Abundance and co-occurrence patterns of core and satellite species of ground beetles on small lake islands

15 lake islands and two mainland sites of Mamry lake in Poland were sampled to investigate community structures and patterns of co-occurrences of ground beetles (Carabidae). The total ground beetle metacommunity of 71 species was divided into a group of core species occupying at least half of all study sites and of satellite species, which occurred at two sites or less. This division is mirrored by reduced dispersal abilities and non-random patterns of site occupancy. Core and satellite species also differed in patterns of relative abundance. The core group followed a lognormal distribution, the satellite group a power function as predicted by the self-similarity model of occurrence. We conclude that the division into core and satellite species is not a sample artefact but reflects different life history strategies. We also conclude that current models of niche division and co-occurrence might miss important aspects of community structure if they do not refer to patterns of dispersal.
From these findings we infer that the regional distribution of core species might be shaped by species interactions and processes of niche divisions whereas the spatial distribution of satellite species are best interpreted as stemming from random dispersal.     

Patterns in the distribution, abundance and body size of carabid beetles (Coleoptera: Caraboidea) in relation to dispersal ability

The effects of dispersal ability, measured as two wing size categories (brachypterous vs. macropterous), on the distribution, abundance and body size, and on the relationships between these variables were examined in eighty-four species of carabid beetles over twenty-two sites in the northern Iberian peninsula. Geographic ranges of species (restricted to the northern Iberian peninsula vs. widespread—European or wider range) were also taken into account in the analyses because macropterous species significantly tended to exhibit wider geographic ranges than did brachypterous species. Regional distributions were wider in brachypterous-restricted and brachypterous-widespread species than in macropterous-widespread species. The three groups did not differ in abundance. Differences in regional distributions between groups may be explained by referring to a trade-off between dispersal ability and establishment ability indicated in the literature. Macropterous species would occupy relatively few sites due to a high frequency of unsuccessful colonizations. The relationships between regional distribution and abundance were positive for all the three groups, brachypterous-restricted, brachypterous-widespread and macropterous-widespread species. The regression line for the last group showed a lower elevation than those for brachypterous-restricted and brachypterous-widespread species. This fact was probably due to differences in regional distributions between groups. No relationship between abundance and body size was significant. Regressions of regional distribution on body size were positive in brachypterous-restricted and brachypterous-widespread carabids, but the relationship was not significant in macropterous-widespread carabids. These results were interpreted in terms of differences in body size–dependency of travelling velocities between flying and running carabids.     

The impact of hedge-forest connectivity and microhabitat conditions on spider and carabid beetle assemblages in agricultural landscapes

Agricultural intensification in terms of decreasing landscape complexity and connectivity has negatively affected biodiversity. Linear landscape elements composed of woody vegetation like hedges may counteract this negative trend by providing habitats and enhancing habitat connectivity for different organisms. Here, we tested the impacts of habitat type (forest edges vs. hedges) and hedges’ isolation (connected vs. isolated hedges) from forests as well as microhabitat conditions (percentage of bare ground and width) on trait-specific occurrence of ground-dwelling arthropods, namely spiders and carabids. Arthropods were grouped by habitat specialisation (forest vs. open-habitat species vs. generalists), hunting strategy (web-building or hunting spiders) and dispersal ability (wing morphology of carabids). Spider and carabid assemblage composition was strongly influenced by habitat type and isolation, but not by microhabitat conditions. Activity density of forest species and brachypterous carabids was higher in forest edges compared to hedges, whereas open-habitat species and macropterous carabids showed reverse patterns, with no effects of isolation. Occurrence of generalist carabids, but not spiders, was higher in hedges compared to forest edges. Habitat type and isolation did not affect spiders with different hunting strategy. Microhabitat conditions were less important for spider and carabid occurrence. Our study concludes that on a landscape scale, type of linear woody habitat is more important for arthropod occurrence than isolation effects and microhabitat conditions, depending on traits. Hedges provide refuges for species specialised to open habitats and species with high dispersal ability, such as macropterous carabids. Forest edges enhance persistence of species specialised to forests and species with low dispersal ability, such as brachypterous carabids.     

Habitat structure and neighbor linear features influence more carabid functional diversity in olive groves than the farming system

The effects of land-use management and environmental features at different scales on carabid beetle diversity and trait structure were assessed across olive groves in northeastern Portugal. We selected organic and integrated olive groves that were distinct in terms of specific management practices, local linear features and landscape configurations. Besides the management intensification levels, differences in carabid diversity and community traits were mainly due to local habitat and ecological linear structures at a finer spatial scale. Carabid community traits related to disturbance, namely traits of body size and species dispersal ability, responded to land-use intensity and particular olive grove features were influencing diversity patterns. Within the olive grove patches, larger and brachypterous species were associated to plots with more dense vegetation cover while macropterous and small-sized species were more associated to open areas. Also, larger carabid species benefitted from higher patch size heterogeneity within the landscape mosaics. Our findings indicate that the effects of farming system is contingent on the specific management practices, local and linear features present in agroecosystems such as olive groves. Particularly, the influence of local features on carabid diversity patterns and community traits linked to dispersal and movement may be crucial in maintaining pest control at a landscape scale.     

Dispersal and reproductive properties of sugarcane bugs,Cavelerius saccharivorus

The distribution of sugarcane bugs, Cavelerius saccharivorus is remarkably patchy at time of the peak emergence of the first generation adult in early summer. In population near carrying capacity 70% of adults become macropterous, and they move to sparse populations or vacuum areas. The experiment on the reproductive difference between females from field populations with different densities, showed that the overcrowding restricted their oviposition. On the further experiment it was shown that reproductive ability of macropterous adults or dispersers was not much inferior to that of brachypterous from sparse populations. Overcrowding at time of the peak emergence is reduced by the dispersal. Hence the intraspecific competition is a transient condition. The oviposition is at first restricted in residents of dense populations as compared with brachypterous adults of sparse populations, but the difference becomes small as the former density decreases by the emigration. The last section considers the relation of the reproductive rate and dispersal risk to the rate of dispersal with the simple model, which explains the characteristic dispersal of this species.     

The ground beetle fauna of ancient and recent woodlands in the lowlands of north-west Germany (Coleoptera, Carabidae)

In north-west Germany the ground beetle fauna was investigated using pitfall traps at 79 sampling sites in ancient woodlands and recent woodlands (with and without direct contact to old stands). Two woodland types were considered: The Quercion robori-petraea-woodlands (oak-beech-type) on mainly sandy soils and the Stellario-Carpinetum-woodlands (hornbeam-type) on mainly loamy soils. The number of recorded ground beetle species inhabiting exclusively or predominantly woodlands in the investigation area is significantly higher in ancient stands of both woodland types than in recent ones. No statistically substantiated relation between habitat size (both about 1800 and in 1990) and the number of characteristic woodland ground beetle species could be ascertained. Carabus glabratus and Abax parallelus show a distinct focus in ancient woodlands. Significantly more records of Carabus violaceus and Abax parallelepipedus are known from ancient woodlands than from recent ones. Twelve of the 16 ground beetle species, for which no difference in the colonisation of ancient and recent woodlands was ascertained, are macropterous. Half of the eight brachypterous woodland species is exclusively or predominantly found in ancient woodlands, suggesting that power of dispersal is an important factor which determines the species number in woodland fragments of different age.     

On the significance of dispersal power for populations of carabid-beetles (Coleoptera,Carabidae)

Summary By various observations on carabid populations the author attempts to give an impression of the quantitative occurrence of dispersal and of the relation between dispersal and the chance of founding populations (dispersal power). Pitfall-catches in the recently reclamed Zuiderzee-polder E-Flevoland demonstrate that within seven years individuals of a number of monomorphic macropterous and dimorphic species had founded populations there. From the very high frequency of full-winged individuals within the latter populations it follows that full-winged carabid individuals generally must have a much greater power of dispersal than flightless ones. Therefore, winged individuals of dimorphic species were about equally able to reach E-Flevoland as were those of monomorphic macropterous ones, whereas individuals of monomorphic brachypterous species obviously are seriously hampered. The early appearance of individuals of riparian species on the shores of an artificial lake in the dune area Meijendel suggests that particularly populations living in unstable environments extensively invest in dispersal. It appears, however, that an important investment in dispersal apparently is not restricted to species from unstable environments; at least some sparse populations living in more stable environments also sacrifice relatively great numbers of individuals for dispersal (Pterostichus strenuus). The hypothesis is proposed, that populations facing a high risk of extinction generally will have a sufficient chance of founding populations (high turnover) when investing extensively in dispersal. Not only macropterous but — at least in some populations — also brachypterous individuals participate in migration, although in the populations studied the dispersal power of flightless individuals is found to be very small (Carabus problematicus). Under certain conditions the dispersal of full-winged individuals from wing-dimorphic populations may ultimately lead to a decrease or even a loss of dispersal power by a decrease of the frequency of macropterous individuals. It is assumed, however, that under certain natural conditions also brachypterous individuals may contribute to the spreading of risk within and between populations. The dispersal power of monomorphic macropterous, dimorphic and monomorphic brachypterous populations in a cultivated countryside like Drenthe is discussed. The connection between the dispersal power of different kinds of carabid populations and the resulting chance of survival under different conditions is discussed. Some suggestions for nature preservation management are given.Communication No. 144     

基于形态及分子特征的鳖扁蜡蝉长翅型研究

研究了鳖扁蜡蝉属Cixiopsis Matsumura长翅型雌虫的形态和分子特征.通过和该属的模式种,即鳖扁蜡蝉Cixiopsis punctatus Matsumura,1900短翅型的形态比较,发现该长翅型雌虫在形态学方面存在某些差异.为了明确该长翅型雌虫的归属,还测定了该长翅型雌虫和鳖扁蜡蝉短翅型的COI序列,结...     

稻飞虱翅型纯系后代个体的翅型分化对光周期变化不敏感

【目的】为了明确光周期和遗传因子在稻飞虱翅型分化中的作用, 研究了3种稻飞虱（褐飞虱Nilaparvata lugens、白背飞虱Sogatella furcifera和灰飞虱Laodelphax striatellus）翅型纯系或近纯系在不同光照时数下的翅型分化比率。【方法】以经过5~45代连续翅型筛选后的褐飞虱、白背飞虱和灰飞虱的长翅型和短翅型纯系或近纯系为材料, 在室内分别测定了其在长光照（16和20 h）、短光照(4~12 h)和正常光照(14 h) 3类光周期条件下饲养后, 雌、雄成虫中长翅和短翅个体出现的比率及存活率。【结果】白背飞虱和灰飞虱的长翅型纯系M♂×M♀或短翅型纯系B♂×B♀在不同光周期下的翅型比率均无显著差异（P>0.05）。褐飞虱短翅型近纯系B♂×B♀的雌虫短翅率和成虫总短翅率在不同光周期下也无显著差异（P>0.05）, 但雄虫短翅率在正常光照14 h和短光照4 h下显著高于长光照20 h下的（P<0.05）。当褐飞虱短翅型达到纯系后, 其后代翅型在6~16 h光照条件下无显著差异。褐飞虱长翅型近纯系M♂×M♀的后代虽有短翅个体出现, 但是雌虫和雄虫的各自短翅率在不同光周期下无显著差异（P>0.05), 仅总体短翅率在12 h光照条件下的显著高于16 h下的（P<0.05）。褐飞虱长、短翅型杂交筛选品系M♂×B♀的雌虫短翅率随光照时数的延长而升高; 灰飞虱杂交筛选品系M♂×B♀的短翅雄虫随光照时数的缩短而增多（P<0.05）, 但当筛选代次达到45代时, 这种趋势不再显著。3种稻飞虱长翅型和短翅型纯系或近纯系若虫的存活率会稍低于长、短翅型杂交后代的存活率, 但长、短翅型品系的存活率在6~16 h光照条件下差异不显著(P>0.05)。【结论】稻飞虱翅型分化对光周期的反应受飞虱本身遗传背景的影响, 翅型纯系后代个体的翅型分化对光周期变化不敏感。     

Soil zoology II: Colonization,distribution, and abundance of terrestrial Heteroptera in open landscapes of former brown coal mining areas

In the post-mining landscape of Lower Lusatia (eastern Germany), four mining areas were studied with respect to distribution and abundance of terrestrial Heteroptera. Colonization dynamics and formation of species communities in devasted open areas with different environmental conditions were investigated. In total, 127 species were found in 30 sampling sites, representing about 30% of all species of the state of Brandenburg. The ratio between purely phytophagous and mainly zoophagous species in younger (<20 years) and older sites (>20 years) did not differ much; the ratio between purely macropterous and partly brachypterous species was higher in younger sites. Macropterous species are able to colonize the sites more rapidly. Correspondence and cluster analyses revealed that community patterns are mainly determined by the architecture of the vegetation. Herb cover, grass cover, vegetation density and height, relation of grass versus herb dominance explained most of the community variances, while soil parameters and age of sites were of minor importance. Species number of Heteroptera is also strongly influenced by the plant species composition of sites. Except of young pioneer stages no significant differences in species number between undisturbed and disturbed sites were detected. Younger and older sites differed only slightly in species number of Heteroptera. Colonization by numerous species takes place rather rapidly, depending on the formation of special features of the vegetation and on the species pool of the surrounding area.     

Wing morph-related physiological differences in adults of temperate population of Pyrrhocoris apterus (L.) (Heteroptera: Pyrrhocoridae)

The reproductive and diapausing adult females of brachypterous morph and macropterous females with reproductive arrest of non-diapause type, originating from the laboratory cultures of Pyrrhocoris apterus, were studied for their feeding and drinking behaviour, digestive enzyme activities, and carbohydrate and lipid contents. The highest feeding and drinking activities were observed in reproductive brachypters, the lowest in macropters. Macropters also differed from brachypters by lower activities of gut lipase, peptidase and protease, lower concentration of haemolymph sugars, and lower weight of fat body, which probably reflects their low feeding activity. The total content of fat body lipids was also lower in macropters (0.6 mg) than in reproductive and diapausing brachypters (4.6 and 7.5 mg, respectively) on day 14. A very high amount of glycogen was found in the fat body of diapausing brachypters, 363 micrograms on day 14, as opposed to 15 and 80 micrograms in macropterous and reproductive brachypterous females, respectively. The obtained data indicate that the most important difference between macropterous and brachypterous females with different types of reproductive arrest consists of an enhanced mobilization of lipids for dispersal in macropters and accumulation of energetic reserves for hibernation in brachypters.     

Wing structure and polymorphism in minute scavenger beetles (Coleoptera,Latridiidae)

The main structural elements of the hind wing in 56 species of the family Latridiidae (Coleoptera) are analyzed. In macropterous forms, wing venation is reduced to 3 modified veins. 10 areas of sclerotization of the wing membrane are distinguished. Three forms with different degrees of wing reduction are revealed: the brachypterous, the micropterous, and the apterous form. Among 56 species examined, 40 are represented only by the macropterous form; 2, 3, 5, and 6 species, by macropterous and brachypterous, macropterous and micropterous, micropterous, and apterous forms, respectively.     

Spatial and temporal pattern of colonization of Nabidae (Heteroptera) in alfalfa (Medicago sativa)

Abstract: Six species of Nabidae (Heteroptera) were collected by standardized sweep net sampling in alfalfa fields in Thuringia, Germany, from 1993 to 1995: Nabis pseudoferus , N. ferus , N. brevis , N. major , Nabicula flavomarginata and Aptus mirmicoides . Colonization of a newly cultivated field was studied over a 3-year period. The density of all the studied nabid species was low (less than five individuals per 100 sweeps) and not related to time since colonization started, or to the distance from the margin of the field. Macropterous species were able to colonize the whole field within one season. The density of one macropterous species, N. pseudoferus , varied between the years of study and was mainly affected by the harvest regime. The brachypterous species reached the margin within one season but for density it took three seasons to reach satiated values also in the centre of the field. The abundance of the brachypterous N. brevis was significantly different both between years and sampling sites. This indicates the importance of the surroundings on the succession of this species. Nabis major , a fully winged species, showed a migration pattern intermediate to macropterous and brachypterous nabids. These results suggest that the total abundance of nabid predators cannot be predicted by time or distance from the expansion source (shelter belts). The abundance of brachypterous nabid individuals can be predicted from time since colonization but is best analysed at the species level.     

Relation between temporal persistence of host plants and wing length in leafhoppers (Hemiptera: Auchenorrhyncha)

Abstract.

• 1 Wing form frequencies in 255 populations of 101 species of leafhoppers (Auchenorrhyncha) in temporary and permanent habitats were documented.
• 2 The proportion of brachypterous specimens in the leafhopper assemblages on ruderal host plants in temporary habitats (median 2%, range 0–8%) was significantly lower than that on permanent host plants in undisturbed habitats (median 22%, range 0–94%).
• 3 Leafhopper species typical of temporary habitats were either monomorphic, macropterous, or wing-dimorphic with macropterous forms prevailing in both sexes.
• 4 Among the eighty-nine species recorded in permanent habitats, forty-five species were wing dimorphic. In forty-one dimorphic species, a brachypterous form prevailed. This prevalence was found for both sexes in thirty-one species, for only females in nine species and for only males in one species.
• 5 The prevalence of brachypters in males, but not in females, found in Anoscopus flavostriatus, is probably the first such documented case in Auchenorrhyncha.
• 6 The hypothesis is proposed that in temporary habitats, density-dependent production of macropters in wing dimorphic species is an adaptation to frequent habitat deterioration caused by factors independent of the density of the species.
• 7 The predominance of brachypters in permanent habitats indicates that a density-dependent decrease in fitness usually does not offset the potential decrease in fitness connected with macroptery and dispersal. Because of this inability of leafhopper populations to decrease significantly the quality of their resources, a high population density cannot be used as a predictor of future quality of these resources, which is information essential for efficient dispersal behaviour.

     

THE EVOLUTION OF WING DIMORPHISM IN INSECTS

Wing-dimorphic insects are excellent subjects for a study of the evolution of dispersal since the nondispersing brachypterous morph is easily recognized. The purpose of this paper is to develop a framework within which the evolution of wing dimorphism can be understood. A review of the literature indicates that the presence or absence of wings may be controlled by a single locus, two-allele genetic system or a polygenic system. Both types of inheritance can be subsumed within a general threshold model. An increase in the frequency of a brachypterous morph in a population may result from an increased relative fitness of this morph or the emigration of the macropterous type. The abundance of wing-polymorphic species argues for an increased fitness of the brachypterous form. An analysis of the life-history characteristics of 22 species of insects indicates that the brachypterous morph is both more fecund and reproduces earlier that the macropterous morph. Unfortunately, data on males are generally lacking. It is suggested that suppression of wing production results when some hormone, perhaps juvenile hormone, exceeds a threshold value during a critical stage of development. Further, it is known that in the monomorphically winged species Oncopeltus fasciatus both flight and oviposition are regulated by the titer of juvenile hormone. These observations are used to construct a possible pathway for the evolution of wing dimorphism. This suggests that evolution to a dimorphic species requires both an increase in the rate of production of the wing suppressing hormone and a change in the threshold level at which wing and wing-muscle production are suppressed. The stage in this evolutionary sequence that an organism will reach depends on the stability of the habitat.     

褐飞虱长翅型和短翅型雌雄成虫体内磁性物质定位和定量检测

【目的】地磁定向是昆虫远距离迁飞定向的重要机制之一。本研究以迁飞性害虫褐飞虱Nilaparvata lugens长翅型和短翅型雌雄成虫为研究对象,系统开展虫体内磁性物质定量研究。【方法】本研究利用MPMS-7型超导量子磁强计检测褐飞虱长翅型和短翅型雌雄成虫体内的磁性物质,并将经普鲁士蓝染色后的虫体超薄石蜡切片于JEM-2100型透射电子显微镜下观察磁性物质的分布状况,最后利用原子发射光谱法对虫体内的磁性物质进行定量分析与比较。【结果】超导量子磁强计检测发现,仅在褐飞虱长翅型和短翅型雌雄成虫腹部的磁滞曲线有明显闭合现象,证明该部位存在磁性物质;经透射电镜观察发现,普鲁士蓝沉淀主要呈点簇状存在于虫体腹部,证明该部位存在铁磁性物质;通过等离子发射光谱检测发现,同一性别长翅型成虫体内铁离子含量显著高于短翅型成虫,且相同翅型雄成虫体内铁离子含量显著高于雌成虫。【结论】褐飞虱长翅型和短翅型雌雄成虫腹部普遍存在铁磁性物质,且不同翅型和性别间磁性物质含量差异显著。     

Wing morph-related physiological differences in adults of temperate population of Pyrrhocoris apterus (L.) (Heteroptera: Pyrrhocoridae)

The reproductive and diapausing adult females of brachypterous morph and macropterous females with reproductive arrest of non-diapause type, originating from the laboratory cultures of Pyrrhocoris apterus, were studied for their feeding and drinking behaviour, digestive enzyme activities, and carbohydrate and lipid contents. The highest feeding and drinking activities were observed in reproductive brachypters, the lowest in macropters. Macropters also differed from brachypters by lower activities of gut lipase, peptidase and protease, lower concentration of haemolymph sugars, and lower weight of fat body, which probably reflects their low feeding activity. The total content of fat body lipids was also lower in macropters (0.6 mg) than in reproductive and diapausing brachypters (4.6 and 7.5 mg, respectively) on day 14. A very high amount of glycogen was found in the fat body of diapausing brachypters, 363 μg on day 14, as opposed to 15 and 80 μg in macropterous and reproductive brachypterous females, respectively. The obtained data indicate that the most important difference between macropterous and brachypterous females with different types of reproductive arrest consists of an enhanced mobilization of lipids for dispersal in macropters and accumulation of energetic reserves for hibernation in brachypters.     

The impact of forest ski-pistes on diversity of ground-dwelling arthropods and small mammals in the Alps

Forest clearing for winter sport activities is the major force driving loss and fragmentation of the alpine forests. The establishment of ski-pistes involves impacts on every ecosystem component. To assess the extent of this threat we studied ground-dwelling arthropods (namely ground beetles and spiders) and small mammals (shrews and voles) at two ski resorts in north-western Italian Alps by pitfall trapping. Diversity parameters (mean abundance, species richness and Shannon index) of spiders and macropterous carabids increased from forest interior to open habitats (i.e., ski-piste or pasture), whereas parameters of brachypterous carabids significantly decreased from forest interior to open habitats. Diversity parameters of macropterous ground beetles were higher on pastures than on ski-pistes. Small mammals were virtually absent from ski-pistes. Observed frequencies in the three adjacent habitats were significantly different from expected ones for the bank vole Myodes glareolus and the pygmy shrew Sorex minutus. Generalized linear models showed that abundance, species richness and diversity of spiders and macropterous carabids of ski-pistes were best modelled by combination of factors, including grass cover and width of the ski-piste. Indicator Species Analysis showed that species that significantly preferred ski-pistes were less than those preferring pastures, and species which were exclusive of ski-pistes were very few. To retain arthropod ground-dwelling fauna of open habitats environmentally friendly ways of constructing pistes should be developed. After tree clearing, only the roughest ground surfaces should be levelled, in order to preserve as much natural vegetation as possible. Where necessary, ski-pistes should be restored through the recovery of local vegetation.     

First report of wing dimorphism in the genus Orthomus (Coleoptera: Carabidae)

Wing polymorphism has been reported for several carabid beetles. Traditionally, a great number of ecological and evolutionary studies have focused on this peculiarity, which has implications on dispersal power. Research based on Orthomus berytensis specimens from two sampling areas of Tenerife (Canary Islands, Spain) has shown that this species exhibits a wing dimorphism, instead of being brachypterous. This makes O. berytensis the first Orthomus wing dimorphic species to date. Statistical differences in macropterous percentage between both sexes and localities were found. Also, a sexual dimorphism in elytra length and width was found, both being higher in females.