Apollo Books, Stenstrup (DK), 2001, 256 pp.

There is a high density of the cicada Cryptotympana facialis (Walker) (Hemiptera: Cicadidae) in urban parks in central Japan during summer. This cicada uses its stylet to pierce holes in the trunks of keyaki trees, Zelkova serrata and then feeds on the exuding xylem sap. Three ant species, Formica japonica Motschulsky, Lasius japonicus Santschi and Crematogaster matsumurai Forel (Hymenoptera: Formicidae) were observed aggregatively feeding on these exudates. In addition, two wasp species, Polistes jokohamae Radoszkowski (Hymenoptera: Vespidae), and Ampulex dissector (Thunberg) (Hymenoptera: Sphecidae) fed on the sap. These ants and wasps can therefore be classified as commensals. Two flower chafers, Protaetia brevitarsis (Lewis) and P. orientalis submarumorea (Burmeister) (Coleoptera: Scarabaeidae) were also observed displacing cicadas from their feeding sites and feeding on the exuding sap. Thus, these chafers can be classified as both commensals and kleptoparasites.

Insects have provided much of the best evidence to date concerning possible costs and benefits of multiple mating, and here we investigate the benefits of polyandry in the two-spot ladybird, Adalia bipunctata, by attempting to replicate the highly promiscuous mating system in this species. We compared the temporal pattern of reproductive success of females mated multiple times to one male with that of females mated an equal number of times to multiple males, and found transient differences in offspring production and hatch rate over time. Our data suggest that polyandrous females benefit from multiple mating in some circumstances, but the patterns are complex. Following how both the costs and benefits to mating accrue over time will be necessary if we are to fully understand why polyandry evolves.

An Erratum has been published for this article: https://doi.org/10.14411/eje.2010.054

Centre suisse de cartographie de la faune & Schweizerische Entomologische Gesellschaft, Neuchâtel, 375 pp. ISBN 2-88414-026-3. Price CHF 56.00.

Afroaltica subaptera, a new genus and species of flea beetles (Chrysomelidae: Alticinae) from the eastern regions of southern Africa (Eastern Transvaal and Kwazulu-Natal), is described. Afroaltica gen. n. shows some similarities with the genus Dibolia Latreille, 1829 but it is easily distinguishable mainly by the simple-shaped apical spur of hind tibiae, not bifid. External habitus, scanning electronic micrographs of particular morphological features and line drawings of metafemoral spring and male and female genitalia of the new taxon are provided.

Phylogenetic relationships among Palaearctic Ribes and/or Onagraceae inhabiting Aphis species from five countries were examined using mitochondrial gene cytochrome oxidase I (CO-I) and nuclear gene elongation factor 1 α (EF-1α) sequences. There was no major conflict between the trees obtained from two data sets; nodes with strong bootstrap support from one analysis never contradicted those strongly supported by the other analysis. Palaearctic species of the subgenus Bursaphis (= "grossulariae" species group of the genus Aphis) form a monophyletic group within the genus Aphis. All these analyses indicated that Aphis grossulariae and A. schneideri are close relatives, which is supported by the information on experimental and probably also natural hybridisation. Our data indicate the independent colonisation of Ribes spp. by two species groups of the genus Aphis: A. triglochinis (subgenus Aphis s. str.), and A. grossulariae and A. schneideri (subgenus Bursaphis). Once the subgenus Bursaphis (and other subgenera) is accepted, the subgenus Aphis s. str. will require further subdivision.

Apollo Books, Stenstrup, 2005, 542 + 321 pp. (271 Pls). ISBN 87-88757-47-1. Price DKK 960,00.

Our study focuses on a series of biological characteristics that Anomalochrysa hepatica exhibits; herein, we compare these features with those expressed by two other species within the endemic Hawaiian lacewing genus. Some of the characteristics (No. 2-3, below) vary greatly among the three congeners and may be of phylogenetic importance; others (No. 1, below) probably are not. Our study showed the following: (1) Developmental response to temperature. Anomalochrysa hepatica's developmental rates under a range of temperatures parallel those of the congener A. maclachlani, but A. hepatica's thermal threshold is lower. It is possible that both species' developmental responses to temperature are subject to considerable geographic variation and thus are of little phylogenetic significance at the species level. (2) Larval color change. Third instars of A. hepatica undergo a striking color change as they mature. In expressing this trait, A. hepatica resembles its closely related congener, A. maclachlani, but differs from the more distantly related congener, A. frater. This color change may have phylogenetic importance. (3) Reproductive behavior. Courtship and mating in Anomalochrysa comprise a consistent sequence of behavioral elements, some of which differ among the three species. For example, during courtship, A. hepatica produces readily audible clicks that are associated with forward flicking of the forewings; in A. maclachlani, readily audible clicking occurs with simultaneous flicking of the fore- and hind wings; in A. frater wing-flicking is present but we did not perceive audible clicks. Some of the interspecific variation in mating behavior may also involve specific morphological modifications; aspects of both the behavioral and morphological variation may provide useful characters for phylogenetic study. (4) Oviposition and rates of egg survival in the field. Unlike other Chrysopidae, endemic Hawaiian Anomalochrysa, including A. hepatica, typically lay unstalked eggs; however, species vary in their patterns of egg laying. Both A. hepatica and A. maclachlani deposit clustered eggs, whereas A. frater lays eggs singly. In nature, the average rate of hatching per A. hepatica egg mass was ~75%. Several species of introduced predators and a species of trichogrammatid parasitoid attacked these eggs.

Since the publication of papers by Polis et al. (1989, 1992), intraguild predation (IGP) has been considered in numerous systems and a growing number of papers have been published, demonstrating the ubiquity and the importance of this interaction. It appears that aphidophagous guilds constitute especially favourable systems for IGP. Temporal and spatial distributions of aphids promote interactions, such as IGP, among natural enemies. However, despite extensive laboratory and field studies, several questions remain to be answered: Which traits of the different protagonists of the system may promote or hamper the occurrence of IGP? How do ants tending aphids modulate the interaction? How should one consider the "sub-lethal" effects (and the defensive mechanisms) associated with the risk of IGP? May IGP disrupt or enhance aphid control? These different issues are discussed by focusing on the predatory species in the complex system of aphidophagous guilds. It appears that, first, IGP may constitute one of the main forces influencing the structure and dynamics of aphidophagous guilds, and therefore it has to be taken into account in research studies, and second, because of the ephemeral nature of aphid colonies and the great number of species belonging to aphidophagous guilds, understanding all the implications of the interaction, both direct and indirect, constitutes a very complex task.

Harvard University Press, Cambridge, MA, London, UK, 2005, 384 pp. ISBN 0-674-01882-6 (hardback). Price GBP 18.95, EUR 25.50.

First descriptions of males of Peltonotellus raniformis (Mulsant & Rey, 1855), P. melichari Horváth, 1897 and Ordalonema faciepilosa Dlabola, 1980 are given. In addition, identification keys to the eight Caliscelidae genera of the Western Palaearctic and to the five Peltonotellus Puton, 1886 species of Europe are presented.

The nymphs of spittlebugs (Hemiptera, Cercopidae) are xylem-feeders and live on herbs, grasses or woody plants within their self-produced spittle masses. Nymphs of the spittlebug Neophilaenus albipennis live aggregated in these spittle masses on their host plant Brachypodium pinnatum, a common grass in dry grassland. The objective of this study was to estimate nymphal mortality rates and to examine what role aggregation and vegetation structure play in the mortality of the nymphs. The aggregation and mortality were measured using two different methods, direct monitoring and caging of nymphs. The nymphs passively aggregated with up to 4 nymphs per spittle and aggregation decreased with instar. The aggregation of the nymphs resulted in a reduced mortality in all instars. Although it has already been argued that aggregation may be an advantage, this study is the first direct evidence (i.e. direct measurement of single individuals) for the benefit of aggregation to individual spittlebug nymphs. Despite a clumped distribution of N. albipennis nymphs in tall vegetation, nymphal mortality was not correlated with vegetation height.

In the years 1998-2000, parasitization of the pupae of various ladybird species by scuttle flies of the genus Phalacrotophora was studied in central Poland. Altogether, 12 ladybird species were found to be parasitized by these flies, and one of them, Anatis ocellata (L.), proved to be a host of P. beuki Disney, a species whose biology had not previously been described. Our studies showed that P. beuki can limit the numbers of A. ocellata. In its typical habitat, i.e. Scots pine forests, 35-40% of this ladybird were parasitized by P. beuki. In other habitats, however, where A. ocellata occurred sporadically, P. beuki was not recorded from A. ocellata or other ladybird pupae. P. beuki was described from a single female collected in Holland. The present paper describes the hitherto unknown male, which is very similar to the males of P. berolinensis Schmitz and P. delageae Disney. The feature that reliably separates the males of these three species (a detail of the hypopygium) is described. This feature enabled the recognition in the collection of the Cambridge University Museum of Zoology of a male of P. beuki from Germany, previously assigned to P. berolinensis.

The duration of development, reproduction and longevity of Gastrophysa viridula (DeGeer) was measured at constant temperatures and a long day photoperiod. At 18, 21.5, 25, and 28°C the average duration of development of the egg, larval and pupal stages and total development time (28.2, 21.6, 16.1, 15.0 days) decreased with temperature but the proportion of time spent in the egg, larval and pupal stages did not significantly change with temperature. Total development required 304.6 day degrees above the lower development threshold of 7.1°C. Pre-adult mortality and the rate of oviposition increased, and the duration of oviposition decreased with increasing temperature. Net reproduction rate Ro decreased (from 157 female eggs at 18°C to 75 female eggs at 28°C) and mean generation time T also decreased (from 45.5 days at 18°C to 24.1 days at 28°C) with increasing temperature. The intrinsic rate of population increase rm increased with temperature (from 0.111 at 18°C to 0.179 at 28°C). On a physiological time scale the average generation time T was 496 day degrees.

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 frontal gland as a sac-like organ in Prorhinotermes simplex is present only in presoldiers, soldiers, and imagoes, but exists also in nymph-soldier intercastes. The secretory epithelium consists of a single type of secretory cells adhering directly to the cuticular intima. Secretory vacuoles originate in electron dense vesicles, which are transformed into large electron lucent vacuoles. Intermediate vacuoles frequently contain lipid droplets. The frontal gland cells in presoldiers reveal modifications connected with the production of a new cuticle; the new cuticle is thin and compact, whereas the old one is thick, porous, and wrinkled. None of these cuticles is present in soldiers (sic!). In soldiers, the cuticular intima is of endocuticular origin and is formed by dispersed dense material; the apical parts of secretory cells are formed by numerous irregular finger-like projections, true microvilli are completely lacking. In imagoes, the cuticle is composed of an epicuticle, a layer of epicuticular filaments, and one more basal layer; sexual differences were not observed. In nymph-soldier intercastes, the structure of the gland differs in the head and in the metathorax; the head part of the gland resembles the imaginal gland whereas the thoracic part resembles more that of the soldier; the development of secretory vacuoles stops at the stage of presence of lipid droplets. E-1-nitropentadecene was found in the highest amount in soldiers (comparable to P. inopinatus soldiers), in moderate amount in imagoes, and it is missing in both presoldiers and intercastes.

Supercooling point (SCP), survival at low temperatures, rate of water loss in dry air at 20°C and survival under desiccating conditions of eggs of Polydesmus angustus (Diplopoda) were determined. The results were compared with those obtained previously for the eight post-embryonic stadia, to obtain an overview of the changes in resistance to cold and desiccation throughout the species' development. The SCP temperatures of egg batches ranged from -14.8 to -30.6°C and were significantly lower than those of the active stadia. Eggs were not affected by prolonged exposure to low temperature above 0°C and survived much better than active stadia when cooled to -6 and -10°C. This indicates that the cold hardiness of P. angustus is highest in the egg stage and decreases during development. On the other hand, the rate of water loss was significantly higher from eggs than from active stadia. When eggs were taken out of their protective nest, they lost water at the high rate of 7% min-1 in dry air. They also survived for a shorter time than active stadia at 76% RH and 20°C. The resistance to desiccation of P. angustus is lowest at the egg stage and increases during development. The results suggest that the life cycle of P. angustus may have responded to selection pressures other than cold and drought, and do not support the hypothesis that cold hardiness and resistance to desiccation are overlapping adaptations in terrestrial arthropods.

Laboratory and field tests support the "voltinism-suitability hypothesis" of host selection at various latitudes as well as in local "cold pockets": The best hosts for rapid development will be selected by herbivorous insects under severe thermal constraints for completion of the generation before winter. Papilio canadensis and P. glaucus females do select the best hosts for rapid larval growth in Alaska and in southern Michigan, but not in northern Michigan and southern Ohio. In addition to latitudinal patterns, local host preferences of P. canadensis are described in relation to "phenological twisting" of leaf suitability for larval growth in cold pockets with "thermally constrained" growing season lengths. White ash leaves (Fraxinus americana) have the highest nutritional quality (relative to cherry, aspen, birch, and other local trees) throughout June and July for P. canadensis populations inside the cold pocket, but not outside. In all areas outside the cold pockets, even with bud-break occurring much later than other tree species, ash leaves rapidly decline in quality after mid-June and become one of the worse tree host species for larvae. This temperature-driven phenology difference creates a geographic mosaic in host plant suitability for herbivores. However, we also report here that the cold pocket of northern Michigan has basically disappeared since 1998. Implications of these changes are discussed in relation to voltinism and host plant selection.
Various physiological and ecological adaptations to thermal unit constraints are evident with both species of naturally hybridizing butterflies (P. canadensis to the North and P. glaucus to the South). The rapid regional climate warming since 1998 in the Great Lakes region has allowed us to document some critical aspects of gene flow via analysis of independent "species-diagnostic" trait clines (including morphological, biochemical, and physiological characters). Narrower black bands on hind-wings, larger fore-wings, larval detoxification abilities for tulip tree leaves, behavioral preference of tulip tree leaves, and species-diagnostic allozymes such as PDG (x-linked) and HK (autosomal) provide evidence of these genodynamics. Laboratory hybridization studies (providing known reference groups) and field observations along the hybrid zone show that gene flow between P. glaucus and P. canadensis has recently been extensive across the historical hybrid zone.

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.

The receptor for photoperiodism in nymphs of Poecilocoris lewisi was examined using a phosphorescent paint, which absorbs light energy and emits phosphorescence in the dark. This species shows a facultative diapause in the fifth (final) nymphal instar and its induction is primarily controlled by photoperiod in the fourth instar. The incidence of diapause in the fifth instar was determined after exposing selected regions of the body surface to a longer photophase than the rest by applying a phosphorescent paint in the fourth instar. The incidence of diapause was significantly lower in insects with their compound eyes painted than in control insects at near-critical daylengths. However, painting the central part of the head had no effect. It is concluded, therefore, that the compound eyes are the principal receptor for photoperiodism in nymphs of P. lewisi. This is the first report implicating the compound eyes in the reception of photoperiod in nymphal insects.

Although a monophyletic group, male (XX/XY) and female heterogametic (WZ/ZZ) sex chromosome systems with a couple of variants like XX/X, Z/ZZ and multiple sex chromosome systems occur in insects. Molecular and morphological differences between X and Y or W and Z range from imperceptible to conspicuous. This article illustrates sex chromosome differentiation mainly in two fly species, Drosophila melanogaster and Megaselia scalaris, and in Lepidoptera. The earliest phases of XY evolution are present in the fly M. scalaris. Occasionally in this species, the male determining gene jumps to another chromosome, transforming the new host chromosome to a functional Y chromosome. Thus, in M. scalaris there are strains with virtually no XY differentiation (except for the sex determining function) and others with a moderate degree of differentiation. Base substitutions and alterations like sequence deletions, duplications, and insertions of mobile sequences mark the onset of molecular differentiation. Accumulation of molecular changes and coarser alterations are thought to lead to the morphological differences seen in WZ chromosome pairs of Lepidoptera. The W chromosome probably evolved in the most numerous clade of Lepidoptera, the Ditrysia, after it diverged from the common lepidopteran stem. Extant species display various degrees of molecular and morphological differentiation of the W chromosome, translocation or fusion with autosomes, and loss of the W.

Wild females of Pyrrhocoris apterus exhibit seasonal changes in neuroendocrine activity and, consequently, reproduction. Long days (18 h light/6 h dark) (LD) stimulate reproduction, whereas short days (12 h light/12 h dark) (SD) induce reproductive arrest (diapause). This study reveals how photoperiod influences the expression of the circadian clock gene, period (per) in the insect's head. There is only a weak diurnal rhythm in per mRNA expression under LD and SD. However, levels of per mRNA are consistently higher (up to 10-fold) under SD than under LD. The influence of photoperiod on per gene expression is linked to a developmental output (diapause vs. reproduction); mutant females, reproducing under both LD and SD, show low per mRNA levels under both photoperiodic conditions. Thus, the magnitude of per gene expression may be important to the translation of photoperiodic signals into a hormonal message. Levels of per mRNA are related to properties of locomotor activity rhythms. Low per mRNA levels (displayed by wild females in LD and mutant females in both LD and SD) are associated with long free-running periods (τ~26-27 h) and late peaks of activity (ψR,L~10-12 h), whereas high per mRNA levels coincide with short free-running periods (τ~24 h) and early peaks of activity (ψR,L~4-6 h). Overall, the data provide a background for a molecular approach to the long-standing question about the role of the circadian system in insect photoperiodism.

Interclonal variability in the photoperiodic responses of the pea aphid Acyrthosiphon pisum and intraclonal differences between wingless viviparous females (=apterae) and winged viviparous females (=alatae) were studied. In 7 clones collected from peas near St.Petersburg the effect of constant diel photoperiods (from 0L : 24D to 24L : 0D at 20°C) on sexual morph determination and dynamics of morph production were recorded. Apterae of 5 clones and apterae and alatae of 2 clones were studied. The mean and age-dependent fecundity of apterae and alatae were compared. The clones studied in detail can be divided in two groups. The first includes clones that produced winged males and had critical photoperiods for female morph determination around 12L : 12D. The second includes clones with critical photoperiods for female morph determination around 17L : 7D; these clones produced wingless males, and one clone produced only oviparae. The intraclonal differences in the photoperiodic limits for ovipara and male production depended on the clone-specific abundance of males. The shapes of the photoperiodic curves for male production also depended on the clone-specific abundance of males. In short-day conditions alatae produced more oviparae and fewer males, and the range of photoperiods that induced ovipara production in alatae was nearly twice as wide as that in apterae. The photoperiodic limits for ovipara and male production differed for apterae and alatae. The fecundity of alatae was lower, although they reproduced for longer and lived longer than apterae. Both apterae and alatae reproduced more intensively over the first 2 weeks. Apterae and alatae began to produce males at the same age. Because of their late onset of larviposition, the reproductive pause that divides female and male production was obscured in alatae. Both apterae and alatae tended to produce initially and finally batches of viviparous offspring, possibly reflecting age-dependent endogenous changes in the hormonal titres in the parents.

The effect of photoperiod on nymphal development in the cricket Modicogryllus siamensis was studied. In constant long-days with 16 hr light at 25°C, nymphs matured within 40 days undergoing 7 moults, while in constant short-days with 12 hr light, 12~23 weeks and 11 or more moults were necessary for nymphal development. When nymphs were transferred from long to short day conditions in the 2nd instar, both the number of nymphal instars and the nymphal duration increased. However, only the nymphal duration increased when transferred to short day conditions in the 3rd instar or later. When the reciprocal transfer was made, the accelerating effect of long-days was less pronounced. The earlier the transfer was made, the fewer the nymphal instars and the shorter the nymphal duration. The decelerating effect of short-days or accelerating effect of long-days on nymphal development varied depending on instar. These results suggest that the photoperiod differentially controls the number of nymphal instars and the duration of each instar, and that the stage most important for the photoperiodic response is the 2nd instar.

The effects of body size on mating success and duration of copulation were investigated in Pyrrhocoris apterus. Under laboratory conditions relative mating success of small and large males was investigated in groups of 2 males (majority sex) : 1 female (minority sex). Large males were recorded significantly more often in copulation than small males when the female was large but not when the female was small. This was also the case when the group size was 24 males : 12 females or population density decreased by increasing the area of the experimental arena. In groups of 2females : 1 male, large females were recorded in copulation significantly more often than small females when the male was large but not when the male was small. Proportion of individuals of the minority sex that copulated was similar for males and females, regardless of body size. The average duration of copulation was similar for small and large males, but shorter for small than large females. The difference in the duration of copulation of small and large females was greater when it was with small rather than large males. The prolonged guarding of large females by small males may be explained by a trade-off between increasing the probability of inseminating an uneasily accessible high quality partner and copulating with more females.

A new harpactorine reduviid, Camptibia obscura, gen. et sp. n., from China is described. A key to related genera is provided. The functional morphology of the fore legs of this species is discussed.

The male of Tetanoptera leucodactyla Verbèke, a genus and species of Sciomyzidae known until now only from one female specimen from the Congo, is described, and the genus is more fully characterized. The external morphology is illustrated and the male genitalia are described and figured for the first time. The relationships of Tetanoptera to genera of the Sepedon group and certain other genera of Tetanocerini are discussed. Tetanoptera appears to be related to Verbekaria, and intermediate in an evolutionary lineage between the relatively primitive Tetanocera and the advanced Thecomyia.

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.

Cold-season beetles, Catops nigricans Spence, Choleva agilis Illiger and Choleva elongata Payk., i.e. beetles which start to lay eggs in autumn, which are active during the winter in the adult stage and develop from the egg stage to the adult stage mainly during the winter months, were collected from various locations in north-western Europe and reared in the laboratory at varying temperatures and photoperiods.
Reproduction of all species started in autumn and continued during the winter months. Highest reproductive and survival rates occurred at low temperatures and within a small thermal window ranging from 5° to 10°C: The fitness of individuals decreased at higher and lower temperatures. The lower thermal threshold for all developmental stages was in the range from -5°C to +2°C. The metabolisms of the species were independent of temperature in both dormant and non-dormant stages and were elevated in the low temperature range in comparison to other species which show a temperature-dependent reaction pattern.
Optimal dates for reproduction were determined by the duration of an obligatory adult summer diapause. In C. nigricans, which favours the litter layer of deciduous forests, this duration was fine-tuned by exogenic factors, such as photoperiod and temperature. In contrast, the soil-inhabiting species Ch. elongata showed a homeostatic response pattern, independent of temperature and photoperiod. Heritability (h2) of the duration of diapause was approximately 0.26 in C. nigricans, less pronounced in Ch. agilis (ca. 0.12) and not evident in the subterranean species Ch. elongata.
All three species compensated for the vagaries of climate through bet-hedging tactics. Bet-hedging is so pervasive that a recent substantial increase in temperature seems to have a negligible effect on the distribution pattern of all three species. Based on life-history data it is conceivable that both soil-inhabiting Choleva species, which require a relatively low thermal sum for their development, were already present in western Europe during the sub-arctic conditions when ice shields reached their maximum extension during glacial periods by shifting their activity from the cold to the warm season. The Atlantic fringe north of the Pyrenees, where the climate was not cold enough for permafrost during glacial stages, was probably the only refuge where Ch. elongata might have survived. In contrast, the Mediterranean region should have been the northernmost refuge for C. nigricans during glacial periods. This species has relatively high day-degree requirements (= 1150 d°) for individual development when compared to both Choleva species (= 700 d°).

The larvae of Netocia morio (Fabricius, 1781), Netocia oblonga (Gory & Percheron, 1833), Potosia opaca (Fabricius, 1787) and Potosia cuprea brancoi Baraud 1992 are described. Comparison of the morphology of both genera revealed important differences in raster structure, mandibles and frontal setae. The systematic position of both genera based on larval characteristics is discussed. Some aspects of larval biology are discussed.