bluuebunny/crossref_metadata_2025 huggingface dataset:
Warthin's tumour: unusual vs. common morphological findings in fine needle aspiration biopsies
Authors: FLEŽAR MARGARETA , POGAČNIK ANA
Published: March 2003

Fine needle aspiration biopsies (FNA) of 47 Warthin's tumours confirmed by histology were re‐evaluated for cytomorphological findings. The majority of aspirates (37/47) contained a typical background with proteinaceous substance and cell debris, along with cellular elements represented by oncocytic, lymphoid, and mast cells with degranulated cytoplasm. Uncommon cellular findings were true squamous cells (1/47), atypical cells with vacuoles (1/47), osteoclastic giant cells (1/47), epithelioid cells (1/47), mast cells with preserved granules in cytoplasm (3/47), and siderophages (4/47). Uncommon findings in the background were corpora amylacea‐like structures and homogeneous bright red droplets. Squamous cells and atypical cells with vacuoles caused diagnostic difficulties in distinguishing a Warthin's tumour from a squamous cell or mucoepidermoid carcinoma. However, other unusual cellular and background findings were not worrying; therefore, they are merely regarded as a curiosity in the cytomorphological appearance of the tumour.
Archival cervical smears: a versatile resource for molecular investigations
Authors: Hamidi Amina E. L. , Liu Hongxiang , Zhang Yun , Hamoudi Rifat , Kocjan Gabrijela , Du Ming‐Qing
Published: March 2003

Archival cervical smears: a versatile resource for molecular investigations

Archival cervical smears represent a huge resource of pathological specimens. This, together with long clinical follow‐up data, makes archival smears the most valuable resource for cervical cancer research. Despite this huge potential, only a few molecular investigations have been carried out based on archival smears. It has been shown that archival smears can be used for amplification of genomic sequences by polymerase chain reaction (PCR). However, it is unknown whether PCR can be applied to minute dyskaryotic cells microdissected from archival cervical smears and whether these archival materials are suitable for reverse transcription PCR (RT‐PCR). To address these issues, we prepared DNA and RNA samples from dyskaryotic cells microdissected from archival cervical smears with a storage time of 11 years and systematically tested the extent that these materials can be used for PCR‐based molecular investigations at both DNA and RNA levels. Our results showed that a crude DNA preparation simply by proteinase K digestion was suitable for PCR amplification of genomic sequences. By targeting the amplified genomic sequence to 250 bp or less, most if not all archival smears could be used for PCR and are therefore suitable for screening gene mutations and loss of heterozygosity, human papillomavirus typing, etc. Purified DNA samples from microdissected dyskaryotic cells were adequate for restriction enzyme digestion and could be used for a PCR‐based clonality analysis of the androgen receptor gene. Finally, RNA samples extracted from dyskaryotic cells microdissected from archival smears were adequate for RT‐PCR as long as a gene‐specific primer was used for the RT reaction and the target sequence was restricted to 150 bp or less. In summary, our results demonstrated that archival cervical smears are suitable for a range of molecular investigations at both DNA and RNA levels. The potential gain of knowledge on cervical cancer by the molecular study of archival smears is immense.
Gaucher's disease: morphological findings in a case studied with fine needle aspiration
Authors: Ortiz J. , Abad M. , Muriel M. , Fernández D. , Bullón A.
Published: March 2003

Fine needle aspiration (FNA) is a diagnostic tool whose inexpensiveness, simplicity and innocuousness have led it to be increasingly accepted in daily medical practice. This method, which is useful for the study of lesions that are accessible by radiological exploration or palpation, provides information about the cytological aspects of punctured lesions. Sometimes, such information can be extended to the histological area through study of cell blocks, true microbiopsies, which are of great diagnostic use. This was the technique used in the case described in the present report.
Stem‐boring insects of fragmented Calamagrostis habitats: herbivore–parasitoid community structure and the unpredictability of grass shoot abundance
Authors: DUBBERT MARK , TSCHARNTKE TEJA , VIDAL STEFAN
Published: March 2003

Abstract.1. Communities of stem‐boring insects attacking the grass
Calamagrostis epigeios (L.) Roth were analysed from twenty‐five pure stands of C. epigeios differing in area and isolation. Insect communities comprised nine phytophagous and eighteen entomophagous species. Most abundant herbivores (attacking > 1% of all shoots) were Tetramesa eximia (Giraud) (Hym. Eurytomidae), Eurytoma sp. (Hym. Eurytomidae), Lasioptera calamagrostidis (Rübs.) (Dipt. Cecidomyiidae), and Eriopeltis sp. (Hom. Pseudococcidae). About 28% of the twenty‐seven species were monophagous, 61% oligophagous (restricted to Poaceae), and 11% polyphagous. Although herbivores generally attacked thick shoots, species‐specific differences in the attacked mean diameter were found.2. The main purpose of this study was to analyse the relative effects of area, isolation and unpredictability of available food resources on the abundance of herbivores, parasitoids and resulting tritrophic effects. Variability of shoot abundance varied greatly between years, and even more between habitats within the same year. On average, shoot density per habitat increased or decreased 2.4‐fold between succeeding years.3. Variability of grass shoot abundance was not related to habitat characteristics such as area, isolation, biomass, shoot density, changes in area or shoot density between years, or shoot features like internode number or diameter, but was negatively influenced by shading of trees. Similarly, habitat area or isolation did not correlate with other habitat features.4. Grass shoot abundance was the most important predictor of species abundance and attack rate of herbivores. In contrast to expectations, area and isolation of habitats did not explain differences in species richness, and only influenced abundance of three species. In addition, even the experimental removal of all grass shoots (and thereby, of all stem‐boring insects) from five habitats in winter did not negatively influence colonization the following year. These results suggest a surprisingly high mobility of this rather specialized community of stem‐boring insects that appeared to superimpose on area and isolation effects. Unpredictability of grass shoot abundance was presumably the main selection pressure for the obviously high dispersal abilities of the Calamagrostis insects.5. Per cent parasitism was mainly influenced by the percentage of attacked shoots. Parasitism of T. eximia by its major parasitoid also correlated with habitat connectivity, emphasizing the hypothesis that a continuum of habitats should be particularly favourable for the third trophic level.
The use of kairomones for foraging decisions by an aphid parasitoid in small host aggregations
Authors: SHALTIEL LIORA , AYAL YORAM
Published: March 2003

1. The wasp Diaeretiella rapae uses honeydew emitted by its host, the cabbage aphid Brevicoryne brassica, as a kairomone (chemicals emitted by an organism as part of its activity and used by its natural enemies to their advantage). The role of the kairomone in foraging decisions by the parasitic wasp was explored by manipulating the amount of honeydew and the number of aphids in a colony independently. The count‐down patch‐exploitation mechanism (Iwasa et al., 1981) was employed to predict the results of these manipulations and contrast them with the predictions of Waage's (1979) model.

2. Kairomonal activity of honeydew decreased as the honeydew aged and lost its activity completely within 72 h.

3. The wasp was exposed to different amounts of honeydew on (a) aphid‐free leaves and (b) leaves bearing colonies of 150 aphids. The parasitoid search time on both leaf types increased with increasing honeydew contamination. On aphid‐bearing leaves, the number of attacked aphids in the colonies also increased with increasing honeydew contamination. The presence of aphids reduced the parasitoid search time compared to search time on aphid‐bearing leaves with the same level of honeydew contamination, as predicted by the count‐down model.

4. Parasitoids exposed to the same amount of honeydew, but a different number of aphids in a colony on the leaf, first increased the number of aphids attacked in relation to the number of aphids in the colony. But as the colony reached a certain size, the number of aphids attacked levelled off, despite the increase in the number of aphids in the colony. Search time was variable but did not exhibit any trend as the number of aphids in the colonies increased.

5. These results suggest that honeydew level is used by D. rapae as a cue for assessment of the number of aphids in the colony. In such cases, a count‐down exploitation mechanism gives the best results to a forager. Many parasitoids may use kairomones for patch assessment and will therefore employ a count‐down rule during patch exploitation.
Influence of host plant vs. natural enemies on the spatial distribution of a pine sawfly,Neodiprion autumnalis
Authors: Mcmillin Joel. D. , Wagner Michael R.
Published: March 2003

Abstract.1. The pine sawfly,Neodiprion autumnalis, infests ponderosa pine,Pinus ponderosa, growing at low densities near the bottom of an altitudinal gradient in Arizona, U.S.A. The relative importance of host‐plant quality vs. natural‐enemy effects in determining the spatial distribution of this sawfly was examined over a 3‐year period.

2. Field and laboratory bioassays were conducted on all life stages ofN. autumnalisat two forest stand densities (high ≥ 23 m2ha–1, low ≤ 7 m2ha–1) and at two elevations (bottom slope = 2390 m, top slope = 2540 m). These experiments were used for constructing life tables ofN. autumnalisthat compared the effects of host‐plant quality on oviposition preference and progeny performance with the effects of natural enemies at different tree densities and elevations.

3. Life‐table analyses determined that mortality attributed to host‐plant effects during the egg and larval stages had the largest impact on fitness between tree densities and elevations.

4. Natural enemies caused a significant reduction in progeny survival, but their effects were similar across all tree densities and elevations during egg and larval life stages. However, cocoon‐stage survival did vary between tree densities and elevations due to natural‐enemy effects.

5. It was concluded that the observed oviposition preference for, and higher progeny performance on, trees at low densities and bottom slope elevations were caused primarily by host‐plant effects.

6. These results further the argument that heterogeneity at the resource level (i.e. bottom‐up forces) determines potential outcomes of multitrophic level interactions.
Desiccation tolerance and starvation resistance exhibit opposite latitudinal clines in Indian geographical populations of Drosophila kikkawai
Authors: Karan Dev. , Parkash Ravi.
Published: March 2003

Abstract.1. Desiccation tolerance and starvation resistance demonstrated significant differentiation among seven Indian geographical populations of Drosophila kikkawai, collected along a latitudinal range of 12.6–32.7 °N. Lack of significant differences in two successive generations suggested that these physiological traits were genetically controlled.

2. North Indian populations of D. kikkawai displayed significantly higher desiccation tolerance than southern populations, whereas there was a reverse trend for starvation tolerance (r > 0.90). Regression slope values indicated an increase of 0.61 h for desiccation and a decrease of 1.71 h per degree latitude for starvation tolerance at 17 °C. The traits evidenced opposite latitudinal clines, and such data also matched thermal climatic conditions on the Indian subcontinent. The survival duration for such traits was significantly higher at 17 than at 25 °C.

3. Significantly higher starvation tolerance in south Indian populations might be due to large population size, species interactions, and higher metabolic rates in the humid tropical environments. In contrast, prolonged unfavourable colder climatic conditions are known to favour starvation tolerance in temperate regions. Thus, the causes of desiccation and starvation tolerance seem quite different under tropical and temperate conditions.

4. Starvation tolerance was correlated negatively with body weight and ovariole number, which might be due to a trade‐off in favour of greater allocation to non‐lipidic reserves for sustaining starvation tolerance in the tropics. Reduction in metabolic rate may not be applicable for observed higher starvation tolerance in the tropical populations.

5. Multiple regression analysis demonstrated a major effect of coefficient of variation of mean monthly temperature for both the traits of ecological significance. Thus, Indian geographical populations of D. kikkawai provided evidence of independent genetic divergence for starvation and desiccation tolerance under natural conditions.
Foraging in yellow dung flies: testing for a small‐male time budget advantage
Authors: Blanckenhorn WolF. U. , Viele StuD. N. T.
Published: March 2003

1. Mating and foraging are generally mutually exclusive activities. Individuals are thus faced with a continuous trade‐off between time and energy expended in foraging and mating, but different phenotypes should respond to this trade‐off in different ways.

2. Sexual selection theory predicts that females should maximize their time and energy spent gathering resources, whereas males should maximize their time and energy spent obtaining mates, thus minimizing their time spent foraging, subject to the constraint that they need to forage minimally to sustain their activity.

3. Smaller individuals require less food to maintain their activity. Small males in particular could therefore increase mating effort at the expense of foraging effort and, all else being equal, may thus enjoy a time budget advantage relative to large males. On the other hand, larger individuals may compensate by being more efficient at finding prey and/or extracting nutrients.

4. The effects of sex, body size, and prey density on foraging time budgets of male and female yellow dung flies, Scathophaga stercoraria, were investigated in the laboratory.

5. Higher prey density (Drosophila melanogaster) resulted in reduced feeding (= handling) and hunting (= waiting or search) times for both sexes, as predicted by the marginal value theorem applied to foraging theory. Females fed longer on a prey item than did males, and also caught the next prey item more quickly. Large individuals extracted nutrients more quickly, but were not faster at catching prey. Small individuals satiated more quickly than larger individuals and also ate fewer prey items.

6. These results are largely consistent with the predictions and suggest a small‐male time budget advantage in the yellow dung fly. Integrating the various predictions to test directly for a small‐male time budget advantage is difficult in the laboratory, however, because hunting times are unlikely to reflect the natural situation. To what extent these results lead to increased probabilities for small males of obtaining matings in the field remains to be demonstrated.
Flexible larval development and the timing of destructive feeding by a solitary endoparasitoid: an optimal foraging problem in evolutionary perspective
Authors: Hemerik LiA. , Harvey Jeffrey A.
Published: March 2003

1. In studying the evolution of life‐history strategies in parasitoids, considerable attention has been paid to the relationship between host quality and parasitoid fitness. Various workers have reported that host quality influences parasitoid size, development time, and survival. Because body size is frequently correlated with fecundity, longevity, and host‐finding ability in parasitoids, this parameter is usually considered to be the main target of selection.

2. In koinobiont parasitoids that consume the entire host before pupation, adult parasitoid size and development time are often strongly correlated with host size at the time when it is developmentally arrested through destructive feeding by the parasitoid larva.

3. Here, a mathematical model is proposed to describe the larval feeding behaviour of the solitary koinobiont endoparasitoid Venturia canescens in four larval stadia of its host Plodia interpunctella. In particular, the model describes how adult size, represented by an exponential growth rate, and development time are traded off when the parasitoid develops in nutritionally suboptimal second stadium hosts.

4. Using a graphical model, the different conditions faced by V. canescens during development in various host species of greatly differing mass are illustrated.

5. It is argued that the relative importance of size and development time on parasitoid fitness is determined by ecological and biological characteristics of both host and parasitoid, and it is suggested that there may be correlations between life‐history traits and host‐utilisation strategies among koinobionts.
Effects of phytochemical variation in quaking aspen Populus tremuloides clones on gypsy moth Lymantria dispar performance in the field and laboratory
Authors: Osier Tod L. , Hwang Shaw‐Y. , Lindroth Richard L.
Published: March 2003

1. This study investigated how phytochemical variation among clones of quaking aspen Populus tremuloides, growing in a common habitat, affects the growth and fecundity of a model herbivore.

2. Gypsy moth Lymantria dispar larvae were reared from egg hatch to pupation on 10 aspen clones in the field or on excised foliage in the laboratory. Foliage was collected from each clone, and concentrations of phenolic glycosides, condensed tannins, nitrogen, and water were determined.

3. Herbivore fitness parameters and aspen phytochemical concentrations varied significantly among clones. In both the field and laboratory, larvae reared on clones containing high concentrations of phenolic glycosides exhibited prolonged developmental times and reduced pupal weights and fecundity. Herbivore performance parameters were also related positively to foliar nitrogen concentrations in the laboratory. Food consumption, but neither growth nor reproductive parameters, were related positively to condensed tannin concentrations.

4. In this study, foliar concentrations of phenolic glycosides were implicated as a significant determinant of food quality for gypsy moths, consistent with results of previous laboratory experiments. Additionally, this study documents a case in which host plant variation at a local level influences the performance and possibly the distribution and abundance of an important herbivore.
The size–distance relationship in the wood ant Formica rufa
Authors: Wright Philip J. , Bonser Robert , Chukwu Uchegbu O.
Published: March 2003

1. The size–distance relationship among honeydew‐collecting foragers of the red wood ant Formica rufa was investigated. Within the colony territory, the size (as measured by head width) and fresh weight of samples of foragers were determined for ants ascending and descending trees near, and farther from, the central nest mound.

2. The mean size of the ants was significantly higher at far trees than at near trees in six out of the seven colonies investigated, confirming the general presence of the size–distance relationship.

3. In three colonies, a load–distance relationship was also found. For a given head width, honeydew‐carrying ants descending far trees were significantly heavier than those descending near trees (i.e. they were carrying heavier loads from trees farther away from the central nest mound).

4. This is the first time that both load–distance and size–distance relationships have been reported in foraging workers from the same ant colony.

5. The combined effects of these characteristics suggest that colony foraging efficiency is enhanced by far trees being visited by the larger workers that then return with heavier loads of honeydew.
Diet and size influence sexual advertisement and copulatory success of males in Mediterranean fruit fly leks
Authors: Kaspi Roy , Taylor Phillip W. , Yuval Boaz
Published: March 2003

1. The objective of the work reported here was to test the hypothesis that in insects that invest considerable energy in sexual displays and courtship, foraging successfully for food affects their subsequent performance and copulatory success in leks. Accordingly, the interactions between body size and diet on initiation of lekking behaviour and copulatory success in male Mediterranean fruit flies Ceratitis capitata (Diptera: Tephritidae) were investigated.

2. Protein‐fed males were heavier and contained more protein and less lipid reserves than protein‐deprived males. Protein‐fed males were more likely to emit pheromone in leks and, consequently, were more likely to copulate than protein‐deprived males. Furthermore, protein‐fed males tended to start calling earlier than their nutritionally deprived competitors.

3. Though size was not related to initiation of lek behaviour, large males were more likely to copulate than small males. Among protein‐fed males, large individuals tended to mate earlier than smaller individuals.

4. Generally, in lek mating systems where a considerable investment of time and energy is required by males, foraging successfully for nutritional resources prior to engaging in territorial or courtship behaviour is essential for reproductive success.
Insect colonisation sequences in bracts of Heliconia caribaea in Puerto Rico
Authors: Richardson Barbara A. , Hull Gillian A.
Published: March 2003

1. It was predicted that insects colonising Heliconia phytotelmata would exploit the different bract conditions along inflorescences, which result from sequential ageing.

2. Flowering of H. caribaea is asynchronous over a 6‐month period. A method of identifying bracts of the same age, regardless of position on the inflorescence or inflorescence age, and from different plants over 2 years, was developed using comparative flowering phenology.

3. Heliconia insect larval communities were remarkably consistent from year to year in species composition and relative abundance. Occurrence within the plant population was also similar from year to year, and most species were Heliconia specific.

4. Significant interspecific differences were found in bract utilisation, with populations peaking at different stages of bract development. Ceratopogonid larvae were the earliest colonisers, followed by psychodids, syrphids, and culicids. Tipulids occurred much later in the cycle of bract development and ageing. These patterns were consistent in both years.

5. Patterns of bract utilisation provide strong support for temporal niche partitioning by variation in oviposition and development time. Communities were not considered to be structured by predation or pH changes along the bract sequence.
Male pioneering as a mating strategy: the case of the beetle Maladera matrida
Authors: Harari Ally R. , Ben‐Yakir David , Rosen David
Published: March 2003

1. The phenomenon of male pioneering, whereby males are active (daily) before females, is compared with protandry, a phenomenon whereby males are sexually matured before females. The effects of natural selection and sexual selection on both phenomena are discussed.

2. In Maladera matrida Argaman (Coleoptera: Scarabaeidae), males emerged from the soil a few minutes before females, every evening, to feed and mate.

3. Aggregations of males and females are formed at sites of plant damage where males initiated feeding.

4. All copulations were initiated at the beginning of the activity period so males that emerge earlier may increase their probability of finding a mate.

5. Females mate only once in an evening.

6. Males that emerge later may not find receptive females with which to mate.

7. The aggregation of beetles per se did not contribute to the individual mating success because it occurred during and after the copulating had begun.

8. Male pioneering may evolve through sexual selection by means of male–male competition in time to achieve receptive females.
Reduced flight capability in British Virgin Island populations of a wing‐dimorphic insect: the role of habitat isolation, persistence, and structure
Authors: Denno Robert F. , Hawthorne David J. , Thorne Barbara L. , Gratton Claudio
Published: March 2003

1. The effects of habitat isolation, persistence, and host‐plant structure on the incidence of dispersal capability (per cent macroptery) in populations of the delphacid planthopper Toya venilia were examined throughout the British Virgin Islands. The host plant of this delphacid is salt grass Sporobolus virginicus, which grows either in undisturbed habitats (large expanses on intertidal salt flats and around the margins of salt ponds, or small patches of sparse vegetation on sand dunes along the shore), or in less persistent, disturbed habitats (managed lawns).

2. Both sexes of T. venilia were significantly more macropterous in disturbed habitats (77.1% in males, 12.5% in females) than in more persistent, undisturbed habitats (19.2% in males, < 1% in females).

3. Males exhibited significantly higher levels of macroptery (26.9 ± 7.6%) than did females (2.0 ± 1.7%), and per cent macroptery was positively density dependent for both sexes in field populations.

4. There was no evidence that the low incidence of female macroptery in a subset of island populations inhabiting natural habitats (1.7 ± 1.2%) was attributable to the effects of isolation on oceanic islands. The incidence of macroptery in British Virgin Island populations of T. venilia was not different from that observed in mainland delphacid species existing in habitats of similar duration.

5. Rather, the persistence of most salt grass habitats throughout the British Virgin Islands best explains the evolution of flight reduction in females of this island‐inhabiting delphacid.

6. Males were significantly more macropterous in populations occupying dune vegetation (37.6 ± 9.8%) than in populations occupying salt flat–pond margin habitats (7.6 ± 5.6%). By contrast, females exhibited low levels of macroptery in both dune (0%) and salt flat–pond margin (< 1%) habitats. Variation in salt‐grass structure probably underlies this habitat‐related difference in macroptery because flight‐capable males of planthoppers are better able to locate females in the sparse‐structured grass growing on dunes. This habitat‐related difference in male macroptery accounted for the generally higher level of macroptery observed in males than in females throughout the islands.

7. The importance of habitat persistence and structure in explaining the incidence of dispersal capability in T. venilia is probably indicative of the key role these two factors play in shaping the dispersal strategies of many insects.
Changes in abundance of Vespula germanica and V. vulgaris in England
Authors: Archer Michael E.
Published: March 2003

1. Thirteen time series, varying from 17 to 27 years, of the abundance of Vespula germanica and V. vulgaris from lowland England are examined. The time series depend on either spring queens and workers taken in Malaise or suction traps, or collected colonies.

2. During the late 1970s and early 1980s, the abundance of V. germanica declined abruptly but that of V. vulgaris did not.

3. During the early 1980s, the 2‐year cycle of annual abundance of V. vulgaris changed to a nearly perfectly damped pattern of annual abundances.

4. The most likely factor causing these population changes was the increased use of pesticides acting directly by killing the wasps and indirectly by reducing their food resources.

5. The difference in response of the two species to increased pesticide use may be related to a difference in foraging ability.
Macrogeographic clines in fecundity, reproductive allocation, and offspring size of the forest tent caterpillar Malacosoma disstria
Authors: Parry Dylan , Goyer Richard A. , Lenhard Gerald J.
Published: March 2003

1. The fecundity of the forest tent caterpillar varies considerably across its geographic range. Field data indicate that populations in the southern United States (Gulf States) produce nearly twice as many eggs as females from Canada or the Lake States, with little or no difference in the size of adult females.

2. In controlled rearing experiments, female forest tent caterpillar from the southern United States (Louisiana) had much larger clutch sizes than same sized females from northern populations in Michigan or Manitoba, Canada. Increased fecundity in Louisiana females was achieved through a significant reduction in egg size and a concomitant increase in the allocation of resources to egg production.

3. Comparison of 10 forest tent caterpillar populations spanning a 27° latitudinal gradient, validated the results of detailed comparisons among the three populations above by confirming the strong negative correlation between latitude and clutch size.

4. Neonate forest tent caterpillars from Manitoba were significantly larger than larvae from either Michigan or Louisiana. Michigan larvae were intermediate in size. It is postulated that large neonates are advantageous in thermally limiting environments. More than three times as many degree‐days are available to Louisiana neonates during the first 2 weeks after hatching. A consistently favourable climate during the vulnerable post‐hatching period may have allowed the evolution of larger clutches at the expense of neonate size in southern populations.
Reduced realised fecundity in the pine looper Bupalus piniarius caused by host plant defoliation
Authors: Šmits Agnis , Larsson Stig , Hopkins Richard
Published: March 2003

1. Whether the potential fecundity of herbivorous insects is realised or not may depend on female behaviour, which in turn may be influenced by host plant acceptability. Female Bupalus piniarius were observed to discriminate against needles growing out the year following defoliation (current‐year needles) of its host plant Pinus sylvestris.

2. It was hypothesised that the discriminatory behaviour was due to current‐year needles being less secure as a substrate. Field and laboratory experiments were designed to test this hypothesis and to estimate the discrepancy between potential and realised fecundity when females were offered defoliated branches.

3. In a laboratory oviposition experiment, B. piniarius females were exposed to branches bearing either current‐year needles only or both mature and current‐year needles. Daily oviposition rate, egg batch size, longevity, and mature eggs and fat retained at death were recorded for each female. In field experiments, the rate at which eggs dropped from expanding needles and the capacity of neonate larvae hatching from the dropped eggs to colonise a tree were assessed.

4. Significantly fewer eggs were laid when females were exposed to defoliated branches.

5. Twenty‐six and 16% of the eggs laid on current‐year needles dropped from the needles in 1998 and 1999 respectively, whereas no eggs dropped from mature needles in 1998 and only one egg (< 1%) dropped in 1999.

6. A very small proportion of larvae hatching on the forest floor (simulated egg drop) was able to recolonise host trees.

7. These results emphasise the importance of oviposition behaviour on realised fecundity when analysing insect population dynamics. In the case of B. piniarius, egg placement, although a minor detail during the normal course of events, became of key importance when defoliation deprived females of their preferred egg attachment site.
Determinants of sperm precedence in a noctuid mothHeliothis virescens: a role for male age
Authors: Lamunyon Craig W.
Published: March 2003

1. Females of the noctuid mothHeliothis virescensF. mate more than once. Thus, sperm from two or more males normally compete for fertilisations within the female reproductive tract. The eggs are typically fertilised by sperm from only one male, either the female's last mate or an earlier mate. Twice‐mated females store only one ejaculate's worth of fertilising sperm (eupyrene) but nearly two ejaculates' worth of a nonfertilising sperm morph (apyrene), which is thought to play a role in sperm competition.

2. The mechanism of sperm use inH. virescenswas investigated by examining factors that vary with paternity, which was assigned based on allozyme variation. The factors included male and female body masses and ages, male genital characters, the size of the sperm package, and the number of sperm stored by the female.

3. One male typically gained sperm precedence; this was nearly twice as likely to be the second male as it was to be the first. Two factors were found to vary significantly with paternity: female mass and male age. The second male to mate was more likely to gain sperm precedence if the female was larger and if the male was older than the female's first mate.

4. The significance of male age and female mass to several hypothetical models of the mechanism of sperm use is discussed.
Oviposition preferences of the Hessian fly and their consequences for the survival and reproductive potential of offspring
Authors: Harris M. O. , Sandanayaka M. , Griffin W.
Published: March 2003

1. The relationship between oviposition preference and offspring performance was investigated experimentally for the Hessian flyMayetiola destructor(Say) using 10 grass genotypes that represented five different genera and six different species. Oviposition preferences were quantified in a choice test using arrays of 200–400 plants. Offspring performance was estimated by recording survival during three phases of the insect–plant association and by measuring wing length, a correlate of adult reproductive potential. Density effects were examined for all offspring variables, and were taken into account when offspring performance was compared across the 10 grasses.

2. Egg counts from the oviposition choice test revealed a consistent ranking of plants: 18ITSN triticale > Otane bread wheat = Caldwell bread wheat = Stacy bread wheat > 3424 bread wheat = PND durum wheat = Fleet barley = Valetta barley = Matua brome grass > Awapuni oat.

3. Survival and adult wing length varied significantly on the 10 plant types. Survival was ranked: Otane bread wheat > 3424 bread wheat = Fleet barley = Matua brome grass > Caldwell bread wheat = Valetta barley > 18ITSN triticale = PND durum wheat = Stacy bread wheat > Awapuni oat. Adult male and female wing lengths were greatest on Otane, the bread wheat that also provided the best survival.

4. For Hessian flies on each of the 10 plant types, data on survival, wing length, and wing length–fecundity relationships were combined into a single fitness measure. When these fitness measures were compared with egg counts, no overall pattern emerged. On seven of the 10 plant types, there was a positive linear relationship between egg counts and offspring fitness. On the other three plant types, egg counts were high while fitness was low. Possible reasons why Hessian fly females lay eggs on plants that are poor hosts for their offspring are discussed.
Parental care in the whitefly Aleyrodes singularis
Authors: Guershon Moshe , Gerling Dan
Published: March 2003

1. Patches of Aleyrodes singularis nymphs are characterised by a distinctive phenotype composed of the nymphs' exuviae, which are piled on the nymph, and by a covering layer of wax secreted by the adults; these characteristics have been found to confer defensive properties against natural enemies.

2. In contrast to the behaviour typical for ovipositing females of other aleyrodids, A. singularis females tend to remain near the patch of their progeny throughout their development. These mothers were therefore tested to show whether they exhibited active defensive behaviour towards natural enemies, beyond their contribution to passive defence achieved through the secretion of wax on the immatures.

3. The behaviour of whitefly adults differed significantly when performed in the presence of conspecific adults from their behaviour in the presence of natural enemies (either a parasitoid or a predator). The differences were expressed in the mean time devoted to some behavioural events, the frequency at which events were performed, and the number of transitions between pairs of events.

4. Most of the recorded behavioural differences were associated with departure of the natural enemies, facilitating immature survival.

5. This is the first report of active behavioural changes that convey defence of immature offspring for the family Aleyrodidae. Conditions characterising these findings and their relationship with those in which parental care is expected are discussed.
Avoidance of occupied hosts by the Hessian fly: oviposition behaviour and consequences for larval survival
Authors: Kanno H. , Harris M. O.
Published: March 2003

Abstract1. Unoccupied wheat plants and wheat plants occupied by conspecific eggs or larvae were presented to ovipositing female Hessian flies in choice tests.

2. The presence of conspecific eggs on the leaf surfaces of wheat plants did not appear to have any effect on the responses of ovipositing Hessian fly females.

3. The presence of conspecific larvae at the base and nodes of wheat plants for 1, 6, or 11 days had significant effects on Hessian fly oviposition. Eggs oviposited on plants were inversely proportional to larval densities and days of larval occupation.

4. Feeding by Hessian fly larvae is associated with several changes in wheat plants. One of these changes, the growth arrestment of the plant, was measured by recording the heights of plants used in oviposition tests. Plant heights were inversely proportional to both larval densities and days of occupation. Plant heights were directly proportional to eggs oviposited on plants.

5. The consequences of adult female avoidance of plants occupied by conspecific larvae were investigated by allowing females to oviposit on unoccupied plants and 1‐day, 6‐day, and 11‐day larval occupied plants, then scoring at the end of the first larval instar the survival of the offspring that resulted from this oviposition.

6. Survival during the first larval instar was 88% for the offspring of females that oviposited on unoccupied plants, decreasing to 82, 31, and 4% on the 1‐day, 6‐day, and 11‐day occupied plant treatments. On these four plant treatments, a positive correlation was found between larval performance (i.e. survival) and the preferences of ovipositing females.

7. On the four plant treatments, relationships between first‐instar larval density and first‐instar larval survival varied significantly. On unoccupied plants, survival was inversely proportional to density. On plants oviposited on at 6 days of larval occupation, survival was directly proportional to density.
Chemical defence ofBattus philenorlarvae against attack by the parasitoidTrogus pennator
Authors: Sime Karen
Published: March 2003

Abstract1. Parasitoids in the genusTrogus(Hymenoptera: Ichneumonidae) attack the larvae of swallowtail butterflies (Lepidoptera: Papilionidae). Only two of the three major tribes of the subfamily Papilioninae are attacked although species of all three tribes commonly occur together. The tribe Troidini is relatively free of parasitoids of any kind, and it has been proposed that the aristolochic acids sequestered by troidines protect them from parasitism.

2. The responses ofT. pennator(Fabricius) to the sympatric troidineBattus philenor(Linnaeus) were examined. Three hypotheses that could explain why this wasp does not parasitiseB. philenorwere considered. (1)Battus philenordoes not produce compounds used by the wasp to locate hosts. (2) The larval integument contains compounds that deter attack. (3) The parasitoid offspring cannot survive inB. philenor.

3. The first hypothesis was not supported as the frass ofB. philenorlarvae was found to act as a searching arrestant comparable to the frass of a host species.

4. The second hypothesis was supported. TheB. philenorlarvae were rejected when the wasps examined them using their antennae, and ethanolic washes ofB. philenorcuticle deterred attack byT. pennatorwhen applied to otherwise acceptable host larvae. Bioassays of fractions of the ethanolic wash and of pure aristolochic acids established that aristolochic acids were at least partly responsible for the deterrent effect.

5. The third hypothesis was also supported. Larvae ofB. philenorattacked by the parasitoids developed into butterflies.

6. These results indicate that both behavioural and physiological barriers, the former attributable at least in part to sequestered compounds and the latter of unknown mechanism, preventT. pennatorfrom parasitisingB. philenor.
Uptake of Bt‐toxin by herbivores feeding on transgenic maize and consequences for the predator Chrysoperla carnea
Authors: Dutton A. , Klein H. , Romeis J. , Bigler F.
Published: March 2003

Abstract  1. Chrysoperla carnea is an important predatory insect in maize. To assess the ecological effects of Bt‐maize, expressing the Cry1Ab protein, on larvae of this predator, the following factors were examined: (1) the performance of three prey herbivores (Rhopalosiphum padi, Tetranychus urticae, and Spodoptera littoralis) on transgenic Bt and non‐transgenic maize plants; (2) the intake of the Cry1Ab toxin by the three herbivores; and (3) the effects on C. carnea when fed each of the prey species.

2. The intrinsic rate of natural increase (rm) was used as a measure of performance for R. padi and T. urticae. No difference in this parameter was observed between herbivores reared on Bt or non‐transgenic plants. In contrast, a higher mortality rate and a delay in development were observed in S. littoralis larvae when fed Bt‐maize compared with those fed the control maize plants.

3. The ingestion of Cry1Ab toxin by the different herbivores was measured using an immunological assay (ELISA). Highest amounts of Cry1Ab toxin were detected in T. urticae, followed by S. littoralis, and only trace amounts detected in R. padi.

4. Feeding C. carnea with T. urticae, which were shown to contain the Cry1Ab toxin, or with R. padi, which do not ingest the toxin, did not affect survival, development, or weight of C. carnea. In contrast, a significant increase in mortality and a delay in development were observed when predators were fed S. littoralis larvae reared on Bt‐maize.

5. A combined interaction of poor prey quality and Cry1Ab toxin may account for the negative effects observed on C. carnea when fed S. littoralis. The relevance of these findings to the ecological risks of Bt‐maize on C. carnea is discussed.
Using age grading by wing injuries to estimate size‐dependent adult survivorship in the field: a case study of the yellow dung fly Scathophaga stercoraria
Authors: Burkhard Dieter U. , Ward Paul I. , Blanckenhorn Wolf U.
Published: March 2003

Abstract 1. Studies of natural selection depend on estimates of longevity and mortality in the wild. In small and mobile species such as insects, direct, mark–recapture (resight), studies are difficult to perform because individuals cannot be tracked easily.

2. It was investigated whether age grading based on wing injuries alone can be used to estimate size‐specific survivorship in the field in the yellow dung fly Scathophaga stercoraria (L.) (Diptera: Scathophagidae).

3. The accumulation of different types of wing injury throughout the spring and autumn flight seasons for both sexes was recorded: tears, notches (both reflecting regular wear), and large missing areas (probably due to intra‐ and inter‐specific interactions).

4. Female longevity increased with body size in both spring and autumn, whereas male longevity increased slightly with size in spring but decreased in autumn.

5. The two sexes and males of different size classes accumulated the various types of wing injury differentially, presumably due to differential patterns of intraspecific interactions. Additionally, body size exhibited a seasonal pattern, complicating interpretation of the relationship between body size and wing injuries.

6. It is therefore concluded that estimating adult viability selection on body size using wing injuries is problematic in dung flies, and potentially also in other species. It is suggested that before this method is applied in any particular species, pilot studies should be conducted to verify whether wing injuries accumulate equally in all classes of individuals of interest. In addition, it is necessary to investigate the causes of different types of wing injury.
Between‐forest variation in vertical stratification of drosophilid populations
Authors: Tanabe Shin‐Ichi
Published: March 2003

Abstract1. The spatial distribution pattern of forest‐dwelling drosophilid flies was compared among species and among four forests with markedly different vertical foliage structures, including secondary and primary forests, with special reference to vertical stratification.

2. All 20 drosophilid species analysed showed vertically stratified distribution patterns, which were detected statistically in at least one forest site during the 2‐year study period. As a whole, the vertical distribution patterns were stable, with or without stratification, over the 2 years.

3. The ratio of species with stratified distribution to the total number of species changed in a similar trend with the vertical foliage complexity of forests, both showing a large gap between secondary and primary forests, even for species common to all four forests.

4. Many species, most of which were tree‐sap feeders, showed highly predictable patterns of vertical stratification across forests and years. This was associated strongly with regular preference for microhabitat, mostly for the canopy, suggesting that the unvarying nature of canopy environments in any forest is very important in producing, maintaining, and promoting the vertical stratification in organism abundance, and contributes to the ubiquity of the pattern.

5. Some species with a wider range of food resources than other species, most of which showed no clear preference for the canopy, were characterised by large between‐forest differences in vertical distribution patterns and tended to show non‐stratified patterns in secondary forests, contributing to the lower ratio of species with stratified distribution in the two secondary forests than in the primary forests.

6. The role of forest structure in organising the environment is discussed; it is suggested that vertical complexity of foliage structure affects the prevalence of vertical stratification in animal communities indirectly through the vertical heterogeneity of environmental conditions.
Life‐history responses of a mayfly to seasonal constraints and predation risk
Authors: Tseng Michelle
Published: March 2003

Abstract. 1. An experiment was conducted in the laboratory to examine the effects of photoperiod and predation risk on life‐history variation in the mayfly Ephemerella subvaria.

2. Both photoperiod and predation risk affected age at maturity significantly but neither factor affected size at maturity. Mayflies perceiving themselves to be late in the growing season matured in fewer days than those perceiving themselves to be early in the growing season. The presence of predators delayed mayfly maturity significantly.

3. These results suggest that the large variation in life‐history traits observed in aquatic insects may be attributed partially to seasonality but that other biotic and abiotic factors may also underlie variation in these traits.