The sterrhine loopers Timandra griseata and T. comae have been treated as distinct species since 1994. However, morphological differences between the taxa are minor and therefore their status has often been disputed. Here, we present a molecular phylogenetic study, which separates T. griseata and T. comae into different clades. Altogether, 43 Timandra specimens from eight European countries were studied. The phylogeny is based on a comparative sequence analysis of mitochondrial genes coding for the cytochrome C oxidase subunit I (COI) and NADH dehydrogenase subunit 1 (ND1). Nevertheless, a single individual of both species was assigned to the "wrong" clade. The symplesiomorphy of T. griseata and T. comae is considered to be a result of introgressive hybridization. Conditions that could lead to the hybridization of T. griseata and T. comae are discussed, as well as the likely distribution history of these taxa in Northern Europe. Results of the current analysis are in favour of retaining the species status of T. griseata and T. comae.

The main influences on the specificity of hoverfly larvae (Diptera: Syrphidae) to particular aphids are outlined. There are four main ones: aphid species, host plant, parasitoid impact and the presence of ants. Studies in the literature are used to illustrate the effect of these factors on larval performance. The use of single components of fitness as measures of performance can be misleading: only "individual fitness" includes all the appropriate components of survival, development time and reproduction. Even generalists appear to choose among aphids on the basis of expected fitness. A new level of complexity is therefore required in studies of food specificity in predatory syrphids.

Field studies were conducted, in order to assess the seasonal occurrence and the spatial distribution of Aphidius colemani Viereck, Aphidius matricariae Haliday, Diaeretiella rapae (M'Intosh), Praon staryi Kavallieratos & Lykouressis and Praon volucre (Haliday), all parasitoids of Myzus persicae (Sulzer) on tobacco. The experiments took place in western Greece (Agrinion, Aitoloakarnania), during the 1996 and 1997 growing seasons, in an area of approximately 2.5 ha, where tobacco was the main crop. The experimental field was insecticide-free and tobacco leaf samples (from the upper and lower half of plants) were taken from June until September, in both years. The distribution of the species found was also represented and discussed. Generally, high M. persicae densities were recorded in August (mid-season) of both seasons. The mummification rate showed a specific increasing trend late in the season (August-September). In 1996, the percentage of mummification reached almost 61% at the end of the period, whereas in 1997 it remained at very low levels (<2%). The density of M. persicae was higher on the leaves collected from the upper part of the plants than on those from the lower part, but without significant difference. In contrast, the numbers of mummified M. persicae individuals were significantly higher on leaves collected from the lower part of the plants than on those from the upper part in both years. The relative abundance of the aphidiine parasitoid species differed between the two years.

The abundance of Coleoptera, Diptera and Collembola on different species of fungi was investigated in relation to the size and abundance of fungal resources at different spatial scales; i.e., the size of the fungal fruiting body, the quality of resource in terms of number of conspecific sporophores growing within a radius of 50 cm, crowding of the clumps of fruiting bodies, and the quality of resource within a plot (20 m × 30 m). Multiple linear regression analyses showed that the influential spatial scale varied among the arthropod orders. The amount of resource at the scale of a clump made a significant contribution to the abundance of Coleoptera, and the fruiting body size significantly affected the abundance of Diptera on each fungal species. Collembolan abundance was significantly affected by the crowding of the clumps of fruiting bodies and the number of fruiting bodies per plot. These results suggest that the spatial distribution of fungal fruiting bodies may determine whether they are selected by arthropods visited.

The hypothesis that small body size is correlated with preference for young leaves was tested in a community of leaf-chewing insect herbivores feeding on Ficus wassa in a humid tropical forest in Papua New Guinea. Feeding experiments on 48 species of herbivorous insects revealed a negative correlation between body size and a preference for feeding on young leaves. While small species preferred young leaves, large species showed no preferences, or preferred young leaves only slightly. This relationship was found for the entire leaf-chewing community, as well as for many of the constituent taxa on several taxonomic levels, from orders to genera. Taxonomic position of a species played little role in determining its preferences. It is proposed that higher toughness and lower nutrient content may act as complementary defences, which prevent small insects from feeding on mature foliage. While the low nutrient content of mature leaves may affect smaller herbivores due to their relatively higher metabolic rate and lower digestion efficiency, their toughness complicates feeding mechanically and may prevent the compensatory feeding necessary to offset the low nutritive value of mature leaves.

We studied the importance of forest structure (shape, edge length and orientation) and the crop mosaic (percentage of crops in the total land cover, within 100 and 2000 m from the forests) to the dynamics of an aphidophagous hoverfly Episyrphus balteatus. Adults were collected by Malaise traps located within and on the south- and north-facing edges of 54 forests. In winter, E. balteatus was only found on south-facing edges because of the greater insolation and temperature. In summer, it was more abundant on north-facing edges because of the abundant presence of flowers. In spring, more adults were found on long and south-facing edges than on northern edges. The presence of shrubs within 2000 m also positively affected abundance. In autumn, abundance was positively associated with length of the north-facing edge and forest shape. Emergence traps revealed that in southern France, E. balteatus may overwinter in the larval or puparial stage in forest edges. Overwintering was earlier reported only in adults. Landscape structure, length of forest edges and probably presence of shrub fallows, influence abundance of Episyrphus balteatus.

Host-plant mediation in ant-hemipteran mutualisms requires three conditions. First, hemipteran attractiveness to ants should vary with plant quality. Second, ants should preferentially tend those Hemiptera that produce the most nutritious attractant. Third, increased ant attendance based on a richer food reward should have a significant effect on some measure of hemipteran fitness. A field experiment is used to test these conditions. This is the first study to simultaneously test these three conditions, and the first to test the effect of plant flowering status on the ant-derived benefits for a honeydew-producing hemipteran. It is hypothesized that membracids (Guayaquila xiphias) feeding on plants (Didymopanax vinosum) with flowers ingest phloem sap of higher quality (higher sugar concentration), produce a higher-quality honeydew and, as a result, are attended by more ants and are better protected compared to those on plants without flowers. Total nitrogen content of the phloem sap of plants with or without flowers did not differ significantly, whereas the sugar concentration was higher in the sap of plants with flowers. Honeydew sugar concentration, honeydew production, and ant tending levels did not vary significantly with flowering status. Membracid survival increased, and natural enemy abundance decreased when ants were present. Plant flowering status did not affect the ant-derived protection afforded to treehoppers, but plants with flowers accumulated more natural enemies through time than plants without flowers. The results suggest that a trade-off between feeding on a higher-quality food and running increased risk of predation on flowering plants could underlie this ant-hemipteran interaction. Based on the parameters measured in this study it is concluded that host-plant mediation does not occur in the ant-Guayaquila system. The results suggest, however, that the way in which the host-plant could affect ant-Guayaquila interactions is complex and likely to involve other species.

The grasshopper Dichroplus pratensis Bruner is polymorphic and polytypic for a complex Robertsonian system. In this species, centric fusions induce changes in number and position of chiasmata, and thus potentially affect intrachromosomal genetic recombination and genetic variability. Males and females, from 23 populations covering most of the geographic range of the species and spanning 22 degrees of latitude, were studied. We analyzed chiasma frequency in relation to variability in six exomorphological characters. The chromosomal polymorphisms of D. pratensis are widely geographically distributed, and show a central-marginal pattern, in which the central populations (those occupying the ecologically optimal habitats) have high mean frequencies of different fusions per individual (F) of up to F = 3.00 and total chiasma frequencies as low as X_T = 8.98 per cell, while those near the margins of the distribution (central Patagonia and the Andes) have very low levels of chromosomal polymorphisms [down to F = 0.00 in most geographically marginal locations), monomorphic karyotypes and high chiasma frequencies (X_T = 11.66, in the southernmost (Rada Tilly, 45°57´S) and X_T = 12.01 in the northernmost population (Volcán, 23°55´S)]. Increasing chiasma frequencies towards the margins of the range are positively and significantly correlated with increasing levels of morphological variability. The decrease in fusion polymorphism and the consequent increase in genetic recombination (both inter- and intrachromosomal) in the marginal areas, is a result of natural selection favouring higher levels of variability, which could be adaptive in ecologically harsher and changing environments.

The genus Platesthes Waterhouse, 1845 (Pimeliinae: Praocini), distributed in the Patagonian steppes in southern Argentina and Chile, is revised. A phylogeny of its 13 species is proposed, based on 48 morphological characters. The cladistic analysis provides one most parsimonious cladogram showing that three unambiguous synapomorphic characters of external morphology and male genitalia support the monophyly of Platesthes. This article includes a redescription of the genus, redescriptions of its species, an identification key, habitus photographs of the most representative species, illustrations of external morphology, genital features and metendosternites, a cladogram and distribution maps. A discussion of the biogeography and status of conservation of Platesthes in the Patagonian steppes and in Central Chile is presented. A new Platesthes species is described: P. neuquensis sp. n. and P. hirtipes Kulzer, 1962 stat. n. is elevated to species status. Other valid species of the genus are: P. depressa (Guérin-Ménéville, 1841), P. similis Kulzer, 1956, P. unicosta Kulzer, 1956, P. nigra Kulzer, 1956, P. pilosa Kulzer, 1956, P. vidali Peña, 1986, P. burmeisteri Haag-Rutenberg, 1877, P. granulipennis Kulzer, 1956, P. kuscheli Kulzer, 1958, P. humeralis Kulzer, 1958 and P. silphoides Waterhouse, 1845 (type species), for which a lectotype is designated.

Modality in the supercooling points of cold tolerant but freezing intolerant terrestrial arthropods has proved a pragmatically reliable means of distinguishing between summer and winter cold hardiness in such species. This paper proposes an ecologically realistic method of modal analysis which may either be used in lieu of the traditional separation of supercooling points into "high" and "low" groups, or as a complementary assessment of the risk of freezing mortality. Instead of a posteriori determinations of modal break points, animal supercooling points are assigned a priori to one of four categories of cold hardiness: (1) summer cold-hardy; (2) semi-cold-hardy; (3) cold-hardy; and (4) winter cold-hardy. Each category is identified by the temperature range within which arthropods can be expected to freeze. The temperature ranges assigned to each category are based on a conservative, but realistic, assessment of the temperatures at which animals can be expected to freeze at a given point in the season. The approach has greater discriminatory power than traditional bimodal descriptors (i.e."summer" and "winter" cold-hardy), as well as allowing animal supercooling points to be related to the temperatures they actually experience in their habitats. Thus, for example, animals considered "summer" cold-hardy according to conventional analysis may actually be "semi-cold-hardy" with supercooling points well within the safety margin of minimum ambient temperatures.

Chilocorus kuwanae Silvestri is an effective predator of Unaspis euonymi (Comstock), a scale insect harmful to spindle trees (Euonymus europeus L. and E. japonicus Thumb). The feeding behaviour was studied on wild adults, collected from spindle trees in the Botanic Garden of Perugia University, and fed on overwintering U. euonymi females. The insects were exposed to gradually changing constant temperatures (13°-->10°-->8°-->6°-->4°-->2°-->13°-->15°C) for a ten day period at each temperature. C. kuwanae adults preyed on the scale also at low temperatures. The number of scales eaten decreased with decreasing temperatures from the initial 13°C to 4°C, and at 2°C the trophic activity of C. kuwanae adults almost stopped although they made brief walks in the petri dishes. At all tested temperatures the ladybirds made holes in or lifted the scale cover and preyed on the female. Sometimes they lifted the scale cover , but did not prey on these U. euonymi females which were destined to die from cold. As the temperature dropped from 13°C to 4°C, the number of females eaten by ladybird males and females did not differ statistically. When the temperature was raised to 13°C and 15°C, the ladybirds resumed feeding. Large differences were recorded between sexes, with females showing a much higher feeding activity than males. Scale cover lifting was most frequent at the beginning of the experiment and then decreased with diminishing temperatures, although no significant difference was recorded among temperatures within the range from 10°C to 4°C. The threshold for trophic activity can be taken as 2°C since we noted that a few (12%) individuals on one day showed predatory activity. At 13°C and 15°C lifting activity rose again but remained at a lower level than at the initial exposure to 13°C. There was no significant difference in activity at 13 and 15°C upon raising the temperature. As for total number of U. euonymi damaged by C. kuwanae the trend in damage revealed the same pattern as for number of scales eaten. At the final exposure to 15°C, 60% of C. kuwanae females laid eggs. Our data demonstrate that C. kuwanae can reduce U. euonymi populations in a submediterranean environment even in winter when the range of temperatures is similar to that tested in this experiment.

Three secondary compounds, pyrocatechol, gramine and ferulic acid from wheat were separately incorporated into artificial diets and fed to cotton bollworm Helicoverpa armigera (Hübner) larvae to determine their effects on larval and pupal weights and the nutritional indices of the larvae. The results show that these three secondary compounds can decrease the mean larval and pupal weights of cotton bollworm, with the mean larvae weights differing significantly between treatments. Mean pupal weight was only significantly reduced by ferulic acid and gramine, but not pyrocatechol. There were significant correlations between mean larval weight and concentration of the three secondary compounds tested, and between mean pupal weight and concentration of ferulic acid and gramine. The three secondary compounds tested affected the nutritional indices of cotton bollworm larvae differently. Compared with the control, ferulic acid and gramine significantly decreased RGR (the relative growth rate), AD (approximate digestibility) and ECD (conversion efficiency) of cotton bollworm larvae, and pyrocatechol only reduced ECD. All three indices were the lowest for cotton bollworm larvae fed on the diet with gramine (0.0984 ± 0.0114 g/g/day, 14.2670 ± 1.1541% and 31.1337 ± 1.1213%).

The developmental time and size of a solitary koinobiont parasitoid, Gronotoma micromorpha (Perkins) (Hymenoptera: Eucoilidae), were measured in two host species: the serpentine leafminer, Liriomyza trifolii (Burgess) (Diptera: Agromyzidae) and tomato leafminer, L. bryoniae (Kaltenbach). There was no significant difference in the developmental time of G. micromorpha in these two hosts. However, significantly larger G. micromorpha adults emerged from L. bryoniae than from L. trifolii puparia. Dissection of larvae revealed that when offered a choice G. micromorpha accepted larvae of L. bryoniae more often than those of L. trifolii. The number of wasps emerging from parasitized hosts did not differ significantly between host species. These results indicate that L. trifolii and L. bryoniae are both acceptable and suitable hosts for G. micromorpha. Gronotoma micromorpha may be a useful biological control agent of both L. trifolii and L. bryoniae.

The anomaly that Anopheles culicifacies (Diptera: Culicidae) species B is a major vector of malaria in Sri Lanka, but a non-vector in India, has been noted for several years. In 1999, a Y chromosome dimorphism associated with Plasmodium vivax infectivity within the Indian A. culicifacies species B suggested that this was itself a complex of two sibling species, B and E. A recent cytogenetic analysis shows the sympatric presence of these sibling species in Sri Lanka, a situation similar to that reported from nearby Rameshwaram Island, India. Species E, with a submetacentric Y chromosome, is a more effective vector of P. vivax than species B with an acrocentric Y chromosome. Larval karyotyping, however, is time-consuming and labour-intensive. Recently, the development of a PCR-RFLP assay distinguishing species B and E of A. culicifacies from India, based on differences in one region of the cytochrome oxidase subunit II (COII) gene, was reported. Here we show that whilst this diagnostic approach reveals polymorphism in Sri Lankan A. culicifacies, this variation is not correlated with Y chromosome karyotype. Hence this assay will not be useful for distinguishing species B and E in Sri Lanka. Further, we found no difference between the sequences of Sri Lankan specimens in any of three other regions (ITS2, D3 region of 28S rDNA, and guanylate cyclase intron) often used for species discrimination.

Larvae of three genera representing the staphylinid subfamily Pseudopsinae are described for the first time and illustrated with 33 morphological drawings: Pseudopsis Newman, Zalobius LeConte and Nanobius Herman. Thirty-six characters (mainly of larval morphology) were scored for representatives of six staphylinid subfamilies and a phylogenetic analysis was carried out. The monophyly of the subfamily Pseudopsinae is supported by the presence of a short oblique ridge on ventral side of larval head capsule laterad of maxillary foramina. The monophyly of each of the subfamilies Paederinae and Staphylininae is discussed based on the characters of the immature stages. The subfamily Pseudopsinae is confirmed to be a sister-group of the subfamilies Paederinae + Staphylininae on the basis of six larval synapomorphies. The latter clade is confirmed to be monophyletic on the basis of five larval synapomorphies. A larval identification key to the studied Pseudopsinae genera is provided.

Proteinase activity in the midgut of the pentatomid stinkbug Podisus maculiventris was investigated. The optimal pH for adult and nymph proteolysis was pH 6.0 and pH 6.5, respectively. Proteinase activity was characterised using a range of diagnostic inhibitors. Activity of both adult and nymphal gut extracts, detected by the hydrolysis of Z-Phe-Arg-pNA, was inhibited to <20% of control levels by several inhibitors (e.g. E-64 and chicken egg white cystatin) associated with the inhibition of cysteine proteinases. The less specific inhibitor leupeptin reduced proteolytic activity to around 1.0% of the control values. In-gel analysis of the enzymes revealed that proteolytic activity was due to at least four proteinases, of ca. 30, 36, 50 and 110 kDa, which were all susceptible to E-64 inhibition. Salivary gland extracts gave maximal activity at pH 8.0 when tested for general proteolytic activity using fluorescent BODIPY-FL casein substrate, and showed moderate levels of inhibition when incubated with inhibitors of serine-, cysteine-, aspartic- and metallo-proteinases. Leupeptin and PMSF gave the highest levels of inhibition of salivary proteolytic activity, at ca. 50%, whilst the plant-derived inhibitors SKTI, CpTI and OC-1 did not inhibit proteolysis.

In this paper a combination of characters by which Poecilimon species (Orthoptera: Tettigonioidea: Phaneropteridae) can be recognised as members of the P. sanctipauli group are described. Most important are the wide fastigium, short ovipositor and song characters. The morphological characters are figured and described (Table 1), and the song patterns illustrated by oscillograms. The proposed phylogenetic relationships of the members of this group are written as [P. mytilenensis (P. pulcher, P. lodosi, P. sanctipauli)]. All species of the group are known from southwest Turkey and some east Aegean islands. The three species P. pulcher, P. lodosi and P. sanctipauli are morphologically and bioacoustically quite similar. P. sanctipauli and P. pulcher are distinct species, P. lodosi, however, possesses a combination of the key characters of the other two species. It may be a relict species or, in our opinion more probably, a species of hybrid origin.

Life-history parameters (juvenile development time, adult longevity, host instar preference and rate of parasitism) of four parasitoids of Bemisia argentifolii (two strains of Encarsia formosa (D and B), Eretmocerus eremicus and Eretmocerus mundus) were studied in the laboratory. At 15°C juvenile development time was the shortest for E. formosa B (48 days), longest for E. eremicus (79.3 days) and intermediate for E. formosa D (62.8 days) and E. mundus (64 days) at 15°C. With increase in temperature, development time decreased to around 14 days for all species/strains at 32°C. The lower developmental threshold for development was 11.5, 8.1, 13.0 and 11.5°C for E. formosa D, E. formosa B, E. eremicus and E. mundus, respectively. E. formosa D and B, and E. mundus all appeared to prefer to parasitize 3^rd instar nymphs. The presence of hosts shortened adult longevity in most of the parasitoids, with the exception of E. formosa B, which lived longer than other species/strains irrespective of the presence of hosts. At 15°C daily parasitism was very low by all parasitoids. The two Encarsia strains had a constant, but low rate of reproduction during adult life, while the two Eretmocerus species had a very high rate of reproduction when one-day old, which then decreased very quickly. Lifetime fecundity, estimated using a non-linear model, indicated that it was higher for the two Encarsia strains than for the Eretmocerus species. Life history parameters reported in the literature for the four parasitoids are reviewed and compared with our results. Finally, the potential value for the biological control of whiteflies on greenhouse crops of parasitoids having either a high reproductive rate over a short period (Eretmocerus spp.) or a low rate of reproduction over a long period (Encarsia spp.) is discussed.

A thioredoxin-like protein (txl) gene was cloned from the bumblebee, Bombus ignitus. The B. ignitus txl (Bitxl) gene spans 1777 bp and consists of three introns and four exons coding for 285 amino acid residues with a conserved active site (CGPC). The deduced amino acid sequence of the Bitxl cDNA was 65% similar to the Drosophila melanogaster txl. Northern blot analysis revealed the presence of Bitxl transcripts in all tissues examined. When H₂O₂ was injected into the body cavity of B. ignitus workers, Bitxl mRNA expression was up-regulated in the fat body tissue. In addition, the expression levels of Bitxl mRNA in the fat body greatly increased when B. ignitus workers were exposed to low (4°C) or high (37°C) temperatures, or injected with lipopolysaccharide (LPS), which suggests that the Bitxl possibly protects against oxidative stress caused by extreme temperatures and bacterial infection.

In the present study the temporal changes in the volume of the corpus allatum in three experimental groups of adult males (macropterous, reproductive brachypterous and diapausing brachypterous) of the flightless bug Pyrrhocoris apterus were determined and related to the size of male accessory glands. The results revealed wing morph- and age-dependent differences in the corpus allatum volume in males of this bug. In 4-14 day old males, the volumes of the corpus allatum and accessory glands were largest in long-day reproductive brachypters, intermediate in long-day macropters, and smallest in short-day diapausing brachypters. The smaller corpus allatum in young macropterous males than in same aged reproductive brachypterous males was due to the spontaneous fasting of the former. Later, starting on day 18 after adult emergence, i.e. when macropterous males were feeding normally, there were no significant differences in the volumes of the corpus allatum between long-day brachypterous and macropterous males. On the other hand, the corpus allatum of 18-28 day old diapausing brachypterous males was significantly smaller than that of same aged long-day macropterous and reproductive brachypterous males. The sizes of the corpus allatum and accessory glands were significantly positively correlated in macropterous and diapausing brachypterous males. This is the first report of corpus allatum volume-dependent wing morph-related differences in the rate of accessory gland maturation in males of insects with a non-functional macropterism. The role of differential activity of the corpus allatum in the different life history strategies of males of the two wing morphs in this wing-polymorphic insect is discussed.

In 1996, an old forest pasture grazed from the 1960s to 1988 was restored by coppicing, fencing and grazing by cattle to protect a local population of the endangered butterfly Euphydryas aurinia. An adjoining ungrazed meadow provided a control. In the first years, the butterfly became almost extinct due to the nearly complete consumption of the host plant of the larva, Succisa pratensis, by cattle. The butterfly population quickly recovered when the grazing pressure was lowered. Thus, the intensity of management should be adjusted by continuous monitoring of the target species. In the 2000s, the annual population was about 50 butterflies, but marked fluctuations took place, probably caused by natural factors. Grazing benefited the meadow flora and improved the habitat of butterflies in general. Extensive forest grazing clearly has the potential for enhancing biodiversity. The value of the experiment is, however, limited because only a single pair of meadows was available for comparison. In the future, it will be even more difficult to arrange a similar experiment due to the great decline in the numbers of traditional meadows and forest grazing in SE Finland.

Habitat fragmentation may affect the dispersal behaviour of individuals across the landscape. If there is a high boundary contrast between the remaining fragments and the matrix, individuals should tend to stay inside the fragments, but the configuration of the landscape, i.e. the level of fragmentation and isolation distance between fragments, may modulate this. To test these ideas, we made several mark-recapture experiments with the ladybird Eriopis connexa (Germ.) in manipulated alfalfa model landscapes (30 × 30 m). Specifically we evaluated (i) ladybird movement and permanence in alfalfa and bare ground areas, (ii) how they move across fragment/matrix boundaries, (iii) how their movement between fragments within a landscape is affected by fragmentation level and isolation distance, and (iv) how their permanence in the landscape is affected by fragmentation level and isolation distance. The fragmented alfalfa landscapes had a constant level of habitat loss (84%), but varied in the level of habitat fragmentation (4 or 16 fragments), and isolation distance between fragments (2 or 6 m). We also sampled aphid abundance in the different landscapes through time. We found that ladybirds stay longer and displace less in alfalfa than on bare ground, and that they move less from the alfalfa fragments to the neighbouring bare ground matrix than vice versa. At the landscape level, ladybirds had a higher inter-fragment movement when fragments were closer, they tended to remain in less fragmented landscapes, regardless of their isolation distance. Aphid abundance increased in time, but it was similar in all landscapes. Ladybird movement within fragments, in the matrix and in the boundary between both habitats explains why ladybirds concentrate within alfalfa fragments. However, their dispersal movements at the landscape level do not reflect the higher abundance sometimes found for several species of ladybirds in more fragmented landscapes. At this larger scale, other mechanisms may have a stronger influence in determining the abundance of ladybirds.

The Large Copper butterfly, Lycaena dispar, is extinct in Britain and rapidly declining in the rest of Europe, due predominantly to loss of its wetland habitats. In the Netherlands the sub-species L. d. batavus is at the edge of its range in Northern Europe and, as with most marginal butterflies, has more specialised food plant and habitat requirements than the core populations of L. d. rutilus. We investigate reasons for the relative specialisation of L. d. batavus on Rumex hydrolapathum in a fenland habitat when compared to the more widespread and common L. d. rutilus. Host-plant choice by ovipositing females and by larvae are measured as well as larval performance on alternative hosts. Laboratory experiments reveal that larvae are able to feed on other Rumex species without detriment to their overall survival and can utilise these alternative host plants at least as efficiently as their natural host plant. This suggests that plant chemistry is not responsible for their lack of utilisation in the wild. Under greenhouse conditions, females showed an equal willingness to oviposit on host and alternative Rumex, expressing no significant preference for any particular plant species. However, in field experiments using free-ranging females in a fenland habitat, eggs were laid only on R. hydrolapathum. Our interpretation is that there are no short distance cues discriminating between the three Rumex species but longer distance cues in the field situation may operate to maintain this host-plant specialisation. The selection pressure maintaining L. d. batavus as a specialist on R. hydrolapathum in a wetland may underlie its current rarity.

1. Flight activity in zygopterans is generally restricted to short-range movements associated with foraging, reproductive activity and escape. Indeed, previous studies have suggested that Calopteryx species, including C. splendens, are relatively sedentary species, with a low tendency for long distance movements.
2. Recent observations suggest that C. splendens is expanding its northern range in the UK; in the northeast the species is now well established in Northumberland and, in the northwest, has recently spread into south-west Scotland. The current study aimed to investigate the mobility and dispersal tendency of C. splendens in a well-established breeding population in NE England.
3. A mark-release-recapture study was carried out on a population of C. splendens along a section of the River Wharfe, West Yorkshire, UK. 831 adult C. splendens were marked uniquely for individual identification in order to monitor the day-to-day, and overall, distance and direction of movement for each individual. Of these 381 were recaptured at least once.
4. The majority of males (85%) and females (88%) moved a distance of 100 m or less and only five of the recaptured individuals (1.3%) moved a minimum distance in excess of 500 m. Although the median distance moved by males was greater than that for females, this was not significant. In addition, there was no significant difference in the number of either males or females moving upstream as opposed to downstream.
5. The results are compared with those from other studies on calopterygid movement. Although most individual C. splendens stay within a suggested home range of approximately 300 m, clearly individuals have the potential to cover relatively long distances, and it is these latter movements that play a fundamental role in increasing the range of the species.

The amount of the trail pheromone substance, 3-ethyl-2,5-dimethylpyrazine, of the leaf-cutting ant Atta sexdens sexdens (Hymenoptera: Formicidae) increases with increasing size of the ant from 0 to 35 ng per individual. The compounds 2,5-dimethylpyrazine and trimethylpyrazine are also consistently present. Trails of venom gland extracts are followed with unequal fidelity by different castes. Minor workers follow best, mediums least well. Workers walk sinuously on narrow trails and less sinuously on wider trails up to 9 mm. Trails wider than 9 mm are not followed. The optimum concentration of pheromone on synthetic trails lies between 15 and 150 pg cm^-1. Given a choice of concentrations at a trail branch, workers always choose the more concentrated. Workers showed slight preference for a trail made with venom gland secretion from their own, over that from an alien colony, but there is no preference for a trail that contains Dufour gland secretion additionally.

Ground beetles (Carabidae: Coleoptera) are predators of the seed of herbaceous plants scattered on the ground, but prefer that of certain species. Foraging beetles encounter both freshly dispersed and seed exhumed from the soil bank. The predation on seed from the soil bank has never been studied and the effect of burial on seed acceptability is unknown. The preferences of two generalist granivorous carabids, Harpalus affinis and Pseudoophonus rufipes, were investigated by offering them fresh (stored frozen after dispersal) and buried (for 6 months in the soil under field conditions) seed of six common weed species. Significantly more of the buried seed of Tripleurospermum inodorum and significantly less of that of Taraxacum officinale was eaten than fresh seed. For four other weed species the consumption of both kinds of seed did not differ. The preferences were similar in both species of carabid. The change in preference probably occurred because the seed of T. officinale was partially decayed and the repellent surface of T. inodorum seed abraded. Provided the seed in the soil bank does not decay it may have a similar or better food value for carabids than fresh seed.

Hoplitis pici (Friese, 1899) is a rare species of bee occurring in southeast Europe, Turkey and the Near East. The females are equipped with conspicuous hooked bristles on the galeae of the proboscis. Microscopical analysis of both pollen contained in the abdominal scopa and sticking to the bodies of females indicates a distinct preference of H. pici for the flowers of Muscari Miller (Hyacinthaceae), which are characterized by having the anthers completely hidden within an urn-shaped corolla. Field observations showed that the specialized bristles serve to scrape pollen out of the Muscari flowers. Specialized bristles aiding female bees to extract pollen from narrow flower tubes must have independently evolved at least eight times in osmiine bees. H. pici is the only osmiine species known to use its pollen-harvesting bristles to exploit host plants other than narrow-tubed Boraginaceae.

Encarsia bimaculata (Heraty & Polaszek) is an abundant parasitoid of Bemisia tabaci in southern China. The effects of constant temperatures on a range of life history traits, including development, survival of immatures, longevity and reproduction of adults, were studied in the laboratory. The developmental period from egg to adult ranged from 34.3 ± 0.4 d at 20°C to 8.7 ± 0.6 d at 32°C, A total of 181.4 ± 2.4 degree-days were required to complete development with a lower developmental threshold of 11.6 ± 0.3°C. The survivorship of E. bimaculata from 2^nd instar to adult varied from 81.3 ± 1.7% at 20°C to 91.0 ± 1.8% at 26°C. Average adult female longevity was 8.4 ± 0.7 d at 20°C and 5.4 ± 0.4 d at 32°C, and daily production of offspring peaked at 29°C with 4.5 offspring per female. The maximum oviposition occurred three days after adult emergence at 23, 26, 29 and 32°C, and four days at 20°C. Total number of offspring produced per female varied from 24.3 ± 2.0 at 32°C to 29.3 ± 2.9 at 20°C. The maximum intrinsic rate of increase (r_m) was 0.2163 ± 0.013 at 29°C, followed by 0.2062 ± 0.022 at 32°C. Results indicate that E. bimaculata reaches its maximum biological potential at temperatures ranging from 26°C to 32°C with 29°C being the optimal temperature.

The Belknap Press of Harvard University Press, Cambridge, Massachusetts, and London, UK, 2004, xiii + 448 pp. ISBN 0-674-01181-3, hard cover. Price USD 29.95, GBP 19.95.

Different cytogenetic techniques including C-banding, base-specific fluorochromes and silver nitrate staining were used to compare the karyotypes of three species of bugs, representatives of the Neotropical genus Antiteuchus, namely A. mixtus, A. sepulcralis and A. macraspis. The species have holokinetic chromosomes which is typical of the Hemiptera, and their diploid chromosome number is 2n = 14 and they have an XX/XY (female/male) sex chromosome system. C-banding revealed telomeric blocks of constitutive heterochromatin in most chromosomes of these three species. In each species, CMA₃-positive blocks were observed in the telomeric heterochromatin region of chromosome pair 1. This chromosome pair carried the nucleolar organizer region (NOR), which silver nitrate staining revealed is located in the telomeric heterochromatin. In contrast to the result obtained with CMA₃, entire chromosome complement stained homogenously with DAPI, except for the telomeric region of pair 1, which remained unstained.