Pitfall trap catches of and aphid predation byPterostichus melanarius andPterostichus madidus in insecticide treated and untreated potatoes

Aphids were countedin situ and carabid beetle populations assessed by pitfall trapping betwen 1983–1985 in potato fields in Scotland treated with demeton-S-methyl (DSM) or untreated.Macrosiphum euphorbiae (Thomas) (Homoptera: Aphididae) was the most abundant aphid. Nineteen species of carabid beetles were trapped but the fauna was dominated byPterostichus melanarius (Ill.) andPterostichus madidus (Fabr.) (Coleoptera: Carabidae). Pitfall trap catches of these carabids were variable but generally lower in sprayed than unsprayed plots for a few days after DSM application and higher a week or two later. Of 1800P. melanarius and 910P. madidus dissected, 14.4 per cent and 30.5 per cent respectively, contained aphid remains. The proportion that had eaten aphids often was higher in sprayed than unsprayed plots immediately after treatment. In additional experiments, aphids treated with DSM fell from plants; four to five per cent of the theoretically applied dose of DSM reached the ground in a closed-canopy potato crop; and no mortality occurred whenPterostichus spp. were exposed to DSM in a field bioassay. It is proposed that observed patterns in trap catch ofPterostichus spp. around times of pesticide application may be due in part to aphids falling to the ground after treatment. Beetles that eat these fallen aphids may be less hungry, less active and less likely to be trapped. Later increases in catches may be attributed to hungry, more active beetles, a consequence of prey removal by the insecticide. Although this hypothesis requires further research, it is clear that the effects of insecticide treatment on carabid populations cannot be measured by pitfall trapping alone.     

Using demographic data to better interpret pitfall trap catches

The results of pitfall trapping are often interpreted as abundance in a particular habitat. At the same time, there are numerous cases of almost unrealistically high catches of ground beetles in seemingly unsuitable sites. The correlation of catches by pitfall trapping with the true distribution and abundance of Carabidae needs corroboration. During a full year survey in 2006/07 in the Lake Elton region (Volgograd Area, Russia), 175 species of ground beetles were trapped. Considering the differences in demographic structure of the local populations, and not their abundances, three groups of species were recognized: residents, migrants and sporadic. In residents, the demographic structure of local populations is complete, and their habitats can be considered "residential". In migrants and sporadic species, the demographic structure of the local populations is incomplete, and their habitats can be considered "transit". Residents interact both with their prey and with each other in a particular habitat. Sporadic species are hardly important to a carabid community because of their low abundances. The contribution of migrants to the structure of carabid communities is not apparent and requires additional research. Migrants and sporadic species represent a "labile" component in ground beetles communities, as opposed to a "stable" component, represented by residents. The variability of the labile component substantially limits our interpretation of species diversity in carabid communities. Thus, the criteria for determining the most abundant, or dominant species inevitably vary because the abundance of migrants in some cases can be one order of magnitude higher than that of residents. The results of pitfall trapping adequately reflect the state of carabid communities only in zonal habitats, while azonal and disturbed habitats are merely transit ones for many species of ground beetles. A study of the demographic structure of local populations and assessment of the migratory/residential status of particular carabid species are potential ways of increasing the reliability of pitfall trap information.     

The life histories and population dynamics of two carabid species on a Dutch heathland

Summary We deal with the causes of the synchronously fluctuating numbers of subpopulations of the carabid species Calathus melanocephalus as compared with the asynchronously fluctuating numbers of subpopulations of the carabid Pterostichus versicolor. Both species continuously occupy a large heath area, Dwingelder Veld (1600 ha), in The Netherlands, and are studied there in the same localities with the same methods. Of the adults of C. melanocephalus, 90% do not cover more than 2 ha during the entire reproductive season, while 90% of adults of P. versicolor cover no more than 12 ha. In C. melanocephalus egg production in the field is usually similar to that under optimal feeding conditions in the laboratory, but in P. versicolor egg production seems to be much lower in the field. In the field 70–80% of the eggs most probably are killed by eelworms, followed by more than 90% mortality among the remaining larvae. Comparing mortality of developmental stages in laboratory experiments with that in field experiments in enclosures, it appears that mortality of larvae is not density-dependent, even when density in the experiments is much higher than it ever is in the field. Larval mortality mainly results from the poor ability of the larvae to find prey, even when in field experiments prey density is increased far above natural densities. We discuss why these poor prey-finding abilities are not improved by natural selection. In the spring breeder P. versicolor differences between localities both in abiotic factors, soil moisture and surface temperature, and biotic factors, reactions of prey species to abiotic factors, in spring and summer when the larvae are maturing contribute to the asynchronous fluctuations of numbers between subpopulations. In the autumn breeder C. melanocephalus possible differences in biotic factors between sites are outnumbered by the effects of winters with a higher or lower than normal amount of precipitation respectively. During a wet winter mortality among the larvae is much higher than during a dry winter. As these winter conditions are similar over large areas (many km²) the fluctuations of numbers between subpopulations are synchronous.Communication No. 443 of The Biological Station, Wijster     

A quarter of a century succession of epigaeic beetle assemblages in remnant habitats in an urbanized matrix (Coleoptera, Carabidae)

We studied the long-term (23-24 years) species turnover and succession of epigaeic beetle assemblages (Coleoptera: Carabidae, incl. Cicindelinae) in three remnant habitats [cottonwood (Populus spp.) and oak (Quercus spp.) stands, and old fields] that are embedded within highly urbanized areas in central Minnesota. A total of 9,710 beetle individuals belonging to 98 species were caught in three sampling years: 1980, 1981 and 2005 in pitfall traps in identical locations within each habitat. Results indicate that there were 2-3 times greater trap catches in 2005 than in 1980 (cottonwood and oak stands, and old fields) and 1.4-1.7 times greater species diversity of beetles in 2005 than in the 1980-1981 suggesting increased habitat association by beetles over time. Although there were no significant differences in catches between 2005 and 1981 (only cottonwood stands and old fields), there was a trend where more beetles were caught in 2005. At the species-level, 10 times more of an open-habitat carabid species, Cyclotrachelus sodalis sodalis LeConte, was caught in 2005 than in 1980. However, trap catches of five other abundant carabid species [Pterostichus novus Straneo, Platynus decentis (Say), Platynus mutus (Say), Calathus gregarius (Say), and Poecilus lucublandus lucublandus (Say)] did not change indicating population stability of some beetle species. These remnant habitats were increasingly colonized by exotic carabid species as Carabus granulatus granulatus Linneaus, Clivina fossor (Linneaus) and Platynus melanarius (Illiger), that were trapped for the first time in 2005. Species composition of epigaeic beetles was quite distinct in 2005 from 1980 with 39 species reported for the first time in 2005, indicating a high turnover of assemblages. At the habitat-level, greatest species diversity was in cottonwood stands and lowest was in old fields, and all habitat types in 2005 diverged from those in 1980s, but not cottonwood stands in 1981. As our sampled areas are among some of the last remnants of the original oak savanna habitats in central Minnesota, we hypothesize that conservation of these sites may be critical to maintaining epigaeic beetle assemblages under increased urbanization pressure.     

Carabid beetles (Coleoptera: Carabidae) in coniferous plantations in Hokkaido,Japan: effects of tree species and environmental factors

The distribution, species composition and abundance of carabid beetles in monospecific plantations of three different coniferous tree species (Japanese spruce, Sakhalin fir and larch) were investigated by baited pitfall traps in Hokkaido, Japan. In total, 16 150 carabid beetles consisting of 31 species in 13 genera were collected in 2011 and 2012. The most predominant species was Pterostichus thunbergii Morawitz, followed by Synuchus melantho (Bates) and Carabus opaculus (Putzeys). Average numbers of beetles per trap were significantly reduced in larch. Large‐sized Carabus species (C. arboreus arboreus Lewis and C. opaculus) were collected in large numbers in Japanese spruce. There was no significant difference in diversity and equitability among the three kinds of plantation. The ordination of redundancy analysis showed that medium‐sized forest generalists, Pterosticus subovatus (Motschulsky) and P. thunbergii, were highly associated with Japanese spruce and Sakhalin fir, and the forest specialist Synuchus nitidus (Motschulsky) was with Sakhalin fir. In contrast, in larch there was no such associated forest species, and some species of Carabus, Pterostichus and Synuchus were considerably reduced in number, suggesting that larch has unfavorable effects on some forest species. The most important environmental variables influencing carabid assemblages were soil moisture and foliage layer cover. Practices in forest management to minimize the effects of plantations on carabid assemblages are discussed.     

The influence of weed-cover on the mortality imposed on artificial prey by predatory ground beetles in cereal fields

Summary Pitfall trapping was carried out in a field of winter wheat in the Vale of York to determine the levels of abundance of adult carabid and staphylinid beetles, (which formed the bulk of the natural predator complex) in the field. A point quadrat survey was carried out at the same time to assess the vegetation cover round each trap. Predation pressure by the beetles in the field was monitored using fruit fly (Drosophila) pupae as artificial prey. These artificial prey were attached to small cards inserted in the field adjacent to the pitfall traps.The numbers of beetles caught were found to be directly related to the frequency and density of Poa annua L. (annual meadow grass) the only abundant non-crop plant present at the time. More beetles were caught in areas where Poa was abundant than where Poa was scarce. This was probably related to the more suitable environmental factors offered by these of the wheat itself was found to be unrelated to captures.The number of fruit fly pupae taken was shown to be related to the numbers of carabid and staphylinid beetles present, and also to the type of vegetation occuring around each card.The implication of these results for the effects of predation on potential pest-outbreaks in the crop are discussed.     

Above- and below-ground assessment of carabid community responses to crop type and tillage

1. Carabid beetles are major predators in agro-ecosystems. The composition of their communities within crop environments governs the pest control services they provide. An understudied aspect is the distribution of predacious carabid larvae in the soil.
2. We used novel subterranean trapping with standard pitfall trapping, within a multi-crop rotation experiment, to assess the responses of above- and below-ground carabid communities to management practices.
3. Crop and trap type significantly affected pooled carabid abundance with an interaction of the two, the highest numbers of carabids were caught in subterranean traps in barley under sown with grass.
4. Trap type accounted for the most variance observed in carabid community composition, followed by crop.
5. Tillage responses were only apparent at the species level for three of the eight species modelled.
6. Responses to crop type varied by species. Most species had higher abundance in under-sown barley, than grass, wheat and barley. Crop differences were greater in the subterranean trap data. For predaceous larvae, standard pitfalls showed lowest abundances in under-sown barley, yet subterranean traps revealed abundances to be highest in this crop.
7. Comprehensive estimation of ecosystem services should incorporate both above- and below-ground community appraisal, to inform appropriate management.

     

The effects of green tree retention and subsequent prescribed burning on ground beetles (Coleoptera: Carabidae) in boreal pine-dominated forests

We studied how two methods to promote biodiversity in managed forests, i.e. green tree retention and prescribed fire, affect the assemblages of carabid beetles. Our experiment consisted of 24 study sites, each 3–5 ha in size, which had been prepared according to factorial design. Each of the eight treatment combinations determined by the two factors explored – tree retention level (0, 10, 50 m³/ha^?1 and uncut controls) and prescribed use of fire (yes/no) – was replicated three times. We sampled carabids using pitfall traps one year after the treatments. Significantly more individuals were caught in most of the burned sites, but this difference was partially reflective of the trap‐catches of Pterostichus adstrictus. The fire did not increase no. of P. adstrictus in the uncut sites as much as in the other sites. Species richness was significantly affected by both factors, being higher in the burned than in the unburned sites and in the harvested than in the unharvested sites. Many species were concentrated in the groups of retention trees in the burned sites, but only a few were in the unburned sites. The species turnover was greater in the burned than in the unburned sites, as indicated by the NMDS ordinations. Greater numbers of smaller sized species and proportion of brachypterous species were present in the burned sites. Fire‐favored species, and also the majority of other species that prefer open habitats were more abundantly caught in the burned sites than in the unburned sites. Dead wood or logging waste around the traps did not correlate with the occurrence of species. We conclude that carabids are well adapted to disturbances, and that frequent use of prescribed fire is essential for the maintenance of natural assemblages of carabid beetles in the boreal forest. Small retention tree groups can not maintain assemblages of uncut forest, but they can be important by providing food, shelter and breeding sites for many species, particularly in the burned sites.     

On the relationship between reproduction,age and survival in two carbid beetles:

Summary In this study the inverse relationship between the amount of reproduction in female carabid beetles and their survival until the next breeding season, suggested by Murdoch (1966), was examined in Pterostichus coerulescens L. and Calathus melanocephalus L. This was tested with individual and differently reproducing females, kept at the same temperature, as well as with groups of females kept at different temperatures, i.e. with very different overall levels of reproduction.No relationship was found between the numbers of eggs laid by individual females and their survival until the next breeding season.The numbers of eggs laid by individual females varies greatly, even under constant and optimal conditions,. In contrast to this, an individual female continues to lay a characteristic number of eggs over several succeeding weeks. The amount of reproduction is highly correlated with temperature when food is optimal. In P. coerulescens there was a positive correlation between the amount of reproduction of the same individuals in two succeeding years, whereas in C. melanocephalus no relationship could be found.Both in the field and in our experiments individuals of P. coerulescens generally live for 3 to 4 years, longer than C. melanocephalus which usually only lives for 2 years. The 3–4 year-old individuals of P. coerulescens die during the breeding season or shortly afterwards, but also during the winter, whereas the 2–3 year-old individuals of C. melanocephalus die during the winter. Males and females show a similar mortality after breeding. The level of reproduction of a population depends on the proportion of old beetles, since especially the very old ones die before the end of the breeding season.We reject the hypothesis of Murdoch because of these data. However, in a different way from that of Murdoch, we also suggest that old beetles are of great importance for the survival of a population, namely that this form of heterogeneity of a population may enhance its stability under varying environmental conditions.Communication No. 204 of the Biological Station, Wijster     

Large scale Agriotes spp. click beetle (Coleoptera: Elateridae) invasion of crop land from field margin reservoirs

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Changes in carabid beetle diversity within a fragmented agricultural landscape

The distribution of carabid and cicindelid (Coleoptera: Carabidae) beetles in five distinct habitats (riparian, mature orchard, pine windbreak, young orchard, natural veld), within Tambuti Citrus Estate (Swaziland) was examined by pitfall trapping over 18 months. Habitats with high vegetation and litter cover had the highest species diversity and larger specimens, e.g. riparian border and pine windbreak, while the lowest diversity was observed in intensively managed mature citrus orchards. While species such as Tefflus delagorguei Guérin occurred in all the habitats sampled, certain species illustrated habitat specificity; e.g. Dromica ambitiosa Péringuey was observed only in the pine windbreaks while Haplotrachelus sp. Chaudoir occurred mainly in the vegetated riparian and natural veld habitats. Four unidentified carabid beetles were exclusive to the riparian border habitat. This habitat was the only one with a distinct assemblage of species in the agricultural mosaic studied. Multivariate analyses were used to assess the role of soil and environmental variables in relation to the ground beetle diversity within the agricultural mosaic studied.     

Ground beetle (Coleoptera: Carabidae) assemblages in conventional and diversified crop rotation systems

Ground beetles (Coleoptera: Carabidae) are important in agro-ecosystems as generalist predators of invertebrate pests and weed seeds and as prey for larger animals. However, it is not well understood how cropping systems affect ground beetles. Over a 2-yr period, carabids were monitored two times per month using pitfall traps in a conventional chemical input, 2-yr, corn/soybean rotation system and a low input, 4-yr, corn/soybean/triticale-alfalfa/alfalfa rotation system. Carabid assemblages were largely dominated by a few species across all cropping treatments with Poecilus chalcites Say comprising >70% of pitfall catches in both years of study. Overall carabid activity density and species richness were higher in the low input, 4-yr rotation compared with the conventionally managed, 2-yr rotation. There were greater differences in the temporal activity density and species richness of carabids among crops than within corn and soybean treatments managed with different agrichemical inputs and soil disturbance regimes. Detrended correspondence analysis showed strong yearly variation in carabid assemblages in all cropping treatments. The increase in carabid activity density and species richness observed in the 4-yr crop rotation highlights the potential benefits of diverse crop habitats for carabids and the possibility for managing natural enemies by manipulating crop rotations.     

Activity and satiation state in Pterostichus melanarius: an experiment in different agricultural habitats

1. A capture–recapture experiment was conducted to examine the effects of satiation state on the activity and foraging efficiency of the carabid beetle Pterostichus melanarius Ill., in four different habitats (a hedge, a transition zone between the hedge and the adjacent wheat crop, the margin of the wheat crop, and the centre of the wheat crop) in an agricultural ecosystem in France. 2. Prey biomass and density decreased from the centre of the hedge to the crop margin and to the centre of the crop, where prey density was low but prey biomass was moderate. Starved and satiated beetles were released in circular enclosures and recaptured using pitfall traps for 6 days. 3. Immediately after release, starved P. melanarius were significantly more active than satiated beetles, but this difference disappeared after the first day. At each recapture date, starved individuals had gained weight whereas satiated individuals had lost weight. The analysis of activity and weight variation at the end of the first day indicated that the centre of the crop seemed to be the most favourable habitat for starved individuals to find food rapidly, whereas the behaviour of satiated individuals was identical in all habitats. 4. This experiment shows that habitat use of P. melanarius is flexible. The results are discussed in the context of the classical view of foraging behaviour in carabid beetles. The activity and foraging efficiency in P. melanarius in different habitats can be explained as the result of the interaction between individual satiation state, prey availability in the habitat, and particular preferences of the species.     

Patterns of movement of radioactive carabid beetles

Summary Tracking of individual ¹⁹²Ir-labeled ground beetles released in the field revealed that both the day-active and night-active species studied showed periods of small distances covered per day in random directions, alternating with periods of directed movement with large distances covered per day. This pattern occurred not only in the reproductive period but outside the breeding season as well in juvenile Pterostichus versicolor and spent Calathus melanocephalus. Although mean locomotory activity increased with temperature, great daily differences occurred between individuals, pointing to asynchronous behavior. In an unfavorable habitat directed movement occurred both more frequently and more extremely, sometimes resulting in escape to more favorable areas. Most of the radioactive beetles died within 7 weeks due to radiation effects, but independent field experiments and simulations showed that the recorded patterns were valid. Simulated individuals of P. versicolor living on 1 ha spread over 49 ha, whereas simulated C. melanocephalus covered only 9 ha after one activity season. Normal locomotory activities lead to both exchange of individuals between subpopulations and dispersal out of the habitat. The significance of these phenomena for population stability and for the survival of the species is discussed.Communication no. 184 of the Biological Station of the Agricultural University (Wageningen), Wijster (Drenthe), The Netherlands     

Pitfall trapping within enclosures: a method for estimating the relationship between the abundances of coexisting carabid species (Coleoptera: Carabidae)

Pitfall trapping within enclosures is proposed as a method to get a reliable impression of the relationship between the abundances of a number of coexisting carabid species. The investigations were performed during two years in a heavily grazed pasture at Melle (Belgium). On a rather large scale soil samples could be compared with both enclosed and open pitfall catches.
In all cases fenced pitfalls gave ratios between the catches of the different species showing a much better correlation with those from soil samples than the catch ratios from open pitfalls. This method seems especially suitable to compare the relative abundances of a number of carabid species in short term investigations during periods of peak activities.     

Influence of within‐field position and adjoining habitat on carabid beetle assemblages in winter wheat

• 1 The influence of within‐field position and adjoining habitat on carabid beetles was studied in 20 winter wheat fields in ten different Swiss agricultural landscapes. In each landscape, two winter wheat fields (one with adjoining sown wildflower area and one with adjoining grassy margin) were investigated.
• 2 Carabid beetles were caught in pitfall traps 3 and 30 m from the edge in each of the 20 wheat fields. Significantly more individuals were found in the centres (30‐m position) than at the edges (3‐m position). Conversely, species richness was significantly higher at the field edges than in the centres.
• 3 Of the ten most abundant species, Poecilus cupreus, Agonum muelleri and Pterostichus melanarius were significantly more abundant in the field centres than at the edges. Harpalus rufipes was significantly more abundant in the fields adjoining sown wildflower areas than in the fields adjoining grassy margins.
• 4 In conclusion, the response of carabid beetles to within‐field position and adjoining habitats was species specific. This needs to be taken into account in habitat management for biodiversity conservation and pest control.

     

Fecundity in relation to wing-morph of three closely related species of the melanocephalus group of the genus Calathus (Coleoptera: Carabidae)

Summary In two successive years the fecundity of the carabid beetles Calathus (Neocalathus) cinctus, C. (N.) melanocephalus and C. (N.) mollis was studied in relation to wing-morph and temperature. Differences were found between the three species in both egg production and timing and length of the oviposition period. In all species the fecundity of laboratory bred beetles was significantly higher than that of females collected in the field. Long-winged females of both cinctus and melanocephalus had significantly higher egg production than short-winged females, and they also tended to produce eggs over a longer period. In mollis only the fecundity of the long-winged morph was established. The observed lower relative fitness of the short-winged morph in both cinctus and melanocephalus contradicts the supposed increase of the frequency of this morph in ageing, more or less isolated, populations of these species. The loss of long-winged genotypes, resulting from flight activities, is considered the most plausible cause of the increase of short-winged beetles in ageing populations. The higher fecundity of macropterous females makes them especially suited for (re)establishing populations.Communication No. 429 of the Biological Station WijsterPresent address and address for offprint requests: Kortenburg 31, NL-6871 ND Rentum     

Taxon specific response of carabids (Coleoptera,Carabidae) and other soil invertebrate taxa on invasive plant Amorpha fruticosa in wetlands

False indigo (Amorpha fruticosa L.) is an invasive exotic plant introduced to Europe in the early eighteenth century. Its spread has been rapid, particularly in disturbed wetland habitats, where it forms dense impermeable monospecific stands and modifies habitat conditions. The impact of A. fruticosa on native plant communities has been well analyzed, however knowledge concerning the possible effects on soil invertebrates and particularly carabid beetles is completely lacking. This study analyzed the impact of an A. fruticosa invasion on carabid beetles and other soil invertebrates. Soil fauna was sampled by pitfall traps at natural habitats, initially colonized by A. fruticosa, and habitats largely invaded by A. fruticosa. In total 2,613 carabid beetles belonging to 50 species and 72,166 soil invertebrates were collected. The invasion of A. fruticosa strongly affected the carabid beetle species composition, which clearly differed between all studied sites. Widespread euritopic carabid beetle species showed positive responses to A. fruticosa invasion, while the activity density of open habitat species strongly declined. Mean individual biomass was significantly higher at invaded sites due to increased incidence of large carabids (genus Carabus Linné, 1758). Carabid beetle activity density and abundance of soil invertebrates were considerably higher at invaded sites than in natural sites. Conversely, the impact of A. fruticosa on carabid beetle species richness and diversity was less pronounced, most likely due to immigration from adjacent habitats. Changes in carabid beetle species composition and abundance of soil invertebrates were most likely due to changes in vegetation structure and microclimate. The results suggest that A. fruticosa invasion considerably affected carabid beetles, an insect group that is only indirectly related to plant composition. Therefore, severe future changes can be expected in invertebrate groups that are closely related to plant composition, since A. fruticosa cannot be completely removed from the habitat and covers relatively large areas.     

Disrupting spring colonization of Colorado potato beetle to nonrotated potato fields

Overwintering Colorado potato beetles (Leptinotarsa decemlineata (Say)) were concentrated primarily within woody borders, and mortality was lower in borders than in potato fields. After overwintering, only 15–44% of live beetles were in the potato fields. In experiments with small plots, colonization of fields from woody borders was reduced ∼60% by a trap crop, either treated with adulticide or with beetles collected daily. Such trap crops, or simply pitfall traps to prevent colonization from woody borders, could significantly reduce early-season adult numbers and subsequent larval populations. However, success is dependent on the local densities of overwintered beetles, and the prevalence of arrestment behavior in the case of trap crops.     

Sampling epigeal arthropods: an evaluation of fenced pitfall traps using mark-release-recapture and comparisons to unfenced pitfall traps in arable crops

The efficiency of fenced pitfall traps for estimating the density of commonly occurring epigeal predatory beetles was examined using mark-release-recapture. Most beetles of those recovered were recaptured within one week of their release. For seven of the ten species tested recapture rates were over 70%, with higher rates for the larger species. The predatory arthropod species composition captured using fenced pitfall traps was compared to unfenced pitfall traps in winter wheat, spring barley and winter oilseed rape. Compositional analysis revealed that the dominance structure of seven carabid beetle (Coleoptera: Carabidae) taxa differed between the trap types and month of sampling in winter wheat and spring barley, but differences were small with the exception of a few taxa. Linear relationships between the two techniques were found for some carabid and rove beetles (Coleoptera: Staphylinidae). The dominance structure of seven linyphiid spider (Araneae: Linyphiidae) taxa differed between the two trap types in wheat but not barley, although large differences were restricted to two taxa. No linear relationships between the two techniques were found for any of the Linyphiidae examined. Rove beetles were more effectively sampled using the fenced compared to unfenced pitfall traps.