bluuebunny/crossref_metadata_2025 huggingface dataset:
Vasoactive neuroendocrine responses associated with tolerance to lower body negative pressure in humans
Authors: Convertino  , Sather
Published: March 2003

The purpose of this investigation was to test the hypothesis that peripheral vasoconstriction and orthostatic tolerance are associated with increased circulating plasma concentrations of noradrenaline, vasopressin and renin–angiotensin. Sixteen men were categorized as having high (HT, n=9) or low (LT, n=7) tolerance to lower body negative pressure (LBNP) based on whether the endpoint of their pre‐syncopal‐limited LBNP (peak LBNP) exposure exceeded −60 mmHg. The two groups were matched for age, height, weight, leg volume, blood volume and maximal oxygen uptake, as well as baseline blood volume and plasma concentrations of vasoactive hormones. Peak LBNP induced similar reductions in mean arterial pressure in both groups. The reduction in legarterial pulse volume (measured by impedance rheography), an index of peripheral vascular constriction, from baseline to peak LBNP was greater (P<0·05) in the HT group (−0·041 ± 0·005 ml 100 ml−1) compared to the reduction in the LT group (−0·025 ± 0·003 ml 100 ml−1). Greater peak LBNP in the HT group was associated with higher (P<0·05) average elevations in plasma concentrations of vasopressin (pVP, Δ=+7·2 ± 2·0 pg ml−1) and plasma renin–angiotensin (PRA, Δ=+2·9 ± 1·3 ng Ang II ml−1 h−1) compared to average elevations of pVP (+2·2 ± 1·0 pg ml−1) and PRA (+0·1 ± 0·1 ng Ang II ml−1 h−1) in the LT group. Plasma noradrenaline concentrations were increased (P<0·05) from baseline to peak LBNP in both HT and LT groups, with no statistically distinguishable difference between groups. These data suggest that the renin–angiotensin and vasopressin systems may contribute to sustaining arterial pressure and orthostatic tolerance by their vasoconstrictive actions.
Digital X‐ray radiogrammetry: a new appendicular bone densitometric method with high precision
Authors: Jørgensen J. T. , Andersen P. B. , Rosholm A. , Bjarnason N. Hannover
Published: March 2003

The precision of any given method for measurement of bone mineral density (BMD) is important in relation to the interpretation of repeated measurements over time, e.g. to monitor the course of suspected osteoporosis or follow the effect of therapy. In the present study a new bone densitometer using the digital X‐ray radiogrammetry (DXR) method (Pronosco X‐posure System™) is investigated with respect to its short‐term precision. The study was carried out on two groups of females, one consisting of 20 women between the ages of 30 and 40, and the other of 20 post‐menopausal women above the age of 64. The mean age of the premenopausal women was 35·2 years and the mean DXR BMD was 0·578 g cm−2. The mean age of the post‐menopausal women was 68·2 years and the mean DXR BMD was 0·489 g cm−2. The short‐term precision of the two groups was evaluated using the coefficient of variation (CV%) and corresponding 90% confidence intervals. The coefficient of variation in the premenopausal group was 0·68% with a 90% confidence interval of 0·57%−0·83%. The coefficient of variation in the postmenopausal group was 0·61% with a 90% confidence interval of 0·52–0·75%. It can be concluded from the present study that the short‐term in vivo precision error of the DXR method is low in both pre‐ and post‐menopausal women. When the results of the study are compared to data reported in the literature, the performance of the DXR method seems to be at least equivalent with peripheral DXA.
The effects of length on fatigue and twitch potentiation in human skeletal muscle
Authors: Rassier Dilson E.
Published: March 2003

Fatigue is the decrease in active force that happens after repeated muscle stimulation, and post tetanic twitch potentiation (PTP) is the increase in twitch force observed after repeated muscle stimulation. This study investigated the effects of length on the interaction between fatigue and PTP, as these two forms of force regulation are length‐dependent and may coexist. A total number of 14 subjects were tested in 3 days, in which fatigue and PTP were induced in the knee extensor muscles in three different knee angles (30°, 60° and 90°; full extension=0°). PTP was evaluated in rested and fatigued muscles with twitch contractions elicited before and after 10 s maximal voluntary contraction (MVC), and fatigue was evaluated with nine 50 Hz electrically elicited contractions (5 s duration, 5 s interval between contractions). Fatigue was length‐dependent, with force values that were (mean ± SEM) 59 ± 5, 56 ± 3 and 38 ± 1% of maximal force at 90°, 60° and 30°, respectively. PTP was also length‐dependent. Rested muscles showed PTP of 39 ± 4, 47 ± 2 and 68 ± 5% at 90°, 60° and 30°, respectively. Fatigued muscles showed PTP of 44 ± 3, 55 ± 6 and 68 ± 5%, at 90°, 60° and 30°, respectively. This study shows that fatigue and PTP may represent independent mechanisms, as they regulate force in opposite directions and are both enhanced in short muscle lengths.
Achieving haemodynamic baseline values with Finapres in elderly subjects during supine rest
Authors: Mehagnoul‐Schipper D. Jannet , Van Kraaij Dave J. W. , Jansen René W. M. M.
Published: March 2003

Background: Clear guidelines for the resting time necessary to achieve stable blood pressure (BP) levels are scant in gerontology research. Therefore, we aimed to determine the minimum period required for obtaining haemodynamic baseline values in elderly subjects during supine rest. In addition, we evaluated the effect of cardiovascular morbidity, such as diastolic heart failure, and the effect of complex comorbidity of geriatric patients, on haemodynamic changes during supine rest. Methods: A total of 17 healthy subjects, 18 heart failure patients with normal systolic function and 24 geriatric patients, aged 70 years and more, participated. After an overnight fast, changes in systolic BP (SBP), diastolic BP (DBP), heart rate (HR), and stroke volume (SV) were determined by Finapres beat‐to‐beat non‐invasive BP monitoring during a 20‐min supine rest. The procedure was repeated in the healthy subjects and geriatric patients on a second day. Results: Complete BP stabilization was reached in each group within 5 min of supine rest, as SBP remained essentially unchanged and DBP did not change significantly anymore after the fourth minute. In the heart failure patients, HR decreased and SV increased until the twelfth minute of rest. The SBP, DBP, HR, and SV changes during supine rest showed good reproducibility. Conclusions: A span of 5 min of supine rest ensured achievement of reliable and reproducible baseline BP values by Finapres in elderly subjects. However, we recommend at least 12 min of rest to obtain full haemodynamic stability in elderly patients with diminished cardiac compliance and diastolic function.
Arterial pressure measurements using infrared photosensors: comparison with CW Doppler
Authors: Sadiq S. , Chithriki M.
Published: March 2003

We evaluated the accuracy of modern infrared photosensors (IPs) from a photoplethysmography (PPG) machine as flow detector in determining the systolic arterial pressures and ankle/brachial indices (ABIs) in comparison to the traditional continuous wave Doppler (Doppler) method. Pressures were obtained by placing an appropriate pneumatic cuff above the elbow and ankle. The Doppler probe was placed at brachial artery, posterior tibial artery and dorsalis pedis artery, and the IP was placed on the pad of the index finger and great toe. The two techniques were compared in 181 limbs in our non‐invasive vascular laboratory, 133 limbs with normal and 48 limbs with abnormal ABIs. The accuracy of absolute ankle pressure measurements was also compared by both methods. We found that IPs from PPG machine have a good correlation (linear regression r=0·96 for normal and r=0·95 for abnormal ankle pressures) with the Doppler method. There was no significant difference (P≤0·0001) in the ABIs calculated by two methods in either normal or abnormal subjects. The PPG method was easier, quicker and automated as compared with the cumbersome Doppler method. While PPG method does not differentiate between occlusive disease of posterior tibial and anterior tibial/dorsalis pedis arteries, it is better suited for non‐compliant patients and is superior to Doppler method in advanced occlusive arterial disease. We recommend that it be used on a routine basis.
Asthma, asthma medication and autonomic nervous system dysfunction
Authors: Jartti Tuomas
Published: March 2003

Asthma is associated with autonomic nervous imbalance: an increased bronchial sensitivity to cholinergic constrictors and possibly a decreased sensitivity to β2‐adrenergic dilators have been reported in this disease. Also, non‐adrenergic and non‐cholinergic (NANC) mediators have a small regulatory effect on airway function. These mediators contribute to the pathogenesis of asthma not only by regulating smooth muscle tone in the airways but also by affecting pulmonary blood flow, endothelial permeability and airway secretions. In many studies increased parasympathetic responsiveness has been associated with clinical asthma or the worsening of asthma in adults. However, most of the studies in children have not found association between autonomic dysfunction and asthma. Therefore, the autonomic dysfunction in asthma may be related to more advanced disease or long‐term asthma medication in adults. This article briefly reviews the relationships between airway inflammation, β2‐agonist, anticholinergic and glucocorticoid medication as well as autonomic nervous function in asthma.
The effect of glutamine on protein balance and amino acid flux across arm and leg tissues in healthy volunteers
Authors: Svanberg Elisabeth , Möller‐Loswick Ann‐Charlotte , Matthews Dwight E. , Körner Ulla , Lundholm Kent
Published: March 2003

Background. Glutamine is important in nitrogen transportation and the physiological control of acid–base regulation. In addition, it has been assumed that glutamine regulates protein balance in skeletal muscles based on findings in both experimental and clinical studies. However, little information on glutamine and its effect on protein dynamics in normal individuals is available. Therefore, the aim of this study was to evaluate whether glutamine improves protein balance and uptake of various indispensable amino acids across peripheral tissue in healthy individuals.

Material and methods. Standard primed constant infusions of L‐[ring‐2H5]phenylalanine and [ring 3,3‐2H2]tyrosine (2 μmol kg−1 h−1) were performed after overnight fast in five healthy male volunteers before and during infusions of a standard and a glutamine/tyrosine enriched amino acid solution. Flux measurements of amino acids (AA) including 3‐methylhistidine, glucose, lactate and free fatty acids (FFA) were performed across arm and leg tissues.

Results. Infusion of the standard AA solution (0·2 g N kg−1 day−1) increased the net uptake of individual amino acids, but provision of the enriched solution (0·4 g N kg−1 day−1) with increased amounts of glutamine and tyrosine seemed to compete unfavourably with the net uptake of other key amino acids as methionine and phenylalanine, which are indispensable in muscles for protein synthesis. Increased flux of amino acids across peripheral tissues did not influence on flux of glucose, free fatty acid and lactate.

Conclusions. Glutamine provision did neither stimulate protein synthesis nor attenuate breakdown of either globular or myofibrillar proteins in skeletal muscles of healthy volunteers.
Characterization of tubular adenoma of breast—diagnostic problem in fine needle aspirates (FNAs)
Authors: KUMAR N. , KAPILA K. , VERMA K.
Published: March 2003

kumar n., kapila k. and verma k. (1998) Cytopathology9, 301–307

Characterization of tubular adenoma of breast—diagnostic problem in fine needle aspirates (FNAs)

FNA smears from six histologically documented cases of tubular adenoma of breast were critically analysed and compared with 10 histologically confirmed cases of fibroadenoma (five pericanalicular and five intracanalicular). Initially a cytological diagnosis of tubular adenoma was rendered only in one case. On review, two cases could be characterized as tubular adenoma, while the findings were suggestive in two others. The features helpful in diagnosis of tubular adenoma were the presence of benign ductal cells as three‐dimensional cohesive balls and tubular structures in highly cellular smears. Stroma was conspicuously scanty or absent. Myoepithelial cells were present along with sheets of ductal cells as well as bipolar naked nuclei. Confusion with fibroadenoma occurred in two cases due to presence of a stag‐horn pattern of ductal cells.
A case‐control study of true‐positive versus false‐negative cervical smears in women with cervical intraepithelial neoplasia (CIN) III
Authors: O'SULLIVAN  , A'HERN  , CHAPMAN  , JENKINS  , SMITH  , Al‐NAFUSSI  , BRETT  , HERBERT  , McKEAN  , WADDELL
Published: March 2003

o'sullivan j. p., a'hern r. p., chapman p. a., jenkins l., smith r., al‐nafussi a.,brett m. t., herbert a., mckean m. e. and waddell c. a. (1998) Cyt_pathology9, 151–161

A case‐control study of true‐positive versus false‐negative cervical smears in women with cervical intraepithelial neoplasia (CIN) III

Cervical smears (n= 150) from five departments showing high‐grade dyskaryosis were examined by three cyt_logists. All the smears came from patients with biopsy‐proven CIN III. One hundred had been correctly reported (true positives) but 50 had originally been reported as negative and had been found to be positive only on review (false negatives). There were significant differences between the two sets in the characteristics of the dyskaryotic cell population. The false‐negative smears tended to have fewer than 200 dyskaryotic cells. The nuclei of the dyskaryotic cells tended to have fine rather than coarse nuclear chromatin. A smear with fewer than 50 dyskaryotic cells is 26 times more likely to be reported as negative than one with more than 200 dyskaryotic cells. The results suggest that there is a type of severely dyskaryotic smear that is inherently likely to be missed on routine screening.
Fine needle aspiration cytology of primary lymphoma of the thyroid: a report of 17 cases
Authors: Sangalli G. , Serio G. , Zampatti C. , Lomuscio G. , Colombo L.
Published: March 2003

Fine needle aspiration cytology of primary lymphoma of the thyroid: a report of 17 cases

Between 1980 and 1998, 4272 thyroid surgical specimens with a preoperative fine needle aspirate were sent to our Anatomical Pathology Department. Among these cases there were 17 primary thyroid lymphomas, which constituted 0.3% of all the thyroid lesions and 2.3% of the thyroid malignancies. Seven cases were diffuse large B‐cell (DLBC) lymphomas and 10 were MALT lymphomas. Of the DLBC lymphomas six were correctly diagnosed by fine needle aspiration cytology (FNAC) and one was diagnosed as positive for malignancy, and among MALT lymphomas four were diagnosed as lymphoma, four as suspicious for lymphoma, and three as Hashimoto’s thyroiditis (HT). Our data indicate that the diagnosis of primary thyroid lymphoma of high grade is easy, and immunocytochemistry (ICC) can confirm suspicious cases. The diagnosis of MALT lymphoma is more difficult; ICC can confirm suspicious cases, and false‐negative results seem to be caused by sampling error, because HT usually coexists with MALT lymphoma.
Effects of submergence by winter floods on diapausing caterpillars of a wetland butterfly, Lycaena dispar batavus
Authors: WEBB MARK R. , PULLIN ANDREW S.
Published: March 2003

1. The influence of seasonal flooding on wetland insects is understudied, and understanding of a potentially important influence on population dynamics is therefore incomplete. This is of particular consequence because many wetland insect species, including the large copper butterfly, Lycaena dispar batavus, are of conservation interest.

2. Previous studies on the submergence tolerance of diapausing L. d. batavus larvae have been inconclusive. This study investigated the effects of different periods of enforced submergence on overwintering survival, using both fresh and brackish water, and comparing effects on larvae in early and late diapause.

3. Larvae were submerged for up to 84 days, and survival was negatively correlated with submergence period, although periods of up to 28 days did not appear to reduce survival. Water type, i.e. fresh vs. brackish water, and larval stage, i.e. early vs. late diapause, had no significant influence on survival.

4. The relevance of these findings to the population biology and conservation of L. d. batavus is discussed. Further studies on the effects of submergence by seasonal flooding on wetland insect populations are encouraged.
Carcass maintenance and biparental brood care in burying beetles: are males redundant?
Authors: MÜLLER JOSEF K. , EGGERT ANNE‐KATRIN , SAKALUK SCOTT K.
Published: March 2003

1. Burying beetles inter small vertebrate carcasses that ultimately serve as a food source for their developing young. The male remains with the female on the carcass after the brood has been produced, purportedly to aid in the feeding and protection of larvae. However, numerous laboratory experiments have failed to demonstrate a beneficial effect of the male on the growth and survival of offspring.

2. A potential difficulty with laboratory studies is that beetles are typically held under relatively benign conditions, protected from the biotic and environmental challenges that they normally encounter. In nature, males may enhance offspring survival by aiding the female in ridding the carcass of mould, and by helping to preserve the carcass through the secretion of antibiotic substances in the beetles’ saliva. To examine more rigorously the potential benefits of male parental care, an experiment was conducted under field conditions in which the reproductive output of male–female pairs was compared to that of single females.

3. Beetles were induced to bury carcasses in soil inside rigid plastic tubes that had been inserted into the ground. The experiment was a paired design involving pairs of sisters reproducing in adjacent tubes; one sister reproduced alone, whereas the other reproduced with the assistance of a male. Soil cores were recovered about 1 month later, and examined for viable pupae.

4. There was no significant difference in the number of offspring produced by single females and those reproducing with the assistance of the male, nor was there any significant difference in total brood mass. These results suggest that any benefits of extended male residency on the carcass do not stem from male participation in carcass maintenance or provisioning young.
The ecological significance of differences in host detection behaviour in coexisting parasitoid species
Authors: VAN DIJKEN M. J. , VAN ALPHEN J. J. M.
Published: March 2003

1. Six species of drosophilid parasitoids of the genus Leptopilina (Hymenoptera: Eucoilidae) exist in Europe. Laboratory experiments reveal that the fundamental niches for most of these species overlap. Field collections indicate that overlap in their realised niches is much smaller.

2. Here data are presented for the little known species Leptopilina longipes. Field and laboratory observations indicate that its niche overlaps with both that of L. clavipes and L. heterotoma.

3. The host detection behaviour of L. longipes is examined and it is shown that L. longipes uses vibrotaxis to detect its hosts. This behaviour of L. longipes is compared with that of L. heterotoma and L. clavipes, which both use the ovipositor in host detection.

4. The ways in which differences in host searching behaviour can contribute to niche segregation and coexistence of these species are discussed.
Organization of predator assemblages in Neotropical tree holes: effects of abiotic factors and priority
Authors: Fincke OlA. M.
Published: March 2003

Abstract. 1. Water‐filled tree holes in a lowland forest in Panama harbour an assemblage of large predators consisting of the larvae of five common species of Odonata, the mosquito Toxorhynchites theobaldi, and tadpoles of Dendrobates auratus. Odonate females oviposit in both large and small tree holes. However, the three largest species emerge from larger tree holes, on average, than do the two smallest species. Can assembly rules explain this and other patterns of predator distribution?

2. Past experiments suggested that fast growth of the largest, but later‐colonizing odonates enabled them to out‐compete the smaller, slower‐growing Mecistogaster in large holes. In small holes, however, the first predator, regardless of species, should presumably kill any later arrivals. Priority effects in small holes were tested for their consistency across predator species. Two alternative explanations for differential odonate survivorship were also tested: abiotic conditions and the effect of non‐odonate predators.

3. Diurnal fluctuations in oxygen content, pH, and temperature within holes were as great as the variation found between large and small tree holes; abiotic conditions were poor predictors of species occupancy.

4. Exchanging the largest and smallest odonate species from their original holes did not affect survivorship, suggesting that the observed patterns of emergence are unlikely to result from differential tolerance to abiotic factors that were not measured.

5. When larger and smaller predators were paired in 400‐ml pots and provided with alternative prey, typically only the larger predator survived, regardless of species. The exception was T. theobaldi, which was often killed by odonates and tadpoles smaller than itself.

6. Between May and July, the occurrence of Mecistogaster in large tree holes declined, before larvae could have emerged. Neither abiotic effects nor differential predation by non‐odonates could explain this habitat‐specific decrease in survivorship. This temporal pattern is most consistent with the previous conclusion that in large holes, Mecistogaster suffer intraguild predation from later‐colonizing, but faster‐growing Megaloprepus and aeshnids. Whereas Mecistogaster can pre‐empt guild members from small tree holes, they cannot do so in large holes where predators with fast initial growth realize a competitive advantage.
Ant attendance in aphids: why different degrees of myrmecophily?
Authors: Stadler B. , Dixon A. F. G.
Published: March 2003

1. Aphids show a range of associations with ants from nonattendance to obligate myrmecophily.Aphis fabae cirsiiacanthoidesis facultatively associated with ants, whileSymydobius oblongusis an obligate myrmecophile. The selection pressures that have shaped these associations are unknown.

2. The consequences for these aphids of their different degrees of associations with ants were determined, in terms of costs and benefits to individuals and colonies in laboratory and field experiments. In the laboratory, individuals ofA. f. cirsiiacanthoidesperformed worse and those ofSymydobius oblongusperformed better when attended by the antLasius nigerthan when unattended. For example, when ant‐attended,A. f. cirsiiacanthoidesdeveloped more slowly, were smaller, and invested less in gonads, whereasS. oblongusdeveloped more quickly, were larger, and invested more in gonads. In addition, the ant regulated the population size ofS. oblongusto an average of 50–70 individuals per birch sapling by removing aphids, but did not regulate the population size ofA. f. cirsiiacanthoides.

3. Under field conditions, ant‐attended colonies of bothA. f. cirsiiacanthoides and S. oblongusachieved higher peak numbers and lasted longer, and ant‐attended colonies ofA. f. cirsiiacanthoidesproduced more alate dispersers than unattended colonies.

4. The implications of divergent selection pressures for the development of myrmecophily in aphids are discussed.
A fitness cost of eugregarine parasitism in a damselfly
Authors: Siva‐Jothy Michael T. , Plaistow Stewart J.
Published: March 2003

1. AdultCalopteryx splendens xanthostomaare infected by the trophozoites of a eugregarine parasite that attaches to the mid‐gut epithelium.

2. The results of this study show: (1) that eugregarines were the predominant parasite in the isolated study population, (2) they were not present in imagos that had just eclosed from larvae but were present in significantly higher numbers in older adults, (3) animals with a eugregarine burden during the prereproductive fat‐accumulation period of their adult development (the teneral stage) had significantly lower fat content, and (4) males infected artificially with eugregarine oocysts showed no correlation between eugregarine burdens and postmanipulation fat content.

3. Infection with eugregarine trophozoites during the teneral life‐history stage affects the ability of damselflies to accumulate fat, and consequently reduces their ability to fight for, and maintain, a territory when they become reproductively active.
Oviposition preferences of aphidophagous hoverflies
Authors: Sadeghi H. , Gilbert F.
Published: March 2003

1. Oviposition preferences of two predatory hoverflies, Episyrphus balteatus and Syrphus ribesii (Diptera, Syrphidae), were studied in the laboratory.

2. There was broad agreement between the two species: two of the top three preferred prey for oviposition in both hoverflies were pea and rose aphids; nettle aphids were consistently the least preferred.

3. Discrimination decreased with age.
Kin recognition by the predatory mite Iphiseius degenerans: discrimination among own, conspecific, and heterospecific eggs
Authors: Faraji Farid , Janssen Arne. , Van Rijn Paul C. J. , Sabelis Maurice W.
Published: March 2003

1. Kin recognition is important in many social insects, but has also been found in several nonsocial insects such as parasitoids, where it plays an important role in oviposition behaviour. In nonparasitic arthropods, however, the fitness of ovipositing females also depends on the oviposition behaviour of related and unrelated females, especially when eggs are oviposited in clusters by several females.

2. In this paper, kin recognition in a predatory mite, Iphiseius degenerans, is studied. Mothers are capable of determining offspring sex ratio, and cannibalism on juvenile stages is a common phenomenon. Therefore, kin recognition is expected to occur in this predator.

3. Oviposition behaviour of this species is particularly interesting because it alternates foraging bouts in flowers with deposition of a single egg at a time on a leaf, where predation risk is lower. The eggs are not scattered but are deposited in clusters. After feeding in a flower, females therefore have to locate clusters of eggs.

4. Experiments on two‐choice arenas showed that females prefer to oviposit close to conspecific eggs rather than close to heterospecific eggs. Females also showed a preference for ovipositing near closely related conspecific eggs rather than more distantly related eggs.

5. Females tended to displace eggs of heterospecifics more frequently than eggs of conspecifics.

6. These behavioural observations show that females can discriminate not only between conspecific and heterospecific eggs but also between eggs that vary in degree of relatedness. This enables females to oviposit in clusters containing related eggs and thus avoid cannibalism by non‐kin and/or produce adaptive sex ratios despite the fact that the adults commute between flowers and leaves.
The relationship between egg load and fecundity among Trichogramma parasitoids
Authors: Mills N. J. , Kuhlmann U.
Published: March 2003

1. The relationships between parasitoid egg load, size, and age (3–72 h) for Trichogramma minutum, T. platneri, and T. pretiosum, reared from two factitious hosts, Ephestia kuehniella and Sitotroga cerealella, were evaluated to test the hypothesis that 24‐h egg load can be used to estimate the fecundity of Trichogramma parasitoids.

2. Egg load increased in relation to female age over the first 3 days of adult life for all three Trichogramma species to a mean egg storage capacity of 46.7 eggs for T. minutum, 41.1 for T. pretiosum, and 35.7 for T. platneri. At 24 h of age, T. minutum had matured enough eggs to fill 67% of its storage capacity, in comparison with 74% for T. pretiosum and 91% for T. platneri. There was a positive relationship between egg load and parasitoid size for all ages of the three Trichogramma species reared from both hosts (with the exception of T. platneri at 3 h post emergence), accounting for 14–69% of the variance in egg load.

3. The potential fecundity, realised (3 day cumulative) fecundity, and oviposition rate (potential fecundity/longevity) of T. platneri were all related linearly to size‐dependent variation in 24‐h egg load, but only the realised fecundity of T. pretiosum, and none of the reproductive characteristics of T. minutum. It is suggested that 24‐h egg load may not be an accurate measure of egg storage capacity in parasitoids and should be used cautiously to represent fecundity.

4. The potential fecundity of seven Trichogramma species reared from E. kuehniella varied from 55 to 150, but neither potential fecundity nor oviposition rate was related significantly to egg load (represented by eggs laid during first 24 h). Selection to avoid egg depletion in the attack of gregarious hosts appears most likely to account for the variation in potential fecundity among Trichogramma species.
Benefits of communal breeding in burying beetles: a field experiment
Authors: Eggert Anne‐Katrin , Sakaluk Scott K.
Published: March 2003

1. The ultimate causes of communal breeding and joint parental care in various species ofNicrophorusburying beetles have not been resolved satisfactorily. One hypothesis suggests that females remain on the carcass for extended periods of time because joint defence affords them improved probabilities of retaining the carcass successfully in the face of intense competition from intra‐generic competitors.

2. In a field experiment designed to test this hypothesis inN. defodiens(Mannerheim), breeding associations of two females and a male were no more successful at retaining their carcass than were monogamous pairs, lending no support to the hypothesis.

3. Intra‐generic intruders that usurped already‐buried carcasses were typically much larger than the original residents.

4. The body size of original residents affected both the burial depth and the probability of a takeover. Larger beetles buried the carcass deeper and were more likely to retain possession of the carcass. Group composition also did not affect the depth at which carcasses were buried.

5. Severe and even fatal injuries incurred by some residents indicated the occurrence of violent and damaging fights between competitors over carcasses in the field.
The functions of plant feeding in the omnivorous predator Dicyphus hesperus: water places limits on predation
Authors: Gillespie D. R. , Mcgregor R. R.
Published: March 2003

1. Dicyphus hesperus Knight (Heteroptera: Miridae) nymphs were fed from egg hatch to the adult stage on Ephestia kuehniella eggs provided either alone or in combination with tomato leaves or with a supplementary water source.

2. Only 6% of individuals completed nymphal development on a diet of eggs alone. In contrast, a high proportion of nymphs completed development on a diet of eggs when either tomato leaves (97%) or a supplementary water source (88%) were provided.

3. The development times of nymphs given access to leaves were significantly shorter than those of nymphs given access only to supplementary water.

4. Adult female D. hesperus that were given access to tomato leaves prior to feeding trials consumed significantly more eggs in a 4‐h period than females that were dehydrated before trials. Dehydrated females that were allowed access to water for 3 h before trials consumed an intermediate number of eggs.

5. Plant feeding or access to some other water source is required for prey feeding, growth, and development in D. hesperus, and acquisition of water is proposed as a primary function of plant feeding. In addition, D. hesperus derives nutrients from plant feeding that increase the rate of nymphal development, although nymphs cannot complete development when provided only with tomato leaves.

6. Three simple models are presented of feeding behaviour in predatory Heteroptera where the amount of plant feeding either decreases, increases, or is constant as a function of the amount of prey feeding. The models are discussed with reference to the results and the probable multifunctional nature of plant feeding in predatory Heteroptera.
The occurrence and effectiveness of hypersensitive reaction against galling herbivores across host taxa
Authors: Fernandes G. Wilson , Negreiros Daniel
Published: March 2003

1. Hypersensitive reaction is an important type of induced defence by which the plant elicits a defence response to pathogens and insects. Hypersensitive reaction has been argued to be the most common plant resistance mechanism against insect herbivores that have intimate associations with their host plants.

2. The work reported here attempted to establish how important and widespread hypersensitive reaction might be against gall‐forming species across host taxa.

3. Hypersensitive reaction was the most important mortality factor against gall formation across host plant taxa in seven out of eight cases.

4. The number of insect galls correlated with the size of the leaves but module (leaf) size was a weak factor influencing the incidence of plant hypersensitive reaction to galling.

5. Insect galls and hypersensitive reactions occurred in genetically distant as well as geographically widespread host plant taxa.
Prey discrimination by a generalist coccinellid predator: effect of prey age or parasitism?
Authors: Roger Caroline , Coderre Daniel , Vigneault Clément , Boivin Guy
Published: March 2003

1. Patterns of prey discrimination by the generalist predatory coccinellid Coleomegilla maculata lengi Timb. (Coleoptera: Coccinellidae) were studied in relation to prey quality, under laboratory conditions.

2. Choice experiments were performed in which second‐ and fourth‐instar coccinellids had the choice between Trichoplusia ni (Lepidoptera: Noctuidae) eggs that were young or old, unparasitised or parasitised by Trichogramma evanescens Westwood (Hymenoptera: Trichogrammatidae).

3. Coleomegilla maculata larvae did not exhibit any preference for parasitised or unparasitised eggs at a similar stage of development but always preferred younger eggs, regardless of whether or not they were parasitised. Furthermore, the percentage of rejection was higher and handling time longer on the less preferred egg type. Pre‐imaginal development time, food intake to reach adulthood, and survival of coccinellid immatures were altered when coccinellid larvae were fed with parasitised and old unparasitised eggs.

4. These results indicate that C. maculata larvae select eggs based on their stage of development regardless of parasitism, and that prey quality of aged prey is lower.

5. Fourth‐instar coccinellid larvae spent less time in patches containing solely parasitised old eggs, and their level of exploitation was greatly reduced, compared with homogeneous patches containing unparasitised young eggs. This suggests that C. maculata larvae respond to variable patch quality by using flexible decision rules that reflect the payoff of the patch.
The reproductive flight phenology of a neotropical ant assemblage
Authors: Kaspari Michael , Pickering John , Windsor Donald
Published: March 2003

1. Alate flights reflect an ant colony's investment in sexual reproduction and dispersal yet little is known about community‐wide patterns of alate phenology. Two Malaise traps (for 2 years) and two light traps (for 1 year) were used to explore the flight phenologies of 22 common neotropical species from Barro Colorado Island, Panama.

2. The traps caught 23 182 individuals and 286 species/morphospecies. The two trap methods shared only 18 species. Samples also differed in sexual composition: light trap samples were 80% female, Malaise trap samples were 2.6% female.

3. Of 22 common species, all but one flew over half the year, with about half flying every month of the year. These data, combined with a literature review, suggest a latitudinal gradient in alate flight season: one north temperate assemblage (42°N) averaged 1.6 lunar months per species. The ever‐warm tropical year provides a larger flight window that allows a diversity of phenologies, from continuous to strongly pulsed.

4. Rainfall was correlated with alate flights in one‐third of the species. Quantile regression suggested that high weekly rainfall was necessary but not sufficient to produce alate flights in about a quarter of the species.

5. By decreasing the number of nests releasing alates on a given day, long flight seasons may lower the probability of finding a mate. At the same time, long flight seasons may increase the opportunity of finding vacant nest sites. High population densities and high incidence of nest disturbance in this community may ameliorate the first cost while enhancing the second benefit.
The spatial distribution of beetles within the canopies of oak trees in Richmond Park, U.K.
Authors: Stork N. E. , Hammond P. M. , Russell B. L. , Hadwen W. L.
Published: March 2003

1. 5054 adult beetles of 144 species were collected in a total of 696 1‐m2 collecting trays by knockdown insecticide fogging of 36 different oak trees in closed canopy woodland at Richmond Park, U.K., with three of the trees sampled on each of 12 dates, at 2‐ to 3‐week intervals, between April and October 1984.

2. In late spring (April/May), more individuals and species of beetles were collected in trays close to the trunks of trees than in trays more distant from the trunk. The reverse was the case in late September/October. Neither pattern prevailed in the intervening months.

3. Individual species exhibited a variety of patterns, with some species more abundant near the trunk, e.g. Leiopus nebulosus (L.), Strophosoma melanogrammum (Forster), Cylindronotus laevioctostriatus (Goeze), and Dromius agilis (Fabricius), and some less abundant near the trunk, e.g. Curculio pyrrhoceras (Marsham) and Rhynchaenus signifer (Creutzer). For Adalia decempunctata (L.), this preference changed with season. The observed species preferences for parts of a tree crown near or distant from the main trunk are discussed with reference to their known biologies.

4. No pronounced pattern of preference for north‐ or south‐facing aspects of trees in closed canopy woodland was observed, however populations of some species exhibited patterns of within‐tree distribution that correlate with compass angle; for one species, the ladybird Adalia decempunctata, this distribution changed with season and between colour morphs.
The nature of migration in the red admiral butterflyVanessa atalanta: evidence from the population ecology in its southern range
Authors: Stefanescu Constantí
Published: March 2003

1. The migrantVanessa atalanta(L.) occurs throughout Europe and North Africa. In autumn, populations emigrate from northern and central Europe to the Mediterranean region to overwinter. In the spring, the northern range is recolonised by migrants from the south. The dynamics of the species in the winter range is poorly known.

2. From 1994 to 1999, adults and immatures ofV. atalantawere monitored all year round in Mediterranean habitats in north‐east Spain.

3. Data showed that the Catalonia lowlands is an area to whichV. atalantamigrates to breed during the winter. Migrants arrive in October and early November and initiate a period of intensive breeding. Larval development occurs throughout the winter until a first annual generation of adults appears in early spring.

4. Most of the butterflies emerging in the spring emigrate and leave the area without breeding. The data suggest strongly that recolonisation of the northern range is by these butterflies not by wintering adults. Altitudinal migration also seems to be a common phenomenon, allowing a further summer generation of adults to occur at high elevations within the Mediterranean region.

5. The complex phenology ofV. atalantain its southern range has evolved as a strategy to track larval resources through space and time. Autumn migration coincides with the greatest availability of the main food plant,Urtica dioicaL. Late spring migration occurs by the time food quality is decreasing.
The phenological window of opportunity for early‐season birch sawflies
Authors: Martel Jocelyn , Kause Antti
Published: March 2003

Abstract 1. The phenological window of opportunity hypothesis posits that an insect herbivore cannot survive outside a specific leaf age interval of its host plant.

2. Previous studies have shown that mountain birch displays extensive seasonal changes in leaf biochemical characteristics. Young, expanding leaves are full of water and amino acids but they also contain large amounts of protein‐precipitating gallotannins as well as flavonoid‐glycosides. Concentrations of these compounds decline during leaf growth whereas concentrations of sugars and proanthocyanidins and leaf toughness increase.

3. Adult birch sawflies hatch in early summer and oviposit on growing leaves, which compels larvae to feed on leaves that are already well developed. The purpose of this study was to test whether leaves that were younger and biochemically different from the leaves available under natural conditions are within the phenological window of opportunity for the larvae of two early‐season birch sawfly species, Amauronematus amplus Konow and Pristiphora alpestris (Konow).

4. Amauronematus amplus larvae survived better and developed faster, and P. alpestris larvae developed faster and became bigger, on atypically young leaves compared with larvae reared on leaves encountered normally. Therefore, these species can exploit the putative nutritional superiority of very young leaves, which probably outweighs the potential impact of the new set of secondary metabolites offered to them. In conclusion, young leaves that are consumed rarely by sawfly larvae are within their phenological window of opportunity, even though the timing of sawfly life cycles constrains their utilisation.
Triangular fecundity function and ageing in ladybird beetles
Authors: Dixon A. F. G. , Agarwala B. K.
Published: March 2003

Abstract1. In insects, the age schedules of fecundity tend to be triangular and this has been attributed more to temporal patterns of mortality than to fecundity. The objective of the work reported here was to test the assumption that senescence shapes the fecundity function in ladybird beetles, and in particular that the production function declines with age.

2. The results of a laboratory study on three species of predatory ladybird beetle indicated that the efficiency with which these insects acquire and process food declined with age. Although supplied with the same amount of food each day, after the onset of reproduction, these beetles ate less and less with increasing age. Egg production mirrored the decline in aphid consumption. Associated with this was a decline in fertility, assimilation, and speed of locomotion with age.

3. This study indicates that production declined with age and that this shaped the fecundity schedules in these ladybird beetles. In addition, the results indicated that ladybirds are income breeders and, as predicted, the reproductive effort of the small species was greater than that of the large species used in this study.
A minimalist approach to the effects of density‐dependent competition on insect life‐history traits
Authors: Agnew Philip , Hide Mallorie , Sidobre Christine , Michalakis Yannis
Published: March 2003

Abstract  1. Due to its effects on the phenotypic and genotypic expression of life‐history traits, density‐dependent competition is an important factor regulating the growth of populations. Specifically for insects, density‐dependent competition among juveniles is often associated with increased juvenile mortality, delayed maturity, and reduced adult size.

2. The aim of the work reported here was to test whether the established phenotypic effects of density‐dependent competition on life‐history traits could be reproduced in an experimental design requiring a minimal number of individuals. Larvae of the mosquito Aedes aegypti were reared at densities of one, two, or three individuals per standard Drosophila vial and in six different conditions of larval food availability. This design required relatively few individuals per independent replicate and included a control treatment where individuals reared at a density of one larva per vial experienced no density‐dependent interactions with other larvae.

3. Increased larval densities or reduced food availability led to increased larval mortality, delayed pupation, and the emergence of smaller adults that starved to death in a shorter time (indicating emergence with fewer nutritional reserves).

4. Female mosquitoes were relatively larger than males (as measured by wing length) but males tended to survive for longer. These differences increased as larval food availability increased, indicating the relative importance of these two traits for the fitness of each sex. The role of nutritional reserves for the reproductive success of males was highlighted in particular.

5. This minimalist approach may provide a useful model for investigating the effects of density‐dependent competition on insect life‐history traits.
Metapopulation dynamics of a flightless alpine insectHemideina maoriin a naturally fragmented habitat
Authors: Leisnham Paul T. , Jamieson Ian G.
Published: March 2003

Abstract1. Despite widespread acceptance of metapopulation theory, the effects that inter‐patch dispersal and variability in patch size have on metapopulation dynamics in insects are two issues that require further study. In addition, previous studies of metapopulations have tended to focus on organisms with high dispersal capabilities such as some species of butterfly and bird.

2. Mountain stone wetaHemideina maoriare a long‐lived, flightless orthopteran that live onislandrock outcrops or tors in the alpine region of southern New Zealand. A total of 480 adults and 789 juveniles was marked over three seasons on four large and 14 small tors to assess the effects of habitat fragmentation on the population dynamics ofH. maori.

3. Only 12 adults (2.5% of marked adults and 4.0% of recaptured adults) and two juveniles (0.3% of marked juveniles and 0.7% of recaptured juveniles) dispersed between tors. The mean dispersal distance was 361 m (range = 36–672 m). Larger tors supported larger populations and had a higher number of emigrants and immigrants while smaller tors had proportionally higher emigration and immigration rates. Although adults on large and small tors had similar mean lifespans, five extinction events and three recolonisation events occurred during the study period, all on small tors.

4.Hemideina maoriconform to many of the predictions of metapopulation theory even though they are flightless, show relatively low dispersal rates, and occur at low densities. Extinction and colonisation events are more common on small tors but may be relatively unimportant for the long‐term survival of the metapopulation because they occur on the smallest habitat patches, which support the smallest proportion of the overall population.