and parasitic Diptera and predatory Hemiptera increased after mulching. 7 Earthworms collected by hand sorting soil increased with straw mulching. 8 No influence on pests was detected. Although Lepidoptera and Sigmurethra, collected in pitfall traps, increased with straw mulching, neither included pest species. 9 The results are discussed with reference to the potential economic impact of mulches.     

The effects of released pheasants on invertebrate populations in and around woodland release sites

The release of gamebirds for recreational shooting exerts a series of effects on the ecosystems into which they are placed. Pheasants (Phasianus colchicus) are omnivorous and eat invertebrates, especially when young or, if females, when breeding. Consequently, the release of large numbers of pheasants into woodland release pens may affect local invertebrate populations. Previous studies have reported mixed evidence. We conducted pitfall trapping at 13 sites (49 pens) in central England over 2 years (totaling 65 pen measures), comprising three surveys annually, immediately prior to releases in mid‐summer, 4 weeks later when most birds were still in the pens, and another 5 weeks later when most birds had dispersed. We compared traps inside and 25 m outside pens in the same wood. We considered release densities and whether the birds had prior experience of eating invertebrates. While accounting for overall seasonal declines in invertebrates trapped, we detected changes for total invertebrate biomass and total counts indicative of released pheasants causing local decreases inside pens, either directly by predation or indirectly by modifying vegetation. There were also relative decreases outside pens when the pheasants start to disperse, suggesting that the released pheasants may be affecting invertebrates in those nearby areas or that their earlier effects inside the pen, modifying vegetation or increasing invertebrate activity, increased the relative susceptibility of invertebrates there to trapping. However, these effects were not seen for specific invertebrate groups believed to be especially susceptible to pheasants. For slugs and detritivores, we detected small population increases inside pens. Across the study period, decreases for most measures were greater outside pens than inside them. We conclude that any effects pheasants have on invertebrate communities at release sites in woodlands are complex and that long‐term and taxon‐specific studies should be considered to understand the local net ecological effects of gamebird releases on invertebrates.     

Seasonality and density of emerging insects of a mixed lowland broadleaf-podocarp forest floor,Orongorongo Valley,New Zealand

Abstract

Emergence traps were used continuously for 2 years to determine the population density and seasonality of invertebrates in a mixed lowland broadleaf-podocarp forest near Wellington, New Zealand. A total of 53 920 individuals of 21 invertebrate orders was caught. Although more individuals were caught in the first year than in the second, this was not consistent amongst the different groups or species. Dipterans, staphylinid beetles, and solitary wasps were the most numerous insects caught. Diptera, Araneida, Opiliones, and Hymenoptera emerged from the forest floor in every month of the 2 year study. Many other invertebrate groups were active throughout the year but seasonal catches were significantly different with more recorded in summer than in other seasons. Numbers of several species were positively correlated with temperature. Likely effects of the extended invertebrate activity on the forest ecology are discussed.