The aphid Tuberculatus quercicola (Matsumura), a non host-alternating species, lives on Daimyo oak, Quercus dentata Thumberg, and other species of oak. In summer there was a significant reduction in the total amino acid concentration in phloem sap of the host plant and fecundity of the aphids. There are two phenotypes of Q. dentata: one produces flush leaves in mid-July and the other does not. This study investigates the effect of the flush leaves produced by Q. dentata in summer on the density, fecundity and honeydew excretion by T. quercicola. Of 20 shoots on each of the study trees, 6-13 (average 8.8 shoots) produced secondary shoots with flush leaves. The number of aphids on flush leaves sharply increased by two-fold compared to that on mature leaves. The aphids reared on flush leaves were significantly larger and had a larger embryo number compared to those on mature leaves. These results suggest that the phloem sap of flush leaves has a high nutritive quality for aphids. However, in mid-summer and early autumn T. quercicola went into reproductive diapause regardless of whether it was reared on flush or mature leaves. Aphid colonies persisted until October even on trees that did not produce secondary leaves. These observations suggest that this aphid does not depend on secondary leaf production. Thus, the use of flush leaves does not enable T. quercicola to avoid nutritional stress in summer and the need for reproductive diapause.

By means of a tracer assay using a labeled synthetic angiotensin converting enzyme (ACE) substrate hippurylglycylglycine, we have detected high ACE activity in the testes of the African migratory locust, Locusta migratoria. Lower, but significant, ACE activity was observed in midgut and hemolymph. In a two-step purification procedure involving anion exchange and gel permeation chromatography, we have purified LomACE from the locust testes. The enzyme of approximately 80 kDa shows substantial amino-acid sequence homology with ACE from both vertebrate and invertebrate origin. The ACE identity of the purified enzyme was further confirmed by cDNA cloning of the Locusta ACE fragment, which, after in silico translation, revealed a mature protein of 623 amino acids with a large structural similarity to other known ACE proteins.

The endemic Costa Rican genus Zurquilla Gauld, 1997, is transferred from the ichneumonid subfamily Tryphoninae (tribe Oedemopsini) to the Cryptinae (tribe Phygadeuontini) and synonymised with Nipponaetes Uchida, 1933. This decision is justified using morphological and molecular (28S D2-3 ribosomal DNA sequence) evidence. We briefly discuss the phylogenetic utility of characters that led to the type species of Zurquilla being described as a tryphonine and provide a host record that indicates that Nipponaetes is a parasitoid of spider egg sacs.

Kluwer Academic Publishers, Dordrecht, The Netherlands, 2003, 309 pp.

During a survey of 23 wet heathland sites in Flanders (north Belgium) in 1999 and 2000, using both manual nest searching and pitfall traps as sampling techniques, we found 28 ant species. One species (Myrmica lonae) was new to the Belgian fauna and several rare species were encountered. Three ecological groups could be distinguished based on soil preference: the first group of species was characteristic of sandy soil, the second contained species that were more numerous on peat soil (with Sphagnum spp.), and the third group of species had no soil preference. Ant nest numbers increased strongly between 1999 and 2000, especially on the plots that were inundated during the winter of 1999-2000, but the number of ant species did not differ significantly between years. Ant nest density showed an optimum at a Purple Moor-grass (Molinia caerulea) cover of about 45%; the number of species did not show such an optimum. Pitfall traps yielded more species than manual nest searching; in particular temporary social parasites, species with a large foraging range and winged females from the surrounding habitats were missed by the latter technique. Finally, we give some recommendations for the conservation of, and suitable management measures for, ants on wet heathland.

Abnormal spermatogenesis in Pityogenes chalcographus (L.) and Ips typographus (L.) results in oversized spermatozoa in all the populations investigated. They can be identified by light microscopy and classified as 2n up to 16n polyploid. The percentage of polyploid sperm increases when allopatric parents are crossed: Parental populations with less than 1% polyploid, result in male F₁ with more than 20% polyploid. Wild populations of P. chalcographus and I. typographus have very different percentages of polyploid sperm. Populations from allochthonous sites for the host tree, Picea abies (Karst.), are distinguished by higher rates of sperm polyploidy than those from autochthonous areas. Thus, it is assumed that polyploid sperm indicates populations originating from the mixing of partially incompatible beetles.

The detailed external morphology and general anatomy of the majority of families and subfamilies of Poduromorpha were investigated and compared. This examination was done in relation to the three remaining orders of Collembola: Entomobryomorpha, Symphypleona and Neelipleona. Within Poduromorpha, homologies among the different families and subfamilies are established for general chaetotaxy, and chaeotaxy of head, buccal cone, sensilla of fourth antennal segment, anal valves and tibiotarsus. A consistent and comprehensive nomenclature is proposed for these morphological features unifying those applied in scattered existing studies. Observations on first instars are reported. Comparison of first instars and adult chaetotaxy suggests a possible paedomorphic trend in the evolution of Poduromorpha.

The species of flea beetles of the genus Chaetocnema Stephens, 1831 occurring in Madagascar are revised. Four new species (C. cachani, C. hygrophila, C. malgascia and C. orophila) are described and five species (C. bamakoensis Bechyné C. confinis Crotch, C. fuscipennis Scherer, C. ganganensis Bechyné and C. picipes Stephens) are added to the Madagascar fauna. The following new synonymies are proposed: C. wollastoni Baly, 1877 = C. fraterna Harold, 1879 syn. nov. = C. monomorpha Bechyné, 1964 syn. nov.; C. pulla Chapuis, 1879 = C. tantilla Weise, 1910 syn. nov.; C. bilunulata Demaison, 1902 = C. sylvia Bechyné, 1964 syn. nov.; C. vadoni Bechyné, 1948 = C. alaotrensis Bechyné, 1964 syn. nov.; C. gregaria Weise, 1910 = C. insularis Weise, 1910 syn. nov. Lectotypes are designated for C. gregaria Weise, 1910, C. insularis Weise, 1910, C. similis Weise, 1910 and C. tantilla Weise, 1910. A key to all the species is presented. Line drawings of male and female genitalia of all the species are included. Ecological and brief zoogeographical data on some species are given.

A 1962 bp cDNA clone of 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/IMP cyclohydrolase (purH) was isolated from diapausing adults of Leptinotarsa decemlineata using RT-PCR and 3' and 5'-RACE. The probe generated from this clone hybridized to a transcript approximately 1960 bp in length on northern blots. The clone encodes for a deduced protein 594 amino acids in length with 73% identity, 83% similarity to purH from Drosophila melanogaster. Northern blot (total RNA) analysis determined that L. decemlineata purH (LdpurH) was downregulated in diapausing beetles stored at 10°C. Developmental studies revealed that LdpurH is expressed at nearly constant high levels in both nondiapausing and prediapause adults. LdpurH expression during the first 20 days of diapause is equivalent to that seen in nondiapausing beetles, after which expression decreases. Exposing 70 day old diapausing beetles to 20°C for 24 h induced an increase in expression of purH indicating that purH is regulated by temperature in diapausing/overwintering beetles.

A phylogenetic analysis of the four coleopteran suborders (Polyphaga, Archostemata, Myxophaga and Adephaga), four other endoneopteran taxa (Strepsiptera, Neuropterida, Mecopterida and Hymenoptera) and three neopteran outgroups (Orthoneoptera, Blattoneoptera and Hemineoptera) is performed based on 63 characters of hind wing venation, articulation and folding patterns, with character states coded for the groundplan of each taxon (not for exemplar genera or species). The shortest tree found using Winclada with Nona exhibits the following topology: Orthoneoptera + (Blattoneoptera + (Hemineoptera + Endoneoptera: (Hymenoptera + ((Neuropterida + Mecopterida) + (Coleoptera + Strepsiptera))))). Homologization of the hind wing venation in Coleoptera is reviewed and updated, and comments are made concerning recent works on wing folding. Recent phylogenetic schemes proposed for the orders of Endoneoptera and suborders of Coleoptera are reviewed and their supporting evidence critically examined. The special role and influence of the hind wing anojugal lobe on the diversification of Neoptera and Endoneoptera is discussed. A scenario is proposed for the origin and evolution of the insect hind wing.

Colletes anchusae Noskiewicz, 1924 and C. wolfi Kuhlmann, 1999 (Colletidae) are closely related bee species with vicariant distributions, the former occurring in east and southeast Europe and Turkey, the latter restricted to the Italian peninsula. Microscopical analysis of scopal pollen revealed that in Europe both species are monolectic collecting pollen exclusively from flowers of Cynoglottis barrelieri (All.) Vural & Kit Tan (Boraginaceae). In Turkey, C. anchusae possibly visits also Cynoglottis chetikiana Vural & Kit Tan. The distributions of the two bee species and of Cynoglottis coincide. The females of both Colletes species are equipped with stout, curved bristles on their foretarsi used for scraping pollen out of the narrow flower tube of Cynoglottis. Compared to other European species of Colletes the foretarsi of C. anchusae and C. wolfi are shortened, presumably an adaptation to the short corolla tube of their host plant.

Great progress has recently been made in cryobiology. One field, however, has been neglected: the temporal sequence of the effects of photoperiod and temperature, and their relative importance in cold hardening. This is relevant to the question of importance of diapause in cold-hardiness. Denlinger (1991) outlined the categories of such relations and stressed a great need for further detailed research. A survey of studies done over the past decade revealed many gaps in the evidence and the ambiguous nature of the data on the photoperiodic regulation of cold-hardiness. We hope that this review will stimulate further research in this field. Among several directions where research is most needed we have stressed (1) simultaneous recording of changes in survival and dynamics of suspected cryoprotectants (stressed also by Danks, 1996), (2) checking the regulation of different phases of cold hardening, and (3) discrimination between direct and indirect (mediated via neuroendocrine system) effects of environmental cues on cold hardening.

1. The Heteroptera, principally mirids, collected in a light-trap run on a field margin at Rothamsted Experimental Station for various periods between 1933 and 2000, have been identified, and the catches analysed to show the extent of change and stability in the community.
2. Trap catch, both in terms of individuals and species, was correlated with maximum daily temperature.
3. α-diversity showed a U-shaped curve over the period. The dip may have been associated with pesticide use, although a lack of days with high maximum temperatures cannot be ruled out.
4. By the late 1990s, α-diversity had again reached a peak (Fisher's = 11), comparable to that in the 1930s.
5. However, the change in the composition of the community over the whole period (β-diversity) was significant, the index of difference being 0.66 on a scale where 0 is no change in composition or relative abundance and 1 no species in common.
6. The value of β-diversity was highest in the water bugs, which disappeared altogether. Categorising the others by host plant type, the greatest change over time was in those associated with perennial herbs. There were decreasing differences in tree-dwellers and grassland species respectively, and the least change was in the community associated with annual plants (arable weeds).
7. Changes in the abundance of Heteroptera since 1933 follow closely those of the macrolepidoptera from the same samples. However changes in diversity show very different patterns, with moth diversity continuing to decline since 1960 in contrast to the increases apparent from the Heteroptera data.

A total of 23 uropodine species of the genus Trachytes (Acari, Mesostigmata) are reliably recorded to occur in Central Europe and included in identification keys for adults (23 spp.) and deutonymphal stages (9 spp.), respectively. For the first time, the diagnostic characters of deutonymphs of the species T. baloghi, T. minima, T. minimasimilis, T. mystacinus and T. splendida are figured. Ten species found in Slovakia are redescribed (T. aegrota, T. baloghi, T. hirschmanni, T. irenae, T. lamda, T. minima, T. minimasimilis, T. mystacinus, T. pauperior and T. splendida) and characterised by their external morphology, geographic distribution and ecological requirements in terms of habitat preference, affinity to merocoenoses and vertical distribution. The zoogeographic origin of Trachytes is analysed. Most species are found only in woodlands and have not been recorded in the distribution area of the Pannonian flora in Central Europe (except for T. aegrota and T. baloghi). Short taxonomic remarks are given for the species of dubious taxonomic status or whose occurrence is not reliably known.

Genus-group taxa of Platerodinae are revised and valid taxa are redescribed. The validity of Plateros Bourgeois, 1879 is reinstated. Libnetomimus Kleine, 1927 is made a junior synonym of Libnetis Waterhouse, 1878. Calleros Gorham, 1881, Calloplateros Pic, 1923, Costatoplateros Pic, 1949, Ditoneces Waterhouse, 1879, Libnetomorphus Pic, 1921, Microplateros Pic, 1921, Planeteros Gorham, 1883, Tolianus Pic, 1921, Melampyrus Waterhouse, 1879, and the subgenus Cautirodes Pic, 1921 are considered to be junior synonyms of Plateros Bourgeois, 1879. The subgenus Pseudeuplectus Pic, 1922 is synonymized to Cavoplateros Pic, 1913, and Pseudoplateros Green, 1951 is made a junior synonym of Falsocalleros Pic, 1933. Macrolibnetis Pic, 1938 formerly classified with Platerodini is synonymized to Platerodrilus Pic, 1921. Samoaneros Blair, 1928 is considered to be a junior objective synonym of Melaneros Fairmaire, 1877, which is excluded from Platerodinae and is kept incertae sedis in Lycidae. Fernandum Pic, 1924 and Subdihammatus Kleine, 1926 are transferred to the subfamily Leptolycinae. Teroplas oculatus sp. n. and Microlycus mexicanus sp. n. are described. Neotype of Plateros brasiliensis (Lucas, 1857) and lectotype of Microlycus minutus Pic, 1922 are designated. In order to understand relationships within the subfamily, included genus-group taxa were cladistically analysed.

The maximum size of ingested ball-shaped particles was determined in three species of adult dung feeding beetle: Anoplotrupes (Geotrupes) stercorosus and Geotrupes spiniger (Geotrupidae, Geotrupinae) and Sphaeridium lunatum (Hydrophilidae, Sphaeridiinae). Maximum diameters were 40-65 µm, 60-75 µm and 16-19 µm in A. stercorosus, G. spiniger and S. lunatum, respectively, and it was concluded that these beetles feed in the same way as found in previous studies on coprophagous scarabaeids (Scarabaeinae and Aphodiinae). Coarse particles, mainly indigestible plant fragments, are rejected by an unknown filtering mechanism, and only very small particles are actually ingested. The two geotrupids, however, tolerate somewhat larger particles than do scarabaeines of similar size. This may reflect a lower degree of specialisation towards dung feeding in the geotrupids than in the scarabaeines. In several ways, the mouthparts of the coprophagous Scarabaeidae, Geotrupidae and Hydrophilidae show essentially the same morphological modifications that must be adaptations for dung feeding. For the hydrophilid (Sphaeridium), such modifications are described for the first time. They include asymmetric mandibular molars (right convex, left concave), fitting exactly into each other, with highly specialised surfaces that may concentrate the food prior to ingestion by squeezing fluid out of it. Other examples are the conjunctives (scarabaeids and geotrupids) or similar structures (the hydrophilid) and the large, hairy, pad-like distal lobes of the maxillar galeae. Provided that current views on the evolutionary history of these beetles are correct, dung feeding has arisen independently in the Scarabaeidae, Geotrupidae and Hydrophilidae. If so, the feeding on very small particles and the concomitant modifications of mouthparts in these three groups must be results of parallel evolution.

The magnitude, direction and symmetry of intraguild predation (IGP) between the developmental stages of the aphidophagous Harmonia axyridis Pallas and Coccinella undecimpunctata L. were characterized and compared. Mobility and body weight were the main factors affecting the magnitude of IGP.
H. axyridis was more often the predator than C. undecimpunctata and eggs the most vulnerable developmental stage. There was significant asymmetrical IGP on eggs by the second and later, and fourth larval stages of H. axyridis and C. undecimpunctata, respectively. Asymmetrical IGP of pupae was only recorded for the fourth larval stage of H. axyridis. There was no IGP between adults, but larvae of both species attacked heterospecifics. The best model of the relationship between rate of predation and the difference in the body weight of IG predator and prey differs for the two ladybirds. A small difference in the body weights leads to a marked increase in the rate of predation in H. axyridis but not in C. undecimpunctata. In asymmetrical combinations, increase in body weight of the intraguild predator did not significantly increase the rate of predation. Mobility and body weight were not the only important parameters involved in the symmetry of IGP. Aggressive behaviour of H. axyridis negatively affected the survival of C. undecimpunctata.

Analysis of the mitochondrial DNA (mtDNA) control region (CR) was used to examine the dispersal of females of a geometrid moth, Epirrita autumnata, in Fennoscandia. A 542-bp-portion of the CR of 200 individuals from four northern and four southern localities was sequenced. The mtDNA CR of E. autumnata contains a substantial amount of variation as a total of 108 mtDNA haplotypes were observed. Between the northern and the southern localities (~1100 km), there was a moderate level of genetic differentiation (F_ST = 0.128). The amount of variation in the mtDNA CR of E. autumnata was lower in the north than in the south. The reduction in genetic variability may result from a combination of historical bottlenecks that date back to the post-glacial recolonization of Fennoscandia and, present-day bottlenecks due to the northern E. autumnata populations experiencing repeated outbreaks followed by collapse in population size. On a small spatial scale (0.6-19 km), within the northern and southern areas, no genetic differentiation was detected suggesting ongoing gene flow due to the dispersal of E. autumnata females among the localities. This finding was contrary to our earlier expectation of poor flying ability of E. autumnata females.

Ten ant species (Hymenoptera: Formicidae) from three subfamilies feed on honeydew excreted by nymphs of the leafhopper Balclutha punctata (Hemiptera: Cicadellidae). This relationship is facultative for the partners. Preliminary field observations suggest a mutualistic interaction that represents an intermediate stage in the spectrum of formicid-hemipteran mutualisms. Behavioural adaptations of the leafhopper (no escape reaction) and the ants (no predation of leafhoppers, protection from spiders) are evident, but characters of advanced facultative mutualism such as physical contact between the partners or ant-triggered excretion of honeydew were not observed.

The relations between the patterns of discontinuous gas exchange cycles (DGCs) and water loss were investigated in non-chilled diapausing pupae of the white cabbage butterfly Pieris brassicae kept at room temperature (22-24°C) in Petri dishes. An electrolytic respirometer, combined with an infrared (IR) actographic device was used for the simultaneous recordings of metabolic rate, cyclic release of carbon dioxide (bursts), passive suction inspirations (PSIs) and body movements. The patterns of cyclic gas exchange in four- and five-month-old non-chilled diapausing pupae varied individually to a considerable extent. About 40% of the pupae displayed long DGCs lasting 1-3 h, while the interburst periods were characterised by rare and almost regular large PSIs succeeding at intervals of 1-4 min. Nearly 30% of the pupae exhibited short DGCs lasting 3-5 min, while between the bursts there occurred unclear frequent gas exchange microcycles. Standard metabolic rate (SMR) did not reveal significant differences between long DGCs and short DGCs ranging from 32-56 (mean 47.6 ± 4.6) ml O₂ g^-1 h^-1, and 28-61 (mean 44.95 ± 5.3) ml O₂ g^-1 h^-1, respectively. The mentioned levels of SMR were characteristic of diapausing pupae.
Water loss in pupae with long DGCs was determined gravimetrically to be 0.29 ± 0.1 mg g^-1 day¹. At the same time, water loss in pupae that showed only short DGCs and irregular microcycles was 1.73 ± 0.31 mg g^-1 day^-1, which was significantly higher than in individuals characterised by long DGCs. We suggest that water loss in the non-chilled diapausing pupae may depend significantly on the patterns of cyclic gas exchange: long cycles and rare but deep PSIs exerted a marked water conserving effect.

Cephalic chaetotaxy of nymphal and adult stages of species from all the subfamilies of Cydnidae s. str. (sensu Froeschner, 1960 and Lis, 1994), namely Garsauriinae, Cephalocteinae, Cydninae, Sehirinae, and Amnestinae, was studied. Two types of setae, primary and secondary, are described, and changes they undergo during ontogeny reviewed. The adaptive, taxonomic and phylogenetic significance of the cephalic setae in the Cydnidae s. str. is discussed. A ground-plan of the original cephalic chaetotaxy of the family, and its evolution within the family Cydnidae s. str. are proposed.

Choice tests showed that tracks left by coccinellid larvae have generally little effect on oviposition site selection by chrysopid females. Fresh tracks of first instar larvae of the coccinellid species Coccinella septempunctata, Cycloneda limbifer, Leis dimidiata and Semiadalia undecimnotata, did not deter females of the chrysopid Chrysopa oculata from laying eggs. Females of Chrysopa perla avoided ovipositing only on substrates with tracks of L. dimidiata larvae.

Labial gland secretions of 26 males of the bumblebee Bombus lucorum (L.), collected in the Czech Republic, were analysed. The secretions consisted of 60 compounds; ethyl (Z)-9-tetradecenoate was the main component (average 53%). Although the males varied in colour, their labial gland secretions were similar in composition, which indicated they belonged to one species. Chemically the B. lucorum occurring in the Czech Republic correspond to the earlier described "blonde form" of this species.

Aphelinus abdominalis Dalman (Hymenoptera: Aphelinidae), a solitary endoparasitoid of cereal aphids [e.g. Sitobion avenae (F.)] and aphids in greenhouses [e.g. Myzus persicae (Sulzer) and Macrosiphum euphorbiae (Thomas)] is available as biological control agent against aphid pests in greenhouses. As little is yet known about its long-range host location after release, the in-flight orientation of female A. abdominalis was investigated with regard to the effects of post-emergence experience, using a wind tunnel bioassay. In no-choice tests experienced females responded to the odour of M. euphorbiae-infested sweet pepper and aubergine plants while naive females exhibited mostly random flights. In a choice test, offering infested and uninfested plants of the same species, experienced wasps were able to recognize the plant-host complex (PHC) and selected it as landing site. In contrast to uninfested plants, host-damaged plants (infested plants with aphids removed) attracted experienced females just as well as infested plants. When the responses of groups of parasitoids with experience on two different plant-host complexes were studied, specifically trained wasps were observed to orientate significantly better towards the infested target plant than wasps with previous experience on the non-target plant. A final choice test, with an infested pepper and an infested aubergine plant as odour sources, showed that females trained on one of the offered plant-host combinations significantly preferred the odour of the learnt PHC to that of the different PHC. The results suggest that A. abdominalis females employ specific volatile signals emitted by host-infested plants (synomones) during long-range host location. These odours must be learnt, e.g. in association with a successful oviposition.

Diapausing larvae of Aphidoletes aphidimyza (Diptera: Cecidomyiidae) had relatively low supercooling points (SCP) ranging from -19.0 to -26.4°C. None of the specimens that froze at this temperature survived. A high survival rate (up to 87%) at -10°C for 10 days was observed in supercooled larvae. Such features are characteristic for insects that use a chill-tolerance strategy of cold hardiness. However, the cocoons formed by the diapausing larvae were penetrable by external ice crystals and the larvae showed a relatively high survival rate (23 - 34%) at -10°C for 10 days also in the frozen state caused by inoculation by external ice at high subzero temperatures. Such a duality with respect to cold hardiness strategies seems to be ecologically relevant to overwintering in soil habitats where there may be unpredictable contact with external ice.

The influence of cucumber offered as a host plant either alone or with Aphis gossypii Glover (Hemiptera: Aphididae) was studied on the various life table and biological characteristics of the predatory bug Macrolophus pygmaeus Rambur (Hemiptera: Miridae). The nymphal development was studied at 15, 20, 25, 30 and 35°C while adult performance was assessed at 15, 20, 25 and 30°C, using a 16L : 8D photoperiod and 65 ± 5% r.h. Nymphs completed their development at all temperatures except at 35°C. Nymphal development took significantly longer time in the absence than in the presence of prey at 20 and 25°C, but the reverse was true at 15°C. Nymphal mortality was highest at 15°C in the presence of prey and it was mainly recorded at the first and second stages. Females oviposited a small number of eggs at all temperatures but not at 30°C in the absence of prey. The average number of eggs per female was almost similar with or without prey, being highest at 20°C, and adult longevity was highest at 15°C. The results concerning population parameters clearly showed that cucumber with or without prey can not support a population increase of M. pygmaeus. However, it seems that A. gossypii on cucumber inhibits development of M. pygmaeus more than when this aphid species is not present. This adverse effect on this host plant-prey system possibly results from the particular aphid genotype on cucumber, leading to high nymphal mortality, reduced fecundity and short adult life-span of M. pygmaeus.

Two new species of Enclisis Townes, 1970 from Spain are described and illustrated: E. dichroma sp.n. and E. schwarzi sp.n. The new species are distinguished from the closest species E. infernator and E. ornaticeps by head and leg characters and body colour. Data on their phenology and a key to these four European species are presented. External and internal scanning electron microscopy of male tyloids revealed that these structures, in both new species, have a secretory role.

Circellium bacchus is a flightless telecoprid (ball-rolling) dung beetle, endemic to the afrotropical region, where it is found in a few restricted populations in the eastern Cape of South Africa. Its apterous condition and large size (mass ranges from 6 to 12 g) are considered to be adaptations to a semi-arid habitat. This beetle is active in the sun for long periods, walking between widely scattered dung pats, thus is under selection pressure to reduce water loss.
C. bacchus has eight spiracles on each side of the body. The metathoracic spiracle and six abdominal spiracles open into the subelytral cavity, which is closed. The mesothoracic spiracle is the largest and most exposed, occurring ventrally in the membrane connecting the prothorax and mesothorax.
When at rest a cyclic form of respiration, known as discontinuous gas exchange cycle, is used by C. bacchus, releasing a burst of carbon dioxide approximately once an hour when the spiracles open for about 33 minutes. Flow-through respirometry was used to measure water loss from the thorax (being the head, prothorax and mesothorax) and elytral case (containing the metathorax and abdomen) separately. The total water loss of C. bacchus could be divided up as 65% cuticular water loss from the thorax, 35% cuticular water loss from the elytral case, 4% respiratory water loss from the thorax and no measurable respiratory water loss from the elytral case. 1.51 µg of water is lost for every µl of CO₂ emitted during respiration in the thorax. Thus, the main avenue for both respiration and respiratory water loss is via the mesothoracic spiracles, suggesting that the primary function of the subelytral cavity is not to reduce respiratory water loss.

Brill, Leiden- Boston, 673 pp.

Components of daily and seasonal timing systems in insects are reviewed. Photoperiod indicates seasonal position reliably, but signals can be much modified by habitat, latitude and season. Several receptor features and pigment systems are known, with different daily, seasonal and general functions, including differences between circadian and seasonal reception. Clocks can serve several different purposes, functioning as daily oscillators, interval timers or through successive requirements. The molecular functioning of circadian clocks is best known, but even so there is considerable complexity and diversity and much remains to be discovered. We know relatively little about the internal states that provide information for timed responses (such as the photoperiodic "counter"), about the central controlling mechanism, or about the effectors that transmit output signals. Nevertheless, temporal responses serve a very great range of purposes in insects, and the reported complexity in all of the components of timing systems reflects complex ecological needs across daily and seasonal intervals. The variety of components and the complexity of interactions reported (even within species), as well as the diversity of such elements as photosensitive pigments, molecular clock function and potential neurotransmitters, suggests that - unlike some earlier expectations - there is no single master clock for all timing functions in insects.
Insect photoperiodism and rhythmicity have been studied by both observational or direct approaches (examination of system elements or devices, and qualities such as survival), and by inferential or indirect approaches (such as interpretation of various responses to photoperiod, modelling, and estimating fitness). Many students work with only one approach, but the power of different approaches is not equal, and knowledge at one level may not give answers at another. These difficulties tend to limit our understanding of the linkages among components.
This overview suggests several lessons for the study of photoperiodism and rhythmicity. There are multiple elements, complex integration and a diversity of clocks, showing that different processes serve different purposes. The diversity of findings also results from the fact that different investigative approaches, which depend on the question being asked and on the perspective of the investigator, can influence the outcome of the investigation. Given these complexities, I believe that the key to interpreting photoperiodic and circadian responses is their ecological value. Notwithstanding the interest of timing mechanisms or their parts and of specific responses, daily rhythms and seasonal timing are best understood through the essential context provided by the ecological demands on the actual organisms under study.