scholarly journals Intraguild Predation between Chrysoperla carnea (Neuroptera: Chrysopidae) and Hippodamia variegata (Coleoptera: Coccinellidae) at Various Extraguild Prey Densities and Arena Complexities

Insects ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 288
Author(s):  
Maryam Zarei ◽  
Hossein Madadi ◽  
Abbas Ali Zamani ◽  
Oldřich Nedvěd
Keyword(s):  
Intraguild Predation ◽  
Life Stage ◽  
Aphis Fabae ◽  
Chrysoperla Carnea ◽  
Exponential Relationship ◽  
Aphid Density ◽  
Aphid Predators ◽  
Hippodamia Variegata ◽  
The Difference ◽  
Negative Exponential

Intraguild predation (IGP) is a ubiquitous, important and common interaction that occurs in aphidophagous guilds. The effects of extraguild prey (EGP, i.e., aphids) density, predator life stage combinations and duration of the interaction on the level, asymmetry and direction of intraguild predation between lacewing Chrysoperla carnea and ladybird Hippodamia variegata were examined in simple laboratory arena and more complex microcosm environment. Three initial densities of 50, 150 and 400 Aphis fabae third instar nymphs and a control without aphids were provided to six combinations of predator life stages (2nd and 3rd larval instars of lacewing and 3rd and 4th instars and adult females of ladybird). The remaining aphid density and occurrence of IGP were checked after 24, 48 and 72 h. The IGP intensity (IGP level, IL) was similar in the simple arena (reaching 0.6 between larvae in absence of EGP and 0.3 between lacewing larvae and ladybird females) and microcosm environment (0.3 without EGP). In both environments, increasing EGP density lowered IL according to negative exponential relationship. IGP was asymmetric (general average asymmetry was 0.82 in simple arena and 0.93 in microcosm, the difference was not significant) and mostly in favour of larvae of C. carnea, except in the combination of 2nd larvae of C. carnea with the 4th larvae and adults of H. variegata. The direction of IGP, but not other characteristics, partially changed during the duration of the experiment. The incidence of IGP interactions among aphid predators under real conditions and its consequences on aphid biological control are discussed.

The influence of natural enemies on wing induction in Aphis fabae and Megoura viciae (Hemiptera: Aphididae)

2007 ◽  
Vol 98 (1) ◽  
pp. 59-62 ◽  
Author(s):  
G. Kunert ◽  
K. Schmoock-Ortlepp ◽  
U. Reissmann ◽  
S. Creutzburg ◽  
W.W. Weisser
Keyword(s):  
Natural Enemies ◽  
Acyrthosiphon Pisum ◽  
Aphis Gossypii ◽  
Aphid Species ◽  
Pea Aphid ◽  
Aphis Fabae ◽  
Chrysoperla Carnea ◽  
Cotton Aphid ◽  
Aphid Density ◽  
Megoura Viciae

AbstractPrevious studies have shown that the aphid species, Aphis fabae Scopoli and Megoura viciae Buckton, do not produce winged offspring in the presence of natural enemies, in contrast to results for the pea aphid (Acyrthosiphon pisum (Harris)) and the cotton aphid (Aphis gossypii Glover); but these studies did not involve exposing aphids directly to natural enemies. We exposed colonies of both A. fabae and M. viciae to foraging lacewing (Chrysoperla carnea (Stephens)) larvae and found that the predators did not induce winged morphs among offspring compared to unexposed controls. Colonies of A. fabae responded to an increase in aphid density with increasing winged morph production, while such response was not found for M. viciae. We suggest that different aphid species differ in their susceptibility to natural enemy attack, as well as in their sensitivity to contact.

Dynamic secondary electron emission characteristics of polymers in negative charging process

2016 ◽  
Vol 30 (11) ◽  
pp. 1650168 ◽  
Author(s):  
Ming Weng ◽  
Tian-Cun Hu ◽  
Na Zhang ◽  
Meng Cao
Keyword(s):  
Surface Potential ◽  
Electron Emission ◽  
Secondary Electron ◽  
Irradiation Time ◽  
Secondary Electron Emission ◽  
Stable State ◽  
Electron Gun ◽  
Exponential Relationship ◽  
The Difference ◽  
Negative Exponential

We studied the dynamic secondary electron emission (SEE) characteristics of a polyimide sample in negative charging process under electron bombardment. The time evolution of secondary electron yield (SEY) has been measured with a pulsed electron gun. The dynamic SEY, as well as the surface potential have been analyzed using a capacitance model. The shift in surface potential caused by the negative charge accumulation on the sample reduces the landing energy of the primary electrons (PEs), which in turn alters the SEY. The charging process tends to be stable when the landing energy of PEs reaches the secondary crossover energy where the corresponding SEY is 1. The surface potential has an approximately negative exponential relationship with the irradiation time. The total accumulated charge at the stable state is found to be proportional to the product of the sample capacitance and the difference between initial incident energy and the secondary crossover energy. The time constant of the exponential function is proportional to the ratio of final accumulated charge to the incident current.

scholarly journals Effect of Cultural Practices on Neopamera bilobata in Relation to Fruit Injury and Marketable Yields in Organic Strawberries

Insects ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 843
Author(s):  
Hannah R. Talton ◽  
Elena M. Rhodes ◽  
Carlene A. Chase ◽  
Marilyn E. Swisher ◽  
Justin M. Renkema ◽  
...  
Keyword(s):  
Cover Crops ◽  
Cover Crop ◽  
Cultural Practices ◽  
Life Stage ◽  
Management Program ◽  
Limited Information ◽  
Significant Difference ◽  
The Difference ◽  
Management Recommendations ◽  
Type Of Injury

The strawberry seed bug, Neopamera bilobata (Say), is an emerging pest of organic and conventional strawberries in Florida. There is limited information on this Rhyparochromidae species. Thus, the type of injury caused is not clearly documented and management recommendations are lacking. In this study, we evaluated the effect of strawberry cultivars, cover crops, and the presence of runners on N. bilobata populations and yield. We also investigated the effect of select cultivars and the presence of runners on N. bilobata injury levels. In addition, we used fruit bagging experiments to investigate the effects of N. bilobata population and life stage (nymph vs. adult) on strawberry fruits. There was no effect of cover crop or cultivar on N. bilobata populations. In the 2017–2018 season, strawberry plots with runners contained higher N. bilobata populations compared with plots without runners, and adult infestation was significantly higher than nymphal infestation. In the 2018–2019 season, the trend was reversed with higher numbers of N. bilobata collected in plots with runners removed. In the 2019–2020 season, there was no significant difference in N. bilobata populations in plots with and without runners. In both 2018–2019 and 2019–2020, nymphal infestation was higher than adult infestation. Less injury was recorded in “Florida Brilliance” compared with the other cultivars tested. In the 2019–2020 season, less injury was recorded from plots without runners while the difference was not significant in 2017–2018 or 2018–2019. Releasing five and ten adult N. bilobata on ripe (red) fruit produced a similar level of injury while no injury to unripe (green) fruit was observed. Both adults and nymphs cause injury to ripe fruit. These findings can help contribute to the development of an integrated pest management program for strawberry N. bilobata.

Predation activity of Chrysoperla carnea (Neuroptera: Chrysopidae) upon Aphis fabae (Hemiptera: Aphididae): Effect of different hunger levels

2015 ◽  
Vol 18 (2) ◽  
pp. 297-302 ◽  
Author(s):  
Mahdi Hassanpour ◽  
Rezvan Maghami ◽  
Hooshang Rafiee-Dastjerdi ◽  
Ali Golizadeh ◽  
Mohsen Yazdanian ◽  
...  
Keyword(s):  
Aphis Fabae ◽  
Chrysoperla Carnea

Comparison of static and dynamic closed chambers for measurement of soil respiration under field conditions

1992 ◽  
Vol 72 (4) ◽  
pp. 605-609 ◽  
Author(s):  
P. Rochette ◽  
E. G. Gregorich ◽  
R. L. Desjardins
Keyword(s):  
Soil Respiration ◽  
Sandy Loam ◽  
Flux Measurement ◽  
Organic Soil ◽  
Exponential Model ◽  
Field Conditions ◽  
Parameter Estimates ◽  
Static Chamber ◽  
The Difference ◽  
Negative Exponential

The objective of this study was to compare the dynamic closed and static chamber techniques for the measurement of soil respiration under field conditions. The static chamber method consistently produced lower soil respiration values than did the dynamic closed system and the difference was larger at higher CO2 fluxes. A negative exponential model describes the relation between CO2 fluxes measured by both techniques. A good fit was obtained for measurements on a sandy loam soil (R2 = 0.61) and an organic soil (R2 = 0.74) but parameter estimates were different for each soil. Key words: Carbon dioxide, enclosure, gas flux measurement

Pedestrian Evacuation Based on a Dynamic Parameters Model

2011 ◽  
Vol 97-98 ◽  
pp. 956-959 ◽  
Author(s):  
Nuo Zhu ◽  
Bin Jia ◽  
Chun Fu Shao
Keyword(s):  
Decision Making ◽  
Cellular Automata ◽  
Decision Making Process ◽  
Two Dimensional ◽  
Dynamic Parameters ◽  
Exponential Relationship ◽  
Evacuation Time ◽  
Pedestrian Evacuation ◽  
Simulation Results ◽  
Negative Exponential

A dynamic parameters model is presented based on cellular automata for pedestrian evacuation in this paper. The dynamic parameters: Direction-parameter, Empty-parameter and Cognition-parameter are formulated to simplify tactically the decision-making process of pedestrians, which can reflect the pedestrian judgment on the surrounding conditions and decide the pedestrian’s choice of action. Pedestrian moving rules were established, according to two-dimensional cellular automaton. The simulation results of the model are analyzed. It is observed that there is a linear relationship between evacuation time and pedestrian density, however, there is a negative exponential relationship between evacuation time and exit width. The simulation results correspond with the actual, it is instructional significant for pedestrian evacuation.

scholarly journals Characterization and Modeling Study on Softening and Seepage Behavior of Weakly Cemented Sandy Mudstone after Water Injection

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Junting Guo ◽  
Teng Teng ◽  
Xiaoyan Zhu ◽  
Yuming Wang ◽  
Zhaolong Li ◽  
...  
Keyword(s):  
Water Saturation ◽  
Water Injection ◽  
Experimental Studies ◽  
Friction Angle ◽  
Engineering Practice ◽  
Permeability Evolution ◽  
Exponential Relationship ◽  
Softening Effect ◽  
Negative Exponential ◽  
Sandy Mudstone

Water injection-induced rock softening and the associated water seepage characteristics are the common and basic problems in underground reservoir construction and the prevention of mine water disaster. In this paper, a series of experimental studies was carried out to investigate these characteristics with the weakly cemented sandy mudstone collected from Shendong Buertai coal mine, China. The characteristics of water softening and the stress-seepage interactions in water-saturated weakly cemented sandy mudstone were directly obtained. Then, a modification method of the constitutive model for rock mass considering the softening effect and a stress-damage-driven model for permeability evolution were established. Research results show that water saturation reduces the tensile strength, compressive strength, and cohesion by 56% and reduces the elastic modulus by 28%. The hydraulic effects on Poisson’s ratio and internal friction angle are negligible. The relationship between the permeability of weakly cemented sandy mudstone with complete compaction deformation is to be divided into three stages of seepage shielding, seepage surge, and seepage recovery. Rock permeability in each stage has a negative exponential relationship with the effective stress. This research provides a theoretical basis for the researches of hydromechanical couplings on weakly cemented sandy mudstone, which is insightful for rock engineering practice.

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