Diet, fecundity and egg size in some polyphagous predatory carabid beetles

Egg size was measured at different rates of egg laying in three polyphagous carabid species, known to be useful predators of cereal aphids; the small Bembidion lampros Herbst and the medium-sized Pterostichus cupreus L. and P. melanarius Illiger. Variations in fecundity, as well as the ability of the medium-sized species to also build up fat reserves, were obtained when beetles were subjected to different dietary regimes consisting of aphids, or foods with a lower or higher protein content. Egg size was found to be dependent on the rate of egg laying within a species. A diet of cereal aphids appeared to be adequate for egg production in these polyphagous carabids, but female P. cupreus were unable to build up fat reserves when they ingested aphids contaminated with the aphicide pirimicarb. Beetles were able to devote resources to more and larger eggs (B. lampros), or to larger eggs and/or fat reserves (P. melanarius/P. cupreus) when given access to a carbohydrate-rich food with low protein content. The highest rate of egg laying was obtained when female P. cupreus and P. melanarius were given a more varied diet at frequent intervals; including regular shifts between unsprayed aphids, carbohydrate-rich food and protein-rich maggots. Within the varied diet treatment a negative relationship was obtained between egg size and egg number among similar-sized individuals of P. cupreus and P. melanarius; females producing the largest number also laid the smallest eggs. Egg size affected larval survival, since first instars hatching from large eggs were found to survive longer than those hatching from small eggs. The influence of differences in food intake on reproduction, maintenance metabolism, and survival of fieldinhabiting carabids is discussed.     

大步甲的分子系统与进化模式

大步甲主要分布于北半球,全世界大约有1000余种。因大步甲后翅退化,不能飞行,其移动能力和扩散范围都受到很大程度的限制,因此,容易产生地理隔离和遗传分化,从而成为研究物种分化和生物多样化的好材料。近年来,通过对大步甲分子系统的详细研究,不仅很大程度上解明了大步甲各分类群间的系统发育关系,而且对大步甲的系统演化过程和形态进化模式也有了较深的理解,获得了很多重要的见解。在此做一个简单的综述。     

pH-preferences and habitat selection in carabid beetles

Summary Seven species of carabid beetles were examined in different pH-Orgeln for pH-preferences. Five of these species showed significant preferences for specific pH-fields. Presumably, this parameter of distribution found in the laboratory is also effective in the field. We caught the beetles in the field on soil of the same pH-values which they prefered in the laboratory. The pH-measurements taken by previous workers in the field match our results.The receptors for H-ions are probably located on the antennae, because the preference distribution of Pt. angustatus changed into a uniform distribution after amputation of the distal segments of the antennae. The structure of these receptors could not be identified in electron microscope pictures (REM) among the multitude of different receptors on the antennae.     

Weed seed availability,carabid intraspecific interference and their interaction drive weed seed consumption by carabid beetles

相似文献   

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.     

Morphological evolutionary trends and their implications for the phylogenetic analysis of metendosternite in Chinese dung beetles (Coleoptera, Scarabaeidae)

后胸叉骨是昆虫胸部的内骨骼,是重要的肌肉联结点,在昆虫运中起着不可替代的作用.该结构在鞘翅目高级阶元系统发育关系重建中扮演了重要角色,但由于其在低级阶元间的差异较小以及在形态分析中使用困难等因素限制,致使后胸叉骨的研究并未受到广泛重视.国内学者对于甲虫后胸叉骨的研究非常少,甚至长期以来没有中文名称,相关内容只零星散布于教科书和学位论文中,针对蜣螂后胸叉骨形态学研究尚未见报道.本文对金龟科蜣螂亚科9族65种的后胸叉骨进行了详细的比较形态学研究,归纳了族级形态特征,进而探究蜣螂后胸叉骨形态演化趋势及其在系统发育分析中的意义.此外,还对利用现代形态学和几何形态学等方法研究后胸叉骨功能形态的前景进行了阐述.     

National-scale metacommunity dynamics of carabid beetles in UK farmland

1. Understanding the wide-scale processes controlling communities across multiple sites is a foremost challenge of modern ecology. Here, data from a nation-wide network of field sites are used to describe the metacommunity dynamics of arable carabid beetles. This is done by modelling how communities are structured at a local level, by changes in the environment of the sampled fields and, at a regional level, by fitting spatial parameters describing latitudinal and longitudinal gradients. 2. Local and regional processes demonstrated independent and significant capacities for structuring communities. Within the local environment, crop type was found to be the primary determinant of carabid community composition. The regional component included a strong response to a longitudinal gradient, with significant increases in diversity in an east-to-west direction. 3. Carabid metacommunities seem to be structured by a combination of species sorting dynamics, operating at two different, but equally important, spatial scales. At a local scale, species are sorted along a resource gradient determined by crop type. At a wider spatial scale species appear to be sorted along a longitudinal gradient. 4. Nation-wide trends in communities coincided with known gradients of increased homogeneity of habitat mosaics and agricultural intensification. However, more work is required to understand fully how communities are controlled by the interaction of crops with changes in landscape structure at different spatial scales. 5. We conclude that crop type is a powerful determinant of carabid biodiversity, but that it cannot be considered in isolation from other components of the landscape for optimal conservation policy.     

Factors determining the direction of ecological specialization in snail-feeding carabid beetles

A stout-slender dimorphism in body shape is observed among carabid beetles of the subtribe Carabina, which feed on land snails. We hypothesized that this dimorphism has resulted from divergent ecological specialization for feeding on different-sized land snails. Therefore, we examined whether the geographic variation in the body shape of Damaster blaptoides, a representative snail-feeding species in Japan, is correlated with the size of Euhadra, a genus of land snails frequently consumed by D. blaptoides. An analysis of beetle specimens from the whole distribution area of D. blaptoides determined that more slender beetle populations occurred in localities harboring larger snails, whereas more stout beetles inhabited localities harboring smaller snails. This pattern could be adaptive because slender beetles exhibit high feeding performance for large snails by inserting their heads into the shells, whereas stout beetles do so for small snails by crushing the shells. The D. blaptoides populations showed a clear genetic isolation-by-distance pattern, which could be effective in promoting such local adaptation. Thus, food resources as well as geographic isolation may have promoted adaptive divergence of external morphology in the snail-feeding carabid beetles.     

Effect of diet on the fecundity of three carabid beetles

Abstract In the present study, the importance of diet in terms of fecundity is compared for three species of the carabid genus Amara (Coleoptera: Carabidae), using an insect diet, two types of seed diet (Capsella bursa‐pastoris, Stellaria media) and a mixed diet. It is expected that the species of carabid studied have different food requirements for reproduction. Diet affects reproduction performance and egg production significantly. A mixed diet and both single‐seed diets are suitable for reproduction in Amara aenea (DeGeer) because a higher proportion of the females reproduce and lay significantly more eggs than on a purely insect diet. Females of Amara familiaris (Duftschmid) do not reproduce unless provided with seeds of S. media. Seeds of C. bursa‐pastoris or a mixed diet are equally suitable diets for reproduction of Amara similata (Gyllenhal); a diet of insects or seeds of S. media is unsuitable. The results support the hypothesis that the species under investigation have specific food requirements, suggesting that seed feeding has evolved to different degrees in particular species: A. aenea is omnivorous, whereas A. familiaris and A. similata specialize on the seed of a particular plant species or family. This resource partitioning facilitates co‐occurrence of carabid species.     

Head capsule characters in the Hymenoptera and their phylogenetic implications

The head capsule of a taxon sample of three outgroup and 86 ingroup taxa is examined for characters of possible phylogenetic significance within Hymenoptera. 21 morphological characters are illustrated and scored, and their character evolution explored by mapping them onto a phylogeny recently produced from a large morphological data set. Many of the characters are informative and display unambiguous changes. Most of the character support demonstrated is supportive at the superfamily or family level. In contrast, only few characters corroborate deeper nodes in the phylogeny of Hymenoptera.     

Predation by polyphagous carabid beetles on eggs of a pest slug: Potential implications of climate change

Harpalus rufipes and Poecilus cupreus are two widespread polyphagous carabids which are known to destroy eggs of the pest slug Deroceras reticulatum in the laboratory. To examine the effect of temperature on the predation of the eggs of D. reticulatum by H. rufipes and P. cupreus, a laboratory experiment with different temperatures and a semi‐field experiment including simulated warming were performed. In both experiments, H. rufipes killed more eggs than P. cupreus, and the predatory activity of the former increased significantly with increasing temperature. To our knowledge, this is the first study on predatory activity of polyphagous carabids on the eggs of a pest slug performed under a climate warming scenario. Results suggest that biological pest control performed by polyphagous carabids such as H. rufipes upon pest slugs may be enhanced under predicted climate warming conditions.     

Interspecific and intraspecific variation of the duration and thermal requirements for egg development in carabid beetles (Coleoptera,Carabidae) in the North-West of Russia

The thermal norms of egg development were studied in the ground beetles Amara communis, A. nitida, Carabus granulatus, Platynus assimilis, Poecilus versicolor, Pterostichus oblongopunctatus (spring breeding species), P. melanarius, and P. niger (autumn breeding species). The adults were collected in soil traps near Arkhangelsk, St. Petersburg, Moscow, and Bryansk in May–June. Females and males were kept in pairs at 20°C and 22 h light per day. The eggs laid by females were kept at constant temperatures (12, 14, 16, 18, 20, and 22 ± 0.1°C). The development time for each egg was determined accurate to 0.5 day. From the values of the individual development rate (a reciprocal of development time) at all the temperatures, the thermal constants for development were calculated: the coefficient of linear regression (CLR) of the development rate on temperature, the sum of degree-days, and the thermal threshold for development (TTD). The egg development time was found to vary significantly between the species, except for A. communis, A. nitida, and C. granulatus. The values of CLR (i.e., the slopes of the regression lines) and TTD varied rather distinctly between the species and populations that revealed differences in the thermal requirements for egg development. In the spring breeding species the mean egg development time was significantly shorter, and the CLR and TTD values were on average higher than those of the autumn breeding species. Intraspecific latitudinal variation of the development time and the thermal requirements for egg development was revealed. The eggs laid by beetles from the Arkhangelsk population developed faster than those of the same species from the southern populations at all experimental temperatures. These differences were not great but statistically significant. At the same time, the differences between the CLR and TTD values for the northern and southern populations of the same species were non-significant in most cases. Thus, the main ecophysiological adaptation of carabid beetles during their northward expansion was the shortening of development time within the entire range of favorable temperatures, while the CLR and TTD values only insignificantly changed.     

Annual activity and life cycles of carabid beetles in two forest communities

The annual activity and life cycles of thirteen species of carabid beetles coexisting in two forests in Belgium were studied by recording above-ground activity of adult and larval populations, and by examining the reproductive condition of adults in the course of the year. The cycles were far more complex and diversified than suggested by previous works. Besides typical "spring breeders" and "autumn breeders", species were found

• –

  with a continuous reproductive period from spring to autumn,
• –

  with several variable breeding periods, part of the population overwintering as adults, part as larvae,
• –

  with a breeding period that begins facultatively in autumn and continues the next spring,
• –

  with a winter reproduction.

Comparison of life cycles in Scandinavia and In Belgium also shows their variability in relation to climate. More flexible and varied cycles are made possible by the milder winters further south. Existing classifications of life cycles of carabids appear unable to account for such a diversity and variability.     

Contrasting predation pressure of different ground beetles on slugs and their eggs

Slugs such as Deroceras reticulatum Müller (Pulmonata: Agriolimacidae) cause crop losses in temperate regions worldwide. Numerous species of ground beetles (Coleoptera: Carabidae) feed on slugs, but possible interactive effects are poorly known. Here, we compared predation pressure on slug eggs and slug immatures among Abax parallelepipedus Piller and Mitterpacher, Pterostichus niger Schaller, and Pterostichus melanarius Illiger. The latter was most effective against slug eggs but least effective against immature slugs compared to the other species, demonstrating some specificity of ground beetle predation on life stages. Slug egg predation of P. niger in combination with both other species was synergistic, with up to twice as many eggs consumed as for single species treatments. The effect of species combinations on immature slugs showed no differences from expectations based on single species treatments. Our results indicate that combinations of ground beetle species are favourable for the suppression of slugs in early life stages.     

Clutch and egg size in ladybird beetles

There was a significant positive correlation between the number of ovarioles and clutch size in the 8 species of cocinellid studied. There was no intraspecific correlation between egg size and clutch size under standard conditions. These tactics are discussed in terms of the allocation of resources to reproduction.      

Small-scale spatiotemporal variability in body size of two common carabid beetles

Adult body size is one of the most ecologically relevant quantitative traits that underlies many other life-history traits of particular organism. In insects, there is positive intraspecific relationship between body size and female fecundity. In this study small scale temporal and spatial and space variability in structural body size of Poecilus cupreus and Anchomenus dorsalis was investigated. The beetles were collected in four fields near Prague-Suchdol in autumn 2009 and 2010, and in spring 2010, 2011 and 2012. In both species structural body size was significantly affected by sex (females were the larger sex). In A. dorsalis structural body size was also significantly affected by arable field identity, overwintering (post-overwintering individuals collected in spring were larger in comparison to pre-overwintering individuals collected in autumn), sampling year, overwintering by year and arable field by year interactions. Our results suggest that spatiotemporal variation in environmental conditions experienced by A. dorsalis during larval growth resulted in differences in adult structural body size among particular fields and particular sampling years. In addition, mean structural body size in A. dorsalis was affected by overwintering, which was probably caused by size-specific winter mortality. Moreover, effect of overwintering varied among years, probably according to the specific weather conditions during a particular winter.     

Peculiarities of chromosome organization in meiosis

Meiotic and mitotic chromosomes have a complex of differences. (1) At the early prophase I of meiosis, chromosomes acquire protein axial elements (AEs) that were absent in mitosis; in addition to somatic cohesins, AEs contain the meiosis-specific cohesins REC8, SMC1β, and STAG3. (2) At the middle prophase I, protein lateral elements (LEs) of synaptonemal complexes (SCs) are formed on the basis of AEs. The LE proteins are not conserved, but in Saccharomyces cerevisiae and Arabidopsis thaliana they contain functional domains with conserved secondary structures. Among the almost 679 thousand proteins of primitive eukaryotes that we studied by bioinformatics methods, in green and brown algae, some lower fungi, and Coelenterata, we revealed proteins or functional domains similar to SC proteins. (3) During the pachytene and diplotene stages of meiosis, chromosomes of spermatocytes and mother pollen cells acquire a general structure resembling the structure of amphibian and avian lampbrush chromosomes in miniature. Lateral chromatin loops with sizes of 90, 160, and even over 480 Kb were observed in human spermatocytes during the diplotene stage. In combination, all these observations confirm the considerable conservation of the scheme of molecular and ultrastructural organization of meiotic chromosomes in a large variety of eukaryotic organisms.     

Catches in pitfall traps in relation to mean densities of carabid beetles

Summary Based on continuous pitfall catches summed over the whole activity period for the carabid beetles Pterostichus versicolor Sturm and Calathus melanocephalus L., a satisfactorily linear relationship is presented between the mean densities in several habitats and in different years and the numbers of beetles trapped. This means that with the help of continuous pitfall sampling a reliable relative measure of the sizes of carabid populations can be obtained.Simulation experiments show that for individuals of P. versicolor the distances covered each day should be represented by strips of some width instead of by lines to obtain numbers trapped that equal the field data. The influence on numbers trapped of the high mobility of beetles in unfavorable habitats is probably not significant. Simulation experiments with C. melanocephalus indicate that a much lower capture efficiency than for P. versicolor has to be programmed to fit the simulation results with the field data.The catch from different types of pitfalls is not always proportional to trap perimeter due to different vegetation cover of the immediate trap surroundings and to different kinds of roofs placed over the pitfalls. For the same species the capture efficiency of a pitfall can also change throughout the season.Simulation experiments show that the number and shape of the pitfalls need not influence the catches, provided that the traps keep the same total perimeter and are broadly spaced.Remodelling of some data from the literature reveals that the linear relationship between mean densities and year-catches in pitfalls is probably a general one among carabid species. This leads to the hypothesis that carabid beetles have to work through a fixed reproductive program each year by means of an almost constant total amount of locomotory activity which is realized step by step during spells of suitable weather.Some recommendations are given for intraspecific and interspecific comparisons of pitfall catches between sites and years.Communication no. 196 of the Biological Station of the Agricultural University (Wageningen), Wijster (Drenthe), The Netherlands