Are solitary progressive-provisioning wasps optimal foragers? A study with the digger wasp Bembix merceti (Hymenoptera: Crabronidae)

Abstract Bembix merceti, a central-place forager that captures dipterans to feed its larvae, could be considered a suboptimal forager. The females tend to optimize their provisioning flights, capturing prey in proportions different from those present in the surrounding environment. These wasps make a positive selection of families of flies with greater mean weights even though they are less abundant and, within the families whose weight is not too great, capture individuals whose weight is larger than the mean. Selection is based on prey size and not on the type (family) to which the prey belongs. A significant correlation between the weight of each female and the weight of the largest prey captured by the wasp was found, suggesting that the females capture prey in consonance with their lift capacity. Nevertheless, captures were not optimized maximally; the females maintained a margin with respect to the maximum prey weights that they could transport efficiently. This margin could be related to the low availability of large prey in the environment; to the type of progressive provisioning shown by the females of this species; and to other factors, such as the good manoeuvrability of their prey and the pressure from their natural enemies and congeners.

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CHANGES IN PREY SIZE PREFERENCES DURING SUCCESSIVE STAGES OF FORAGING IN THE MEDITERRANEAN WATER SHREW NEOMYS ANOMALUS

Behaviour ◽

10.1163/156853999501360 ◽

1999 ◽

Vol 136 (3) ◽

pp. 345-365 ◽

Cited By ~ 7

Author(s):

Leszek Rychlik

Keyword(s):

Predation Risk ◽

Prey Size ◽

Large Prey ◽

Habitat Conditions ◽

Food Hoarding ◽

Food Quantity ◽

Competition For Food ◽

Mediterranean Water ◽

Selection Of ◽

Food Portions

AbstractPrey size preferences in successive stages of foraging of Mediterranean water shrews Neomys anomalus Cabrera, 1907 were investigated in a terrarium. Seven shrews were tested individually in five experimental variants (simulating different habitat conditions) totally for 504 hours. Water shrews displayed partial preferences for prey size but they were selective from the very beginning of the foraging period. When searching for food, N. anomalus preferred big food portions, abandoning significantly more small than big portions. This tendency was especially strong when few food portions were available on land and there were no natural structures in the terrarium. Selection of big portions was intensified probably by their easier detection. Shrews hoarded proportionally more big than small portions in the scattered hiding-places. This tendency was intensified by the presence of natural structures, dispersion of food and reduction of food quantity placed on land. Later, however, more small than big food portions were eaten, apparently because small portions were easier to manipulate. Scattered food hoarding and preference of large prey are proposed to be the strategy of N. anomalus to maximise the energy net gain and minimise the predation risk and competition for food.

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Size-related shift in feeding strategy and prey-size selection in young grayling (Thymallus thymallus)

Canadian Journal of Zoology ◽

10.1139/z96-176 ◽

1996 ◽

Vol 74 (9) ◽

pp. 1597-1603 ◽

Cited By ~ 9

Author(s):

Philippe Sempeski ◽

Philippe Gaudin

Keyword(s):

Body Length ◽

Feeding Behaviour ◽

Prey Size ◽

Feeding Strategy ◽

River Channel ◽

Large Prey ◽

Thymallus Thymallus ◽

Chironomid Larvae ◽

Size Selection ◽

The Mean

Observations of feeding behaviour and analysis of prey-size selection by young grayling revealed a shift in feeding strategy coinciding with a shift in habitat occurring between larval (observed in lateral habitats) and juvenile (observed in the river channel) stages of grayling. The mean number of foraging attempts per minute decreased four times between both stages, while in the same time the mean distance travelled during each foraging attempt decreased from 1.5 body lengths to 1 body length. Gape-limited postemergent larvae fed mainly on small chironomid larvae (<0.5 mm3) but larger larvae and pupae (0.5 – 1 mm3) were consumed with increasing size. The diet spectrum of juveniles >40 mm was characterized by the appearance of very large prey (> 10 mm3), such as simuliid and ephemeropteran larvae, but also by a new increase of the contribution of small chironomid larvae. Changes in the feeding strategy of young grayling are discussed in relation to internal (e.g., morphological limitations) and external (e.g., physical characteristics of habitat) constraints.

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Selection of Prey by Size in Ningaui Yvonneae

Australian Journal of Zoology ◽

10.1071/zo9960319 ◽

1996 ◽

Vol 44 (3) ◽

pp. 319 ◽

Cited By ~ 11

Author(s):

AP Woolnough ◽

SM Carthew

Keyword(s):

Energy Efficient ◽

Prey Size ◽

Handling Time ◽

Optimal Foraging Theory ◽

Large Prey ◽

Small Prey ◽

Upper Limit ◽

The Relationship ◽

Prey Items ◽

Selection Of

The small dasyurid marsupial, Ningaui yvonneae, feeds opportunistically on invertebrates dominated by the orders Hymenoptera, Coleoptera and Araneae, but is capable of, and will, consume vertebrates such as skinks. When presented with a choice of prey N. yvonneae exhibited a strong preference for prey items on the basis of size. It consistently selected small prey items over large prey items. Small prey items represented the most energy-efficient prey option as the ningaui can more efficiently capture, subdue and consume them than it can larger prey. The relationship between prey size and handling time was exponential, indicating that there is an upper limit to the ability of N. yvonneae to process prey. Moreover, smaller cockroaches provided greater energy gain than larger ones, indicating that the costs of eating larger cockroaches energetically outweighed the energy return. These results are in agreement with optimal foraging theory.

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Der Sommer und Herbst 2003 aus phänologischer Sicht | Summer and autumn 2003 from a phenological point of view

Schweizerische Zeitschrift fur Forstwesen ◽

10.3188/szf.2004.0142 ◽

2004 ◽

Vol 155 (5) ◽

pp. 142-145 ◽

Cited By ~ 2

Author(s):

Claudio Defila

Keyword(s):

Time Series ◽

New Record ◽

Point Of View ◽

Late Spring ◽

Mean Deviation ◽

Leaf Shedding ◽

The Mean ◽

Very High ◽

Selection Of

The record-breaking heatwave of 2003 also had an impact on the vegetation in Switzerland. To examine its influences seven phenological late spring and summer phases were evaluated together with six phases in the autumn from a selection of stations. 30% of the 122 chosen phenological time series in late spring and summer phases set a new record (earliest arrival). The proportion of very early arrivals is very high and the mean deviation from the norm is between 10 and 20 days. The situation was less extreme in autumn, where 20% of the 103 time series chosen set a new record. The majority of the phenological arrivals were found in the class «normal» but the class«very early» is still well represented. The mean precocity lies between five and twenty days. As far as the leaf shedding of the beech is concerned, there was even a slight delay of around six days. The evaluation serves to show that the heatwave of 2003 strongly influenced the phenological events of summer and spring.

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Faculty Opinions recommendation of A voltage-gated sodium channel is essential for the positive selection of CD4(+) T cells.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.717952689.793462954 ◽

2012 ◽

Author(s):

Nick Gascoigne ◽

Guo Fu

Keyword(s):

T Cells ◽

Sodium Channel ◽

Positive Selection ◽

Cd4 T Cells ◽

Voltage Gated Sodium Channel ◽

Voltage Gated ◽

Selection Of

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Faculty Opinions recommendation of Thymoproteasomes produce unique peptide motifs for positive selection of CD8(+) T cells.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.725582462.793508535 ◽

2015 ◽

Author(s):

Nick Gascoigne

Keyword(s):

T Cells ◽

Positive Selection ◽

Cd8 T Cells ◽

Unique Peptide ◽

Peptide Motifs ◽

Selection Of

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Faculty Opinions recommendation of Tumor evolution. High burden and pervasive positive selection of somatic mutations in normal human skin.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.725509016.793507115 ◽

2015 ◽

Author(s):

William H Colledge

Keyword(s):

Positive Selection ◽

Human Skin ◽

Somatic Mutations ◽

Tumor Evolution ◽

Normal Human Skin ◽

High Burden ◽

Normal Human ◽

Selection Of

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Caracterização da Peneira Média em Clones de Coffea canephora

REVISTA FIMCA ◽

10.37157/fimca.v5i2.58 ◽

2018 ◽

Vol 5 (2) ◽

pp. 28-31

Author(s):

Darlan Darlan Sanches Barbosa Alves ◽

Victor Mouzinho Spinelli ◽

Marcos Santana Moraes ◽

Carolina Augusto De Souza ◽

Rodrigo da Silva Ribeiro ◽

...

Keyword(s):

Genetic Improvement ◽

Block Design ◽

Coffea Canephora ◽

Coffee Production ◽

Randomized Block Design ◽

Significant Difference ◽

The Mean ◽

Four Blocks ◽

Selection Of

Introdução: O estado de Rondônia se destaca como tradicional produtor de café, sendo o segundo maior produtor brasileiro de C. canephora. No melhoramento genético de C. canephora, a seleção de plantas de elevada peneira média está associada à bebida de qualidade superior. Objetivos: O objetivo desse estudo foi avaliar a variabilidade genética de clones de C. canephora para o tamanho dos grãos, mensurado a partir da avaliação da peneira média (PM). Materiais e Métodos: Para isso, foi conduzido ao longo de dois anos agrícolas experimento no campo experimental da Embrapa no município de Ouro Preto do Oeste-RO, para a avaliação da peneira média de 130 genótipos (clones) com características das variedades botânicas Conilon, Robusta e híbridos intervarietais. O delineamento experimental utilizado foi de blocos ao acaso, com quatro repetições de quatro plantas por parcela. Resultados: Não houve resultados significativos para a interação clones X anos, indicando uma maior consistência no comportamento das plantas ao longo do tempo. Porém foram observadas diferenças significativas para o tamanho dos grãos entre os genótipos avaliados, possibilitando selecionar genótipos superiores. Conclusão: Os genótipos agruparam-se em cinco classes de acordo com o teste de média, subsidiando a caracterização de um gradiente de variabilidade da característica avaliada ABSTRACTIntroduction: Coffea canephora accounts for approximately 35% of the world's coffee production. The state of Rondônia stands out as a traditional coffee producer, being the second largest Brazilian producer of C. canephora. In the classical genetic improvement of C. anephora, the selection of plants of high average sieve is associated with a drink of superior quality. Objectives: The objective of this udy was to evaluate the genetic variability of Coffea canephora clones for the agronomic medium sieve (PM). Materials and Methods: The experiment was conducted in the experimental field of Embrapa, municipality of OuroPreto do Oeste-RO, located at coordinates 10º44'53 "S and 62º12'57". One hundred thirty genotypes (clones) of botanical characteristics Conilon, Robusta and intervarietal hybrids were evaluated in the agricultural years 2013-2014 and 2014-2015. The experimental design was a randomized block design with four blocks and four plants per plot, spacing 3.5 x 1.5 meters between plants. Results: Significant difference was found for the grain size. According to the F test, at 5% probability, the genotypes were grouped into five classes according to the mean test. Conclusion: The results obtained subsidized the characterization of a variability gradient of the evaluated trait.

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Prey Size Decline as a Unifying Ecological Selecting Agent in Pleistocene Human Evolution

Quaternary ◽

10.3390/quat4010007 ◽

2021 ◽

Vol 4 (1) ◽

pp. 7

Author(s):

Miki Ben-Dor ◽

Ran Barkai

Keyword(s):

Prey Size ◽

Prey Availability ◽

Stone Tool ◽

Foraging Efficiency ◽

Energetic Cost ◽

Large Prey ◽

Biomass Density ◽

Cultural Changes ◽

Progressive Decline ◽

Brain Expansion

We hypothesize that megafauna extinctions throughout the Pleistocene, that led to a progressive decline in large prey availability, were a primary selecting agent in key evolutionary and cultural changes in human prehistory. The Pleistocene human past is characterized by a series of transformations that include the evolution of new physiological traits and the adoption, assimilation, and replacement of cultural and behavioral patterns. Some changes, such as brain expansion, use of fire, developments in stone-tool technologies, or the scale of resource intensification, were uncharacteristically progressive. We previously hypothesized that humans specialized in acquiring large prey because of their higher foraging efficiency, high biomass density, higher fat content, and the use of less complex tools for their acquisition. Here, we argue that the need to mitigate the additional energetic cost of acquiring progressively smaller prey may have been an ecological selecting agent in fundamental adaptive modes demonstrated in the Paleolithic archaeological record. We describe several potential associations between prey size decline and specific evolutionary and cultural changes that might have been driven by the need to adapt to increased energetic demands while hunting and processing smaller and smaller game.

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