scholarly journals Artificial nighttime light changes aphid-parasitoid population dynamics

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Dirk Sanders ◽  
Rachel Kehoe ◽  
Katie Tiley ◽  
Jonathan Bennie ◽  
Dave Cruse ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Aphid Parasitoid ◽  
Parasitoid Population ◽  
Nighttime Light

scholarly journals Multi-Level Relationships between Satellite-Derived Nighttime Lighting Signals and Social Media–Derived Human Population Dynamics

2018 ◽  
Vol 10 (7) ◽  
pp. 1128 ◽  
Author(s):  
Ting Ma
Keyword(s):  
Social Media ◽  
Population Dynamics ◽  
Big Data ◽  
Human Activities ◽  
Human Population ◽  
City Size ◽  
Human Settlements ◽  
Good Opportunity ◽  
Nighttime Light ◽  
Multi Level

Satellite-based measurements of the artificial nighttime light brightness (NTL) have been extensively used for studying urbanization and socioeconomic dynamics in a temporally consistent and spatially explicit manner. The increasing availability of geo-located big data detailing human population dynamics provides a good opportunity to explore the association between anthropogenic nocturnal luminosity and corresponding human activities, especially at fine time/space scales. In this study, we used Visible Infrared Imaging Radiometer Suite (VIIRS) day/night band (DNB)–derived nighttime light images and the gridded number of location requests (NLR) from China’s largest social media platform to investigate the quantitative relationship between nighttime light radiances and human population dynamics across China at four levels: the provincial, city, county, and pixel levels. Our results show that the linear relationship between the NTL and NLR might vary with the observation level and magnitude. The dispersion between the two variables likely increases with the observation scale, especially at the pixel level. The effect of spatial autocorrelation and other socioeconomic factors on the relationship should be taken into account for nighttime light-based measurements of human activities. Furthermore, the bivariate relationship between the NTL and NLR was employed to generate a partition of human settlements based on the combined features of nighttime lights and human population dynamics. Cross-regional comparisons of the partitioned results indicate a diverse co-distribution of the NTL and NLR across various types of human settlements, which could be related to the city size/form and urbanization level. Our findings may provide new insights into the multi-level responses of nighttime light signals to human activity and the potential application of nighttime light data in association with geo-located big data for investigating the spatial patterns of human settlement.

scholarly journals Phenological responses in a sycamore–aphid–parasitoid system and consequences for aphid population dynamics: A 20 year case study

2020 ◽  
Vol 26 (5) ◽  
pp. 2814-2828 ◽  
Author(s):  
Vicki L. Senior ◽  
Luke C. Evans ◽  
Simon R. Leather ◽  
Tom H. Oliver ◽  
Karl L. Evans
Keyword(s):  
Population Dynamics ◽  
Aphid Population ◽  
Aphid Parasitoid

The impact of parasitoid emergence time on host–parasitoid population dynamics

2009 ◽  
Vol 75 (2-3) ◽  
pp. 201-215 ◽  
Author(s):  
Christina A. Cobbold ◽  
Jens Roland ◽  
Mark A. Lewis
Keyword(s):  
Population Dynamics ◽  
Emergence Time ◽  
Parasitoid Population ◽  
The Impact

Electrophoretic study of five aphid parasitoid species of the genus Aphidius (Hymenoptera: Braconidae), including evidence for reproductively isolated sympatric populations and a cryptic species

1998 ◽  
Vol 88 (1) ◽  
pp. 3-13 ◽  
Author(s):  
P. Atanassova ◽  
C.P. Brookes ◽  
H.D. Loxdale ◽  
W. Powell
Keyword(s):  
Cryptic Species ◽  
Acyrthosiphon Pisum ◽  
Genetic Relationships ◽  
Pea Aphid ◽  
Parasitoid Species ◽  
Sympatric Populations ◽  
Electrophoretic Study ◽  
Aphid Parasitoid ◽  
Parasitoid Population ◽  
The Uk

AbstractFour polymorphic enzymes (PEP, PGI, PGM and IDH) were separated from adult individuals of five aphid parasitoid species of the genus Aphidius Nees (A. ervi Haliday, A. microlophii Pennacchio & Tremblay, A. eadyi Starý, Gonzalez & Hall, A. picipes Nees and A. urticae Haliday) using horizontal cellulose acetate plate electrophoresis. These markers were used to investigate the genetic relationships, including reproductive isolation and host adaptation/specificity, in laboratory and field populations. Samples were collected from the pea aphid, Acyrthosiphon pisum (Harris) and/or the nettle aphid, Microlophium carnosum (Buckton) in the UK and Bulgaria between 1991 and 1994. Whilst all loci discriminated between some species, PGM discriminated all five species, one species (A. eadyi) bearing two unique alleles (PGMa and PGMc). Aphidius microlophii (from nettle aphid) and A. ervi (from pea aphid), which are difficult to separate morphologically, possessed unique PGM alleles – PGMb and PGMe, respectively. Both parasitoids occur sympatrically, and whilst hybrids heterozygous for PGM were produced in the laboratory (PGMb,e), such genotypes were not observed in the field populations sampled. Hence, the species appear to be reproductively isolated. Most parasitoid populations studied showed mean heterozygote deficiencies per locus (homozygote excess) compared with Hardy-Weinberg expectations. In particular, A. eadyi bearing PGMa alleles were always homozygous whilst additionally, many were homozygous for another allele, PGIb. This is evidence for the existence of one or more morphologically-indistinguishable ‘cryptic’ species occurring sympatrically within European field populations. A dendrogram of relatedness was produced following calculation of Nei's genetic identity coefficient, I from the parasitoid population allele frequency data. All species showed very high similarity between populations at the intraspecific level (>0.9), but fewer interspecific similarities (0.23–0.63). These values compare well with previously published values for Aphidius populations and for other insects.

scholarly journals Global redistribution and local migration in semi-discrete host-parasitoid population dynamic models

2019 ◽  
Author(s):  
Brooks Emerick ◽  
Abhyudai Singh
Keyword(s):  
Population Dynamics ◽  
Functional Response ◽  
Dynamic Models ◽  
Constant Density ◽  
Spatial Effects ◽  
Modeling Framework ◽  
Type Iii ◽  
Stable Coexistence ◽  
Vulnerable Period ◽  
Parasitoid Population

ABSTRACTHost-parasitoid population dynamics is often probed using a semi-discrete/hybrid modeling framework. Here, the update functions in the discrete-time model connecting year-to-year changes in the population densities are obtained by solving ordinary differential equations that mechanistically describe interactions when hosts become vulnerable to parasitoid attacks. We use this semi-discrete formalism to study two key spatial effects: local movement (migration) of parasitoids between patches during the vulnerable period; and yearly redistribution of populations across patches outside the vulnerable period. Our results show that in the absence of any redistribution, constant density-independent migration and parasitoid attack rates are unable to stabilize an otherwise unstable host-parasitoid population dynamics. Interestingly, inclusion of host redistribution (but not parasitoid redistribution) before the start of the vulnerable period can lead to stable coexistence of both species. Next, we consider a Type-III functional response (parasitoid attack rate increases with host density), where the absence of any spatial effects leads to a neutrally stable host-parasitoid equilibrium. As before, density-independent parasitoid migration by itself is again insufficient to stabilize the population dynamics and host redistribution provides a stabilizing influence. Finally, we show that a Type-III functional response combined with density-dependent parasitoid migration leads to stable coexistence, even in the absence of population redistributions. In summary, we have systematically characterized parameter regimes leading to stable/unstable population dynamics with different forms of spatial heterogeneity coupled to the parasitoid’s functional response using mechanistically formulated semi-discrete models.

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