bluuebunny/crossref_metadata_2025_split huggingface dataset:
Population dynamics of Siphoninus philyreae in California in the presence and absence of a parasitoid, Encarsia partenopea
Authors: GOULD JULI R. , BELLOWS THOMAS S. , PAINE TIMOTHY D. 
Published: March 2008

Abstract. 1. Densities of the whitefly, Siphoninus phillyreae Haliday, remained at low levels at two sites where a parasitoid, Encarsia parknopea (Walker), was released on whitefly‐infested ash, Fraxinus sp., and pomegranate, Punica granatum. Populations of S.phillyreae at control sites, where parasitoids were absent, were increasing in density at the beginning of the summer.2. By mid‐summer, E.partenopea had appeared at all four control sites, and densities of S.phillyreae declined to levels similar to those at the release sites.3. In the absence of the parasitoid, the age structure of S.phillyreae populations was dominated by the egg stage, indicating a population increasing in density. After E.partenopea became abundant at a site, the age structure of the population had a decreasing proportion of young stages.4. The changes in S.phillyreae age structures were explained by examining the percentage of fourth instar S.phillyreae from which E.partenopea, as opposed to adult whiteflies, emerged. After the parasitoid became abundant at a site, the majority of fourth instars produced parasitoids rather than whitefly adults. The result was that the adult S.phillyreae population declined, and few eggs were laid.5. The dynamics of the interaction between E.partenopea and S.phillyreae were similar on ash and pomegranate.
The influence of temperature on nest site choice and reproductive strategy in a temperate zone Polistes wasp
Authors: JEANNE ROBERT L. , MORGAN RANDY C. 
Published: March 2008

Abstract. 1. Field experiments with Polistes fuscutus showed that more nests were initiated, co‐foundress groups were larger, broods developed faster, and workers eclosed earlier in sun‐warmed sites than in cool ones.2. These results suggest that colonies nesting in sun‐warmed shelters gained a fitness advantage over those in cooler shelters. More rapid brood development means that such colonies reach the ergonomic stage more quickly, which in turn means a higher expectancy of survival and greater productivity at the end of the season.3. We argue that thermal properties constitute an important component of Polistes nest site quality in temperate regions and that these properties influence joining and usurping strategies as well as nest site choice in spring Polistes females. Other factors being equal, a joining or usurping female should opt for a colony in a warm site over one in a cool site, leading to the larger foundress groups we found in warm shelters.4. We hypothesize that the selective advantage of philopatry in temperate zone Polistes populations is that it brings spring females to nest sites of proven quality.
Family structured patterns of mortality in the false Colorado potato beetle
Authors: McCAULEY DAVID E. 
Published: March 2008

Abstract.1. The distribution of mortality within and among groups of immatureLeptinotursu juncta(Germar) (Coleoptera: Chrysomelidae) was studied in the field at three points in the life‐cycle in order to test whether the fates of individuals occupying the same host plant were non‐independent.2. Studies were conducted on eggs subject to cannibalism and predation, on newly hatched larvae subject to predation, and on older larvae subject to parasitism byMyiophurus doryphorue(Riley), a tachinid fly.3. At all three points in the life‐cycle the variance in group‐specific survivorship rates was demonstrated to be significantly greater than expected when individual deaths are distributed randomly among groups, with standardized variances ranging from 42% to 52% of the maximum possible.4. A statistically significant positive correlation was shown between the number of individuals in a group and the group‐specific survivorship rate at all three life stages.5. The distribution of genetic variants within and among groups of larvae showed the groups to be mixtures of full and half siblings, with an average coefficient of genetic relatedness,r, equal to 0.38.
Daily biphasic behaviour in keratin‐feeding desert trogid beetles in relation to climate
Authors: SCHOLTZ C. H. , CAVENEY S. 
Published: March 2008

Abstract. 1. Patterns of daily activity of two ectothermic species of the trogid genus Omorgus were studied in the Kalahari of southern Africa in summer. The relationship between time and type of activity, and environmental temperature, relative humidity and light intensity, was investigated.2. Beetle activity was biphasic, with peaks in activity at sunset and sunrise in both species.3. Afternoon activity coincided with high temperatures and low humidity and morning activity with minimum daily temperature and maximum humidity.4. Afternoon activity, which peaked at about 34°C and 25% r.h., consisted predominantly of complex breeding behaviour and dispersal. High temperatures are necessary for these activities.5. In the morning feeding predominated. At this time temperature was about 27°C and r.h. above 60%. High r.h. is important because it restricts respiratory loss of water, improves food (moist hair and skin keratin) quality and may compensate for faecal water loss.6. No evidence of competition between the two species was found.
Sex ratio and maternal investment in the multivoltine large carpenter bee Xylocopa sulcatipes (Apoideh: Anthophoridae)
Authors: STARK ROLAND E. 
Published: March 2008

Abstract. 1. Females of the multivoltine carpenter bee Xylocopa sulcutipes (Maa) (Hymenoptera: Anthophoridae) usually excavate a straight tunnel in dead twigs and mass provision a linear array of up to ten brood cells with pollen and nectar. An egg is deposited upon each food mass within one cell.2. Female offspring generally receive a higher provisioning mass (0.180 ± 0.048 g) than males, a significant difference (P > 0.001). There are, however, male larvae that receive as much food or more as their sisters or female larvae reared in another nest.3. There is a close positive association between the size of a mother and the weight of provisions for individual daughters, but not for sons.4. Female offspring are positioned in the innermost brood cells (Gositions 1, 2 and 3). The sex ratio of the outer cells is either significantly male biased (positions 4–6) or skewed towards males (positions 8 and 9). Positions 7 and 10 are in equilibrium.5. Solitary females produce a significantly female biased sex ratio (P < 0.01). Sex ratio in social nests is skewed toward females, but not significantly so (P < 0.2). There is no significant difference between the sex ratio of solitary and social nests (P= 0.361). The population sex ratio (pooled sex ratio of all broods produced) is significantly female biased (P= 0.003).6. Females kept in the laboratory produced female biased sex ratios whilst unmated females produced all‐male broods indicating that insemination and ovarian development are not causally related.7. The expected sex ratio (ESR) under equal investment, calculated as 1/CR (CR = mean male provision weight/mean female provision weight), is 137.5:117.5 (males:females), and differs significantly from that observed, 104:151 (males:females) (P < 0.001). The ‘Local Resource Enhlancement’ hypothesis best explains the female biased sex ratio found in X.sulcatipes and its maintenance in the population.
Leaf miner assemblies: effects of plant succession and grazing management
Authors: STERLING P. H. , GIBSON C. W. D. , BROWN V. K. 
Published: March 2008

Abstract. 1. Changes in leaf‐miner assemblies during 4 years of secondary succession, under different controlled sheep‐grazing treatments, are described and compared to the miner fauna of older grazed grassland nearby.2. Multivariate analyses were used in conjunction with examination of individual common species to assess the independent effects of time, grazing treatment, plant species composition and architecture on the leaf‐miner assemblies.3. Leaf‐miner species composition was strongly related to plant species composition, but was modified by plant structure under different grazing treatments. There was a strong successional trend in miner assemblies, even when the effects of changes in plant composition had been taken into account. Conversely, local variation in miner species composition generally reflected foodplant distribution alone.4. Grazed treatments had fewer mines than controls, but there were also species specializing in grazed areas, despite the abundance of their foodplants elsewhere. There was a weak indication that miner species in grazed treatments were more likely to fluctuate in abundance than those in controls.5. The results are discussed in relation to the assembly of grassland insect communities during succession, and the use of ‘indicator groups’ in management for nature conservation.
The effects of male body size on territorial and mating success in the landmark‐defending fly Hermetia comstocki (Stratiomyidae)
Authors: ALCOCK JOHN 
Published: March 2008

Abstract.

Males of Hermetia comstocki Williston compete for territorial control of certain agaves and yuccas. Winners copulate with females that visit these plants solely to acquire a mate.
Males vary in body weight by more than an order of magnitude and larger flies almost always defeat smaller ones in aerial contests for control of landmark territories.
The mean body size (as measured by wing‐length) was significantly greater for males retaining residency at a site for at least one hour compared to males unable to do so. Likewise, males able to return to a perch site in the study area on more than one day were larger on average than males unable to do so.
Male preferences for landmark territories remained similar across years. Large males dominated the perch landmarks most likely to be occupied by males and most likely to be visited by females.
Despite the fighting and territorial advantages enjoyed by large males, the mean size of males found mating with females was not significantly larger than that of the general population.
The apparent failure of large males to secure a statistically significant mating advantage may be a statistical consequence of the small sample size of males observed mating. On the other hand, any mating advantage of large males may be reduced because (a) receptive females visit many different landmarks, (b) females mate with the first male they encounter at a landmark, regardless of his size, (c) there are usually many vacant landmarks available for smaller males, and (d) even popular territories are often open to small males, thanks to the low site‐tenacity of territory owners.
Temperature and the pollinating activity of social bees
Authors: CORBET SARAH A. , FUSSELL M. , AKE R. , FRASER A. , GUNSON C. , SAVAGE A. , SMITH K. 
Published: March 2008

Abstract.

Thermal constraints on flight acivity limit the pollinating effectiveness of bees. Each species of social bee has a microclimatic ‘window’ within which foraging flight can be sustained.
To predict whether a given species of social bee is worth testing as a pollinator in a given climate, it is useful to know at least the lower limits of that microclimatic ‘window’. We consider how information from a series of bee counts through a day can be used to characterize a bee species in terms of activity/microclimate relations as a basis for predicting the diel pattern of foraging activity of a bee introduced into a new climate as a pollinator.
We discuss the relative merits of bee counts at a foraging patch and counts based on hive traffic as indices of the proportion of bees active.
We suggest that the activity/microclimate relations of a species be expressed in terms of the lower threshold black globe temperature for flight activity. Black globe temperature, Tg, is easily measured with inexpensive equipment, and can substitute for measurements of ambient temperature and radiation as a predictor of diel patterns of bee activity.
We use examples of field data to explore the relationship between microclimate and activity for the honeybee Apis mellifera and several species of bumblebee, Bombus. Regression analysis is used to relate activity to Tg and to identify the lower temperature threshold for activity from field bee counts.
In field studies analysed here, the bumblebees Bombus terrestrisllucorum, B.pascuorum and B.hortorum began foraging at lower temperatures than honey‐bees or B.lapidarius.
Social structure in the ant Lasius flavus: multi‐queen nests or multi‐nest mounds?
Authors: BOOMSMA J. J. , WRIGHT P. J. , BROUWER A. H. 
Published: March 2008

Abstract.

The yellow subterranean ant Lasius flavus is generally considered to have a single queen in mature nests. Yet, many anecdotal observations have suggested that the conspicuous earth mounds of this ant may, at least occasionally, contain several queens and their offspring.
To estimate the number of matrilines per mound, samples for horizontal starch gel electrophoresis were collected from a total of thirty‐seven mounds in three sites of old chalk‐grassland in southern England.
Allozymatic variation at an esterase and hexokinase locus showed that probably more than 50% of the mounds contained more than one queen and that the mean number of queens per mound is at least 1.5–2.
Further results strongly suggested that workers from different matrilines may share the same galleries, at least in the top of the mound.
The apparently variable social structure of Lasius flavus colonies is discussed, both technically and with reference to ecological processes related to the presence of ants in the nest mounds.
Female‐biased sex ratio in a wild bruchid seed‐predator, Kytorhinus sharpianus. I. Larval competition and other factors
Authors: ISHIHARA MICHIHIRO , SHIMADA MASAKAZU 
Published: March 2008

Abstract.

A wild bruchid seed‐predator, Kytorhinus sharpianus, has a complex life cycle consisting of bi‐ and trivoltinism on a wild leguminous plant, Sophola flavescens. Observations of adults showed significant female‐biased sex ratios (from 1:2 to 1:6) for nine generations over 4 years.
To investigate the potential effects of larval competition on the sex ratio, we altered the number of hatched eggs per seed and counted emergent males and females under laboratory conditions. Although only one adult could emerge per seed, the ratio of the females that emerged increased with the number of hatched eggs per seed. However, the sex ratio was not significantly different from 1:1 in the case of one hatched egg per seed.
We dissected seeds bearing two hatched eggs at regular intervals, and classified the surviving and the dead larvae according to their developmental stage. Over time, one larva within each seed always survived, while the other larva died from the second to fourth instar before the seed resource became exhausted.
In order to study the effects of the difference in the stages of two larvae in a seed on the emergence sex ratio, we manipulated intervals between the first and second ovipositions in the laboratory. As the difference in developmental stages of the two larvae increased, the closer to 1:1 the emergence sex ratio became.
Field observations, however, showed that about 60% of infested seeds were bored by only one K.sharpianus larva. This suggests that female dominance in larval competition within a seed may be relatively unimportant in causing the female‐biased sex ratio in the field.
Windborne moth migration over the Middle East
Authors: PEDGLEY D. E. , YATHOM S. 
Published: March 2008

Abstract.

From 10 years' records of moths caught in a light trap at Eilat, Israel, eleven selected occasions with sudden increases in catch involving seventeen species were related to accompanying changes in wind.
At all times of the year examined, sudden increases in catch of all species were associated with winds changing direction to blow from the Nile Delta or from the Levant.
All seventeen species are inferred to be windborne over at least several hundred kilometres.
The results are consistent with huge plumes of moths streaming downwind each night from the Delta and the Levant, sometimes crossing Eilat, sometimes crossing the Mediterranean, but more often passing into the deserts.
Plumes are produced throughout the breeding season of each species.
The results are probably representative of migration elsewhere from the southern limits of breeding on rain‐fed vegetation, with inferred widespread adult mortality and renewed breeding most likely after migration on brief spells of southerly winds.
Resilience of the natural arthropod community on apple to external disturbance
Authors: BROWN M. W. 
Published: March 2008

Abstract.

A naturally evolved arthropod community in a 6‐year‐old apple orchard was treated with three applications of permethrin; a second naturally evolved community was studied as an untreated control. Disturbance to the community was measured with Shannon's index of species diversity for the phytophagous and beneficial portions of the community.
Initially, there was a reduction in diversity of both phytophagous and beneficial arthropods because of the insecticide. Reduction in diversity was a result of both lower number of species and lower evenness of species abundance.
Two months after the last permethrin spray, there was no difference between diversity in the phytophagous community, but the beneficial community was more diverse in the treated orchard than in the untreated control.
The year after treatment there were few differences between the phytophagous communities, but the beneficial community was more diverse in the treated orchard than in the untreated orchard in May and early June; however, by September the beneficial community was less diverse in the treated orchard.
Although diversity statistics of the phytophagous communities were similar 15 months after treatment, differences still remained with the treated community being dominated by more r‐selected species and the control orchard dominated by more K‐selected species.
The arthropod community on apple has a high level of stability as reflected by its resilience to a severe external disturbance. This stability would allow for large, but infrequent, disturbances for pest management and still maintain long‐term ecological equilibrium in the community.
Increase in cold‐shock tolerance by selection of cold resistant lines in Drosophila melanogaster
Authors: CHEN C‐P. , WALKER V. K. 
Published: March 2008

Abstract.

In Drosophila melanogaster, the cold‐shock tolerance of adult flies at ‐7°C increased 22% after a prior 2h exposure to 4°C as measured by LD50, the dose (degree minutes of exposure to subzero temperature) which resulted in 50% mortality.
Cold‐shock tolerance was further significantly increased by selecting cold resistant lines by exposure of adults (1) to 4°C for 2 h (short‐term chilling), or (2) to ‐7°C for 80–120 min (cold shock), or (3) to short‐term chilling followed by cold‐shock.
After ten generations of selection, the greatest increase in cold‐shock tolerance was found in flies selected using the combined exposure of short‐term chilling and cold shock. LD50s increased 33% in comparison with the unselected control strain when no chilling pre‐treatment was given prior to cold shock at ‐7°C.
The rapid cold‐hardening response increased 82% in the line selected by the short‐term chilling and cold‐shock regime.
The enhanced cold‐shock tolerance was relatively stable since no decrease was observed after four generations without selection.
This report shows the role of short‐term adaptation as well as selection in the capacity to survive low temperatures in non‐diapausing stages of insects.
Choice of flowers by foraging honey bees (Apis mellifera): possible morphological cues
Authors: DUFFIELD G. E. , GIBSON R. C. , GILHOOLY P. M. , HESSE A. J. , INKLEY C. R. , GILBERT F. S. , BARNARD C. J. 
Published: March 2008

Abstract.

Honey bees foraging for nectar on lavender (Lavandula stoechas) chose inflorescences with more of their flowers open. The number of open flowers predicted whether an inflorescence was visited by bees, inspected but rejected, or ignored. Inflorescences chosen arbitrarily by observers had numbers of open flowers intermediate between those of visited and ignored inflorescences.
Differences in morphological characters between types of inflorescence correlated with nectar volume and sugar weight per flower so that visited inflorescences had a disproportionately greater volume of nectar and weight of sugar per flower and greater variance in nectar volume.
Although there were significant associations between nectar content and the morphological characters of inflorescences, discriminant function analysis revealed discrimination on the basis of morphology rather than nectar content.
Visited inflorescences tended to have smaller than average flowers but bees tended to probe the largest flowers on visited inflorescences.
Choice of flowers within inflorescences is explicable in terms of the relationship between flower size and nectar content.
Evidence for mutualism between a flower‐piercing carpenter bee and ocotillo: use of pollen and nectar by nesting bees
Authors: SCOTT PETER E. , BUCHMANN STEPHEN L. , O'ROURKE MARY KAY 
Published: March 2008

Abstract.

Carpenter bees (Xylocopa californica arizonensis) in west Texas, U.S.A., gather pollen and ‘rob’ nectar from flowers of ocotillo (Fouquieria splendens). When common, carpenter bees are an effective pollen vector for ocotillo. We examined ocotillo's importance as a food source for carpenter bees.
The visitation rate of carpenter bees to ocotillo flowers in 1988 averaged 0.51 visits/flower/h and was 4 times greater than that of queen bumble bees (Bombus pennsylvanicus sonorus), the next most common visitor. Nectar was harvested thoroughly and pollen was removed from the majority of flowers. Hummingbird visits were rare.
Pollen grains from larval food provisions were identified from sixteen carpenter bee nests. On average, 53% of pollen grains sampled were ocotillo, 39% were mesquite (Prosopis glandulosa), and 8% were Zygophyllaceae (Larrea tridentata or Guaiacum angustifolium). Carpenter bee brood size averaged 5.8 per nest.
We measured the number of flowers, and production of pollen and nectar per flower by mature ocotillo plants, as well as the quantity of pollen and sugar in larval provisions. An average plant produced enough pollen and nectar sugar to support the growth of eight to thirteen bee larvae. Ocotillo thus has the potential to contribute significantly to population growth of one of its key pollinators.
Although this carpenter bee species, like others, is a nectar parasite of many plant species, it appears to be engaged in a strong mutualism with a plant that serves as both a pollen and as a nectar source during carpenter bee breeding periods.