bluuebunny/crossref_metadata_2025 huggingface dataset:
Endocrine responses to 7 days of head‐down bed rest and orthostatic tests in men and women
Authors: Millet C. , Custaud M.–A. , Maillet A. , Allevard A.–M. , Duvareille M. , Gauquelin‐Koch G. , Gharib C. , Fortrat J.–O.
Published: March 2003

The objective of this study was to investigate plasma volume (PV), total body water, hormones and hydroelectrolyte responses in eight males (25–40 years) and eight females (25–31 years) during 7 days of exposure to simulated microgravity (–6° head‐down bed rest, HDBR). Bed rest is a model that has commonly been used to simulate spaceflight. Heart rate (HR), blood pressure (BP) and vasoactive hormone responses were studied before and after HDBR during a 10‐min stand test. No change in total body water and body mass was noted in either sex. The decrease in PV was similar in both men (9·1 ± 1·4%) and women (9·4 ± 0·8%). Urinary normetanephrine (NMN) was decreased during HDBR in both sexes. Urinary metanephrine (MN) and plasma catecholamines were unchanged. Daily urinary excretion of urea, an indirect index of protein breakdown, was increased only in the female subjects during HDBR. Plasma active renin (AR) and aldosterone were increased in both sexes, but urinary atrial natriuretic peptide (ANP) and arginine vasopressin (AVP) were unchanged throughout the study. Also, the hormonal responses to 7 days of HDBR were comparable between men and women. Moreover, the results show similar cardiovascular and endocrine responses to standing after HDBR. However, the orthostatic intolerance following HDBR was associated with a blunted increase in noradrenaline (NA) only in the women during the stand test. It is concluded that: (i) 7 days of physical inactivity achieved during HDBR resulted in a reduced sympathetic activity in both sexes and alterations in protein metabolism in women and (ii) standing after HDBR resulted in an attenuated release of noradrenaline in women.
Evaluation of impaired dynamic cerebral autoregulation by the Mueller manoeuvre
Authors: Reinhard Matthias , Hetzel Andreas , Lauk Michael , Lücking Carl H.
Published: March 2003

Arterial blood pressure (ABP) shows polyphasic changes during the Mueller manoeuvre (voluntary negative intrathoracic pressure). The aim of the present study was to investigate (1) whether these changes could be applied to detect impaired dynamic cerebral autoregulation (dCA) in carotid stenosis and (2) whether the degree of indicated impairment correlates with transfer function phase as another current measure for dCA (deep breathing method) and CO2‐reactivity. We examined 13 patients with severe unilateral carotid artery stenosis and 16 age‐matched controls during 15‐s Mueller manoeuvres (MM) at −30 mmHg using bilateral transcranial Doppler sonography and non‐invasive ABP recordings (Finapres, 2300, Ohmeda, Englewood, CO, USA). After an initial biphasic oscillation, cerebral blood flow velocity (CBFV) and ABP decreased to below baseline. CBFV reincreased in controls and on contralateral sides in patients 6·0 s (3·8–9·5 s, median and range) after the onset of the decrease, despite a further fall in ABP. CBFV over the affected side revealed a significantly delayed reincrease (8·0 (5·6–10·3) s; P<0·01) combined with a relatively flat and inertial amplitude behaviour. An applied autoregulation index derived from the MM (mROR), phase shift and CO2‐reactivity were severely reduced on the affected side in patients (P<0·01). Reduction of the mROR correlated significantly with reduction of phase shift (r=0·69; P=0·002) and CO2‐reactivity (r=0·78; P=0·002). In conclusion, the different cerebral haemodynamic pattern during the MM in patients is likely to reflect impaired dCA. The degree of indicated impairment correlates with that of transfer function phase and CO2‐reactivity. Therefore, the MM represents a convenient method for grading of compromised cerebral haemodynamics in patients with carotid artery stenosis.
An integrated model of the human ventilatory control system: the response to hypoxia
Authors: Ursino Mauro , Magosso Elisa , Avanzolini Guido
Published: March 2003

The mathematical model of the respiratory control system described in a previous companion paper is used to analyse the ventilatory response to hypoxic stimuli. Simulation of long‐lasting isocapnic hypoxia at normal alveolar PCO2 (40 mmHg=5·33 kPa) shows the occurrence of a biphasic response, characterized by an initial peak and a subsequent hypoxic ventilatory decline (HVD). The latter is about as great as 2/3 of the initial peak and can be mainly ascribed to prolonged neural hypoxia. If isocapnic hypoxia is performed during hypercapnia (PACO2=48 mmHg =6·4 kPa), the ventilatory response is stronger and HVD is minimal (about 1/10–1/5 of the initial peak). During poikilocapnic hypoxia, ventilation exhibits smaller changes compared with the isocapnic case, with a rapid return toward baseline within a few minutes. Moreover, a significant undershoot occurs at the termination of the hypoxic period. This undershoot may lead to apnea and to a transient destabilization of the control system if the peripheral chemoreflex gain and time delay are twofold greater than basal.
Difficulties in the fine needle aspiration (FNA) diagnosis of schwannoma
Authors: Yu G. H. , Sack M. J. , Baloch Z. , Gupta P. K.
Published: March 2003

Difficulties in the fine needle aspiration (FNA) diagnosis of schwannoma

The results of nine FNAs of eight histologically proven schwannomas are presented. In only one of the aspirates was a diagnosis of schwannoma made; three additional cases were diagnosed as ‘spindle cell neoplasm’. Two of the cases were considered to be non‐diagnostic due to hypocellularity, while two cases containing cellular material raised the differential diagnosis of granulation tissue and granulomatous inflammation due to the presence of epithelioid cells and an inflammatory infiltrate, and are illustrated here. The remaining FNA was felt suggestive of branchial cleft cyst due to the presence of only cystic fluid in a neck mass. We observe that: (i) the acquisition of an adequate, representative specimen via FNA is often difficult in schwannoma, and (ii) diagnostic difficulties may be encountered in cases in which cellular material is obtained.
Xanthogranulomatous sialadenitis following diagnosis of Warthin's tumour: a possible complication of fine needle aspiration (FNA)
Authors: Stephen M. R. , Matalka I. , Stewart C. J. R. , Mackenzie K.
Published: March 2003

Introduction
Fine needle aspiration (FNA) in the management of palpable masses in Ibadan: impact on the cost of care
Authors: Thomas J. O. , Amanguno A. U. , Adeyi O. A. , Adesina A. O.
Published: March 2003

Fine needle aspiration (FNA) in the management of palpable masses in Ibadan: impact on the cost of care

Fine needle aspiration cytology is a relatively new technique in the management of palpable lesions in Ibadan. In the University College Hospital (UCH) Ibadan, as in most centres in Nigeria, inadequate facilities, a heavy patient load, financial constraints and an unreliable supply of basic necessities like water, often delay definitive diagnosis and management. In order to alleviate the patient's problems and provide prompt and accurate diagnosis, an FNA Cytology Clinic was set up in the Pathology Department, UCH, Ibadan, managed by the pathology team. This report represents the results of our experience. The cost effectiveness and impact on cost of care are highlighted. FNA costs N250.00 (£2.00), whilst cost of biopsy can vary from N5000.00 to N10 000.00 (£35.00 to £70.00). A total of 752 satisfactory smears was reviewed during the 3‐year period 1995–97 from various sites including breast (n = 295), lymph node (n = 183) and thyroid (n = 143). Diagnostic accuracy varied with different sites, the accuracy rate for breast, lymph node and thyroid malignancy being approximately 100%, 80% and 93%, respectively.
Potentially difficult smears of women with squamous cell carcinoma pose fewer problems when PAPNET is used for primary screening
Authors: Kok M. R. , Schreiner‐Kok P. G. , van der Veen G. , Boon M. E.
Published: March 2003

Potentially difficult smears of women with squamous cell carcinoma pose fewer problems when PAPNET is used for primary screening

The diagnosis of squamous cell carcinoma (SCC) on a cervical smear is often far from easy. This study reports the analysis of 40 true‐positive SCC smears detected in primary PAPNET screening and eight false‐negative (FN) conventionally screened smears. All FN cases contained sparse abnormal material (< 10% of the slide). In these potentially difficult cases the diagnosis on the PAPNET images was not hard. Statistical analysis of the quantitative data indicated that the PAPNET images of the FN cases and the true‐positive cases differed in some aspects. PAPNET highlighted the importance of background information (old blood, fibrin and necrosis). In addition, all FN smears contained cancer cells in the PAPNET images, allowing a correct diagnosis.
Efficacy of Ki‐67 antigen staining in Papanicolaou (Pap) smears in post‐menopausal women with atypia—an audit
Authors: Ejersbo D. , Jensen H. A. , Hølund B.
Published: March 2003

Efficacy of Ki‐67 antigen staining in Papanicolaou (Pap) smears in post‐menopausal women with atypia—an audit

In cervical smears from post‐menopausal women with mucosal atrophy it can be difficult to distinguish atrophic epithelial cell groups from neoplastic cell groups on cytomorphological criteria only. The consequence of post‐menopausal atypia is that the woman is referred for a repeat smear after local oestrogen treatment or for colposcopy. We investigated whether immunocytochemical expression of Ki‐67 (MIB‐1) on the primary Papanicolaou‐stained smear could be of any diagnostic help. Our data showed that negative Ki‐67 expression is a very reliable indicator of a normal atrophic cell pattern, and by using this method on the original smear we were able to reduce the false‐positive cytologic diagnoses by 86%.
Validation of a decision support system for the cytodiagnosis of fine needle aspirates of the breast using a prospectively collected dataset from multiple observers in a working clinical environment
Authors: Cross S. S. , Stephenson T. J. , Mohammed T. , Harrison R. F.
Published: March 2003

Validation of a decision support system for the cytodiagnosis of fine needle aspirates of the breast using a prospectively collected dataset from multiple observers in a working clinical environment

We have used a 692 case dataset, collected retrospectively by a single observer, to develop decision support systems for the cytodiagnosis of fine needle aspirates of breast lesions. In this study, we use a 322 case dataset that was prospectively collected by multiple observers in a working clinical environment to test two predictive systems, using logistic regression and the multilayer perceptron (MLP) type of neural network. Ten observed features and the patient age were used as input features. The systems were developed using a training set and test set from the single observer dataset and then applied to the multiple observer dataset. For the independent test cases from the single observer dataset, with a threshold set for no false positives on the training set, logistic regression produced a sensitivity of 82% (95% confidence interval 73–91) and a predictive value of a positive result (PV +) of 98% (95–99), the values for the MLP were 79% (69–89) and 100%, respectively. However the performance on the prospective multiple observer dataset was much worse, with a sensitivity of 72% (65–80), and PV + of 97% (94–99) for logistic regression and 67% (60–75) and 91% (85–97) for the MLP. These results suggest that there is considerable interobserver variability for the defined features and that this system is unsuitable for further development in the clinical environment unless this problem can be overcome.
Efficacy and pattern of use of sputum cytology as a diagnostic test
Authors: Murray K. L. , Duvall E. , Salter D. M. , Monaghan H.
Published: March 2003

Sputum cytology is regarded by many clinicians as a noninvasive, cheap and simple test for the diagnosis of bronchogenic carcinoma. Since the introduction of fibre‐optic bronchoscopy and more easily obtained bronchial biopsies reliance on sputum cytology has diminished. However, in Edinburgh it was perceived that sputum samples were still being sent as well as, rather than instead of, bronchoscopic specimens. This retrospective study was undertaken to determine whether or not cytological examination of sputum is an efficient and sensitive test in the investigation of patients with suspected bronchogenic carcinoma. It demonstrated that the Lothian University Hospitals NHS Trust Pathology Directorate receives many sputa from departments not specializing in respiratory disease when there is no indication for the test. In addition, we have shown that the absolute sensitivity of the test is only 5% and that when there is a strong clinical suspicion of bronchogenic carcinoma the results of sputum cytology do not play a significant role in the management of the patient. We recommend that sputum cytology is restricted to those patients under the care of Respiratory Units in whom bronchoscopy is inappropriate or unsuccessful.
Altitudinal differentiation in the diapause response of two species of dung flies
Authors: BLANCKENHORN WOLF U.
Published: March 2003

1. Seasonality is a prime selective factor promoting genetic differentiation of populations. Local adaptation in diapause response was investigated in the two geographically and altitudinally widespread dung flies Scathophaga stercoraria (Diptera: Scathophagidae) and Sepsis cynipsea (Diptera: Sepsidae).

2. Replicate sibships from three sites in Switzerland with low and high altitude dung fly populations were raised in a common laboratory environment simulating the natural decreasing photoperiod and temperature regimen before winter. From field phenologies, the critical photoperiod inducing diapause was predicted to be longer for high than for low altitude populations (12 vs. 10 h for Sc. stercoraria, and 12.25 vs. 11 h for Se. cynipsea) if they are locally adapted.

3. Contrary to expectation and to Sc. stercoraria, which diapauses in the pupal stage, Se. cynipsea diapauses in the adult stage.

4. Low but significant levels of genetic differentiation in pre‐winter adult emergence were evident between low and high altitude populations of both species, but they were far from the differences predicted. Scathophaga stercoraria also showed geographical differentiation independent of altitude.

5. Sepsis cynipsea females stopped reproducing at some point before winter, but altitude did not affect the timing of adult diapause. High altitude females and females that did not initiate reproduction before winter survived the simulated winter better.

6. Both species largely used temperature rather than photoperiod as a cue inducing winter diapause, an untypical case of phenotypic plasticity. The hypothesis that Sc. stercoraria, whose generation times are much longer than those of Se. cynipsea, responds to a greater extent to temperature rather than photoperiod only was rejected.
Prey species and prey diet affect growth of invertebrate predators
Authors: STROHMEYER HEATHER HORAN , STAMP NANCY E. , JARZOMSKI CHRISTINE M. , BOWERS DEANE M.
Published: March 2003

1. The effects of prey species and leaf age used by prey on performance of two generalist invertebrate predators were studied. The focal plant was Plantago lanceolata, which contains iridoid glycosides.

2. Diet of the herbivorous prey influenced their growth rate.

3. The generalist herbivore (Vanessa cardui) and the novel‐plant feeder (Manduca sexta) contained very low levels of iridoid glycosides in their haemolymph, whereas the specialist (Junonia coenia) levels were 50–150‐fold higher.

4. Predatory stinkbugs (Podisus maculiventris) fed either the novel‐plant feeder or the specialist exhibited similar developmental rates. However, stinkbugs ate less of the generalist but grew faster. The growth rate of the stinkbugs was higher when the caterpillar species were raised on the new‐leaf powder diet, which contained twice as much protein and iridoid glycosides as the mature‐leaf powder diet.

5. Jumping spiders (Phidippus audax) ate more mealworms (Tenebrio molitor) than specialist J.coenia caterpillars, fed either new‐ or mature‐leaf powder diets, and could not gain weight when fed J.coenia.

6. These results indicate that prey quality was not determined solely by the iridoid glycoside concentration in the diet.
Direct and indirect effects of climate change on insect herbivores: Auchenorrhyncha (Homoptera)
Authors: MASTERS  , BROWN  , CLARKE  , WHITTAKER  , HOLLIER
Published: March 2003

1. Novel manipulations of local climate were employed to investigate how warmer winters with either wetter or drier summers would affect the Auchenorrhyncha, a major component of the insect fauna of grasslands. Direct and indirect effects of climate manipulation were found.

2. Supplemented summer rainfall resulted in an increase in vegetation cover, leading to an increase in the abundance of the Auchenorrhyncha.

3. Summer drought, however, caused a decrease in vegetation cover, but this did not lead to a corresponding decrease in the abundance of the Auchenorrhyncha.

4. Egg hatch and the termination of nymphal hibernation occurred earlier in winter warmed plots; however, the rate of nymphal development was unaffected.
Testing assumptions of mark–recapture protocols for estimating population size using Australian mound‐building, subterranean termites
Authors: EVANS THEODORE A. , LENZ MICHAEL , GLEESON PATRICK V.
Published: March 2003

1. Forager population size of two species of mound‐building, subterranean termite (Coptotermes lacteus, Rhinotermitidae and Nasutitermes exitiosus, Termitidae) was estimated using three mark–recapture protocols. These estimates varied widely within and between colonies (≈ 0.3–200 million for C. lacteus and 0.2–3 million for N. exitiosus). The variation in the estimates is explained in part by violation of the assumptions of the protocols.

2. The fat‐stain markers, although persistent in the laboratory, faded rapidly in the field, and were transferable from marked individuals to unmarked individuals by cannibalism.

3. Marked individuals did not mix randomly or evenly with unmarked foraging individuals in space or time, as marked individuals were recaptured in widely varying numbers at different feeding sites sampled simultaneously. Importantly, foragers displayed feeding site fidelity and avoided disturbed feeding sites.

4. The likelihood of recapture differed between castes and instars; there was a higher recapture rate of large workers and soldiers relative to smaller workers.

5. The mark–recapture protocols provided inaccurate and unreliable forager population estimates, up to two orders of magnitude larger than direct counts of entire mound colonies. Thus the weighted mean estimates from more complex triple‐mark–recapture protocols were not necessarily better than Lincoln index estimates from simpler single‐mark–recapture protocols.

6. Mark–recapture studies may provide useful information about forager behaviour and foraging territories.
Virginity in haplodiploid populations: a comparison of estimation methods
Authors: WEST  , COMPTON  , VINCENT  , HERRE  , COOK
Published: March 2003

1. The presence of ovipositing virgin females, who are able to produce only male offspring, may have several important consequences for the evolution of reproductive strategies.

2. The prevalence of virginity for five fig wasp species was estimated using three different methods: (1) the proportion of females developing in fruit that contained no conspecific males; (2) dissection of females caught on sticky traps; and (3) dissection of females that had emerged from their galled flowers into the fruit cavity.

3. The estimates obtained by method 1 (females developing in single sex broods) were lower than those obtained by the other methods.

4. Across species, the estimates obtained by method 1 (females developing in single sex broods) were significantly correlated with those obtained by method 2 (sticky trap caught females).

5. Mating with sperm‐depleted males is unlikely to occur in these species.
Oviposition preference of a Eucalyptus herbivore and the importance of leaf age on interspecific host choice
Authors: STEINBAUER  , CLARKE  , MADDEN
Published: March 2003

1. Paropsine chrysomelids are eucalypt folivores for which it has been hypothesized that the availability of suitable age class foliage (i.e. young foliage) is a more important determinant of host use than the physical and/or chemical characteristics of foliage from different hosts. This prediction was tested by assessing the oviposition preference of Chrysophtharta bimaculata (Olivier) on excised branches of Eucalyptus regnans F. Mueller and E. nitens (Deane & Maiden) Maiden.

2. In cage trials, and as observed in the wild, beetles oviposited preferentially on E. regnans when the branches of both eucalypt species displayed the full range of foliar developmental classes, from immature to fully expanded. However, when the branches were pruned so that both species displayed only immature and expanding leaves, no difference in oviposition between the species occurred. Further, when the branches were pruned so that E. regnans displayed only fully expanded leaves and E. nitens displayed only immature and expanding leaves, females oviposited entirely on the latter species.

3. These results support and extend the hypothesis that C. bimaculata's ovipositional preference is dictated more by leaf age class than by the tree species from which the leaves derive. In the discussion it is proposed that a eucalypt that initiates and expands leaves rapidly will be less preferred for oviposition than one that develops and expands leaves slowly, because of the smaller area of its canopy with less sclerophyllous foliage.
Scramble competition in the southern pine beetle, Dendroctonus frontalis
Authors: Reeve John. D. , Rhodes Douglas J. , Turchin Peter
Published: March 2003

Abstract.1. The nature of intraspecific competition was investigated in the southern pine beetle, Dendroctonus frontalis, a highly destructive pest of pine forests in the southern U.S.A. Data were analysed from an observational study of naturally‐attacked trees, and from field experiments where attack density was manipulated by adding different numbers of beetles to caged trees.

2. The effect of attack density on gallery construction, oviposition, brood survival, and the overall rate of increase was examined, and a flexible model of intraspecific competition used to classify the type of competition (contest or scramble) at different points in the life cycle.

3. The results of these analyses suggest that contest competition occurs during gallery construction and oviposition, in accord with previous work on D. frontalis. Strong scramble competition occurs later on in development, however, and the overall competitive process is better characterized as scramble competition, similar to other bark beetles. Trees with attack densities sufficiently high to produce significant competition are common in the field.
Plant cues influence searching behaviour and parasitism in the egg parasitoid Trichogramma nr. brassicae
Authors: Bjorksten Tracey A. , Hoffmann Ary. A.
Published: March 2003

Abstract.1. The effect of experience of plant cues at emergence on searching behaviour and parasitism was investigated in two strains of Trichogramma nr. brassicae (Hymenoptera: Trichogrammatidae).

2. Wasps reared on Sitotroga cereallela were allowed to emerge on a tomato plant or in a vial, with or without food. For one of the strains, females emerging on tomato searched significantly longer on a tomato seedling than females emerging in a vial.

3. The experience effect lasted between 1 and 2 days. It involves associating plant stimuli with the remains of the host, because females emerging from their host on a tomato plant had an increased searching response to tomato, but females transferred to the plant immediately after emergence did not.

4. The effect of emergence environment on parasitism of the host Helicoverpa punctigera on tomato and lettuce seedlings was tested. Wasps were allowed to emerge on seedlings of tomato or lettuce, or in an empty vial. For one strain, females experienced with tomato at emergence parasitized significantly more hosts on tomato than did females emerging on lettuce or in a vial. Parasitism on lettuce was not influenced by the treatments.
Mortality rate, reproductive output, and trap response bias in populations of the blowfly Lucilia sericata
Authors: Hayes E. J. , Wall R. , Smith K. E.
Published: March 2003

1. The ages of 877 females of the blowfly Lucilia sericata, collected from two farms in south‐west England between May and September 1996, were determined using a combination of ovarian dissection and wing fray analysis.

2. Using survivorship analysis, the mortality rates over the entire field season were estimated to be 2.2 and 1.9% per day‐degree at the two farms, respectively. These gave a mean life expectancy of 46 and 53 day‐degrees, and a lifetime reproductive output of 130 and 172 eggs per female.

3. The mortality rate remained relatively constant over time, with one exception, the first sample of the season when no older flies were present, indicating that underlying changes in demography (emergence and senescence of generations) over the field season were not sufficient to affect the rates calculated by survivorship analysis.

4. The response of L. sericata to liver‐baited traps was affected strongly by age and reproductive status, with gravid females and females in the early stages of ovarian development being most markedly over‐represented relative to other age categories.
Intrinsic and extrinsic competitive interactions between two larval parasitoids of Heliothis virescens
Authors: De Moraes Consuelo M. , Cortesero A. M. , Stapel J. O. , Lewis W. J.
Published: March 2003

1. Competition between parasitoid species may be a key factor in the community dynamics of plant–herbivore‐parasitoid systems and is an important consideration in the selection and management of effective biological control agents.

2. Interspecific competition can occur between adult parasitoids searching for hosts (extrinsic competition) and between multiple parasitoid larvae developing within a single host individual (intrinsic competition). A model system comprising the lepidopteran pest Heliothis virescens and two key hymenopteran endoparasitoids, Microplitis croceipes and Cardiochiles nigriceps, was employed to explore parasitoid host‐location strategies and the consequences of intrinsic and extrinsic competitive interactions between parasitoid species.

3. The less specialised of the two parasitoids, M. croceipes, was found to have a shorter hatching time and to dominate intrinsic competition, except when its oviposition followed that of the more specialised parasitoid, C. nigriceps, by 16 h or more. This interval corresponded to the differential in hatching time between the two species.

4. Cardiochiles nigriceps, however, displayed superior host‐searching efficiency that may compensate for its disadvantage in intrinsic competition. This parasitoid was more effective at detecting host infestation sites via airborne odours and at locating and attacking early instar host larvae than was M. croceipes.
Contrasting diel activity and feeding patterns of four species of carnivorous stoneflies
Authors: Elliott J. M.
Published: March 2003

1. The hypothesis under test was that larvae of Dinocras cephalotes (Curtis), Perla bipunctata Pictet, Isoperla grammatica (Poda), and Perlodes microcephalus (Pictet) differed markedly in their diel activity and feeding patterns. Mature larvae collected about 1 month prior to adult emergence were used either for gut analyses or for observations of their activity and feeding patterns in three stream tanks with natural substrata and glass bottoms, so that activity could be observed above and below the substratum. A dull red light was used for observations in the dark. Food (larvae of Ephemeroptera, Simuliidae, and Chironomidae) was provided in excess.

2. Larvae for gut analyses were taken 1 h before dusk or dawn (n = 30 larvae per species for each day or night sample). The only species with food in the gut for the day samples was P. microcephalus. All species fed at night, the mean number of prey per larva being very similar for D. cephalotes, P. bipunctata, and I. grammatica but significantly higher for P. microcephalus. Most prey were insect larvae, especially Simuliidae and Chironomidae.

3. Diel activity patterns of single larvae differed interspecifically but not intraspecifically. Larvae of D. cephalotes and P. bipunctata were rarely active during the day; their activity increased at dusk and decreased at dawn, and was highest during the night; their success at prey capture was highest at dusk and dawn, with an ambush rather than a search strategy. Isoperla grammatica was rarely active during the day, most active at dusk and dawn when prey capture was highest, using a search strategy, and less active for the rest of the night. Perlodes microcephalus was active during the day, but only below the substratum, and very active from dusk to dawn with a high prey‐capture success, using a search strategy. These experiments provided support for the hypothesis under test. The discussion concludes that the results could also help to explain known differences in growth rate and the length of the life‐cycle in these four species.
Consequences of foundress aggregation in the brown citrus aphid Toxoptera citricida
Authors: Michaud J. P. , Belliure B.
Published: March 2003

1. A field study was conducted in which colonies of Toxoptera citricida (Kirkaldy) were initiated with different numbers of foundresses on ungrafted citrus trees var. ‘Carrizo’ within an existing citrus grove in central Florida.

2. The growth rate, longevity, and final size of T. citricida colonies were all positively correlated with number of foundresses.

3. Colonies initiated by many foundresses produced alatae earlier than those initiated by fewer foundresses.

4. Nymphal developmental time was reduced in colonies initiated by more foundresses but the mean number of grand‐progeny per foundress was lower when only surviving colonies were compared.

5. The longevity of foundresses was unaffected by their number but foundress fecundity and nymphal survival decreased as foundress number increased.

6. The most abundant natural enemies were Diptera: Syrphidae, primarily Pseudodorus clavatus (F.), and Chamaemiidae (Leucopis sp.), followed by Coleoptera: Coccinellidae, primarily Cycloneda sanguinea (L).

7. Colonies initiated with more foundresses attracted more oviposition by dipteran predators than did colonies initiated with fewer foundresses.
Variation in predation costs with Chiastocheta egg number on Trollius europaeus: how many seeds to pay for pollination?
Authors: Jaeger Nicolas , Pompanon François , Després Laurence
Published: March 2003

1. In obligate plant/seed parasite–pollinator mutualisms, the plant is exclusively pollinated by an insect whose larvae are specific seed predators. Hence, outcomes of the interaction for the plant can vary with the number of eggs laid and the number of seeds eaten per larva.

2. In the work reported here, predation by Chiastocheta larvae on seeds of Trollius europaeus was analysed as a function of the number of eggs laid on the flower. Flowers with an increasing number of eggs were bagged in three populations and seeds were counted after the end of larval predation, in order to assess whether there was competition among larvae.

3. Seed predation on single‐egg flowers was high and variable (mean per population ranging from 15 to 40% of the developed seeds). Seed predation increased weakly with increasing egg load and was lower than gross seed production (always < 85%) whatever the number of eggs laid. This corresponds to a strong decrease in seed consumption per larva with increasing egg load, i.e. severe larval competition for resources.

4. The results suggest that both interference among Chiastocheta larvae and carpel dehiscence may protect T. europaeus seeds from total predation. Estimates of seed predation based on egg load observed in 20 natural populations in the French Alps typically ranged from 30 to 60%. The interaction was always beneficial for the plant and there was no risk of total seed destruction by Chiastocheta larvae, favouring stability of the mutualism.
Past attacks influence host selection by the solitary bark beetle Dendroctonus micans
Authors: Gilbert Marius , Vouland Gérard , Grégoire Jean‐Claude
Published: March 2003

1. A spatio‐temporal study of host selection and local spread of a solitary bark beetle attacking live spruce Dendroctonus micans (Kugelann) was carried out using a combination of standard statistical methods, geostatistical analyses, and modelling. The study was based on data from three plots (150–300 trees, 0.3–1 ha) from 1978 to 1993. All trees were mapped and successful and abortive bark‐beetle attacks on each tree were counted annually. Because the attacked trees usually survived, temporal attack patterns as well as spatial patterns could be analysed.

2. The distribution of successful insect attacks on the trees was slightly aggregative, indicating some degree of choice rather than totally random establishment.

3. The level of yearly individual attacks per tree was very stable, suggesting that D. micans usually leave the host in which they develop.

4. The attacked trees were distributed randomly in the plots; at the study's spatial scale, the insects dispersed freely throughout the plot (no spatial dependence).

5. On the other hand, time dependence was strong; some trees were attacked repeatedly while others were left untouched.

6. Among a choice of scenarios (random attack, fixed variability in individual host susceptibility, induced host susceptibility following random attack), the best fit was obtained with the model involving induced individual host susceptibility. This type of relation to the host tree contrasts strongly with patterns generally described in host–plant relationships (including gregarious, tree‐killing bark beetles), where local herbivore damage results in induced resistance.

7. These results suggest that the first attacks in a new stand are made at random, that all or most of the beetles emerging from a tree disperse and resample the stand, and that they settle preferentially on trees that were colonised successfully by previous generations.
Resource availability and population dynamics of Nicrophorus investigator, an obligate carrion breeder
Authors: Smith Rosemary J. , Merrick Melissa J.
Published: March 2003

1. Food resources for rearing young may influence insect populations. This is particularly true for insects that breed obligately on rare, ephemeral resources such as dung, fungi, or carrion.

2. Beetles in the genus Nicrophorus bury small vertebrate carcasses for rearing their young. Studies reviewed by Scott (1998) have found a positive relationship between carcass mass and total brood size. It is likely that access to carcasses suitable for breeding, and not food or mates, limits reproduction in both male and female Nicrophorus. Thus, small mammal densities could determine Nicrophorus population sizes.

3. The work reported here examined the relationship between Nicrophorus investigator (Coleoptera: Silphidae) population size and small mammal abundance at two sites over a 4‐year period.

4. Nicrophorus investigator buried and reared young on all the native small rodent species trapped at two sites in south‐western Colorado, U.S.A. (Peromyscus maniculatus, Microtus montanus, Zapus princeps, Tamias minimus, Thomomys talpoides). They preferred to bury and reproduce on rodent carcasses weighing between 16 and 48 g; rodents of this size represented 82% of captures.

5. Population sizes of N. investigator and small rodents were estimated simultaneously using mark‐recapture censuses over a 4‐year period. Considering only rodents within the size range used by N. investigator, the estimated small mammal biomass per hectare in one year and the beetle population size in the following year were correlated significantly.
Jasmonate‐mediated induced plant resistance affects a community of herbivores
Authors: Thaler Jennifer S. , Stout Michael J. , Karban Richard , Duffey Sean S.
Published: March 2003

1. The negative effect of induced plant resistance on the preference and performance of herbivores is a well‐documented ecological phenomenon that is thought to be important for both plants and herbivores. This study links the well‐developed mechanistic understanding of the biochemistry of induced plant resistance in the tomato system with an examination of how these mechanisms affect the community of herbivores in the field.

2. Several proteins that are induced in tomato foliage following herbivore damage have been linked causally to reductions in herbivore performance under laboratory conditions. Application of jasmonic acid, a natural elicitor of these defensive proteins, to tomato foliage stimulates induced responses to herbivory.

3. Jasmonic acid was sprayed on plants in three doses to generate plants with varying levels of induced responses, which were measured as increases in the activities of proteinase inhibitors and polyphenol oxidase.

4. Field experiments conducted over 3 years indicated that induction of these defensive proteins is associated with decreases in the abundance of all four naturally abundant herbivores, including insects in three feeding guilds, caterpillars, flea beetles, aphids, and thrips. Induced resistance killed early instars of noctuid caterpillars. Adult flea beetles strongly preferred control plants over induced plants, and this effect on host plant preference probably contributed to differences in the natural abundance of flea beetles.

5. The general nature of the effects observed in this study suggests that induced resistance will suppress many members of the herbivore community. By linking plant biochemistry, insect preference, performance, and abundance, tools can be developed to manipulate plant resistance sensibly and to predict its outcome under field conditions.
Survival rates in a natural population of the damselfly Ceriagrion tenellum: effects of sex and female phenotype
Authors: Andrés Jose A. , Rivera Adolfo Cordero
Published: March 2003

Summary

1. Ceriagrion tenellum females show genetic colour polymorphism. Androchrome (erythrogastrum) females are brightly (male‐like) coloured while gynochrome females (typica and melanogastrum) show cryptic colouration.

2. Several hypotheses have been proposed to explain the existence of more than one female morph in damselfly populations. The reproductive isolation and intraspecific mimicry hypotheses predict greater survival of gynochrome females, while the density dependent hypothesis predicts no differential survival between morphs.

3. Mature males had greater recapture probability than females while the survival probability was similar for both sexes. Survival and recapture rates were similar for androchrome and gynochrome females.

4. Gynochrome females showed greater mortality or migration rate than androchrome females during the pre‐reproductive period. This result is not predicted by the above hypotheses or by the null hypothesis that colour polymorphism is only maintained by random factors: founder effects, genetic drift, and migration.
Gut content analysis and a new feeding group classification of termites
Authors: Donovan S. E. , Eggleton P. , Bignell D. E.
Published: March 2003

1. Gut content analysis of termites was undertaken using microscopical techniques. The 46 study species covered the entire range of taxonomic and feeding forms within the Order.

2. Inter‐specific gut contents data were analysed using principal components analysis, placing species along a clear humification gradient based on variations in the amount of silica and plant tissue fragments in the gut.

3. Redundancy analysis was used to find morphological correlates of the observed variation in gut contents. A total of 22 morphological characters (out of 45 candidate characters) were correlated significantly with the gut contents.

4. Three of the 22 significantly correlated characters unambiguously defined feeding groups, which were designated groups I to IV in increasing order of humification of the feeding substrate. Group I contains lower termite dead wood and grass‐feeders; group II contains Termitidae with a range of feeding habits including dead wood, grass, leaf litter, and micro‐epiphytes; group III contains Termitidae feeding in the organic rich upper layers of the soil; group IV contains the true soil‐feeders (again all Termitidae), ingesting apparently mineral soil. These groupings were generally supported statistically in a canonical covariance analysis, although group II apparently represents termite species with a rather wide range of feeding habits.

5. Using existing hypotheses of termite phylogenetic relationships, it seems probable that group I feeders are phylogenetically basal, and that the other groupings have arisen independently on a number of occasions. Soil‐feeding (i.e. group III and group IV feeding) may have evolved due to the co‐option of faecal material as a fungal substrate by Macrotermitinae‐like ancestral forms. As a consequence, these forms would have been constrained to build nest structures from soil and would therefore have passed at least some soil through their guts.
Reproductive allocation within a polygyne, polydomous colony of the antMyrmica rubra
Authors: Walin Laura , Seppä Perttu , Sundström Liselotte
Published: March 2003

1. Ant colonies commonly have multiple egg‐laying queens (secondary polygyny). Polygyny is frequently associated with polydomy (single colonies occupy multiple nest sites) and restricted dispersal of females. The production dynamics and reproductive allocation patterns within a population comprising one polygyne, polydomous colony of the red antMyrmica rubrawere studied.

2. Queen number per nest increased with nest density and the number of adult workers increased with the number of resident queens and with nest density. This suggests that nest site limitation promotes polygyny and that workers accumulate in nest units incapable of budding.

3. Nest productivity increased with the number of adult workers and production per queen was independent of queen number. Productivity increased with nest density, suggesting local resource enhancement. This shows that productivity can be a linear function of queen numbers and that the limiting factor is not the egg‐laying capacity of queens.

4. The total and per capita production of reproductives decreased towards the periphery of the colony, suggesting that the spatial location of nest units affects sexual production. Thus nests at the periphery of the colony invested more heavily in new workers. This is consistent with earlier observations in plants and could either represent investment in future budding or increased defence.

5. The colony produced only five new queens and 2071 males, hence the sex ratio was extremely male biased.
Hosts as habitats: faunal similarity of phytophagous insects between host plants
Authors: Frenzel Mark , Brandl Roland
Published: March 2003

Summary

1. Published lists on the phytophages recorded on 86 cabbage plant species (Brassicaceae) and 30 thistle species (Cynaroideae) were used to investigate patterns in the faunal similarity of phytophages. This was done by calculating the Jaccard index and a standardised index of similarity between pairs of host species using presence/absence data.

2. The faunal similarity measured as Jaccard indices indicated that pairs of cabbage hosts share on average 36% of phytophagous species whereas pairs of thistle hosts share only 10%.

3. The faunal similarity between two host species increased with the taxonomic affinity of hosts. This increase was more pronounced in thistles than in cabbage plants.

4. Irrespective of the taxonomic affinity of hosts, in the cabbage plants the faunal similarity of endophages was lower than in ectophages. In contrast, in the thistles faunal similarity differed only between endophages and ectophages for hosts of the same genera.

5. Differences in the patterns of faunal similarity between the two host taxa may be due to idiosyncratic characteristics of the plant taxa, e.g. the unique chemical properties of the cabbage plants and the resource‐rich flower heads of thistles.
Effects of photoperiod, temperature, and host plant age on induction of reproductive diapause and development time in Danaus plexippus
Authors: Goehring Liz , Oberhauser Karen S.
Published: March 2003

Abstract 1. Diapause induction in monarch butterflies Danaus plexippus was studied using adults captured from the wild in Minnesota and Wisconsin, and individuals reared under outdoor and controlled conditions.

2. Oocyte presence in females and ejaculatory duct mass in males were used to indicate reproductive status.

3. Some wild individuals were in diapause in mid‐August, and all males and females were in diapause by late August and early September respectively.

4. Individuals reared under decreasing day lengths and fluctuating temperatures were more likely to be in diapause than were individuals reared under long or short day lengths or constant temperatures.

5. Individuals fed potted old Asclepias curassavica plants were more likely to be in diapause than were those fed potted young host plants; when cuttings of Asclepias syriaca plants from the field or greenhouse pots were used, there was no effect of host plant age.

6. Extremely high temperatures increased the number of day‐degrees required for development from egg to adult, while decreasing day lengths and older host plants tended to decrease the number of day‐degrees required for development.

7. There appears to be a continuum of reproductive development in monarchs, with gradual declines in mean ejaculatory duct mass and oocyte production during the late summer.

8. None of the experimental treatments led to 100% diapause, and diapause was more likely to occur in monarchs subjected to more than one diapause‐inducing cue.
High‐altitude migration of the diamondback moth Plutella xylostella to the U.K.: a study using radar, aerial netting, and ground trapping
Authors: Chapman Jason W. , Reynolds Don R. , Smith Alan D. , Riley Joe R. , Pedgley David E. , Woiwod Ian P.
Published: March 2003

Abstract 1. The high‐altitude wind‐borne migration of the diamondback moth Plutella xylostella in the U.K. in 2000 was investigated (a) by direct monitoring of insect flight by vertical‐looking radar and by aerial netting, and (b) through evidence of temporal variation in P. xylostella abundance deduced from a network of light traps.

2. Migrating P. xylostella were identified by a unique combination of size and shape data derived from the continuously operating vertical‐looking radar.

3. Radar‐detected migratory overflights correlated significantly with associated peaks in abundance of P. xylostella estimated by catches in a U.K.‐wide light trap network; however the correlation was stronger when light trap catches were lagged by 1 day.

4. The first notable catches of P. xylostella in the U.K. occurred in early May, and were accompanied by migrations over the radar from the east.

5. Radar data and back‐tracking indicated that a major wind‐borne migration of P. xylostella from The Netherlands to southern England took place in early May, and that this was responsible for the establishment of the U.K. population.

6. The origin of early‐season P. xylostella occurring in Britain is discussed.