北京东北旺农田景观步甲群落结构的时空动态比较

2000年5～10月在北京海淀区东北旺实验基地,采用陷阱法对林地、农田边界和农田3类生境共14个处理的步甲进行了取样。并在此基础上分析了不同生境和不同季节步甲科昆虫群落的动态分布特征。结果表明,林地和农田边界类生境相对于农田类生境拥有更多的步甲个体数和物种数;无论是优势种还是稀有种都趋向于在林地和边界处生活;边界对相邻农田步甲群落的多样性有积极影响;对边界进行适度的干扰(秋季翻耕)有利于提高步甲群落的个体数量;农田生境中灌溉、施肥和秸秆还田对农田中步甲群落的个体数量和物种数量的空间分布均无显著影响。此外,还结合步甲的时空分布特性对步甲受威胁状况进行了初步的分析。     

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.     

Effects of pirimicarb, dimethoate and benomyl on natural enemies of cereal aphids in winter wheat

The insecticides, pirimicarb and dimethoate are commonly applied to cereal crops in the UK and when this study was begun the fungicide benomyl was also regularly used. The effects of these chemicals on natural enemies of cereal aphids were examined in replicated plots of winter wheat. Benomyl did not affect any of the groups examined but it was applied early in the season (April/May) when most natural enemies were few or absent from the crop. Numbers of carabid beetles, staphylinid beetles and spiders, sampled using pitfall traps and a vacuum net sampler, were all reduced by dimethoate but not by pirimicarb, although these effects were only detected by pitfall traps when the small plots were surrounded by polyethylene barriers to prevent inter-plot movements. Parasitic Hymenoptera were decreased by both insecticides, partly due to direct toxicity and partly to host removal. Data on the aphid predators, Coccinellidae, Syrphidae and Chrysopidae were inconclusive because there were very few in the crop due to the scarcity of aphids. Ways in which pesticides can affect natural enemy populations other than by direct mortality and the dangers associated with routine, prophylactic pesticide applications are discussed.     

Intraguild interference and biocontrol effects of generalist predators in a winter wheat field

Arable land typically harbours communities of polyphagous invertebrate natural enemies, among them numerous soil-surface dwelling predators such as ground beetles (Carabidae) and spiders (Lycosidae, Linyphiidae). Numbers of these predators were experimentally manipulated in a winter wheat field in order to study the predation impact of a generalist predator assemblage on herbivorous insects, the possible interferences among the predators concerned, and subsequent effects on wheat plant parameters. Removing ground beetles doubled numbers of Lycosidae indicative of intraguild interference between these two predator groups. Aphid densities were highest in carabid removal plots implying a substantial predation impact of ground beetles on the pest population. The predation impact of ground beetles was strongest earlier and disappeared later in the season. In mid-season, at intermediate aphid densities, the combined impact of carabid beetles and spiders appeared to be responsible for the reduction in aphid abundance. This result was probably due to a biomass effect rather than to a synergistic effect of the predator community. Thysanoptera decreased when spiders were removed (perhaps because spiders were preying on a predator of thrips), while Cicadellidae and Delphacidae showed no effect at all. The rise of aphid numbers in carabid removal plots corresponded to an increase in protein content of the wheat grains, while other plant parameters such as plant numbers and grain mass were not affected. In conclusion, this study provided field evidence for intraguild interference among generalist ground predators in arable land. Despite this interference the polyphagous predator community was able to depress numbers of aphids in winter wheat, a result cascading down to plant quality parameters.     

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.     

Relative importance of predators and parasitoids for cereal aphid control

Field experiments with manipulations of natural enemies of plant-feeding insects may show how a diverse enemy group ensures an important ecosystem function such as naturally occurring biological pest control. We studied cereal aphid populations in winter wheat under experimentally reduced densities of: (i) ground-dwelling generalist predators (mostly spiders, carabid and staphylinid beetles); (ii) flying predators (coccinellid beetles, syrphid flies, gall midges, etc.) and parasitoids (aphidiid wasps), and a combination of (i) and (ii), compared with open controls. Aphid populations were 18% higher at reduced densities of ground-dwelling predators, 70% higher when flying predators and parasitoids were removed, and 172% higher on the removal of both enemy groups. Parasitoid wasps probably had the strongest effect, as flying predators occurred only in negligible densities. The great importance of parasitism is a new finding for aphid control in cereal fields. In conclusion, a more detailed knowledge of the mechanisms of natural pest control would help to develop environmentally sound crop management with reduced pesticide applications.     

Spatial and temporal patterns of carabid activity-density in cereals do not explain levels of predation on weed seeds

Seed predation is an important component of seed mortality of weeds in agro-ecosystems, but the agronomic use and management of this natural weed suppression is hampered by a lack of insight in the underlying ecological processes. In this paper, we investigate whether and how spatial and temporal variation in activity-density of granivorous ground beetles (Coleoptera: Carabidae) results in a corresponding pattern of seed predation. Activity-density of carabids was measured by using pitfall traps in two organic winter wheat fields from March to July 2004. Predation of seeds (Capsella bursa-pastoris, Lamium amplexicaule, Poa annua and Stellaria media) was assessed using seed cards at the same sites and times. As measured by pitfall traps, carabids were the dominant group of insects that had access to the seed cards. In the field, predation of the four different species of seed was in the order: C. bursa-pastoris>P. annua>S. media>L. amplexicaule; and this order of preference was confirmed in the laboratory using the dominant species of carabid. On average, seed predation was higher in the field interior compared to the edge, whereas catches of carabids were highest near the edge. Weeks with elevated seed predation did not concur with high activity-density of carabids. Thus, patterns of spatial and temporal variation in seed predation were not matched by similar patterns in the abundance of granivorous carabid beetles. The lack of correspondence is ascribed to effects of confounding factors, such as weather, the background density of seeds, the composition of the carabid community, and the phenology and physiological state of the beetles. Our results show that differences in seed loss among weed species may be predicted from laboratory trials on preference. However, predator activity-density, as measured in pitfall traps, is an insufficient predictor of seed predation over time and space within a field.     

Ground beetle (Coleoptera: Carabidae) diversity, activity density, and community structure in a diversified agroecosystem

Diversity and abundance of ground beetles (Coleoptera: Carabidae) can be enhanced in vegetable and field intercropping systems, but the complexity of polycultures precludes the application of generalized assumptions of effects for novel intercropping combinations. In a field experiment conducted at Lacombe and Ellerslie, Alberta, Canada, in 2005 and 2006, we investigated the effects of intercropping canola (Brassica napus L.) with wheat (Triticum aestivum L.) on the diversity and community structure of carabid beetles, and on the activity density responses of individual carabid species. Shannon-Wiener diversity index scores and species evenness increased significantly as the proportion of wheat comprising total crop plant populations increased in one site-year of the study, indicating a positive response to enhanced crop plant species evenness in the intercrops, and in that same site-year, ground beetle communities in intercrops shifted to more closely approximate those in wheat monocultures as the percentage of wheat in the intercrops increased. Individual carabid species activity densities showed differing responses to intercropping, although activity densities of some potential root maggot (Delia spp.) (Diptera: Anthomyiidae) predators were greater in intercrops with high proportions of wheat than in canola monocultures. The activity density of Pterostichus melanarius (Illiger), the most abundant species collected, tended to be greater in canola monocultures than high-wheat intercrops or wheat monocultures. We conclude that intercrops of canola and wheat have the potential to enhance populations of some carabid species, therefore possibly exerting increased pressure on some canola insect pests.     

Effects of metal contamination on the activity and diversity of carabid beetles in an ancient Pb-Zn mining area at Plombières (Belgium)

Carabid beetles were monthly sampled with pitfall traps in the ancient Pb-Zn mining area of Plombières during one year. Based on the total soil concentrations of lead, zinc, cadmium and copper, it was expected that zinc would probably have the most adverse effects on the populations. Activity and species richness of carabid beetles were, however, not significantly correlated with total zinc concentration nor with the water soluble and the calciumchloride extractable concentration. In fact, despite the high soil concentrations, carabid beetles did not seem to be affected in the study area. The apparent lack of effects at the high observed zinc concentrations is probably caused by the low bioavailability of zinc to the beetles in the litter of the study sites which was also reflected in the low observed water soluble zinc concentrations.     

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.     

苜蓿邻作麦田地表步甲和蜘蛛种群动态及其对苜蓿刈割的响应

设计苜蓿-麦邻作与麦-麦邻作的农田界面捕食性天敌空间分布对比试验,在距离交接界面3、6、9、12、15、18、21、24和27 m处设诱集小区,采用陷阱法诱集调查地表步甲和蜘蛛种类与数量.结果表明: 不同界面麦田边缘地表步甲和蜘蛛物种多样性和多度都表现出一定的边际效应.苜蓿 麦界面15～18 m范围内边际效应明显,超过20 m, 边际效应逐渐消失.麦-麦界面的边缘效应明显弱于苜蓿 麦界面.苜蓿的刈割使苜蓿田中的天敌向邻作麦田迁移,苜蓿刈割后10 d内,邻作小麦田20 m内地表步甲和蜘蛛种类和个体数都有所增加,其中个体数的增长幅度大、速度快.绘制了苜蓿-麦界面地表步甲和蜘蛛的物种多样性和优势种(毛青步甲和星豹蛛)种群数量空间动态分布图,能直观地看出天敌由苜蓿向小麦田的迁移过程.     

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 toxicity of some soil insecticides to carabid predators of the cabbage root fly (Erioischia brassicae (Bouché))

In laboratory tests concentrations of dieldrin in soil, below that required to control cabbage root fly, were found to be toxic to several species of carabid beetles which prey on the immature stages of this pest. These results confirm previous findings from field experiments that dieldrin residues in soil can, by reducing the populations of predaceous beetles, increase the survival of the cabbage root fly and the subsequent crop damage caused. The toxicity of selected organophosphorus insecticides to these beneficial insects was studied in soils of different moisture content. Thionazin was found to be highly toxic at all moisture levels as was diazinon in moist soil. Chlorfenvinphos and azinphos-methyl and, in dry soil diazinon, were very much less toxic.     

Migration to and dispersal from oilseed rape by the pollen beetle,Meligethes aeneus,in relation to wind direction

1 Host‐plant‐odour‐induced upwind anemotaxis is accepted as the main mechanism by which herbivorous insects find their host plant within an heterogenous environment, but field data supporting this hypothesis are scarce. 2 The flight directions of the pollen beetle Meligethes aeneus to and from a plot of winter oilseed rape and the direction of the wind were recorded concurrently. The beetles were sampled by eight double‐sided window traps encircling the plot. Distal sides of the traps, relative to the plot, sampled the beetles as they flew towards the plot, whereas the proximal sides of the traps sampled them as they flew away from the plot. Paired data on daily catch of beetles in distal or proximal traps and the volume of air impacting each trap were compared. 3 Correlations between daily catch of M. aeneus into distal traps and trap wind volume were negative, indicating that flights by both overwintered‐ and new‐generation insects towards the plot were upwind. 4 Correlations between daily catch of M. aeneus into proximal traps and trap wind volume varied with generation. Catch of overwintered‐generation M. aeneus was negatively correlated with trap wind volume, indicating that flight was upwind. Proximal trap catch of the new‐generation M. aeneus was weakly/modestly positively correlated with trap wind volume, indicating that flights were downwind or crosswind. 5 Understanding the effect of wind direction on flight of M. aeneus holds potential for improving the forecasting of their arrival and spatial distribution on the crop for integrated pest management.     

农田步甲的生物学研究

本文报道12种农田常见步甲的种群动态和捕食习性,施用杀虫剂对步甲的影响。     

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.

     

Convergence in Arthropod Assemblages with Various Restoration Approaches for Canadian Deciduous Forests

Silvicultural practices are traditionally aimed at increasing forest profits; however, recent approaches to forest conservation have broadened to include nature-based silviculture for regenerating forests. In southern Ontario (Canada), originally dominated by deciduous forests, conifer plantations were established on abandoned agricultural sites. Currently, there is an increasing interest to convert these conifer stands to a state that mimics the original deciduous forest. We investigated arthropod abundance, species richness of carabid beetles, and abundance of arthropod assemblages (trophic and prey groups) under five silvicultural treatments conducted to regenerate deciduous forests (the natural forest type) from the old conifer plantations. The treatments included: (1) uniform canopy removal; (2) uniform canopy removal and understory removal; (3) group canopy removal; (4) group canopy removal and understory removal; and (5) untreated control plots (relatively pure red pine). Insects were sampled annually using sweepnets and pitfall traps. Results revealed treatment effects on the abundance of Coleoptera, Heteroptera, herbivores, and small arthropods (<3 mm) caught in sweepnet samples, where plots subjected to group shelterwood removal and understory removal supported higher abundances than the control plots. There was no treatment effect on the abundance of other arthropod groups or on the species richness and abundance of carabid beetles. The silvicultural treatments used to encourage natural regeneration did not seem to affect arthropod food availability for insectivorous vertebrates. Thus, the type of silvicultural strategy used to convert pine plantations to a stage that mimics the natural deciduous forests had little overall impact on arthropods.     

转植酸酶基因玉米对步甲群落动态的影响

本研究以陷阱法研究转植酸酶基因玉米及其亲本玉米在整个生长季节对地表步甲类群的影响。每个玉米品系设置6块样地, 两个玉米品系交替排列, 每个样地设置2个采样点, 共设置24个样点, 整个玉米生育期取样8次。本研究共采集步甲标本8 012头, 隶属于11属23种, 其中黄斑青步甲Chlaenius micans个体数量分别占个体总数的87.54%, 为玉米田内的主要常见物种, 蠋步甲Dolichus halensis、 后斑青步甲Chlaenius posticalis和单齿蝼步甲Scarites terricola个体数量分别占除黄斑青步甲之外所有步甲个体总数的34.77%, 31.16%和6.21%, 这些物种组成当地玉米田内的常见物种。步甲物种多样性与常见物种个体数量随季节变化明显, 且转植酸酶基因玉米与其亲本玉米田内步甲物种多样性和常见物种个体数量的季节变化趋势相似度较高。重复测量方差分析（Repeated ANOVA）结果表明, 转植酸酶基因玉米对步甲物种丰富度、 物种多度、 香农威纳多样性指数和均匀度指数均没有显著影响; 转植酸酶基因玉米田内的后斑青步甲个体数量明显增加, 但其他常见物种没有显著变化。基于非度量多维度（NMDS）的群落结构分析表明转植酸酶基因玉米与亲本玉米田内的步甲群落结构非常相似。本文结果表明转植酸酶基因玉米的种植对步甲物种多样性及常见物种没有明显影响。     

Farmland carabid beetle communities at multiple levels of spatial scale

Carabid beetle communities were studied at three levels of spatial scale, i.e. within fields (three sets of traps, mean distance 15 m), between fields (five fields within 1 km from each other) and between patches of farmland (four study areas 4-8 km from each other). We compared carabid assemblages sampled on five crop types in each study area, i.e. ley. set-aside, spring cereal, potato, and sugar beet. Because of small sample sizes, only the community composition was studied within fields with a DCA ordination, but the differences were small. Analyses of species richness, activity density, community composition as revealed by DCA ordinations, dominance structure, diversity, and evenness showed that carabid communities varied significantly among patches of farmland but not between fields with different crops within the patches. Only the communities of potato fields were found lo resemble each other. Only five carabid beetle species showed a preference for crops, and twelve species favoured some study areas. We conclude that the effect of spatial scale should be emphasised in further studies as it seems that carabid beetles may be very localised even in agricultural habitats.     

Impact of rubber plantation on carabid beetle communities and species distribution in a changing tropical landscape (southern Yunnan, China)

Carabid beetles (Coleoptera: Carabidae) have widely been used to assess biodiversity values of different habitats in cultivated landscapes, but rarely in the humid tropics. This study aimed to investigate effects of land use change on the carabid assemblages in a tributary valley of the Mekong River in tropical southern Yunnan, China. The study area includes habitats of traditional land use systems (rice production and shifting cultivation successions) and was dominated by natural forests until about 30?years ago. Since then, large areas of forest have been, and still are, successively transformed into commercial rubber monoculture plantations. In total, 102 species of Carabidae (including Cicindelinae) were recorded from 13 sites over different seasons, using pitfall traps, Malaise traps and aerial collectors in trees. Cluster analysis and indicator species analysis showed that three types of habitat (rice field fallows, early natural successions and natural forest) possess a degree of uniqueness in species composition. Non-metric multidimensional scaling revealed that the environmental factors explaining 80% of the total variation in carabid assemblage composition are the degree of vegetational openness of a habitat and its plant species diversity. Rice field fallows had significantly higher numbers of species and individuals than any other type of habitat and are probably dominated by species originating from other regions. Carabid assemblages of young rubber plantations (5 and 8?years) were quantitatively similar to those of forests, but without species of significant indicator value. With increasing plantation age (20 and 40?years), the number of carabid species decreased. Increasing age and a further spatial expansion of rubber plantations at the expense of forest areas will have negative impacts on the native forest carabid assemblages with strongest effects on forest specialists and rare species.