Population Dynamics of Myzuspersicae (Sulzer) on Intercropping Potatoes with Other Plants on Karo Highland

Green peach aphid (MyzuspersicaeSulze) represents one of the major pest affecting decreased production which found in different potato fields in Karo highland. Decreasing incurredin two ways: the direct damages that are caused by the insectfeeding on the plants and the indirect damages caused to potato planting materials as a virus vector. There are different methods for controlling green peach aphids, all of them relying inthe use of chemicals and this method makes food production contaminated by pesticide residu. So, using non-chemical methods of cultivation contribute to “ecological” food production.Intercropping is one way of reducing pest insect populations in such vegetable crops.This study was conducted to determine the population dynamics of Myzuspersicae (Sulzer) on Intercropping system of potato plant with other vegetables plant on Karo Highland. The host plant was cultivar Granola of potato and the intercropping plant respectively were cabbage, mustard, celery, onions, carrot and bean. The results showed that M. persicae was consistently at different densities in different intercropping plant on potato. The aphid was first recorded at three week until planting. The kind of inter cropping culture plants significantly reduced the number of aphid. The lowest number of aphid found respectively inintercroppingpotatoesandmustard, potatoesandonions, andpotatoesandcelery. There was 0.80 aphids /leaf, 1,12aphids/leaf, 1,48 aphids/leaf. At the 2nd observation found the number of aphid was lowest atpolyculture potatoes and mustards were 1,68 aphid/leaf, at popatoes and onions were 3,28 aphid/leaf, at popatoes and celery 3,00 aphid/leaf. The number of aphids steadily increased with significant at differencesintercroppingplant till the 3rd observation (9 weeks until planting) respectively where 2,80aphid/leaf, 3,42 aphid / leaf and 4,20 aphid/leafwere recorded. Observation for natural enemies of M. persicaeshowed that fewnatural enemiesfound in theagro-ecosystem. There are Episyrphusbalteatus, Chrysoperlacarnea, phidiusmatricarieae and Coccinellaseptempunctata. The population density of all of the natural enemies was highest at polyculture than monoculture of potato. After that, as the population of M. persicae started decline, the same trend was followed by all of its natural enemies

Constrained distributed optimization : A population dynamics approach

Large-scale network systems involve a large number of states, which makes the design of real-time controllers a challenging task. A distributed controller design allows to reduce computational requirements since tasks are divided into different systems, allowing real-time processing. This paper proposes a novel methodology for solving constrained optimization problems in a distributed way inspired by population dynamics. This methodology consists of an extension of a population dynamics equation and the introduction of a mass dynamics equation. The proposed methodology divides the problem into smaller sub-problems, whose feasible regions vary over time achieving an agreement to solve the global problem. The methodology also guarantees attraction to the feasible region and allows to have few changes in the decision-making design when a network suffers the addition/removal of nodes/edges. Then, distributed controllers are designed with the proposed methodology and applied to the large-scale Barcelona Drinking Water Network (BDWN). Some simulations are presented and discussed in order to illustrate the control performance.Peer ReviewedPostprint (author's final draft

Population dynamics of Windermere perch

This paper looks briefly at some of the more recent analyses and interpretations of the changes that have occurred in the population dynamics of Windermere perch and at the present level of understanding. The long-term study has shown how flexible the population is and how it has behaved in different ways over successive periods of time since 1939. Through one of these periods it was possible to account for nearly all the variance in recruitment by a relatively simple explanatory model. The reduction in numbers on the outbreak of disease in 1976 started a natural experiment which will form a baseline for future studies

Particle Statistics and Population Dynamics

We study a master equation system modelling a population dynamics problem in a lattice. The problem is the calculation of the minimum size of a refuge that can protect a population from hostile external conditions, the so called critical patch size problem. We analize both cases in which the particles are considered fermions and bosons and show using exact analitical methods that, while the Fermi-Dirac statistics leads to certain extinction for any refuge size, the Bose-Eistein statistics allows survival even for the minimal refuge

Stochastic gain in population dynamics

We introduce an extension of the usual replicator dynamics to adaptive learning rates. We show that a population with a dynamic learning rate can gain an increased average payoff in transient phases and can also exploit external noise, leading the system away from the Nash equilibrium, in a reasonance-like fashion. The payoff versus noise curve resembles the signal to noise ratio curve in stochastic resonance. Seen in this broad context, we introduce another mechanism that exploits fluctuations in order to improve properties of the system. Such a mechanism could be of particular interest in economic systems.Comment: accepted for publication in Phys. Rev. Let

Discreteness Effects in Population Dynamics

We analyse numerically the effects of small population size in the initial transient regime of a simple example population dynamics. These effects play an important role for the numerical determination of large deviation functions of additive observables for stochastic processes. A method commonly used in order to determine such functions is the so-called cloning algorithm which in its non-constant population version essentially reduces to the determination of the growth rate of a population, averaged over many realizations of the dynamics. However, the averaging of populations is highly dependent not only on the number of realizations of the population dynamics, and on the initial population size but also on the cut-off time (or population) considered to stop their numerical evolution. This may result in an over-influence of discreteness effects at initial times, caused by small population size. We overcome these effects by introducing a (realization-dependent) time delay in the evolution of populations, additional to the discarding of the initial transient regime of the population growth where these discreteness effects are strong. We show that the improvement in the estimation of the large deviation function comes precisely from these two main contributions

Nonlinear Relaxation in Population Dynamics

We analyze the nonlinear relaxation of a complex ecosystem composed of many interacting species. The ecological system is described by generalized Lotka-Volterra equations with a multiplicative noise. The transient dynamics is studied in the framework of the mean field theory and with random interaction between the species. We focus on the statistical properties of the asymptotic behaviour of the time integral of the i-th population and on the distribution of the population and of the local field.Comment: 11 pages, 4 figures, in press in Int. Journal of Fractals (2001