Academic Press, London, 1997, 409 pp., 102 ill., 4 tab.

A study on the effect of heat stress on the activity of the medial A1 and A2 neurosecretory neurons (NSN), and the activity of midgut a-amylase and protease was performed on the fifth larval instar of Morimus funereus. Exposure of the larvae to 35°C led to a decrease in the activity of both A1 and A2 NSN, the former being more marked than the latter. These neurons responded differently to heat stress in terms of neurosecretory material synthesis and release. The changes in the size of both A1 NSN and their nuclei and protease activity in the larvae exposed to elevated temperature were significantly correlated, which suggests that A1 NSN play a role in the regulation of the activity of this enzyme during heat stress. The significant correlations between the size of A2 NSN and protease activity in the controls, and the size of both A2 NSN and their nuclei and amylase activity in larvae exposed to heat stress, similarly may mean that A2 NSN regulate both digestive enzyme activities depending on environmental temperature.

In both vertebrates and insects, steroid hormones are known to control diverse physiological events from reproduction to growth and development, primarily by affecting the expression of specific genes. Despite the vast evolutionary distance between arthropods and vertebrates, the molecular mechanisms by which steroids act to regulate genes appear to be conserved. Our understanding of these principles has been advanced significantly during the past few years, owing to the molecular characterisation of genes which encode steroid hormone receptors. This article provides a general survey of the superfamily of nuclear hormone receptors and their mode of action and summarizes the recent knowledge on members of this superfamily discovered in Drosophila and other insects.

Three experimental groups of adult females of Pyrrhocoris apterus (reproductive brachypterous, diapausing brachypterous, and macropterous with non-diapause type of reproductive arrest) were analysed for their dose dependency of adipokinetic response, sensitivity of the fat body to Pya-AKH and locomotor activity during a 24 hour cycle. The greatest adipokinetic response (lipid elevation after hormonal treatment) was observed in macropterous, lower in diapausing brachypterous and the lowest in reproductive brachypterous females. Macropterous females also exhibited the highest activity of walking, while the lowest locomotor activity was found in diapausing brachypters. Diel changes of adipokinetic response were recorded in all three experimental groups, with maximal response occurring during the day at 6-7 h after the onset of light. On the contrary, the minimal adipokinetic response was found in the night and early after the onset of light. No significant differences in diel rhythms were observed between groups exposed to various day lengths. Diel changes in locomotor activity were found only in reproductive brachypterous females and females of macropterous morph, and showed a diurnal rhythm with only one peak of activity during a 24 hour cycle. In the latter, the rhythmic pattern of walking activity was positively correlated with diel changes of adipokinetic response. This indicates an important role of Pya-AKH in dispersal strategy of macropterous females of this heteropteran.

Three antibodies against secretions of the male accessory glands of Tenebrio molitor react with specific regions of the male reproductive system in a damselfly, cockroach, cricket and the bug Pyrrhocoris apterus. Immunoreactivity was used to assess maturation of the system in the reproducing and diapausing P. apterus. In bugs reared continuously at 16 h photophase and 25°C (LD regimen), antigens detected with the PL 6.3 and PL 15.2 antibodies accumulate in the accessory glands and vas deferens (in case of PL 6.3 also in the testes) gradually during the last larval instar. The PL 3.4 antibody begins to react three days after adult emergence (1 day before the males become ready to mate), and the reaction is confined to the accessory glands. Insects reared, since the 3rd larval instar, under the diapause-inducing SD conditions(10 h photophase at 25°C and 14 h scotophase at 15°C), do not exhibit any immunoreactivity throughout the last larval instar or during the first week of adult life, and only a weak reaction to PL 15.2 is detected in the older males. Immunoreactivity to PL 6.3 and PL 15.2 can be induced in the last instar SD larvae by brains implants from the LD larvae or two injections of 1 µg makisterone A.

Kluwer Academic Publishers, Dordrecht, Boston, London, 2000, x + 659 pp.

The aim of this study was to determine if there is a latitudinal gradient in the photoperiodic regulation of wing dimorphism in the flightless bug, Pyrrhocoris apterus (L.). For this purpose individuals from three geographical populations (Israel, Spain and Czech Republic) were reared under different photoperiods and the wing length of the adults analyzed. The highest percentage of long-winged (macropterous) specimens was found in the population from Israel (35.3%), whereas percentages of macroptery were lower in the cultures from Spain (9.5%) and Czech Republic (8.6%). A higher proportion of macropterous specimens was recorded in the northern population of P. apterus kept under long daylengths (Czech Republic, 16 h) than in the southern populations (Spain, 14-15 h; Israel, 12 h). The results indicate that there is a latitudinal gradient in the critical photoperiod determining wing length in P. apterus.

The univoltine leaf miner Chromatomyia fuscula (Zetterstedt) (Diptera: Agromyzidae) is a regular cereal pest in Scandinavia. The fly and its most important parasitoids were studied in a 15.5 ha organically-grown field in southern Norway. Each year (1992-1997), one Malaise trap was placed in the spring barley part (2.5 ha) of the field, and (except for 1994) another along the nearest wooded boundary for the whole season. Because of crop rotation, the traps changed position every year. C. fuscula and 15 parasitoid species previously reared from C. fuscula were sorted from the catches.
Few C. fuscula were trapped in the boundary, suggesting that at least the lower vegetation strata were unimportant for the overwintering fly (C. fuscula overwinters as an adult). The parasitoid complex was remarkably stable over years, and 13-15 of the species were: found each year (habitats combined); 0-6 of the species were not found in both habitats each year. Only 4 species attained fractions higher than 10% of the total annual catches in both habitats during the 6 years: the larval parasitoids Diglyphus begini (Ashmead) and Hemiptarsenus unguicellus (Zetterstedt), and the pupal parasitoids Cyrtogaster vulgaris Walker and Chrysocharis pubicornis (Zetterstedt). In the boundary, C. vulgaris dominated every year (43-83%). In the crop, this species alternated with D. begini (1992, 1994) or H. unguicellus (1997) as the dominant species.
In most years, the catches of both the leaf miner and its parasitoids were larger in the crop than in the boundary, but the species number and composition were fairly similar in the two habitats. The parasitoid diversity (Shannon-Wiener H') tended to be higher in the crop (0.8-2.0) than in the boundary (0.8-1.8). Correspondingly, the evenness (both Shannon-Wiener J' and species rank on In abundance) was higher, and the dominance (Berger-Parker) lower, in the crop than in the boundary. Every year, overwintered C. fuscula invaded the crop, but only in 1993 and 1997 did the trapping reveal a distinct next generation, suggesting a very high pre-adult mortality the other years. In 1993 and 1997, C. vulgaris and D. begini had rather similar abundances in the crop, and the lowest combined fractions (less than 60%) of the years, leading to the highest diversity and the lowest dominance through the 6 years (in both habitats).
Our results indicate that the boundary was part of the parasitoids' foraging/overwintering area, and that the boundary was more important to the parasitoids than to their leaf miner host. Boundaries therefore seem to be important for the control of C. fuscula.

A greenhouse experiment was conducted to study the indirect effects of soil salinity on a caterpillar that induces gall formation on a non-halophilic plant. Larvae of Epiblema scudderiana (Clemens) were allowed to feed on potted goldenrods (Solidago altissima L.) treated with 3 concentrations of NaCl (0, 8,000, 16,000 PPM). Experiments were also carried out with the larvae of two species of leaf beetles, Trirhabda borealis Blake, a leaf-chewer, and Microrhopala vittata F., a leaf-miner, to determine the influence of feeding guild. Adding salt to the soil affected both the plant and insect herbivores. The biomass of roots and shoots as well as root/shoot ratios of salt-stressed plants were lower, relative to controls. The biomass of the fully grown larvae and galls were decreased for the plants treated with the highest salt concentration. The percentage of biomass allocated to the gall was increased by soil salinity. All gall-inducing larvae completed their development (from second to final instar) even though their biomass was significantly reduced in the 16,000 PPM treatment. Soil salinity increased nitrogen concentrations in both gall and stem (normal) tissues but the levels were always higher in the gall. The salt treatments also increased sodium and potassium concentrations in galls and stems. Interestingly, sodium concentrations as well as the ratio of sodium ions to potassium ions increased more rapidly in the stem compared with the gall. Responses of folivorous insects to salt-stressed plants varied. Leaf-chewing larvae ate smaller amounts of plant tissue with high salt content compared with control, which also resulted in shorter feeding periods. The performance of the leaf-mining insect was not affected. However, it was able to complete its larval development within a smaller portion of the leaves. This study showed that soil salinity has a strong negative effect on S. altissima, especially on root development. Conversely, salt stress effects seemed to be progressively decreasing from the stem to the gall to the gall-inducer, which suggests that the gall tissue might act as a buffer against drastic changes in the mineral balance of the host plant. Nevertheless, it seems that unless the host plant dies, larvae of E. scudderiana can always produce a gall in which they can complete their development. On the other hand, leaf-chewing insects appeared to be sensitive to salt-rich tissues since they were deterred by them. Leaf-miners could complete their development with fewer food without any effect on their growth, suggesting that the peculiar tissues on which they feed within leaves became more abundant or nutritious in salt-treated plants.

The foraging behaviour of individual females of Aphidius uzbekistanicus Luzhetski (Hymenoptera: Aphidiidae) on oat plants with one colony of the grain aphid Sitobion avenae F. (Homoptera: Aphididae) was examined in laboratory experiments. Patch time allocation was analysed under semi-natural conditions when individual hyperparasitoid females, Alloxysta victrix Westwood (Hymenoptera: Alloxystidae) or their volatiles 6-methyl-5-hepten-2-one or a mixture of iridoid substances soaked on vermiculite dummies were present simultaneously. Patch residence times of foraging primary parasitoid females were significantly reduced in all analysed treatment groups. Attack numbers on aphids and resulting aphid mummies were also significantly reduced. The presence of hyperparasitoids or their volatiles had no influence on the proportion of time spent engaged in different behaviour by the primary parasitoid. After encounters with hyperparasitoid females or vermiculite dispensers, which had been soaked with the synthetical iridoids, A.uzbekistanicus females changed their behaviour more frequently, and they left the aphid colony at a higher rate than in the controls, where dispensers had been soaked with only pure pentane. The identification of the associated iridoid substances, produced in the hyperparasitoid mandibular glands, is briefly described and their biological significance is discussed.

Larvae of 13 species of the bembidiine subtribes Tachyina (the genera Tachyta Kirby, Tachys Dejean, Polyderis Motschulsky, Elaphropus Motschulsky, Sphaerotachys G. Müller, Paratachys Casey, Porotachys Netolitzky) and Xystosomina (the genus Mioptachys Bates) were studied. Larvae of all studied taxa are described, diagnosed and illustrated. A key to genera is provided separately for the first- and older-instar larvae. Monophyly and phylogenetic position of the subtribes and genera are discussed on the basis of presumably apomorphic character states of larvae. Based on at least six synapomorphic character states the subtribes Tachyina and Xystosomina appear to form a monophyletic group. On the other hand, there are no synapomorphies to propose a sister-group relationship between Tachyina and Xystosomina within the supertribe Trechitae.

The capacity of the green lacewing Chrysoperla rufilabris (Burmeister) to modify its oviposition strategy in response to extraguild prey availability in an oviposition site was studied. Gravid females were placed in presence and absence of aphids. Fecundity, fertility, dispersion and hatching synchrony were compared. Results indicate a statistical difference in the hatching synchrony of eggs. However, no statistical differences were observed in the proportion of infertile eggs and in egg dispersion. We suggest that C. rufilabris can alter hatching synchrony of eggs in condition of food scarcity in order to favour intra-clutch egg cannibalism by newly hatched larvae and thus increase its overall reproductive success.

Aphis triglochinis and A. grossulariae clones from southern Poland produced fertile hybrid eggs under experimental conditions. Established hybrid clones expressed normal parthenogenetic reproduction but bisexual generations were obtained only in three hybrid clones out of twenty six. Fertile F₁ hybrid eggs were obtained in one hybrid clone. Morphological and host-specificity features of A. grossulariae dominated in the majority of hybrid clones. The present results do not exclude the possibility of natural hybridisation of studied aphid species. Natural hybrids may be difficult to detect because of their "pure" morphological and host-specificity features.

The effect of the oviposition deterring pheromone (ODP) in the larval tracks of conspecific and heterospecific ladybirds on oviposition in Harmonia axyridis Pallas was studied in semi natural conditions. Gravid females of H. axyridis were deterred from ovipositing on plants contaminated with conspecific larval tracks, but not on those with heterospecific tracks. H. axyridis females spent significantly less time on plants contaminated with conspecific ODP than on those with heterospecific ODP. This behaviour may account for why fewer eggs were laid on plants contaminated with conspecific ODP.

Chapman & Hall, London, 1998, 409 pp.

Pea aphids (Acyrthosiphon pisum) have been reported to produce winged offspring in the presence of predatory ladybirds. These offspring may leave host plants by flight after they have developed into winged adults. The inter-generational nature of this response raises the question about the chances of survival of aphids developing in attacked colonies. We studied the behaviour of predatory ladybirds on host plants by releasing adult 7-spot ladybirds (Coccinella septempunctata) on bean plants hosting either no prey individuals or colonies of 10 or 30 pea aphids. Interactions between predator and prey were recorded until the ladybird left the plant. Ladybird patch residence time increased with the number of aphids present on a plant but beetles generally left a plant before all aphids were eaten. The time budget of the ladybirds revealed a high proportion of time not spent in feeding activities. Predation rate was about one aphid killed per 10min residence time in both treatments with aphid-infested plants. Aphids that survived an attack by the predator or that were alarmed when a conspecific was attacked often emigrated from the host plant, and their number was of the same magnitude as the number of aphids killed by the predator. On average, pea aphid numbers at the end of an experiment were reduced to less than a third of the initial value. The results of the experiment show that attack by single ladybirds does on average not cause immediate extinction of small aphid colonies. The short patch residence times of on average less than two hours show that a predator individual that induces winged-offspring production in an aphid colony will not any longer be present in the colony when the induced offspring mature. To understand the adaptiveness of predator-induced wing development in pea aphids the probabilities of subsequent attacks on an aphid colony need to be investigated.

The univoltine leaf miner Chromatomyia fuscula Zetterstedt is a Scandinavian cereal pest. We wanted to compare the phenology of C. fuscula in southern Norway with that of its most important natural enemies: 15 parasitoids of the families Eulophidae and Pteromalidae (Hymenoptera: Chalcidoidea). The use of two Malaise traps in an organically-grown spring barley field and its boundary through 6 seasons (1992-1997) also allowed us to compare these two habitats and to observe the effect of harvesting on the parasitoid activity without interference from pesticides. C. fuscula overwinters as an adult and oviposits in May/June. Few specimens of the next generation, emerging in the crop, were caught in the boundary traps, suggesting the fly hibernates elsewhere. In contrast, the F₁ generation of the parasitoids was caught in considerable amounts both in the crop and boundary. The abundance of parasitoids was highest in July/August; in the crop it usually started decreasing well before harvesting; in the boundary it peaked two weeks or more after harvesting. The results suggest that many parasitoids (especially females) move from the crop to the boundary (or beyond) before harvesting. In both habitats parasitoid species richness usually increased until harvesting, and thereafter decreased. The pooled parasitoid female proportion was 0.36; in crop and boundary it was 0.30 and 0.66, respectively, and the majority of species had a higher proportion of females in the boundary than in the crop. The phenology of two of the most common parasitoids is presented: The pupal parasitoid Cyrtogaster vulgaris Walker (Pteromalidae) had a high activity in the boundary, also very early (females only) and late (both sexes) in the season. The larval parasitoid Diglyphus begini (Ashmead) (Eulophidae) was less active early and late in the season, and had a much smaller boundary activity than C. vulgaris. Both sexes were present throughout the season. The annual sex ratio of D. begini was density dependent, being highly male biased in the two years with highest catches. In C. vulgaris neither density nor habitat explained the sex ratio. D. begini probably overwinters inside the mine as a preadult, having one generation on C. fuscula in the crop and another one in an alternate host away from the habitats sampled here. C. vulgaris overwinters as fertilized females in the border habitat.

Adalia bipunctata is a well-known predaceous ladybird distributed in Europe, Central Asia and North America. This species has not been recorded in Japan. Recently, we found this species in the Osaka Bay area in central Japan, and assume that it was imported with goods such as timber by ships. We studied the life history and the distribution in the Osaka Bay area since the initial discovery. The larvae and adults preyed on aphids (mainly, Periphyllus viridis) on trees such as Acer buergerianum and Rhaphiolepis umbellata. The over-wintered adults appeared in March and laid eggs. The adults emerged in spring, and were in the rolled leaves throughout the rest of the year. Thus, in Japan this ladybird is univoltine with long inactivity in adult. The life history of Japanese population of A. bipunctata differs considerably from other areas where populations are multivoltine. The developmental threshold was estimated to be 6.3°C and the sum of effective temperatures was 322.6 day-degrees for the period from egg to adult emergence. Predation on prepupae of A. bipunctata by the larvae of native species such as Harmonia axyridis was observed occasionally.

In 1995-1997, we studied the factors which may influence the ground "activity density" of Carabidae using pitfall traps placed in winter wheat, winter rape and pea stands (1995 only) grown within a 1 km² area with uniform physical conditions. The traps were placed in plots of bare ground established within the crops and under surrounding intact plant stands. The communities were similar between crops within years (Pearson's correlation coefficient r = 0.60 - 0.81), and between years within crops (r = 0.89 - 0.91), except for the poor winter rape stand in 1997. Factors influencing carabid "activity density" were: (i) Density of crop stand. The carabids preferred crop-shaded ground as long as crop density was low or medium but moved to bare ground plots when crop density became high. Under moderate crop density the preference differed between beetle species, most of which preferred crop-shaded ground while a few ones preferred bare ground. Carabid preferences were probably determined by microclimatic differences caused by presence and density of crop cover. (ii) Presence of seeds dropped on the ground. In rape stands, presence of crop and weed seeds increased the "activity density" of seed predators (species of genera Amara, Harpalus, Ophonus and Pseudoophonus). Scattering of rape seeds significantly increased local activity density of Harpalus affinis and H. distinguendus in the wheat stand. (iii) Presence of aphids. Activity density of Bembidion lampros and Trechus quadristriatus and between-year variation in pooled abundance of the five species recognised as aphid predators was associated with variation in aphid abundance.

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.

Monoctonus paulensis is a solitary parasitoid of several species of aphids, including the pea aphid, Acyrthosiphon pisum. We evaluated host-instar selection by comparing the parasitoid's preference for the four nymphal instars of the pea aphid, presented two at a time in dichotomous choice tests. Females parasitized more, and laid more eggs in, the relatively smaller aphids among those available. This preference was independent of aphid instar: L1 > L2 > L3 > L4. Preference was not influenced by female size or age. Normal and anaesthetized aphids were accepted equally. The total time needed by a female to capture, position, and parasitize an aphid varied among host instars, with fourth instars requiring nearly twice as much time as first, second, and third instars. The probability of an attacked aphid escaping or avoiding parasitism increased with aphid instar, from ~10% in first and second instars to ~50% in fourth instars. Although fourth-instar pea aphids contain more resources for offspring development than smaller counterparts, it may not be profitable for a female to invest opportunity time in attacks on large aphids.

The cixiid planthopper Hyalesthes obsoletus Signoret is an efficient vector of the stolbur phytoplasma, the cause of various crop diseases. In the field, this monovoltine species feeds on a wide variety of woody and herbaceous plants. It overwinters as larvae on the roots of its host plants. During this study, we collected adults mainly from lavender (Lavendula angustifolia Miller), bindweed (Convolvulus arvensis L. and C. sepium L.), hoary cress (Cardaria draba L.), and occasionally from plantain (Plantago cynops L.), toadflax (Linaria striata L.), bedstraw (Galium verum L.), and mountain savory (Satureia montana L.). Fertility of field collected females from sites at two different elevations differed significantly. Fertility at 300 m (50.6 eggs per female; N = 28) was more than twice that at 900 m (22.8 eggs per female; N = 19). Only one specimen of the species was found to be parasitized by an undetermined species of Dryinidae (Hymenoptera). H. obsoletus was reared in controlled conditions on lavender. Unlike in the field, larvae developed in the laboratory at the base of the host plant and on basal shoots. Egg incubation averaged 7 ± 1.2 weeks (N = 10). Total development time from egg to adult averaged 27 ± 4 weeks (N = 5) on lavender. A morphological description of the five instars is provided. The study was supplemented by scanning electron microscopy. Particular attention was paid to the structure of the wax-plates and the absence of compound eyes in the early larval stages.

Although there are few studies of the sexual life of coccinellids these phenomena have attracted the interest of isolated groups of coccinellidologists. Probably the most important finding is that at least some coccinellid species (Adalia bipunctata and Harmonia axyridis) do not mate at random with the females prefering certain males. This phenomenon was first observed in Adalia bipunctata by Lusis and then studied in detail by Majerus, O'Donald, de Jong and others. In Japan, Harmonia axyridis was similarly studied by Osawa and Ueno. While the former author found that in this species (as in A. bipunctata) the colour of the elytra is most important in mate choice by females, the latter stresses that size and activity are important. Sperm competition is another interesting phenomenon, most often the sperm of the last male fertilizes the eggs (Ueno, Katakura). Obata and Hidaka have contributed in an important way to elucidating the function of the spermatophore in mating. The studies by Hodek and Ceryngier recorded the maturation and regression of testicular follicles and the relation of mating activity to diapause in four coccinellid species. In contrast to females, where induction of diapause prevents maturation of ovaries, in diapausing males the tissue of testicular follicles remains active until the temperatures decrease in late autumn. Dissection of spermathecae revealed principal difference in autumn mating activity between Coccinella septempunctata, in which 40-60% of the beetles mated before hibernation and Ceratomegilla (syn. Semiadalia) undecimnotata, which does not mate in autumn.

The olfactory orientation of the aphidophagous ladybird Coccinella septempunctata L. was assessed in a Y-tube olfactometer and a choice arena. The response of the predator to 22 plants, aphid prey and conspecifics was tested. The ladybird was attracted to the odour of chopped Berberis vulgaris L. leaves, and of Tripleurospermum inodoratum (L.) Sch.-Bip. flowerheads, and males were attracted to females. Methanol extracts of B. vulgaris leaves were also attractive.

A range of nuclear magnetic resonance (NMR) techniques, ¹H liquid spectroscopy and T₁ and T₂ relaxation measurements, and microimaging, have been used to observe changes taking place within the bodies of live samples of Coccinella septempunctata, under a variety of conditions. NMR measurements showed that various organs could be seen and identified. It also showed that by changing the diet of the ladybird from aphids [Acyrthosiphon pisum (Harris)] to a standard artificial diet, major changes took place in the insects' tissues. By using a combination of all three techniques it was concluded that on changing the diet of C. septempunctata a mass of nutrient was built up within the insect's abdomen possibly in the same manner as happens before diapause. Changes in the response to NMR measurements were also seen after infection of C. septempunctata by the parasitoid wasp (Dinocampus coccinellae). Most significantly an image of the parasitoid larva could be seen within the body mass of the ladybird. It was concluded that NMR could become a major tool in the non-destructive study of insects not just as a means of studying anatomy but also to observe changes in the nature of body tissue.

Laboratory and field experiments were performed to test the ability of steinernematid nematodes to control larvae of the black vine weevil, Otiorrhynchus sulcatus, which infests rhododendrons and azaleas in Czech Republic. Of five strains tested in the laboratory the best results were achieved with the Steinernema feltiae strain Hyl isolated in Czech Republic, which provided a 100% elimination of the weevil larvae on azaleas in laboratory tests. Field tests were made in a nursery of ornamentals at Plzen-Krimice where an outbreak of the pest had lasted a long time. Preventative treatment, three releases of the nematode, was performed in three beds in successive seasons 1989-90, resulting in a 72% to 88% protection of plants in the beds, including a 52% to 77% protection in adjacent plots due to migration of nematodes from the treated areas. Only 30% of plants survived on more distant control plots. This system of control of O. sulcatus with steinernematids is a promising method of biological protection in ornamental nurseries and gardens.

The effects of imidacloprid on 1-day-old third instars of Harmonia axyridis were assessed by topical treatment and contact with treated glass plates in laboratory bioassays. When 5 µl of imidacloprid solutions were applied topically, the LD₅₀ was 0.085 g/l per insect after 24 h. Contact with imidacloprid-treated plates had little effect on the number of third instars that became adults. Average duration of larval development was not significantly affected by duration of contact and imidacloprid concentrations. There were no significant differences in maximal larval weight, weight gain and day at maximum larval weight. There were significant differences in average weight gain per day (from third instar to prepupa) after treatments with different imidacloprid concentrations. A temporary knockdown effect was observed with higher concentrations and longer durations of contact with treated plates. Compared with untreated third instars, contact with imidacloprid-treated plates caused an increase in time spent (in seconds) on the glass plates resulting from an increase in number of stops (per second) and angular speed (degrees per second) and a decrease in linear speed, excluding stops (mm/second). The changes in locomotory behavior (i.e., duration of stay on untreated plate, number of stops and angular speed) lasted up to 24 h after contact with imidacloprid-treated plates.

Johns Hopkins University Press, Baltimore and London, 1999, xvi + 261 pp.

The effects of combinations of photoperiod and temperature on diapause induction in six species of lacewings (Chrysopidae) from the forest-steppe zone (Russia, 50°N) were examined. Diapause induction in the short day was temperature-independent ill all species, with exception of Chrysopa phyllochroma. In this species the incidence of diapause decreased within the range from 25 to 33°C. The long day prevented diapause only within particular temperature limits, which were species specific. In species with typical long-day photoperiodic response (C. perla, C. septempunctata and Chrysoperla carnea) daily temperature fluctuations were less favourable to diapause induction than constant mean temperature. In C. phyllochroma and C. abbreviata the similar high incidence of diapausing prepupae was induced both by daily natural thermoperiods and constant mean temperature. In experiments carried out under 12-h thermophase: 12-h cryophase conditions it was revealed that photo-thermoperiodic responses of C. phyllochroma were significantly dependent on cryophase temperature, whereas diapause of C. perla was determined mainly by photoperiod. The diversity of seasonal cycles in Chrysopa species and the role of photoperiod and thermoperiod in the development and diapause control in nature are discussed.

Feeding experiments with female Pisaura mirabilis were carried out in the laboratory. Several species of Diptera, ranging in their size from small fruitflies to large blowflies, were offered. Each spider received a single fly, and then the absolute as well as the relative amount of prey consumption was recorded. Absolute consumption was measured as the amount of a fly consumed by the spiders. Relative consumption, i.e. the utilization rate, was calculated as amount of fly consumed by the spiders divided by the initial mass of the fly. Absolute consumption was positively correlated with the mass of the fly, i.e. the larger the fly the more the spider consumed. No satiation effects were observed. P. mirabilis ingested on average 75% of the prey item, but was able to extract up to 95%. The relative consumption showed no relationship with mass of fly, i.e. the prey size did not influence the utilization rate. Also, neither body size nor age of spiders affected absolute or relative consumption. Furthermore, the fly remnants discarded by the spiders, and uneaten control flies were analysed for their C and N contents. Fly remnants showed a significantly higher C and N content, whereas their C/N ratio was lower. The results show that in the single-prey situation P. mirabilis increases absolute biomass intake with increasing amount of prey available. However, low values and a high variance of the utilization rate indicated that it is not only prey quantity which may be essential for the spiders. We therefore conclude that in future studies the nutritional qualities of prey should be considered more closely.