Oviposition behaviour of Delia radicum is not only influenced by host plant duality but also by the duality of the substrate in which the plant grows. Direct behavioural observations showed that the females partition their visits to a host plant (cauliflower) into ovipositional bouts separated by exploration of the host plant surface. Ovipositional bouts were further partitioned into acts of egg deposition separated by exploration of the substrate. While the mean number of ovipositional bouts per visit (2.6), and eggs laid per egg deposition event (1.4) were stable, the mean number of egg deposition events per ovipositional bout significantly varied (from 2.1 to 7.3) with the duality of the substrate and the physiological state of the female (egg load). Ovipositing females adjusted the final number of eggs laid around the plant during the behavioural stage of substrate exploration. Additional experiments using plant surrogates treated with methanolic extract of Brassica leaves mounted in different substrates showed that: (a) the presence of living Brassica, Hordeum or Allium roots in a substrate enhances the number of eggs laid into this substrate, but females do not discriminate between the different plants; (b) females avoid both wet and dry substrates and prefer the substrates with a dry surface and moist particles directly accessible at a depth of about 5 mm; (c) substrates rich in organic matter are preferred to sand; (d) olfactory perception of volatile chemicals from the substrate must at least partial

Some previous work on arthropod development is insufficiently detailed or incompletely reported. Much of the published information in this area is of limited use for the general analysis of life cycles. These difficulties arise primarily because many experiments do not control fully for the strain of the material (and even its specific identity) nor for rearing conditions, do not adequately take account of the complexity of life cycles and their stages, or are restricted to only part of the life cycle. For example, 285such factors as variable numbers of instars, sexual differences, abbreviated or hidden stages and dormancies may mean that the "average durations" reported apply to an unknown mixture of developmental types. Nor are experiments always designed or results reported and analysed in a logical and transparent manner. Undefined terms may obscure what actual developmental intervals were measured. Highly derived developmental or demographic measures may obscure core data. Statistical information may be inadequate. Such pitfalls are reviewed here, suggesting ways to ensure that results on the duration of development are both valid for specific studies and more widely useful. General experimental difficulties, recommended background information that should be provided, recommended life-cycle intervals and their terminology, and recommended ways to report numerical and statistical information are briefly summarized in tabular form.

The abundance and distribution of coccinellids in non-crop habitats was studied using removal sampling and visual observation. Coccinellids were most frequently found on grassland habitats. Coccinellid abundance appeared to be most strongly correlated with the percentage ground cover of thistle, grasses and nettles. The most commonly collected coccinellids were Coccinella septempunctata and Adalia bipunctata comprising 60% and 35% of the catches respectively. Most coccinellids were found on Rubus spp. with nettles (Urtica dioica) and grasses being the next most favoured plant species. Adalia bipunctata was the most commonly found coccinellid species on nettles and birch (Betula spp.) whereas C. septempunctata was the most commonly found species on grasses, Rubus spp. and oak (Quercus spp.). These results are discussed in light of current thinking on the importance of \"island\" habitats as pali of an integrated pest management programme.

CABI Publishing, Wallingford, U.K., 2001. ix + 1032 pp.

The effects of temperatures of 15, 20, 25 and 30°C on the duration of premating and preoviposition periods of Harmonia axyridis reared on the aphid Aphis fabae, were compared in the laboratory. The course of oviposition was monitored at 25°C in females reared on Aphis fabae and the peak of egg laying was recorded at the age of 15 to 45 days. The size of egg groups (batch size), as well as daily and total fecundity was recorded. Half of the total number of eggs was laid in batches of 10-30 eggs. The mean daily and total fecundity reached a maximum of 42 and 1,641.6 eggs, respectively. Adult females oviposited for almost their entire life.

Cambridge University Press, Cambridge, UK, 2001, 315 pp.

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.

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.

Elsevier, Amsterdam, 2001, 234 pp.

Texas A&M University Press, 2000, 308 pp.,

A radiochemical assay (RCA) has been used for the measurement of juvenile hormone (JH) synthesis in vitro by corpora allata (CA) from the Eri silkworm, Samia cynthia ricini. Using CA from newly emerged female adults for the bioassay, the most suitable incubation conditions were determined. A high rate of JH synthesis was found in medium TC199 at pH 6.5, 30°C and 4 mM Ca²⁺. The time course of JH synthesis showed a steady decrease during the first 6 hours of incubation.
Under optimal incubation conditions, CA from the 4th and 5th larval instars, pupae and adults were used for measuring JH synthesis in vitro. The highest rates of JH synthesis were found on the 1st day of both larval stages, and then JH synthesis decreased steadily during the following two days of each instar. From the 4th day of the 5th larval instar to the 2nd day after pupation, CA could still synthesize small amounts of JH. However, from the 3rd day of the pupal stage to 12 hours before adult emergence, no JH release was observed. About 6 hours before emergence, CA of both female and male pharate adults regained the ability to synthesize JH. JH synthesis increased to a maximum shortly after emergence and then decreased again during the following two days. During this period, JH synthesis in vitro by CA from females was always higher than that of males. This is the first report on JH synthesis in vitro by CA from both female and male pharate adults and adults of a lepidopteran species, where the adults do not feed, are relatively short-lived, mate only once, and ovarian maturation and vitellogenesis are completed before emergence.

Four case studies are used to examine the relationships of water, ice nucleators and desiccation in the cold survival of invertebrates and the viability of frozen plant material: the freeze intolerant Antarctic springtail Cryptopygus antarcticus (Willem) (Collembola, Isotomidae), the freeze tolerant larvae of the fly Heleomyza borealis Boh. (Diptera: Heleomyzidae), the freeze intolerant Arctic springtail Onychiurus arcticus (Tullberg) (Collembola, Onychiuridae) and meristems of the currant Ribes ciliatum Humb. & Bonpl.(Grossulariaceae) from Mexico. Prevention of ice nucleation, lowering the water content by removal of osmotically active (freezable) water are critical features of the different cold survival strategies of the three species of invertebrates. In C. antarcticus, which desiccates rapidly by losing water via the cuticle to the atmosphere, the number of ice nucleators (and their activity) increases with lowered ambient temperature. During prolonged cold exposure ice nucleators are masked, but re-activated rapidly by water uptake in this species. Larval H. borealis do not readily desiccate and conserve their body water, 20-25% of it being bound (osmotically inactive). Experiments showed that a high proportion (c. 80%) of slowly cooled larvae survived exposure to -60°C. By comparison O. arcticus is able to sustain up to 40% loss of its body water and desiccation lowers its supercooling point to promote over winter survival. Dehydration leading to partial vitrification of currant (R. ciliatum) meristems improves their viability after cryopreservation in liquid nitrogen. From this comparison of four biological systems, it is concluded that the role of water and its activity at sub-zero temperatures are fundamental to the survival of freezing conditions by all the species studied. Although similar features exist in the four systems, no common basic mechanism was found.

Diapause intensity (DI) is a physiological trait represented by the duration of diapause under given conditions of environment. In many species, it is highly variable, probably being controlled by multiple genes and tends to form a cline in response to the latitudinal gradient of selection pressure. DI clines could be established artificially by crossing between lines of a cricket selected for different levels of DI, indicating the importance of genetic factors in the adaptive variation of DI. However, DI may be modified in response to seasonal cues both before and after the onset of diapause. Polymorphism in the intensity of prolonged diapause may split adults of a single population to emerge in different years. A unimodal distribution of DI may also result in polymodal termination of diapause, if DI variation is so large that chilling in one winter is not enough to terminate diapause for all members of a population. Bimodal termination of diapause after overwintering suggests heterogeneity in the final phase of diapause that requires high temperatures in spring. Polymodal termination of diapause subserves a bet-hedging strategy. Variability in DI thus provides insects with an important means of adaptation to their environments changing in space and time.

Eggs of thirteen synanthrophic psocids of the families Trogiidae, Psyllipsocidae, Liposcelididae and Lachesillidae, commonly occurring in stored products in Europe, are described. Descriptions are based on overall appearance during embryogenesis, size and surface sculpturing. Morphological details are illustrated using scanning electron micrographs. A key for distinguishing eggs at both the generic and species level is provided. The presence or absence of a micropyle and aeropyle is discussed.

A comparative study of the direct influence of single, non-repetitive changes of light and/or temperature on the daily pattern of adult eclosion was conducted in laboratory conditions with the egg parasitoid, Trichogramma embryophagum (Hartig). In all experiments, the entire development occurred under the same regimen (12L : 12D, 20°C). However, just in the day when records of eclosion were made, the time of light-on was changed (from the total absence of a dark period to the 12-h-long scotophase). In addition, in different treatments of each experiment a thermophase (30°C during 2 or 4 hours) was applied in various positions relative to light-on. Results showed that light-on or a temperature step-up could induce eclosion in a certain percentage of individuals practically at any time of the 24-h-long cycle (masking effects). The fraction of adults emerging during 2 h after the beginning of the action of an exogenous factor depended not only on the preceding scotophase duration, but also on the stimulus itself (light, temperature or both). The temperature stimulus was found to modify the responsiveness to light considerably, depending on the order of application of the stimuli. The simultaneous action of light-on and a temperature step-up exerted a more considerable influence than could be expected based on their separate impacts. On the contrary, a high temperature pulse preceding the onset of the photophase inhibited the response of individuals to light-on, evidently acting by phase delay of a circadian rhythm of light responsiveness. These effects were more pronounced in the first half of the 12-h-long scotophase. The data suggest a complex interaction between the exogenous factors in their influence on the daily pattern of adult eclosion.

Although some parts of diapause development have been clarified up by endocrinologists, knowledge of the underlying processes remains insufficient. The survey of ecophysiological aspects of diapause development has thus to be limited to inputs and outputs from the blackbox. The terms diapause development, diapause intensity, post-diapause quiescence, horotelic processes of diapause, and tachytelic processes of diapause (reactivation) are defined. Andrewartha's term diapause development has been accepted because it shows diapause as a dynamic event.
In about the last 20 years, some views on diapause development have been updated, while others have fossilised. The assumption that chilling is a general prerequisite for completion of diapause development in all insects still survives in part of the scientific community, in spite of much contradictory evidence and often due to inadequate interpretation of experiments (examples given in figures and tables). On the contrary, it has been generally recognised that in temperate climates overwintering diapause is usually already completed in early/mid winter and the dormancy is then temperature quiescence. The conception of multiple pathways of diapause completion postulates that diapause can be completed either by the normal (slow) progress of diapause development (horotelic processes), or by a faster activation (tachytelic processes). There are important differences between the mechanisms regulating activation and the horotelic processes. Thus, e.g., the photoperiodic response is lost during horotelic completion, while after photoperiodic activation it persists. In addition to photoperiodic activation other kinds of activation are being studied, particularly activation by high temperature.
Some conclusions can be made from modern studies on diapause development. In every individual, several (at least two) possible pathways exist that are evidently interlinked and mutually complementary. Thus the time of diapause passed at any condition has to be considered, as well as the exposure to very low temperatures. In temperature studies the experimental range ought to be adequately wide and less affected by a priori assumptions. Stimulation by temperature increase or improvement in food or other conditions has to be considered.
The success of diapause completion should be measured by at least four parameters: (1) incidence (%) of developmental steps; (2) duration of delay; (3) synchronization; (4) vigour of post-diapause insects (shown by long-term survival or fecundity). The last two parameters have usually been neglected.

Pests, Predators, Opportunists. xv + 507 pp.

A series of experiments were conducted to compare the susceptibility of P. regina larvae reared in isolation or in groups to the effects of diet-borne metabolic inhibitors: chlorogenic acid (CGA) and mimosine. Larvae were presented with diets containing 0.4 mM CGA or 0.4 mM CGA in combination with 22 mM lysine or methionine or with diets containing 1.5, 15 or 30 mM concentrations of mimosine. Methionine and CGA caused significantly reduced pupal weights when compared with larvae presented with lysine and CGA. All concentrations of mimosine resulted in 100% mortality with larvae unable to successfully complete pupation even at the lowest concentration. In general, larvae reared in groups were less susceptible to the toxic effects resulting from diet-borne metabolic inhibitors. The results are discussed in relation to the chemical factors that result from the feeding activity of saprophagous dipterans.

Naturally occurring veinless specimen of the swallowtail Papilio xuthus show an extremely aberrant colour pattern. In spite of the fact that we have no breeding data, these veinless specimen are provisionally called veins-reduced mutant. In these mutants seven longitudinal veins of the fore wing and five of the hind wing are absent. The absence of wing veins is associated with a loss of the broad black venous stripes that normally are present along the proximal portion of the veins. In addition, missing veins cause a loss of the dislocation of black bands in adjacent wing cells, so that what are discrete black segments in normal wings become continuous bands in the veinless wing. Computer simulations show that the morphology of the striped patterns on both the veinless and veined wing can be explained if the wing margin acts as an inductive source of pattern formation and the veins act simply as boundaries to the propagation of the signal from the wing margin. The vein-dependent patterns by contrast, require that the veins act as inductive sources, at least along their proximal portion. This dual role of wing veins is consistent with prior observations on the biology of colour pattern formation. The unique veinless colour pattern strongly supports the hypothesis that the wing margin is the dominant organiser of colour pattern in this species, and possibly in other Papilionidae.

Chill tolerance (time of survival at -5°C) increased in non-diapausing (reproducing) adults of Pyrrhocoris apterus after a gradual, 4-week-long decrease in ambient temperature from 25° to 0°C. The level of chill tolerance attained after cold-acclimation was considerably lower than that in similarly cold-acclimated diapausing adults. Some physiological changes accompanied the cold-acclimation, irrespective of developmental state (diapause vs. reproduction). They were: A decreased oxygen consumption, loss of body water, an increased haemolymph osmolality, an increased proportion of phosphatidylethanolamines vs. a decreased proportion of phosphatidylcholines in membrane phospholipids, and an increased proportion of linoleic vs. a decreased proportion of oleic acid in phosphatidylethanolamines. Such changes could contribute to the limited potential for cold-acclimation found in non-diapausing insects. Other physiological changes appeared to require the induction of diapause prior to cold-acclimation. They were: Down regulation of ice nucleators resulting in a lowering of the individual supercooling point, synthesis and accumulation of specific "winter" polyols, an increased proportion of palmitic acid in membrane phospholipids; and regulation of the concentrations of Na⁺ and K⁺ in the haemolymph. The potential contributions of these changes to the cold hardiness of P. apterus are discussed.

Larval Manduca prothoracic gland cells in vitro responded to prothoracicotropic hormone (PTTH) from neurosecretory cells of the brain with an increase of intracellular free calcium. This effect is reversible and dose-dependent. Preincubation of the glands with TMB-8 and dantrolene, which inhibit the release of calcium from intracellular stores, did not decrease the PTTH-stimulated increase in calcium, indicating that intracellular calcium stores are not involved in the control of ecdysteroidogenesis. Pharmacological studies of the PTTH effect with calcium channel blockers revealed that the increase in calcium was totally blocked by cadmium, partially inhibited by nickel and lanthanum and by amiloride, an antagonist of T-type calcium channels. All other inhibitors tested were ineffective, suggesting that the increase in cytosolic calcium is induced by opening of calcium channels, presumably of the T-type, in response to PTTH. The action of PTTH on these channels may be mediated by a G-protein as shown by the effect of mastoparan, a G-protein activator, which increased the concentration of cytosolic calcium comparable to that evoked by PTTH.

A model optimizing the number of eggs laid in an aphid colony by an adult ladybird reveals that there exists an optimum number, which maximizes the resulting offspring biomass. This remains true even if the model is expanded to include more than one adult ladybird and several aphid colonies. Adult ladybirds should not continue to aggregate in areas of aphid abundance (Kareiva & Odell, 1987), but should leave an aphid aggregate, even though the aphids are still increasing in abundance, as soon as a certain number of eggs are laid and/or larvae are present. If the ladybirds lay the optimal number of eggs, then their offspring have only a slight effect on the peak number of aphids.

There is much current discussion about the factors that control the distribution and abundance of animal species, particularly at the edges of their range. The significance of temperature for survival and development is compared in two closely related psyllid species (Craspedolepta nebulosa and C. subpunctata) living on the same host plant (Chamerion angustifolium) (Onagraceae) but displaying different distributions along latitudinal and altitudinal gradients. The following measurements were made at critical periods during the life cycle (a) winter supercooling points (SCPs), (b) tolerance of short (1 min) and long term (1-25) days exposure to sub-zero temperatures above the SCP, (c) tolerance of short term exposure to high spring/summer temperatures and (d) comparative field development rates among species and sites during the early critical part of the growing season. Successful completion of the life cycle is related to heat availability during the growing season. This appears to limit the distribution of the Craspedolepta species, rather than their survival response to thermal extremes. No significant differences were found between the two species in the supercooling point or in their long and short term survival responses at low or high temperatures.

Eumerus purpurariae, described from the Canary Islands (Atlantic), has been reared from the stems (platyclades) of the cactus Opuntia maxima (the first known host) on Nueva Tabarca, a Mediterranean island close to the Iberian coast. The egg, larva and puparium of E. purpurariae, as well as its life cycle on the above host-plant are described. The feeding behaviour of the larva in relation to the cephalopharyngeal skeleton morphology is analysed. Based on the present data, comparative table containing the main morphological characteristics of the injurious Eumerus species of the Palaearctic region is presented.

We determined if mature ladybirds use colour to initially find suitable host plants. We also determined whether ladybird beetles are capable of associating characteristics such as colour with the presence of prey. Here, we show that the multicoloured Asian ladybird beetle, Harmonia axyridis, has a differential response to yellow compared to green colours. Naive ladybirds, of both sexes, make significantly more visits and spend more time on yellow vs. green coloured pillars. After pairing yellow and green colours with the presence or absence of aphid prey, ladybirds alter their foraging behaviour. Beetles conditioned to having food on both pillar colours exhibited the same responses as naive beetles, while beetles conditioned to only yellow or green pillars did not exhibit a preference for visiting or spending time on different colours. However, there was a trend towards females spending more time on pillar colours on which they received reinforcement, and males spending more time foraging on colours opposite to that which they were reinforced. Thus, H. axyridis is capable of responding to cues such as colour, and its foraging behaviour can be altered as a result of prior experience.

Kluwer Academic Publisher, Dordrecht, The Netherlands, 1998, 537 pp + 12 pp, 151 ill., 39 tab.

Only in the southern part of the Iberian Peninsula the large white butterfly Pieris brassicae was recorded to pass the summer in pupal aestivation, induced by long-day photoperiods. It is not clear why this photoperiodic response is regionally restricted. We investigated whether the change of life history in P. brassicae may affect the infestation by parasites. This was done by testing the coincidence of photoperiodic responses in both the host P. brassicae and in its main parasitoid Cotesia glomerata. While the response under short-day conditions was very similar in both species, no summer dormancy of any type was found in the parasitoid at photophases >= 15h and temperatures of 15°-25°C in contrast to 100% aestivation in the host. We suggest that aestivation is a response which allows the host to desynchronise its life cycle from that of its parasitoid. This is effective because parasitoid wasps cannot pass the temporary absence of suitable host stages by a similar developmental rest. C. glomerata is then forced to switch to less adequate host species which diminishes its reproductive success.

A study of the diurnal rhythms in the postfeeding dispersal of the larvae of two coexisting carrion blowfly species, Calliphora vomitoria and Lucilia caesar, from corpses was conducted in the field. Larvae of both species dispersed exclusively at night. The emigration of white coloured larvae is risky. By dispersing at night the larvae minimise interactions with diurnal and crepuscular predators.

Pulsations of dorsal vessel were monitored by the noninvasive techniques of contact thermography on the dorsal cuticle and by strain gauge detection of abdominal elongation movements. Diapausing pupae exhibited periods of forward-oriented, or anterograde pulsations (average duration of each pulsation 5-8 min, frequency of individual systolic strokes 10-15 per min) alternating with somewhat slower, backward-oriented or retrograde cardiac pulsations (average duration of each pulsation 6-10 min, frequency of systolic strokes 7-12 per min). The highest rate of hemolymph flow was associated with the anterograde pulsations. We studied cardiac functions in diapausing pupae because of the almost complete absence of extracardiac hemocoelic pulsations, which are much stronger and could interfere with the recordings of heartbeat in all other developing stages. The movement of abdomen associated with the heartbeat was extremely small, only some 0.14 to 0.9 µm (i.e. from one 428000^th to one 66000^th of the body length) and thus was not practical for routine recordings of heartbeat.
Simultaneous recordings from multiple thermographic sensors revealed the complete absence of retrograde cardiac pulsations in the head region. There are some indications that the retrograde pulsations were also lacking in the thoracic region of the aorta. The retrograde peristalsis appeared to be used for circulatory functions in the abdomen alone. By contrast, the anterograde cardiac pulsations underwent a profound amplification in the anterior part of the abdomen, entering thoracic aorta with considerable strength before reaching the final destination in the head region. The amplification of anterograde peristalsis was manifested by enhanced hemolymph flow towards the head associated with a two-fold increase in frequency of anterograde heartbeat before reaching the head region. The sensors distributed along the dorsal vessel revealed that the rate of the backward-oriented, retrograde cardiac flow of the hemolymph was also location specific. The rate of flow was lowest at the front of the abdomen, medium in the middle and highest close to the end of the abdomen. The finding of lowest hemolymph circulation at the beginning of the cardiac peristaltic waves suggested that the physiological "raison d' être" for heartbeat reversal was a need for differential enhancement of hemolymph flow towards the extremities of the immobile pupal body. The switchovers from the retrograde to anterograde cardiac pulsations were usually immediate, while the reciprocal, antero- to retro-switchovers were mostly associated with a brief cardiac arrest. Increasing temperature gradients (in 5°C steps) progressively diminished duration of both reciprocal heartbeat periods. The amplitudes of the cardiac systolic strokes also decreased with increasing temperature while the frequencies were substantially elevated.