scholarly journals Procedee de ecologizare a sistemelor de protecție integrată a mărului și a viței de vie

2020 ◽  
Author(s):  
Vasile Voineac ◽  
◽  
Vasilisa Odobescu ◽  
Svetlana Jalba ◽  
Ina Voineac ◽  
...  
Keyword(s):  
Population Density ◽  
Natural Populations ◽  
Pheromone Traps ◽  
Apple Orchards ◽  
Protection Measures ◽  
Financial Costs

The results of experiments obtained in 2015 in apple orchards and in 2017 in vineyards showed that pheromone methods of capturing and sterilizing males of natural populations of apple worm and grape moth, installation of sticky pheromone traps and treated with biorational sterilizer Admiral 10 EC (pyriproxyfen), in the amount of 10-20 traps/ha depending on the population density, reduce their damage to the level of PED, do not act negatively on entomophagous insects from families (Coccinellidae, Chrysopida) and Arahnidae, and reduce energy and financial costs to carry out protection measures at 30-40%.

scholarly journals Natural variation in social conditions affects male mate choosiness in the amphipod Gammarus roeselii

2021 ◽  
Author(s):  
Konrad Lipkowski ◽  
Sophie Steigerwald ◽  
Lisa M Schulte ◽  
Carolin Sommer-Trembo ◽  
Jonas Jourdan
Keyword(s):  
Population Density ◽  
Sex Ratio ◽  
Natural Variation ◽  
Natural Populations ◽  
Social Background ◽  
Social Conditions ◽  
Background Information ◽  
Male Mating ◽  
Natural Environments ◽  
Male Mate

Abstract The extent of male mate choosiness is driven by a trade-off between various environmental factors associated with the costs of mate acquisition, quality assessment and opportunity costs. Our knowledge about natural variation in male mate choosiness across different populations of the same species, however, remains limited. In this study, we compared male mate choosiness across 10 natural populations of the freshwater amphipod Gammarus roeselii (Gervais 1835), a species with overall high male mating investments, and evaluated the relative influence of population density and sex ratio (both affecting mate availability) on male mate choosiness. We investigated amplexus establishment after separating mating pairs and presenting focal males with a novel, size-matched female from the same population. Our analysis revealed considerable effects of sex ratio and (to a lesser extent) population density on time until amplexus establishment (choosiness). Male amphipods are able to perceive variable social conditions (e.g., sex ratio) and modify their mating strategy accordingly: We found choosiness to be reduced in increasingly male-biased populations, whereas selectivity increases when sex ratio becomes female biased. With this, our study expands our limited knowledge on natural variations in male mate choosiness and illustrates the importance of sex ratio (i.e., level of competition) for male mating decisions in natural environments. Accounting for variation in sex ratios, therefore, allows envisioning a distinctive variation of choosiness in natural populations and highlights the importance of considering social background information in future behavioral studies.

scholarly journals Status of Astragalus cornutus Pall. populations in the Samara Region

2018 ◽  
Vol 7 (1) ◽  
pp. 37-41
Author(s):  
Valentina Nikolaevna Ilina
Keyword(s):  
Population Change ◽  
Natural Populations ◽  
Average Density ◽  
Effective Density ◽  
Anthropogenic Factors ◽  
Efficiency Criterion ◽  
Protection Measures ◽  
Additional Protection ◽  
Geographical Populations ◽  
Satisfactory State

This paper examines features of the demographic structure of natural populations of a rare representative of the steppe flora Astragalus cornutus Pall. (Fabaceae). The rarity of the species makes it necessary to include it in the Red Books of the Russian Federation and some steppe regions. In the Samara Region, species populations require additional protection in connection with the peculiarities of biology and ecology, a significant anthropogenic load on communities, and a reduction in the number of habitats. We studied the features of the structure of populations in the Samara Trans-Volga Region. A total of 84 cenopopulations were surveyed, tendencies of population change, features of demographic and spatial structure were revealed. The structure of populations is affected by the ecological and phytocenotic conditions of the environment and anthropogenic factors. The replacement and recovery of individuals in A. cornutus populations is slow. The ontogenetic structure of populations has a fluctuation dynamics. Assessment of the studied geographical populations by L.A. Zhivotovsky efficiency criterion (2001) showed that they are all mature. Specific cenopopulations of A. cornutus are aging (5%) and old (8%). The average density of individuals is about 3 individuals/m. The average effective density is 2,4 individuals/m, the largest - 4,1, the smallest - 1,3. The condition of all studied populations (even in a satisfactory state) on the territory of the Samara Region causes alarm. Populations of the species in the region need additional protection measures.

scholarly journals Use of mating disruption for control of New Zealand leafrollers in apple orchards

2011 ◽  
Vol 64 ◽  
pp. 215-221 ◽  
Author(s):  
J.T.S. Walker ◽  
D.J. Rogers ◽  
P.L. Lo ◽  
D.M. Suckling ◽  
A.M. El-Sayed ◽  
...  
Keyword(s):  
New Zealand ◽  
Mating Disruption ◽  
Virgin Female ◽  
Pheromone Traps ◽  
Apple Orchards ◽  
Pheromone Trapping ◽  
Fruit Damage ◽  
Lightbrown Apple Moth ◽  
Pheromone Dispensers ◽  
Pheromone Blend

Leafrollers are important pests of apples and infested fruit can result in rejection of export consignments Leafroller mating disruption using a pheromone blend with activity against three species was examined in 12 Hawkes Bay orchards over two seasons (200910 and 201011) Pheromone dispensers (600/ha) and a single insecticide were applied to trees in early November and subsequent insecticide use was based on leafroller pheromone trapping and thresholds The pheromone blend substantially suppressed mating of virgin female lightbrown apple moth in treated orchards and reduced male catch in pheromone traps by up to 98 compared with the season prior to implementation Insecticide use for leafroller control decreased accordingly from 2127 insecticides per block in 2008/09 to 1018 in 2010/11 Leafroller control using mating disruption was acceptable fruit damage varied from 03 to 016 and no leafroller larvae were found on fruit in both field assessments and phytosanitary inspections of packed cartons

scholarly journals Balancing selection maintains polymorphisms at neurogenetic loci in field experiments

2017 ◽  
Vol 114 (14) ◽  
pp. 3690-3695 ◽  
Author(s):  
Eija Lonn ◽  
Esa Koskela ◽  
Tapio Mappes ◽  
Mikael Mokkonen ◽  
Angela M. Sims ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Population Density ◽  
Arginine Vasopressin ◽  
Field Experiments ◽  
Balancing Selection ◽  
Regulatory Region ◽  
Natural Populations ◽  
Myodes Glareolus ◽  
Sexual Antagonism ◽  
Reproductive Behaviors

Most variation in behavior has a genetic basis, but the processes determining the level of diversity at behavioral loci are largely unknown for natural populations. Expression of arginine vasopressin receptor 1a (Avpr1a) and oxytocin receptor (Oxtr) in specific regions of the brain regulates diverse social and reproductive behaviors in mammals, including humans. That these genes have important fitness consequences and that natural populations contain extensive diversity at these loci implies the action of balancing selection. In Myodes glareolus, Avpr1a and Oxtr each contain a polymorphic microsatellite locus located in their 5′ regulatory region (the regulatory region-associated microsatellite, RRAM) that likely regulates gene expression. To test the hypothesis that balancing selection maintains diversity at behavioral loci, we released artificially bred females and males with different RRAM allele lengths into field enclosures that differed in population density. The length of Avpr1a and Oxtr RRAMs was associated with reproductive success, but population density and the sex interacted to determine the optimal genotype. In general, longer Avpr1a RRAMs were more beneficial for males, and shorter RRAMs were more beneficial for females; the opposite was true for Oxtr RRAMs. Moreover, Avpr1a RRAM allele length is correlated with the reproductive success of the sexes during different phases of reproduction; for males, RRAM length correlated with the numbers of newborn offspring, but for females selection was evident on the number of weaned offspring. This report of density-dependence and sexual antagonism acting on loci within the arginine vasopressin–oxytocin pathway explains how genetic diversity at Avpr1a and Oxtr could be maintained in natural populations.

scholarly journals Flight pattern of Archips podana (Lep.: Tortricidae) based on data from pheromone traps

2010 ◽  
Vol 40 (No. 3) ◽  
pp. 75-81
Author(s):  
J. Stará ◽  
F. Kocourek
Keyword(s):  
Czech Republic ◽  
Flight Activity ◽  
Pheromone Traps ◽  
Apple Orchards ◽  
Degree Days ◽  
Flight Pattern ◽  
The Czech Republic ◽  
Summer Generation ◽  
Richards Function

In 9 years of the period 1993–1999 and 2001–2003 the flight activity of <I>Archips podana</I> was investigated by pheromone traps placed in four apple orchards in Central and East Bohemia. The cumulative catches of <I>A. podana</I> males were plotted against time of the catch expressed in sum of degree-days (DD) above 10°C and approximated by Richards’ function. Common parameters of Richards’ function could be found for the overwintering generation of <I>A. podana</I> from all localities. The beginning, peak and end of flight activity of the overwintering generation of the <I>A. podana </I>population in Central and East Bohemia can be predicted by use of DD. <I>Archips podana </I>is usually bivoltine in the Czech Republic, rarely univoltine in cold years or cold localities. Construct the flight pattern of the summer generation could of <I>A. podana </I>not be constructed, because the course of flight of this generation in dependence on DD differed significantly in particular years and localities.

The Role of Predators and Other Biotic Agents in Regulating the Population Density of Phytophagous Mites in Ontario Peach Orchards

1966 ◽  
Vol 98 (8) ◽  
pp. 808-820 ◽  
Author(s):  
W. L. Putman ◽  
D. H. C. Herne
Keyword(s):  
Population Density ◽  
Population Growth ◽  
Tetranychus Urticae ◽  
Considerable Extent ◽  
Panonychus Ulmi ◽  
Apple Orchards ◽  
Rapid Population Growth ◽  
One Year ◽  
Heavy Mortality

AbstractMore than 40 species of insects and arachnids attack Panonychus ulmi (Koch), Tetranychus urticae Koch, T. canadensis (McGregor), Bryobia arborea Morgan and Anderson, or Aculus cornutus (Banks) in peach orchards of the Niagara Peninsula. The most effective predators attacking P. ulmi are Typhlodromus caudiglans Schuster, Haplothrips faurei Hood, Stethorus punctillum Weise, and Chrysopa spp. Peach orchards lack the predatory mirids characteristic of apple orchards. A condition, presumably disease, caused heavy mortality in one year. Endemic densities of P. ulmi are maintained in that state by predators, chiefly T. caudiglans, that subsist to a considerable extent on other sources of food, whereas epidemics of P. ulmi are reduced largely by other predators, chiefly H. faurei and S. punctillum, that increase in numbers by feeding on the mite during its period of rapid population growth but exert their greatest effect later in the season by destroying the winter eggs.

Distinguishing error from chaos in ecological time series

1990 ◽  
Vol 330 (1257) ◽  
pp. 235-251 ◽  
Keyword(s):  
New York ◽  
Population Density ◽  
Sampling Error ◽  
Natural Populations ◽  
Real Data ◽  
Environmental Stochasticity ◽  
Population Variation ◽  
Data Sets ◽  
Spatial Effects ◽  
Low Dimensional

Over the years, there has been much discussion about the relative importance of environmental and biological factors in regulating natural populations. Often it is thought that environmental factors are associated with stochastic fluctuations in population density, and biological ones with deterministic regulation. We revisit these ideas in the light of recent work on chaos and nonlinear systems. We show that completely deterministic regulatory factors can lead to apparently random fluctuations in population density, and we then develop a new method (that can be applied to limited data sets) to make practical distinctions between apparently noisy dynamics produced by low-dimensional chaos and population variation that in fact derives from random (high-dimensional)noise, such as environmental stochasticity or sampling error. To show its practical use, the method is first applied to models where the dynamics are known. We then apply the method to several sets of real data, including newly analysed data on the incidence of measles in the United Kingdom. Here the additional problems of secular trends and spatial effects are explored. In particular, we find that on a city-by-city scale measles exhibits low-dimensional chaos (as has previously been found for measles in New York City), whereas on a larger, country-wide scale the dynamics appear as a noisy two-year cycle. In addition to shedding light on the basic dynamics of some nonlinear biological systems, this work dramatizes how the scale on which data is collected and analysed can affect the conclusions drawn.

scholarly journals If we cannot eliminate them, should we tame them? Mathematics underpinning the dose effect of virus infection and its application on covid-19 virulence evolution

2021 ◽  
Author(s):  
Zhaobin Xu ◽  
Hongmei Zhang
Keyword(s):  
Virus Infection ◽  
Population Density ◽  
Turning Point ◽  
Host Population ◽  
Infection Process ◽  
Dose Effect ◽  
Sigmoid Function ◽  
Protection Measures ◽  
Inoculum Dose ◽  
Function Relationship

There is a dose effect in the infection process, that is, different initial virus invasion loads will lead to nonlinear changes in infection probability. Experiments already proved that there was a sigmoid functional relationship between virus infection probability and inoculum dose. By means of mathematical simulation of stochastic process, we theoretically demonstrate that there is a sigmoid function relationship between them. At the same time, our model found three factors that influence the severity of infection symptoms, those are virus toxicity, virus invasion dose and host immunity respectively. Therefore, the mortality rate cannot directly reflect the change of virus toxicity, but is the result of the comprehensive action of these three factors. Protective measures such as masks can effectively reduce the severity of infection while reducing the probability of infection. Based on the sigmoid function relationship between virus infection probability and initial virus invasion dose, we deduce that for highly infectious viruses, such as SARS-COV-2, the evolution of its toxicity is closely related to the host population density, and its toxicity will first increase and then decrease with the increase of host population density. That is to say, on the basis of extremely low host population density, increasing population density is beneficial to the development of virus towards strong toxicity. However, this trend is not sustainable, and there is a turning point of population density. Beyond this turning point, increasing population density will be beneficial to the development of virus towards weak toxicity. This theory can well explain the differences of mortality in Covid-19 in different countries. Countries with high population density and extremely low population density often correspond to lower mortality, while countries with population density in the range of 20-100/km2 often have higher mortality. At the same time, we propose that social distance and masks can effectively accelerate the evolution of virus towards low toxicity, so we should not give up simple and effective protection measures while emphasizing vaccination.

scholarly journals Larval densities of the protected Striped lychnis moth Shargacucullia lychnis (Lepidoptera: Noctuidae) in Buckinghamshire

2021 ◽  
Author(s):  
Juliano Morimoto ◽  
Lucy Kerr
Keyword(s):  
Natural History ◽  
Population Density ◽  
Developmental Stages ◽  
Larval Density ◽  
Natural Populations ◽  
Adaptive Responses ◽  
Larval Population ◽  
History Information ◽  
The Uk ◽  
Lepidoptera Noctuidae

Natural history information is essential for ecologically-relevant inferences about (adaptive) responses in organismal biology. Yet, natural history data can be difficult to obtain, particularly for the developmental stages of holometabolous insects. This gap can compromise our ability to design controlled experiments that provide useful understanding of insect responses to changing environments and precludes our ability to understand how natural populations may respond to unpredictable climatic changes in their natural environment. In this study, we collated data from previous reports from the Butterfly Conservation Upper Thames Branch on the larval population density of Shargacucullia lychnis (Lepidoptera: Noctuidae) in Buckinghamshire. In the UK, S. lychnis is a protected species, for which natural history information can be invaluable for its effective conservation. We report here that the natural range of larval densities observed for S. lychnis across locations and years is 0.001 to 6.417 larvae per spike. More importantly, S. lychnis larval density has overall declined from 1996 to 2020, which could support previous reports of a contraction in population range for this species. Overall, this study provides invaluable information about larval population density for an important protected Lepidopteran species of the UK.

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