Landscape configuration determines gene flow and phenotype in a flightless forest-edge ground-dwelling bush-cricket, Pholidoptera griseoaptera

Spatial configuration of habitats influences genetic structure and population fitness whereas it affects mainly species with limited dispersal ability. To reveal how habitat fragmentation determines dispersal and dispersal-related morphology in a ground-dispersing insect species we used a bush-cricket (Pholidoptera griseoaptera) which is associated with forest-edge habitat. We analysed spatial genetic patterns together with variability of the phenotype in two forested landscapes with different levels of fragmentation. While spatial configuration of forest habitats did not negatively affect genetic characteristics related to the fitness of sampled populations, genetic differentiation was found higher among populations from an extensive forest. Compared to an agricultural matrix between forest patches, the matrix of extensive forest had lower permeability and posed barriers for the dispersal of this species. Landscape configuration significantly affected also morphological traits that are supposed to account for species dispersal potential; individuals from fragmented forest patches had longer hind femurs and a higher femur to pronotum ratio. This result suggests that selection pressure act differently on populations from both landscape types since dispersal-related morphology was related to the level of habitat fragmentation. Thus observed patterns may be explained as plastic according to the level of landscape configuration; while anthropogenic fragmentation of habitats for this species can lead to homogenization of spatial genetic structure.     

Tonotopic organization of auditory receptors of the bushcricket Pholidoptera griseoaptera (Tettigoniidae, Decticinae)

The peripheral and central tonotopy of auditory receptors of the bushcricket Pholidoptera griseoaptera is described. Out of 24 auditory receptor cells of the crista acustica 18 were identified by single-cell recordings in the prothoracic ganglion and complete staining with neurobiotin. Proximal receptor cells of the crista acustica were most sensitive to 6 kHz, with medial cells being sensitive to 20–30 kHz, whereas distal cells were most sensitive to frequencies higher than 50 kHz. Projection areas within the auditory neuropile in the prothoracic ganglion were to- notopically arranged. Proximal cells projected anteriorly, medial cells ventrally and posteriorly, and distal cells to more dorsal regions. Identified receptor cells revealed an interindividual variability of tuning and central projections. Receptor cells from the intermediate organ of a bushcricket were identified for the first time. Receptors of the distal intermediate organ were broadly tuned and less sensitive than those of the crista acustica. Receptor cells of the proximal intermediate organ were most sensitive to frequencies below 10 kHz. They projected in anterior portions of the auditory neuropile, whereas cells of the distal intermediate organ had terminations spread over almost the whole auditory neuropile.     

Comparison of player movement patterns between 1-day and test cricket

Physical demands of cricket presumably vary by both game format and performance level. Differences in player movement patterns between 2 game formats (1 day and multiday) and 2 levels of elite performance (state and international) were quantified with global positioning system technology. Five movement categories were established, and 15 movement pattern variables were reported. Data from state (n = 42, 200 files) and international (n = 12, 63 files) cricketers were scaled to hourly values to compare movement demands. Cricketers generally covered similar distances in both formats, except for state 1-day fielders who covered moderately greater distance (~0.7 km·h?1 more; 21 ± 8%; mean ± 90% confidence interval) than state multiday (first-class) fielders. State 1-day cricketers also covered small to moderately greater distances (running 41 ± 13%; striding 38 ± 16%; sprinting 39 ± 36%) in the faster movement patterns and consequently had moderately less recovery time (13-67%) between high-intensity efforts as first-class cricketers. Comparisons of movements between performance levels revealed similar total distances between state and international cricketers. However, Test fielders covered moderately greater (29-48%) distances at the higher-intensity movement patterns (running, striding, and sprinting) than first-class fielders. In summary, although movement patterns were broadly similar between formats and levels, it appears that one day cricket (compared with multiday games) and test matches (compared with state-level competition) require more higher-intensity running. Conditioning coaches should train state and international 1-day cricket players similarly, but should account for the higher physical demands of international multiday cricket.     

农田景观格局变化对昆虫的生态学效应

景观格局变化是全球变化的一个重要内容。农田是由人类赖以生存所种植的人工栽培作物组成的生态系统。在该景观系统中,多种植物-害虫-天敌相互作用、相互制约,形成有机整体。研究农田景观格局对害虫和天敌种群动态影响,不仅在害虫生物防治的实践中有重要意义,而且对于揭示人类活动对生物多样性结构与功能的影响,阐明农田景观中生物多样性整合、维持机理有重大的理论意义。本文从农田景观格局的"质、量、形、度"4个方面,系统地论述了农田景观格局变化对害虫和天敌的作用,分析了农田景观的生物控制服务功能,指出了未来研究发展的方向。     

The articulation of cricket palps: morphology and movement patterns in behaviour

ABSTRACT. The morphology of the palp joints in Gryllus bimaculatus DeGeer is described in the context of their use in various behavioural situations. Two patterns of movements are distinguished: the goal-directed movement of each individual palp, as seen during grooming and food intake actions, and the rhythmic probing movement of the two maxillary palps together during exploratory behaviour and walking. Their details were studied by single frame analysis of video and cine records. The functional characteristics of the maxillary palps with regard to the dimensions of space within which they move in these patterns ('operational space') and the potential sensory stimuli they receive ('reception space') are compared with those of the antennae and discussed from the viewpoint of division of labour.     

Female Bush-Crickets,Pholidoptera griseoaptera,that have Received Smaller Ejaculates Show a Higher Mating Rate in the Field

Females of numerous insect species are known to be polyandrous, but there have been relatively few studies of factors associated with the degree of polyandry in females in the field. Number of copulations by females is negatively associated with ejaculate size across bush-cricket species. Assessing intraspecific variability is important when looking for and interpreting trait evolution. Therefore the aim of this study was to test the association between ejaculate size (i.e. volume of spermatodose–spermatophore-like structure formed within the spermatheca) and mating rate (i.e. number of spermatodoses) of females of Pholidoptera griseoaptera, while accounting for female body size (pronotum length) and age (number of hind leg’s cuticular bands). The results based on field-caught individuals suggested that there were statistically significant negative association between smallest and mean spermatodose volume, respectively, and number of copulations in this nuptial gift-giving bush-cricket species. This is in accordance with interspecific associations between ejaculate size and polyandry. However, lower slope of the intraspecific relationship may suggest lower importance of the ejaculate size in explaining females’ mating rate variability in this nuptial gift-giving species.     

Diversity of intersegmental auditory neurons in a bush cricket

Various auditory interneurons of the duetting bush cricket Ancistrura nigrovittata with axons ascending to the brain are presented. In this species, more intersegmental sound-activated neurons have been identified than in any other bush cricket so far, among them a new type of ascending neuron with posterior soma in the prothoracic ganglion (AN4). These interneurons show not only morphological differences in the prothoracic ganglion and the brain, but also respond differently to carrier frequencies, intensity and direction. As a set of neurons, they show graded differences for all of these parameters. A response type not described among intersegmental neurons of crickets and other bush crickets so far is found in the AN3 neuron with a tonic response, broad frequency tuning and little directional dependence. All neurons, with the exception of AN3, respond in a relatively similar manner to the temporal patterns of the male song: phasically to high syllable repetitions and rhythmically to low syllable repetitions. The strongest coupling to the temporal pattern is found in TN1. In contrast to behavior the neuronal responses depend little on syllable duration. AN4, AN5 and TN1 respond well to the female song. AN4 (at higher intensities) and TN1 respond well to a complete duet.     

Acoustic communication between the sexes of the bush cricket, Leptophyes punctatissima

ABSTRACT. Both sexes of the speckled bush cricket, Leptophyes punctatissima (Bosc) (Tettigoniidae) produce sound by stridulation. The sound is used in courtship. The male sings for periods throughout the day and night, and there is a peak of activity in the early afternoon. The female sings only in response to a male chirp. The male increases his rate of singing if he receives replies from a female. After 3 days isolation from male song, the female replies most readily to male song mimics of short duration (10 ms) whose carrier frequency is 30 or 45 kHz. Females that have been isolated from male song for 10 days respond less readily than those isolated for 3 days. The short duration of the songs of both sexes reduces their value as locating signals. This disadvantage may be outweighed by the fact that a short signal reduces the chance of a predator detecting the singer by acoustic or visual cues.     

Acoustic behaviour of both sexes of the speckled bush cricket Leptophyes punctatissima

As in other phaneropterine bush-crickets, both male and female Leptophyes punctatissima can stridulate. Stridulation in the female, which had previously been overlooked, occurs in response to the male call. The main frequency of the very brief chirps is around 40 kHz. The male is stimulated to chirp more frequently by receiving response chirps from the female. Unlike most Tettigoniidae the male moves toward the female and is thus dependant on her response signal. Communication can occur over distances of at least 5 m. Some structures involved in stridulation in the female differ from that described in other phaneropterines. The insects used in these experiments were all reared in the laboratory from wild-caught parents. Between forty and fifty different insects were used at various times for laboratory studies on the song, and four different males and three females were used on the field communication experiments. The sexes were kept separate from the moult to adult or for at least 10 days before experiments.     

The influences of landscape structure on butterfly distribution and movement: a review

We review the literature on the influence of landscape structure on butterfly distribution and movement. We start by examining the definition of landscape commonly used in spatial ecology. Landscape-level processes are reviewed before focusing on the impact of the geometry and spatial arrangement of habitat patches on butterflies e.g. the nature of the matrix, patch size and shape, minimum area requirements, immigration and emigration, and temporal habitat dynamics. The role of landscape elements is reviewed in terms of corridors (and stepping-stones), barriers, nodes, environmental buffers, and prominent landmark features.     

Connecting landscape structure and patterns in body size distributions

Understanding the interaction between community structure and landscape structure represents a pressing theoretical challenge of great applied importance considering the increasing structural modification of ecosystems through habitat loss and fragmentation. Dispersal ability and energetic demands coupled to body size determine the landscape structure experienced by an organism, which could essentially be fragmented for small individuals but continuous for large ones. Although discontinuities in species assemblages have been predicted and detected, no explicit association between habitat structure and body size distributions has been demonstrated. In this contribution, we propose that body size structure in local communities should reflect such different perceptions of landscape structure. To this end, we explore this association in a simple metacommunity located in the Atacama Desert, in northern Chile. Using graph theory we found that species of different size and trophic position (carnivores and herbivores) perceive the landscape at contrasting spatial scales. In each community (n = 31) we determined the observed and the expected body size distributions – in a random sample from the metacommunity of 18 727 individuals –, which allowed us to identify the body sizes at which an overrepresentation or underrepresentation of individuals occur. Such aggregations and discontinuities in body sizes were related, for carnivores, to patch location within the landscape, and to the internal banded vegetation pattern within patches for herbivores. Our study shows, for the first time, an empirical connection between the spatial distribution of communities, their local attributes, and the existence and locations of discontinuities and aggregations in body size distributions.     

瓢虫种群对棉花-玉米农田景观格局的响应

本文研究了华北棉花-玉米农田景观格局中龟纹瓢虫Propylaea japonica(Thunberg)和异色瓢虫Harmonia axyridis(Pallas)种群动态,发现农田景观格局中作物类型(棉花与玉米)对两种瓢虫种群密度动态有显著的影响,两种天敌瓢虫都趋向在玉米斑块上栖息。两种瓢虫在棉花斑块上呈现出时间分化,其中龟纹瓢虫在棉花种植的前中期种群密度较大,后期较少;而异色瓢虫在棉花前中期种群密度较少,后期较多,表明农田景观中种植玉米有利于增强瓢虫对棉花害虫的控制作用。进一步的研究表明,农田景观系统中玉米斑块所占的面积比对龟纹瓢虫和异色瓢虫种群密度均产生显著影响。这说明在农田景观系统中开展区域性生态调控的时候,需要考虑到各类斑块组合的面积比例,从而有利于增强多种天敌昆虫的协调控害作用。     

Formation of the acrosome complex in the bush cricket Gampsocleis gratiosa (Orthoptera: Tettigoniidae)

The acrosome complex plays an indispensable role in the normal function of mature spermatozoa. However, the dynamic process of acrosome complex formation in insect remains poorly understood. Gampsocleis gratiosa Brunner von Wattenwyl possesses the typical characteristic of insect sperms, which is tractable in terms of size, and therefore was selected for the acrosome formation study in this report. The results show that acrosome formation can be divided into six phases: round, rotating, rhombic, cylindrical, transforming and mature phase, based on the morphological dynamics of acrosome complex and nucleus. In addition, the cytoskeleton plays a critical role in the process of acrosome formation. The results from this study indicate that: (1) glycoprotein is the major component of the acrosome proper; (2) the microfilament is one element of the acrosome complex, and may mediate the morphologic change of the acrosome complex; (3) the microtubules might also shape the nucleus and acrosome complex during the acrosome formation.     

Leaf movement of bush bean: a biometeorological perspective

 Leaf movements of bush bean plants were studied at the relatively low photon flux density of 0.2 mmol/m² per s, and air temperatures of 25° and 35° C in a growth chamber. A beta-ray gauge system was used to monitor continuously pulvinus water status and bending. Leaf angles were below the horizontal and were linearly related to the soil water content (R≥−0.91 at 25° C and R≥−0.93 at 35° C). The beta-ray transmission maxima coincided with the stem temperature minima in darkness and vice versa when brightness prevailed as the growth chamber temperature varied with the photoperiod. Leaf angle increased linearly with increased beta-ray transmission. The Q₁₀ temperature coefficient, a measure of the metabolic energy requirement for leaf movement between 25° and 35° C was estimated at 1.8, and the corresponding mean Arrhenius constant at 423 kJ/mol for bush bean. Received: 19 July 1996 / Accepted: 9 September 1996     

Effects of tail loss on the movement patterns of the lizard, Psammodromus algirus

1. Many lizards use caudal autotomy as a defensive strategy. However, subsequent costs related to the alteration of locomotor abilities might decrease the fitness of individuals. In this paper, the movement patterns of spontaneously moving Psammodromus algirus lizards and their escape performance running at high speed were compared before and after tail loss. A control tailed group was also studied to assess the repeatability of locomotor patterns between trials.
2. Tail loss had a significant effect on spontaneous movement patterns. Tailless individuals moved at significantly slower speeds during bursts of locomotion, and distances moved within bursts were significantly reduced. The overall time spent pausing increased, and, as a result, overall speeds decreased to an even greater extent than burst speeds. However, mean durations of individual locomotor bursts and mean pause durations did not change significantly after tail loss.
3. Loss of the tail decreased mean stride length, although the positive relation between stride length and speed was retained.
4. Escape performance was also greatly affected; loss of the tail resulted in substantially reduced attained, maximal and overall escape speeds. These changes resulted in shorter escape distances (the time of the first pause after the initiation of the escape response) because the mean duration of escape responses did not change.
5. The relevance of these alterations for the ecology of this species, and how individuals may compensate for the costs of tail loss, favouring autotomy as an escape strategy, are discussed.     

The complete mitogenome of the Chinese bush cricket, Gampsocleis gratiosa （Orthoptera： Tettigonioidea）

The complete mitochondrial genome (mitogenome) of Gampsocleis gratiosa was determined. The 15, 929 bp in the size of G. gratiosa mitogenome contains a typical gene content, base composition, and codon usage found in metazoan. All 13 protein coding genes (PCGs) of the G. gratiosa mitogenome start with a typical ATN codon. The usual termination codons (TAA and TAG) were found from 10 PCGs. However, the atp6, nad4, and nad5 had incomplete termination codon (T). The anticodons of all tRNAs are identical to those observed in Drosophila yakuba and Locusta migratoria, and can be folded in the form of a typical clover leaf structure except for trnS (AGN). The secondary structure of trnS (AGN) was drawn according with the Steinberg-Cedergren tertiary structure. The A T content (67.4%) of the A T-rich region is relatively lower among the mitogenome regions, in contrast, it usually contains the highest A T content for most insects. Two isolated sequence repeat regions (202 bp) were found in the A T-rich region with mapping and secondary structure information.     

Dispersal in a metapopulation of the bush cricket, Metrioptera bicolor (Orthoptera: Tettigoniidae)

1. I present a stochastic simulation model that describes individual movements of Metrioptera bicolor Philippi in a heterogeneous landscape, consisting of patches of suitable habitat surrounded by a matrix of unprofitable habitats. Although the model is parameterized with information about daily movement behaviour, it can generate spatially explicit predictions about inter-patch dispersal rates for much longer periods, e.g. one generation.
2. Long-term dispersal experiments were conducted to evaluate model predictions. Patch-specific emigration rates and the total distance moved by individuals could be predicted with satisfactory precision. Because of the stochastic nature of the model, it failed to predict which recipient patches emigrating individuals actually chose in a particular situation.
3. Spatially explicit simulations of the movement model were made for the whole natural distribution area of M. bicolor . The results suggest that emigration rates are negatively correlated with patch size. Local populations occurring on small patches may be more prone to extinction than those on large patches, by losing more emigrants than are compensated for by immigration.     

Effects of landscape structure and habitat type on a plant-herbivore-parasitoid community

The effects of local habitat and large-scale landscape factors on species diversity and species interactions were studied using the insect community in stems of the creeping thistle Cirsium arvense . Thistle abundance was higher in fallows than in crop fields and field margins, with fallows providing 67% of thistle abundance within 15 study areas on a landscape scale. Species richness of the herbivores was positively related with thistle abundance, parasitoid species richness was influenced by habitat type and was positively correlated with herbivore species richness. The abundance of herbivores and parasitoids was affected by local factors such as habitat type and host abundance, but also by landscape factors such as the percentage of non-crop area and the isolation of habitats. The infestation rate caused by the agromyzid Melanagromyza aeneoventris was positively related to percent non-crop area, whereas the parasitism rate of this fly increased with increasing habitat diversity on the landscape scale. For these two interactions and for total herbivore abundance, a scale-dependency of the landscape effects was found. The results emphasize that biological diversity and ecological functions within a plant-insect community are not only affected by local habitat factors but also by large-scale landscape characteristics. Hence, to improve future agri-environmental schemes for biodiversity conservation and biological control large-scale landscape effects and their scale-dependency should be considered.